src/third_party/WebKit/Source/core/paint/BoxPainter.cpp

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "config.h"
   6 #include "core/paint/BoxPainter.h"
   7
   8 #include "core/HTMLNames.h"
   9 #include "core/frame/Settings.h"
  10 #include "core/html/HTMLFrameOwnerElement.h"
  11 #include "core/paint/BackgroundImageGeometry.h"
  12 #include "core/paint/BoxDecorationData.h"
  13 #include "core/rendering/ImageQualityController.h"
  14 #include "core/rendering/PaintInfo.h"
  15 #include "core/rendering/RenderBox.h"
  16 #include "core/rendering/RenderBoxModelObject.h"
  17 #include "core/rendering/RenderLayer.h"
  18 #include "core/rendering/RenderObject.h"
  19 #include "core/rendering/RenderTable.h"
  20 #include "core/rendering/RenderTheme.h"
  21 #include "core/rendering/RenderView.h"
  22 #include "core/rendering/compositing/CompositedLayerMapping.h"
  23 #include "core/rendering/style/BorderEdge.h"
  24 #include "core/rendering/style/ShadowList.h"
  25 #include "platform/LengthFunctions.h"
  26 #include "platform/geometry/LayoutPoint.h"
  27 #include "platform/graphics/GraphicsContextStateSaver.h"
  28
  29 namespace blink {
  30
  31 void BoxPainter::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
  32 {
  33     LayoutPoint adjustedPaintOffset = paintOffset + m_renderBox.location();
  34     // default implementation. Just pass paint through to the children
  35     PaintInfo childInfo(paintInfo);
  36     childInfo.updatePaintingRootForChildren(&m_renderBox);
  37     for (RenderObject* child = m_renderBox.slowFirstChild(); child; child = child->nextSibling())
  38         child->paint(childInfo, adjustedPaintOffset);
  39 }
  40
  41 void BoxPainter::paintBoxDecorationBackground(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
  42 {
  43     if (!paintInfo.shouldPaintWithinRoot(&m_renderBox))
  44         return;
  45
  46     LayoutRect paintRect = m_renderBox.borderBoxRect();
  47     paintRect.moveBy(paintOffset);
  48     paintBoxDecorationBackgroundWithRect(paintInfo, paintOffset, paintRect);
  49 }
  50
  51 void BoxPainter::paintBoxDecorationBackgroundWithRect(PaintInfo& paintInfo, const LayoutPoint& paintOffset, const LayoutRect& paintRect)
  52 {
  53     RenderStyle* style = m_renderBox.style();
  54     BoxDecorationData boxDecorationData(*style, m_renderBox.canRenderBorderImage(), m_renderBox.backgroundHasOpaqueTopLayer(), paintInfo.context);
  55
  56     // FIXME: Should eventually give the theme control over whether the box shadow should paint, since controls could have
  57     // custom shadows of their own.
  58     if (!m_renderBox.boxShadowShouldBeAppliedToBackground(boxDecorationData.bleedAvoidance()))
  59         paintBoxShadow(paintInfo, paintRect, style, Normal);
  60
  61     GraphicsContextStateSaver stateSaver(*paintInfo.context, false);
  62     if (boxDecorationData.bleedAvoidance() == BackgroundBleedClipBackground) {
  63         stateSaver.save();
  64         RoundedRect border = style->getRoundedBorderFor(paintRect);
  65         paintInfo.context->clipRoundedRect(border);
  66     }
  67
  68     // If we have a native theme appearance, paint that before painting our background.
  69     // The theme will tell us whether or not we should also paint the CSS background.
  70     IntRect snappedPaintRect(pixelSnappedIntRect(paintRect));
  71     bool themePainted = boxDecorationData.hasAppearance && !RenderTheme::theme().paint(&m_renderBox, paintInfo, snappedPaintRect);
  72     if (!themePainted) {
  73         if (boxDecorationData.bleedAvoidance() == BackgroundBleedBackgroundOverBorder)
  74             paintBorder(m_renderBox, paintInfo, paintRect, style, boxDecorationData.bleedAvoidance());
  75
  76         paintBackground(paintInfo, paintRect, boxDecorationData.backgroundColor, boxDecorationData.bleedAvoidance());
  77
  78         if (boxDecorationData.hasAppearance)
  79             RenderTheme::theme().paintDecorations(&m_renderBox, paintInfo, snappedPaintRect);
  80     }
  81     paintBoxShadow(paintInfo, paintRect, style, Inset);
  82
  83     // The theme will tell us whether or not we should also paint the CSS border.
  84     if (boxDecorationData.hasBorder && boxDecorationData.bleedAvoidance() != BackgroundBleedBackgroundOverBorder
  85         && (!boxDecorationData.hasAppearance || (!themePainted && RenderTheme::theme().paintBorderOnly(&m_renderBox, paintInfo, snappedPaintRect)))
  86         && !(m_renderBox.isTable() && toRenderTable(&m_renderBox)->collapseBorders()))
  87         paintBorder(m_renderBox, paintInfo, paintRect, style, boxDecorationData.bleedAvoidance());
  88 }
  89
  90 static bool skipBodyBackground(const RenderBox* bodyElementRenderer)
  91 {
  92     ASSERT(bodyElementRenderer->isBody());
  93     // The <body> only paints its background if the root element has defined a background independent of the body,
  94     // or if the <body>'s parent is not the document element's renderer (e.g. inside SVG foreignObject).
  95     RenderObject* documentElementRenderer = bodyElementRenderer->document().documentElement()->renderer();
  96     return documentElementRenderer
  97         && !documentElementRenderer->hasBackground()
  98         && (documentElementRenderer == bodyElementRenderer->parent());
  99 }
 100
 101 void BoxPainter::paintBackground(const PaintInfo& paintInfo, const LayoutRect& paintRect, const Color& backgroundColor, BackgroundBleedAvoidance bleedAvoidance)
 102 {
 103     if (m_renderBox.isDocumentElement()) {
 104         paintRootBoxFillLayers(paintInfo);
 105         return;
 106     }
 107     if (m_renderBox.isBody() && skipBodyBackground(&m_renderBox))
 108         return;
 109     if (m_renderBox.boxDecorationBackgroundIsKnownToBeObscured())
 110         return;
 111     paintFillLayers(paintInfo, backgroundColor, m_renderBox.style()->backgroundLayers(), paintRect, bleedAvoidance);
 112 }
 113
 114 void BoxPainter::paintRootBoxFillLayers(const PaintInfo& paintInfo)
 115 {
 116     if (paintInfo.skipRootBackground())
 117         return;
 118
 119     RenderObject* rootBackgroundRenderer = m_renderBox.rendererForRootBackground();
 120
 121     const FillLayer& bgLayer = rootBackgroundRenderer->style()->backgroundLayers();
 122     Color bgColor = rootBackgroundRenderer->resolveColor(CSSPropertyBackgroundColor);
 123
 124     paintFillLayers(paintInfo, bgColor, bgLayer, m_renderBox.view()->backgroundRect(&m_renderBox), BackgroundBleedNone, CompositeSourceOver, rootBackgroundRenderer);
 125 }
 126
 127 void BoxPainter::paintFillLayers(const PaintInfo& paintInfo, const Color& c, const FillLayer& fillLayer, const LayoutRect& rect,
 128     BackgroundBleedAvoidance bleedAvoidance, CompositeOperator op, RenderObject* backgroundObject)
 129 {
 130     Vector<const FillLayer*, 8> layers;
 131     const FillLayer* curLayer = &fillLayer;
 132     bool shouldDrawBackgroundInSeparateBuffer = false;
 133     bool isBottomLayerOccluded = false;
 134     while (curLayer) {
 135         layers.append(curLayer);
 136         // Stop traversal when an opaque layer is encountered.
 137         // FIXME : It would be possible for the following occlusion culling test to be more aggressive
 138         // on layers with no repeat by testing whether the image covers the layout rect.
 139         // Testing that here would imply duplicating a lot of calculations that are currently done in
 140         // RenderBoxModelObject::paintFillLayerExtended. A more efficient solution might be to move
 141         // the layer recursion into paintFillLayerExtended, or to compute the layer geometry here
 142         // and pass it down.
 143
 144         if (!shouldDrawBackgroundInSeparateBuffer && curLayer->blendMode() != WebBlendModeNormal)
 145             shouldDrawBackgroundInSeparateBuffer = true;
 146
 147         // The clipOccludesNextLayers condition must be evaluated first to avoid short-circuiting.
 148         if (curLayer->clipOccludesNextLayers(curLayer == &fillLayer)
 149             && curLayer->hasOpaqueImage(&m_renderBox)
 150             && curLayer->image()->canRender(m_renderBox, m_renderBox.style()->effectiveZoom())
 151             && curLayer->hasRepeatXY()
 152             && curLayer->blendMode() == WebBlendModeNormal
 153             && !m_renderBox.boxShadowShouldBeAppliedToBackground(bleedAvoidance))
 154             break;
 155         curLayer = curLayer->next();
 156     }
 157
 158     if (layers.size() > 0  && (**layers.rbegin()).next())
 159         isBottomLayerOccluded = true;
 160
 161     GraphicsContext* context = paintInfo.context;
 162     if (!context)
 163         shouldDrawBackgroundInSeparateBuffer = false;
 164
 165     bool skipBaseColor = false;
 166     if (shouldDrawBackgroundInSeparateBuffer) {
 167         bool isBaseColorVisible = !isBottomLayerOccluded && c.hasAlpha();
 168
 169         // Paint the document's base background color outside the transparency layer,
 170         // so that the background images don't blend with this color: http://crbug.com/389039.
 171         if (isBaseColorVisible && isDocumentElementWithOpaqueBackground(m_renderBox)) {
 172             paintRootBackgroundColor(m_renderBox, paintInfo, rect, Color());
 173             skipBaseColor = true;
 174         }
 175         context->beginTransparencyLayer(1);
 176     }
 177
 178     Vector<const FillLayer*>::const_reverse_iterator topLayer = layers.rend();
 179     for (Vector<const FillLayer*>::const_reverse_iterator it = layers.rbegin(); it != topLayer; ++it)
 180         paintFillLayer(paintInfo, c, **it, rect, bleedAvoidance, op, backgroundObject, skipBaseColor);
 181
 182     if (shouldDrawBackgroundInSeparateBuffer)
 183         context->endLayer();
 184 }
 185
 186 void BoxPainter::paintFillLayer(const PaintInfo& paintInfo, const Color& c, const FillLayer& fillLayer, const LayoutRect& rect,
 187     BackgroundBleedAvoidance bleedAvoidance, CompositeOperator op, RenderObject* backgroundObject, bool skipBaseColor)
 188 {
 189     BoxPainter::paintFillLayerExtended(m_renderBox, paintInfo, c, fillLayer, rect, bleedAvoidance, 0, LayoutSize(), op, backgroundObject, skipBaseColor);
 190 }
 191
 192 void BoxPainter::applyBoxShadowForBackground(GraphicsContext* context, RenderObject& obj)
 193 {
 194     const ShadowList* shadowList = obj.style()->boxShadow();
 195     ASSERT(shadowList);
 196     for (size_t i = shadowList->shadows().size(); i--; ) {
 197         const ShadowData& boxShadow = shadowList->shadows()[i];
 198         if (boxShadow.style() != Normal)
 199             continue;
 200         FloatSize shadowOffset(boxShadow.x(), boxShadow.y());
 201         context->setShadow(shadowOffset, boxShadow.blur(), boxShadow.color(),
 202             DrawLooperBuilder::ShadowRespectsTransforms, DrawLooperBuilder::ShadowIgnoresAlpha);
 203         return;
 204     }
 205 }
 206
 207 // FIXME: See crbug.com/382491. The use of getCTM in this context is incorrect because the matrix returned does not
 208 // include scales applied at raster time, such as the device zoom.
 209 static LayoutRect shrinkRectByOnePixel(GraphicsContext* context, const LayoutRect& rect)
 210 {
 211     LayoutRect shrunkRect = rect;
 212     AffineTransform transform = context->getCTM();
 213     shrunkRect.inflateX(-static_cast<LayoutUnit>(ceil(1 / transform.xScale())));
 214     shrunkRect.inflateY(-static_cast<LayoutUnit>(ceil(1 / transform.yScale())));
 215     return shrunkRect;
 216 }
 217
 218 RoundedRect BoxPainter::getBackgroundRoundedRect(RenderObject& obj, const LayoutRect& borderRect, InlineFlowBox* box, LayoutUnit inlineBoxWidth, LayoutUnit inlineBoxHeight,
 219     bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
 220 {
 221     RoundedRect border = obj.style()->getRoundedBorderFor(borderRect, includeLogicalLeftEdge, includeLogicalRightEdge);
 222     if (box && (box->nextLineBox() || box->prevLineBox())) {
 223         RoundedRect segmentBorder = obj.style()->getRoundedBorderFor(LayoutRect(0, 0, inlineBoxWidth, inlineBoxHeight), includeLogicalLeftEdge, includeLogicalRightEdge);
 224         border.setRadii(segmentBorder.radii());
 225     }
 226
 227     return border;
 228 }
 229
 230 RoundedRect BoxPainter::backgroundRoundedRectAdjustedForBleedAvoidance(RenderObject& obj, GraphicsContext* context, const LayoutRect& borderRect, BackgroundBleedAvoidance bleedAvoidance, InlineFlowBox* box, const LayoutSize& boxSize, bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
 231 {
 232     if (bleedAvoidance == BackgroundBleedShrinkBackground) {
 233         // We shrink the rectangle by one pixel on each side because the bleed is one pixel maximum.
 234         return BoxPainter::getBackgroundRoundedRect(obj, shrinkRectByOnePixel(context, borderRect), box, boxSize.width(), boxSize.height(), includeLogicalLeftEdge, includeLogicalRightEdge);
 235     }
 236     if (bleedAvoidance == BackgroundBleedBackgroundOverBorder)
 237         return obj.style()->getRoundedInnerBorderFor(borderRect, includeLogicalLeftEdge, includeLogicalRightEdge);
 238
 239     return BoxPainter::getBackgroundRoundedRect(obj, borderRect, box, boxSize.width(), boxSize.height(), includeLogicalLeftEdge, includeLogicalRightEdge);
 240 }
 241
 242 void BoxPainter::clipRoundedInnerRect(GraphicsContext * context, const LayoutRect& rect, const RoundedRect& clipRect)
 243 {
 244     if (clipRect.isRenderable()) {
 245         context->clipRoundedRect(clipRect);
 246     } else {
 247         // We create a rounded rect for each of the corners and clip it, while making sure we clip opposing corners together.
 248         if (!clipRect.radii().topLeft().isEmpty() || !clipRect.radii().bottomRight().isEmpty()) {
 249             IntRect topCorner(clipRect.rect().x(), clipRect.rect().y(), rect.maxX() - clipRect.rect().x(), rect.maxY() - clipRect.rect().y());
 250             RoundedRect::Radii topCornerRadii;
 251             topCornerRadii.setTopLeft(clipRect.radii().topLeft());
 252             context->clipRoundedRect(RoundedRect(topCorner, topCornerRadii));
 253
 254             IntRect bottomCorner(rect.x(), rect.y(), clipRect.rect().maxX() - rect.x(), clipRect.rect().maxY() - rect.y());
 255             RoundedRect::Radii bottomCornerRadii;
 256             bottomCornerRadii.setBottomRight(clipRect.radii().bottomRight());
 257             context->clipRoundedRect(RoundedRect(bottomCorner, bottomCornerRadii));
 258         }
 259
 260         if (!clipRect.radii().topRight().isEmpty() || !clipRect.radii().bottomLeft().isEmpty()) {
 261             IntRect topCorner(rect.x(), clipRect.rect().y(), clipRect.rect().maxX() - rect.x(), rect.maxY() - clipRect.rect().y());
 262             RoundedRect::Radii topCornerRadii;
 263             topCornerRadii.setTopRight(clipRect.radii().topRight());
 264             context->clipRoundedRect(RoundedRect(topCorner, topCornerRadii));
 265
 266             IntRect bottomCorner(clipRect.rect().x(), rect.y(), rect.maxX() - clipRect.rect().x(), clipRect.rect().maxY() - rect.y());
 267             RoundedRect::Radii bottomCornerRadii;
 268             bottomCornerRadii.setBottomLeft(clipRect.radii().bottomLeft());
 269             context->clipRoundedRect(RoundedRect(bottomCorner, bottomCornerRadii));
 270         }
 271     }
 272 }
 273
 274 void BoxPainter::paintFillLayerExtended(RenderBoxModelObject& obj, const PaintInfo& paintInfo, const Color& color, const FillLayer& bgLayer, const LayoutRect& rect,
 275     BackgroundBleedAvoidance bleedAvoidance, InlineFlowBox* box, const LayoutSize& boxSize, CompositeOperator op, RenderObject* backgroundObject, bool skipBaseColor)
 276 {
 277     GraphicsContext* context = paintInfo.context;
 278     if (rect.isEmpty())
 279         return;
 280
 281     bool includeLeftEdge = box ? box->includeLogicalLeftEdge() : true;
 282     bool includeRightEdge = box ? box->includeLogicalRightEdge() : true;
 283
 284     bool hasRoundedBorder = obj.style()->hasBorderRadius() && (includeLeftEdge || includeRightEdge);
 285     bool clippedWithLocalScrolling = obj.hasOverflowClip() && bgLayer.attachment() == LocalBackgroundAttachment;
 286     bool isBorderFill = bgLayer.clip() == BorderFillBox;
 287     bool isDocumentElementRenderer = obj.isDocumentElement();
 288     bool isBottomLayer = !bgLayer.next();
 289
 290     Color bgColor = color;
 291     StyleImage* bgImage = bgLayer.image();
 292     bool shouldPaintBackgroundImage = bgImage && bgImage->canRender(obj, obj.style()->effectiveZoom());
 293
 294     bool forceBackgroundToWhite = false;
 295     if (obj.document().printing()) {
 296         if (obj.style()->printColorAdjust() == PrintColorAdjustEconomy)
 297             forceBackgroundToWhite = true;
 298         if (obj.document().settings() && obj.document().settings()->shouldPrintBackgrounds())
 299             forceBackgroundToWhite = false;
 300     }
 301
 302     // When printing backgrounds is disabled or using economy mode,
 303     // change existing background colors and images to a solid white background.
 304     // If there's no bg color or image, leave it untouched to avoid affecting transparency.
 305     // We don't try to avoid loading the background images, because this style flag is only set
 306     // when printing, and at that point we've already loaded the background images anyway. (To avoid
 307     // loading the background images we'd have to do this check when applying styles rather than
 308     // while rendering.)
 309     if (forceBackgroundToWhite) {
 310         // Note that we can't reuse this variable below because the bgColor might be changed
 311         bool shouldPaintBackgroundColor = isBottomLayer && bgColor.alpha();
 312         if (shouldPaintBackgroundImage || shouldPaintBackgroundColor) {
 313             bgColor = Color::white;
 314             shouldPaintBackgroundImage = false;
 315         }
 316     }
 317
 318     bool colorVisible = bgColor.alpha();
 319
 320     // Fast path for drawing simple color backgrounds.
 321     if (!isDocumentElementRenderer && !clippedWithLocalScrolling && !shouldPaintBackgroundImage && isBorderFill && isBottomLayer) {
 322         if (!colorVisible)
 323             return;
 324
 325         bool boxShadowShouldBeAppliedToBackground = obj.boxShadowShouldBeAppliedToBackground(bleedAvoidance, box);
 326         GraphicsContextStateSaver shadowStateSaver(*context, boxShadowShouldBeAppliedToBackground);
 327         if (boxShadowShouldBeAppliedToBackground)
 328             BoxPainter::applyBoxShadowForBackground(context, obj);
 329
 330         if (hasRoundedBorder && bleedAvoidance != BackgroundBleedClipBackground) {
 331             RoundedRect border = backgroundRoundedRectAdjustedForBleedAvoidance(obj, context, rect, bleedAvoidance, box, boxSize, includeLeftEdge, includeRightEdge);
 332             if (border.isRenderable()) {
 333                 context->fillRoundedRect(border, bgColor);
 334             } else {
 335                 context->save();
 336                 clipRoundedInnerRect(context, rect, border);
 337                 context->fillRect(border.rect(), bgColor);
 338                 context->restore();
 339             }
 340         } else {
 341             context->fillRect(pixelSnappedIntRect(rect), bgColor);
 342         }
 343
 344         return;
 345     }
 346
 347     // BorderFillBox radius clipping is taken care of by BackgroundBleedClipBackground
 348     bool clipToBorderRadius = hasRoundedBorder && !(isBorderFill && bleedAvoidance == BackgroundBleedClipBackground);
 349     GraphicsContextStateSaver clipToBorderStateSaver(*context, clipToBorderRadius);
 350     if (clipToBorderRadius) {
 351         RoundedRect border = isBorderFill ? backgroundRoundedRectAdjustedForBleedAvoidance(obj, context, rect, bleedAvoidance, box, boxSize, includeLeftEdge, includeRightEdge) : getBackgroundRoundedRect(obj, rect, box, boxSize.width(), boxSize.height(), includeLeftEdge, includeRightEdge);
 352
 353         // Clip to the padding or content boxes as necessary.
 354         if (bgLayer.clip() == ContentFillBox) {
 355             border = obj.style()->getRoundedInnerBorderFor(border.rect(),
 356                 obj.paddingTop() + obj.borderTop(), obj.paddingBottom() + obj.borderBottom(),
 357                 obj.paddingLeft() + obj.borderLeft(), obj.paddingRight() + obj.borderRight(), includeLeftEdge, includeRightEdge);
 358         } else if (bgLayer.clip() == PaddingFillBox) {
 359             border = obj.style()->getRoundedInnerBorderFor(border.rect(), includeLeftEdge, includeRightEdge);
 360         }
 361
 362         clipRoundedInnerRect(context, rect, border);
 363     }
 364
 365     int bLeft = includeLeftEdge ? obj.borderLeft() : 0;
 366     int bRight = includeRightEdge ? obj.borderRight() : 0;
 367     LayoutUnit pLeft = includeLeftEdge ? obj.paddingLeft() : LayoutUnit();
 368     LayoutUnit pRight = includeRightEdge ? obj.paddingRight() : LayoutUnit();
 369
 370     GraphicsContextStateSaver clipWithScrollingStateSaver(*context, clippedWithLocalScrolling);
 371     LayoutRect scrolledPaintRect = rect;
 372     if (clippedWithLocalScrolling) {
 373         // Clip to the overflow area.
 374         RenderBox* thisBox = toRenderBox(&obj);
 375         context->clip(thisBox->overflowClipRect(rect.location()));
 376
 377         // Adjust the paint rect to reflect a scrolled content box with borders at the ends.
 378         IntSize offset = thisBox->scrolledContentOffset();
 379         scrolledPaintRect.move(-offset);
 380         scrolledPaintRect.setWidth(bLeft + thisBox->scrollWidth() + bRight);
 381         scrolledPaintRect.setHeight(thisBox->borderTop() + thisBox->scrollHeight() + thisBox->borderBottom());
 382     }
 383
 384     GraphicsContextStateSaver backgroundClipStateSaver(*context, false);
 385     IntRect maskRect;
 386
 387     switch (bgLayer.clip()) {
 388     case PaddingFillBox:
 389     case ContentFillBox: {
 390         if (clipToBorderRadius)
 391             break;
 392
 393         // Clip to the padding or content boxes as necessary.
 394         bool includePadding = bgLayer.clip() == ContentFillBox;
 395         LayoutRect clipRect = LayoutRect(scrolledPaintRect.x() + bLeft + (includePadding ? pLeft : LayoutUnit()),
 396             scrolledPaintRect.y() + obj.borderTop() + (includePadding ? obj.paddingTop() : LayoutUnit()),
 397             scrolledPaintRect.width() - bLeft - bRight - (includePadding ? pLeft + pRight : LayoutUnit()),
 398             scrolledPaintRect.height() - obj.borderTop() - obj.borderBottom() - (includePadding ? obj.paddingTop() + obj.paddingBottom() : LayoutUnit()));
 399         backgroundClipStateSaver.save();
 400         context->clip(clipRect);
 401
 402         break;
 403     }
 404     case TextFillBox: {
 405         // First figure out how big the mask has to be. It should be no bigger than what we need
 406         // to actually render, so we should intersect the dirty rect with the border box of the background.
 407         maskRect = pixelSnappedIntRect(rect);
 408         maskRect.intersect(paintInfo.rect);
 409
 410         // We draw the background into a separate layer, to be later masked with yet another layer
 411         // holding the text content.
 412         backgroundClipStateSaver.save();
 413         context->clip(maskRect);
 414         context->beginTransparencyLayer(1);
 415
 416         break;
 417     }
 418     case BorderFillBox:
 419         break;
 420     default:
 421         ASSERT_NOT_REACHED();
 422         break;
 423     }
 424
 425     // Paint the color first underneath all images, culled if background image occludes it.
 426     // FIXME: In the bgLayer->hasFiniteBounds() case, we could improve the culling test
 427     // by verifying whether the background image covers the entire layout rect.
 428     if (isBottomLayer) {
 429         IntRect backgroundRect(pixelSnappedIntRect(scrolledPaintRect));
 430         bool boxShadowShouldBeAppliedToBackground = obj.boxShadowShouldBeAppliedToBackground(bleedAvoidance, box);
 431         bool isOpaqueRoot = (isDocumentElementRenderer && !bgColor.hasAlpha()) || isDocumentElementWithOpaqueBackground(obj);
 432         if (boxShadowShouldBeAppliedToBackground || !shouldPaintBackgroundImage || !bgLayer.hasOpaqueImage(&obj) || !bgLayer.hasRepeatXY() || (isOpaqueRoot && !toRenderBox(&obj)->height()))  {
 433             if (!boxShadowShouldBeAppliedToBackground)
 434                 backgroundRect.intersect(paintInfo.rect);
 435
 436             GraphicsContextStateSaver shadowStateSaver(*context, boxShadowShouldBeAppliedToBackground);
 437             if (boxShadowShouldBeAppliedToBackground)
 438                 BoxPainter::applyBoxShadowForBackground(context, obj);
 439
 440             if (isOpaqueRoot && !skipBaseColor) {
 441                 paintRootBackgroundColor(obj, paintInfo, rect, bgColor);
 442             } else if (bgColor.alpha()) {
 443                 context->fillRect(backgroundRect, bgColor, context->compositeOperation());
 444             }
 445         }
 446     }
 447
 448     // no progressive loading of the background image
 449     if (shouldPaintBackgroundImage) {
 450         BackgroundImageGeometry geometry;
 451         calculateBackgroundImageGeometry(obj, paintInfo.paintContainer(), bgLayer, scrolledPaintRect, geometry, backgroundObject);
 452         if (!geometry.destRect().isEmpty()) {
 453             CompositeOperator compositeOp = op == CompositeSourceOver ? bgLayer.composite() : op;
 454             RenderObject* clientForBackgroundImage = backgroundObject ? backgroundObject : &obj;
 455             RefPtr<Image> image = bgImage->image(clientForBackgroundImage, geometry.tileSize());
 456             InterpolationQuality interpolationQuality = chooseInterpolationQuality(obj, context, image.get(), &bgLayer, geometry.tileSize());
 457             if (bgLayer.maskSourceType() == MaskLuminance)
 458                 context->setColorFilter(ColorFilterLuminanceToAlpha);
 459             InterpolationQuality previousInterpolationQuality = context->imageInterpolationQuality();
 460             context->setImageInterpolationQuality(interpolationQuality);
 461             context->drawTiledImage(image.get(), geometry.destRect(), geometry.relativePhase(), geometry.tileSize(),
 462                 compositeOp, bgLayer.blendMode(), geometry.spaceSize());
 463             context->setImageInterpolationQuality(previousInterpolationQuality);
 464         }
 465     }
 466
 467     if (bgLayer.clip() == TextFillBox) {
 468         // Create the text mask layer.
 469         context->setCompositeOperation(CompositeDestinationIn);
 470         context->beginTransparencyLayer(1);
 471
 472         // FIXME: Workaround for https://code.google.com/p/skia/issues/detail?id=1291.
 473         context->clearRect(maskRect);
 474
 475         // Now draw the text into the mask. We do this by painting using a special paint phase that signals to
 476         // InlineTextBoxes that they should just add their contents to the clip.
 477         PaintInfo info(context, maskRect, PaintPhaseTextClip, PaintBehaviorForceBlackText, 0);
 478         context->setCompositeOperation(CompositeSourceOver);
 479         if (box) {
 480             RootInlineBox& root = box->root();
 481             box->paint(info, LayoutPoint(scrolledPaintRect.x() - box->x(), scrolledPaintRect.y() - box->y()), root.lineTop(), root.lineBottom());
 482         } else {
 483             LayoutSize localOffset = obj.isBox() ? toRenderBox(&obj)->locationOffset() : LayoutSize();
 484             obj.paint(info, scrolledPaintRect.location() - localOffset);
 485         }
 486
 487         context->endLayer();
 488         context->endLayer();
 489     }
 490 }
 491
 492 void BoxPainter::paintMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 493 {
 494     if (!paintInfo.shouldPaintWithinRoot(&m_renderBox) || m_renderBox.style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseMask)
 495         return;
 496
 497     LayoutRect paintRect = LayoutRect(paintOffset, m_renderBox.size());
 498     paintMaskImages(paintInfo, paintRect);
 499 }
 500
 501 void BoxPainter::paintMaskImages(const PaintInfo& paintInfo, const LayoutRect& paintRect)
 502 {
 503     // Figure out if we need to push a transparency layer to render our mask.
 504     bool pushTransparencyLayer = false;
 505     bool compositedMask = m_renderBox.hasLayer() && m_renderBox.layer()->hasCompositedMask();
 506     bool flattenCompositingLayers = m_renderBox.view()->frameView() && m_renderBox.view()->frameView()->paintBehavior() & PaintBehaviorFlattenCompositingLayers;
 507     CompositeOperator compositeOp = CompositeSourceOver;
 508
 509     bool allMaskImagesLoaded = true;
 510
 511     if (!compositedMask || flattenCompositingLayers) {
 512         pushTransparencyLayer = true;
 513         StyleImage* maskBoxImage = m_renderBox.style()->maskBoxImage().image();
 514         const FillLayer& maskLayers = m_renderBox.style()->maskLayers();
 515
 516         // Don't render a masked element until all the mask images have loaded, to prevent a flash of unmasked content.
 517         if (maskBoxImage)
 518             allMaskImagesLoaded &= maskBoxImage->isLoaded();
 519
 520         allMaskImagesLoaded &= maskLayers.imagesAreLoaded();
 521
 522         paintInfo.context->setCompositeOperation(CompositeDestinationIn);
 523         paintInfo.context->beginTransparencyLayer(1);
 524         compositeOp = CompositeSourceOver;
 525     }
 526
 527     if (allMaskImagesLoaded) {
 528         paintFillLayers(paintInfo, Color::transparent, m_renderBox.style()->maskLayers(), paintRect, BackgroundBleedNone, compositeOp);
 529         paintNinePieceImage(m_renderBox, paintInfo.context, paintRect, m_renderBox.style(), m_renderBox.style()->maskBoxImage(), compositeOp);
 530     }
 531
 532     if (pushTransparencyLayer)
 533         paintInfo.context->endLayer();
 534 }
 535
 536 void BoxPainter::paintClippingMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 537 {
 538     if (!paintInfo.shouldPaintWithinRoot(&m_renderBox) || m_renderBox.style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseClippingMask)
 539         return;
 540
 541     if (!m_renderBox.layer() || m_renderBox.layer()->compositingState() != PaintsIntoOwnBacking)
 542         return;
 543
 544     // We should never have this state in this function. A layer with a mask
 545     // should have always created its own backing if it became composited.
 546     ASSERT(m_renderBox.layer()->compositingState() != HasOwnBackingButPaintsIntoAncestor);
 547
 548     LayoutRect paintRect = LayoutRect(paintOffset, m_renderBox.size());
 549     paintInfo.context->fillRect(pixelSnappedIntRect(paintRect), Color::black);
 550 }
 551
 552 void BoxPainter::paintRootBackgroundColor(RenderObject& obj, const PaintInfo& paintInfo, const LayoutRect& rect, const Color& bgColor)
 553 {
 554     GraphicsContext* context = paintInfo.context;
 555     if (rect.isEmpty())
 556         return;
 557
 558     ASSERT(obj.isDocumentElement());
 559
 560     IntRect backgroundRect(pixelSnappedIntRect(rect));
 561     backgroundRect.intersect(paintInfo.rect);
 562
 563     Color baseColor = obj.view()->frameView()->baseBackgroundColor();
 564     bool shouldClearDocumentBackground = obj.document().settings() && obj.document().settings()->shouldClearDocumentBackground();
 565     CompositeOperator operation = shouldClearDocumentBackground ? CompositeCopy : context->compositeOperation();
 566
 567     // If we have an alpha go ahead and blend with the base background color.
 568     if (baseColor.alpha()) {
 569         if (bgColor.alpha())
 570             baseColor = baseColor.blend(bgColor);
 571         context->fillRect(backgroundRect, baseColor, operation);
 572     } else if (bgColor.alpha()) {
 573         context->fillRect(backgroundRect, bgColor, operation);
 574     } else if (shouldClearDocumentBackground) {
 575         context->clearRect(backgroundRect);
 576     }
 577 }
 578
 579 bool BoxPainter::isDocumentElementWithOpaqueBackground(RenderObject& obj)
 580 {
 581     if (!obj.isDocumentElement())
 582         return false;
 583
 584     // The background is opaque only if we're the root document, since iframes with
 585     // no background in the child document should show the parent's background.
 586     bool isOpaque = true;
 587     Element* ownerElement = obj.document().ownerElement();
 588     if (ownerElement) {
 589         if (!isHTMLFrameElement(*ownerElement)) {
 590             // Locate the <body> element using the DOM. This is easier than trying
 591             // to crawl around a render tree with potential :before/:after content and
 592             // anonymous blocks created by inline <body> tags etc. We can locate the <body>
 593             // render object very easily via the DOM.
 594             HTMLElement* body = obj.document().body();
 595             if (body) {
 596                 // Can't scroll a frameset document anyway.
 597                 isOpaque = body->hasTagName(HTMLNames::framesetTag);
 598             } else {
 599                 // FIXME: SVG specific behavior should be in the SVG code.
 600                 // SVG documents and XML documents with SVG root nodes are transparent.
 601                 isOpaque = !obj.document().hasSVGRootNode();
 602             }
 603         }
 604     } else if (obj.view()->frameView()) {
 605         isOpaque = !obj.view()->frameView()->isTransparent();
 606     }
 607
 608     return isOpaque;
 609 }
 610
 611 static inline int getSpace(int areaSize, int tileSize)
 612 {
 613     int numberOfTiles = areaSize / tileSize;
 614     int space = -1;
 615
 616     if (numberOfTiles > 1)
 617         space = lroundf((float)(areaSize - numberOfTiles * tileSize) / (numberOfTiles - 1));
 618
 619     return space;
 620 }
 621
 622 void BoxPainter::calculateBackgroundImageGeometry(RenderBoxModelObject& obj, const RenderLayerModelObject* paintContainer, const FillLayer& fillLayer, const LayoutRect& paintRect,
 623     BackgroundImageGeometry& geometry, RenderObject* backgroundObject)
 624 {
 625     LayoutUnit left = 0;
 626     LayoutUnit top = 0;
 627     IntSize positioningAreaSize;
 628     IntRect snappedPaintRect = pixelSnappedIntRect(paintRect);
 629
 630     // Determine the background positioning area and set destRect to the background painting area.
 631     // destRect will be adjusted later if the background is non-repeating.
 632     // FIXME: transforms spec says that fixed backgrounds behave like scroll inside transforms.
 633     bool fixedAttachment = fillLayer.attachment() == FixedBackgroundAttachment;
 634
 635     if (RuntimeEnabledFeatures::fastMobileScrollingEnabled()) {
 636         // As a side effect of an optimization to blit on scroll, we do not honor the CSS
 637         // property "background-attachment: fixed" because it may result in rendering
 638         // artifacts. Note, these artifacts only appear if we are blitting on scroll of
 639         // a page that has fixed background images.
 640         fixedAttachment = false;
 641     }
 642
 643     if (!fixedAttachment) {
 644         geometry.setDestRect(snappedPaintRect);
 645
 646         LayoutUnit right = 0;
 647         LayoutUnit bottom = 0;
 648         // Scroll and Local.
 649         if (fillLayer.origin() != BorderFillBox) {
 650             left = obj.borderLeft();
 651             right = obj.borderRight();
 652             top = obj.borderTop();
 653             bottom = obj.borderBottom();
 654             if (fillLayer.origin() == ContentFillBox) {
 655                 left += obj.paddingLeft();
 656                 right += obj.paddingRight();
 657                 top += obj.paddingTop();
 658                 bottom += obj.paddingBottom();
 659             }
 660         }
 661
 662         // The background of the box generated by the root element covers the entire canvas including
 663         // its margins. Since those were added in already, we have to factor them out when computing
 664         // the background positioning area.
 665         if (obj.isDocumentElement()) {
 666             positioningAreaSize = pixelSnappedIntSize(toRenderBox(&obj)->size() - LayoutSize(left + right, top + bottom), toRenderBox(&obj)->location());
 667             left += obj.marginLeft();
 668             top += obj.marginTop();
 669         } else {
 670             positioningAreaSize = pixelSnappedIntSize(paintRect.size() - LayoutSize(left + right, top + bottom), paintRect.location());
 671         }
 672     } else {
 673         geometry.setHasNonLocalGeometry();
 674
 675         IntRect viewportRect = pixelSnappedIntRect(obj.viewRect());
 676         if (fixedBackgroundPaintsInLocalCoordinates(obj))
 677             viewportRect.setLocation(IntPoint());
 678         else if (FrameView* frameView = obj.view()->frameView())
 679             viewportRect.setLocation(IntPoint(frameView->scrollOffsetForFixedPosition()));
 680
 681         if (paintContainer) {
 682             IntPoint absoluteContainerOffset = roundedIntPoint(paintContainer->localToAbsolute(FloatPoint()));
 683             viewportRect.moveBy(-absoluteContainerOffset);
 684         }
 685
 686         geometry.setDestRect(pixelSnappedIntRect(viewportRect));
 687         positioningAreaSize = geometry.destRect().size();
 688     }
 689
 690     const RenderObject* clientForBackgroundImage = backgroundObject ? backgroundObject : &obj;
 691     IntSize fillTileSize = calculateFillTileSize(obj, fillLayer, positioningAreaSize);
 692     fillLayer.image()->setContainerSizeForRenderer(clientForBackgroundImage, fillTileSize, obj.style()->effectiveZoom());
 693     geometry.setTileSize(fillTileSize);
 694
 695     EFillRepeat backgroundRepeatX = fillLayer.repeatX();
 696     EFillRepeat backgroundRepeatY = fillLayer.repeatY();
 697     int availableWidth = positioningAreaSize.width() - geometry.tileSize().width();
 698     int availableHeight = positioningAreaSize.height() - geometry.tileSize().height();
 699
 700     LayoutUnit computedXPosition = roundedMinimumValueForLength(fillLayer.xPosition(), availableWidth);
 701     if (backgroundRepeatX == RoundFill && positioningAreaSize.width() > 0 && fillTileSize.width() > 0) {
 702         long nrTiles = std::max(1l, lroundf((float)positioningAreaSize.width() / fillTileSize.width()));
 703
 704         if (fillLayer.size().size.height().isAuto() && backgroundRepeatY != RoundFill) {
 705             fillTileSize.setHeight(fillTileSize.height() * positioningAreaSize.width() / (nrTiles * fillTileSize.width()));
 706         }
 707
 708         fillTileSize.setWidth(positioningAreaSize.width() / nrTiles);
 709         geometry.setTileSize(fillTileSize);
 710         geometry.setPhaseX(geometry.tileSize().width() ? geometry.tileSize().width() - roundToInt(computedXPosition + left) % geometry.tileSize().width() : 0);
 711         geometry.setSpaceSize(IntSize());
 712     }
 713
 714     LayoutUnit computedYPosition = roundedMinimumValueForLength(fillLayer.yPosition(), availableHeight);
 715     if (backgroundRepeatY == RoundFill && positioningAreaSize.height() > 0 && fillTileSize.height() > 0) {
 716         long nrTiles = std::max(1l, lroundf((float)positioningAreaSize.height() / fillTileSize.height()));
 717
 718         if (fillLayer.size().size.width().isAuto() && backgroundRepeatX != RoundFill) {
 719             fillTileSize.setWidth(fillTileSize.width() * positioningAreaSize.height() / (nrTiles * fillTileSize.height()));
 720         }
 721
 722         fillTileSize.setHeight(positioningAreaSize.height() / nrTiles);
 723         geometry.setTileSize(fillTileSize);
 724         geometry.setPhaseY(geometry.tileSize().height() ? geometry.tileSize().height() - roundToInt(computedYPosition + top) % geometry.tileSize().height() : 0);
 725         geometry.setSpaceSize(IntSize());
 726     }
 727
 728     if (backgroundRepeatX == RepeatFill) {
 729         geometry.setPhaseX(geometry.tileSize().width() ? geometry.tileSize().width() - roundToInt(computedXPosition + left) % geometry.tileSize().width() : 0);
 730         geometry.setSpaceSize(IntSize());
 731     } else if (backgroundRepeatX == SpaceFill && fillTileSize.width() > 0) {
 732         int space = getSpace(positioningAreaSize.width(), geometry.tileSize().width());
 733         int actualWidth = geometry.tileSize().width() + space;
 734
 735         if (space >= 0) {
 736             computedXPosition = roundedMinimumValueForLength(Length(), availableWidth);
 737             geometry.setSpaceSize(IntSize(space, 0));
 738             geometry.setPhaseX(actualWidth ? actualWidth - roundToInt(computedXPosition + left) % actualWidth : 0);
 739         } else {
 740             backgroundRepeatX = NoRepeatFill;
 741         }
 742     }
 743     if (backgroundRepeatX == NoRepeatFill) {
 744         int xOffset = fillLayer.backgroundXOrigin() == RightEdge ? availableWidth - computedXPosition : computedXPosition;
 745         geometry.setNoRepeatX(left + xOffset);
 746         geometry.setSpaceSize(IntSize(0, geometry.spaceSize().height()));
 747     }
 748
 749     if (backgroundRepeatY == RepeatFill) {
 750         geometry.setPhaseY(geometry.tileSize().height() ? geometry.tileSize().height() - roundToInt(computedYPosition + top) % geometry.tileSize().height() : 0);
 751         geometry.setSpaceSize(IntSize(geometry.spaceSize().width(), 0));
 752     } else if (backgroundRepeatY == SpaceFill && fillTileSize.height() > 0) {
 753         int space = getSpace(positioningAreaSize.height(), geometry.tileSize().height());
 754         int actualHeight = geometry.tileSize().height() + space;
 755
 756         if (space >= 0) {
 757             computedYPosition = roundedMinimumValueForLength(Length(), availableHeight);
 758             geometry.setSpaceSize(IntSize(geometry.spaceSize().width(), space));
 759             geometry.setPhaseY(actualHeight ? actualHeight - roundToInt(computedYPosition + top) % actualHeight : 0);
 760         } else {
 761             backgroundRepeatY = NoRepeatFill;
 762         }
 763     }
 764     if (backgroundRepeatY == NoRepeatFill) {
 765         int yOffset = fillLayer.backgroundYOrigin() == BottomEdge ? availableHeight - computedYPosition : computedYPosition;
 766         geometry.setNoRepeatY(top + yOffset);
 767         geometry.setSpaceSize(IntSize(geometry.spaceSize().width(), 0));
 768     }
 769
 770     if (fixedAttachment)
 771         geometry.useFixedAttachment(snappedPaintRect.location());
 772
 773     geometry.clip(snappedPaintRect);
 774     geometry.setDestOrigin(geometry.destRect().location());
 775 }
 776
 777 InterpolationQuality BoxPainter::chooseInterpolationQuality(RenderBoxModelObject& obj, GraphicsContext* context, Image* image, const void* layer, const LayoutSize& size)
 778 {
 779     return ImageQualityController::imageQualityController()->chooseInterpolationQuality(context, &obj, image, layer, size);
 780 }
 781
 782 bool BoxPainter::fixedBackgroundPaintsInLocalCoordinates(const RenderObject& obj)
 783 {
 784     if (!obj.isDocumentElement())
 785         return false;
 786
 787     if (obj.view()->frameView() && obj.view()->frameView()->paintBehavior() & PaintBehaviorFlattenCompositingLayers)
 788         return false;
 789
 790     RenderLayer* rootLayer = obj.view()->layer();
 791     if (!rootLayer || rootLayer->compositingState() == NotComposited)
 792         return false;
 793
 794     return rootLayer->compositedLayerMapping()->backgroundLayerPaintsFixedRootBackground();
 795 }
 796
 797 static inline void applySubPixelHeuristicForTileSize(LayoutSize& tileSize, const IntSize& positioningAreaSize)
 798 {
 799     tileSize.setWidth(positioningAreaSize.width() - tileSize.width() <= 1 ? tileSize.width().ceil() : tileSize.width().floor());
 800     tileSize.setHeight(positioningAreaSize.height() - tileSize.height() <= 1 ? tileSize.height().ceil() : tileSize.height().floor());
 801 }
 802
 803 IntSize BoxPainter::calculateFillTileSize(const RenderBoxModelObject& obj, const FillLayer& fillLayer, const IntSize& positioningAreaSize)
 804 {
 805     StyleImage* image = fillLayer.image();
 806     EFillSizeType type = fillLayer.size().type;
 807
 808     IntSize imageIntrinsicSize = obj.calculateImageIntrinsicDimensions(image, positioningAreaSize, RenderBoxModelObject::ScaleByEffectiveZoom);
 809     imageIntrinsicSize.scale(1 / image->imageScaleFactor(), 1 / image->imageScaleFactor());
 810     switch (type) {
 811     case SizeLength: {
 812         LayoutSize tileSize = positioningAreaSize;
 813
 814         Length layerWidth = fillLayer.size().size.width();
 815         Length layerHeight = fillLayer.size().size.height();
 816
 817         if (layerWidth.isFixed())
 818             tileSize.setWidth(layerWidth.value());
 819         else if (layerWidth.isPercent())
 820             tileSize.setWidth(valueForLength(layerWidth, positioningAreaSize.width()));
 821
 822         if (layerHeight.isFixed())
 823             tileSize.setHeight(layerHeight.value());
 824         else if (layerHeight.isPercent())
 825             tileSize.setHeight(valueForLength(layerHeight, positioningAreaSize.height()));
 826
 827         applySubPixelHeuristicForTileSize(tileSize, positioningAreaSize);
 828
 829         // If one of the values is auto we have to use the appropriate
 830         // scale to maintain our aspect ratio.
 831         if (layerWidth.isAuto() && !layerHeight.isAuto()) {
 832             if (imageIntrinsicSize.height())
 833                 tileSize.setWidth(imageIntrinsicSize.width() * tileSize.height() / imageIntrinsicSize.height());
 834         } else if (!layerWidth.isAuto() && layerHeight.isAuto()) {
 835             if (imageIntrinsicSize.width())
 836                 tileSize.setHeight(imageIntrinsicSize.height() * tileSize.width() / imageIntrinsicSize.width());
 837         } else if (layerWidth.isAuto() && layerHeight.isAuto()) {
 838             // If both width and height are auto, use the image's intrinsic size.
 839             tileSize = imageIntrinsicSize;
 840         }
 841
 842         tileSize.clampNegativeToZero();
 843         return flooredIntSize(tileSize);
 844     }
 845     case SizeNone: {
 846         // If both values are ‘auto’ then the intrinsic width and/or height of the image should be used, if any.
 847         if (!imageIntrinsicSize.isEmpty())
 848             return imageIntrinsicSize;
 849
 850         // If the image has neither an intrinsic width nor an intrinsic height, its size is determined as for ‘contain’.
 851         type = Contain;
 852     }
 853     case Contain:
 854     case Cover: {
 855         float horizontalScaleFactor = imageIntrinsicSize.width()
 856             ? static_cast<float>(positioningAreaSize.width()) / imageIntrinsicSize.width() : 1;
 857         float verticalScaleFactor = imageIntrinsicSize.height()
 858             ? static_cast<float>(positioningAreaSize.height()) / imageIntrinsicSize.height() : 1;
 859         float scaleFactor = type == Contain ? std::min(horizontalScaleFactor, verticalScaleFactor) : std::max(horizontalScaleFactor, verticalScaleFactor);
 860         return IntSize(std::max(1l, lround(imageIntrinsicSize.width() * scaleFactor)), std::max(1l, lround(imageIntrinsicSize.height() * scaleFactor)));
 861     }
 862     }
 863
 864     ASSERT_NOT_REACHED();
 865     return IntSize();
 866 }
 867
 868 static LayoutUnit computeBorderImageSide(const BorderImageLength& borderSlice, LayoutUnit borderSide, LayoutUnit imageSide, LayoutUnit boxExtent)
 869 {
 870     if (borderSlice.isNumber())
 871         return borderSlice.number() * borderSide;
 872     if (borderSlice.length().isAuto())
 873         return imageSide;
 874     return valueForLength(borderSlice.length(), boxExtent);
 875 }
 876
 877 bool BoxPainter::paintNinePieceImage(RenderBoxModelObject& obj, GraphicsContext* graphicsContext, const LayoutRect& rect, const RenderStyle* style, const NinePieceImage& ninePieceImage, CompositeOperator op)
 878 {
 879     StyleImage* styleImage = ninePieceImage.image();
 880     if (!styleImage)
 881         return false;
 882
 883     if (!styleImage->isLoaded())
 884         return true; // Never paint a nine-piece image incrementally, but don't paint the fallback borders either.
 885
 886     if (!styleImage->canRender(obj, style->effectiveZoom()))
 887         return false;
 888
 889     // FIXME: border-image is broken with full page zooming when tiling has to happen, since the tiling function
 890     // doesn't have any understanding of the zoom that is in effect on the tile.
 891     LayoutRect rectWithOutsets = rect;
 892     rectWithOutsets.expand(style->imageOutsets(ninePieceImage));
 893     IntRect borderImageRect = pixelSnappedIntRect(rectWithOutsets);
 894
 895     IntSize imageSize = obj.calculateImageIntrinsicDimensions(styleImage, borderImageRect.size(), RenderBoxModelObject::DoNotScaleByEffectiveZoom);
 896
 897     // If both values are ‘auto’ then the intrinsic width and/or height of the image should be used, if any.
 898     styleImage->setContainerSizeForRenderer(&obj, imageSize, style->effectiveZoom());
 899
 900     int imageWidth = imageSize.width();
 901     int imageHeight = imageSize.height();
 902
 903     float imageScaleFactor = styleImage->imageScaleFactor();
 904     int topSlice = std::min<int>(imageHeight, valueForLength(ninePieceImage.imageSlices().top(), imageHeight)) * imageScaleFactor;
 905     int rightSlice = std::min<int>(imageWidth, valueForLength(ninePieceImage.imageSlices().right(), imageWidth)) * imageScaleFactor;
 906     int bottomSlice = std::min<int>(imageHeight, valueForLength(ninePieceImage.imageSlices().bottom(), imageHeight)) * imageScaleFactor;
 907     int leftSlice = std::min<int>(imageWidth, valueForLength(ninePieceImage.imageSlices().left(), imageWidth)) * imageScaleFactor;
 908
 909     ENinePieceImageRule hRule = ninePieceImage.horizontalRule();
 910     ENinePieceImageRule vRule = ninePieceImage.verticalRule();
 911
 912     int topWidth = computeBorderImageSide(ninePieceImage.borderSlices().top(), style->borderTopWidth(), topSlice, borderImageRect.height());
 913     int rightWidth = computeBorderImageSide(ninePieceImage.borderSlices().right(), style->borderRightWidth(), rightSlice, borderImageRect.width());
 914     int bottomWidth = computeBorderImageSide(ninePieceImage.borderSlices().bottom(), style->borderBottomWidth(), bottomSlice, borderImageRect.height());
 915     int leftWidth = computeBorderImageSide(ninePieceImage.borderSlices().left(), style->borderLeftWidth(), leftSlice, borderImageRect.width());
 916
 917     // Reduce the widths if they're too large.
 918     // The spec says: Given Lwidth as the width of the border image area, Lheight as its height, and Wside as the border image width
 919     // offset for the side, let f = min(Lwidth/(Wleft+Wright), Lheight/(Wtop+Wbottom)). If f < 1, then all W are reduced by
 920     // multiplying them by f.
 921     int borderSideWidth = std::max(1, leftWidth + rightWidth);
 922     int borderSideHeight = std::max(1, topWidth + bottomWidth);
 923     float borderSideScaleFactor = std::min((float)borderImageRect.width() / borderSideWidth, (float)borderImageRect.height() / borderSideHeight);
 924     if (borderSideScaleFactor < 1) {
 925         topWidth *= borderSideScaleFactor;
 926         rightWidth *= borderSideScaleFactor;
 927         bottomWidth *= borderSideScaleFactor;
 928         leftWidth *= borderSideScaleFactor;
 929     }
 930
 931     bool drawLeft = leftSlice > 0 && leftWidth > 0;
 932     bool drawTop = topSlice > 0 && topWidth > 0;
 933     bool drawRight = rightSlice > 0 && rightWidth > 0;
 934     bool drawBottom = bottomSlice > 0 && bottomWidth > 0;
 935     bool drawMiddle = ninePieceImage.fill() && (imageWidth - leftSlice - rightSlice) > 0 && (borderImageRect.width() - leftWidth - rightWidth) > 0
 936         && (imageHeight - topSlice - bottomSlice) > 0 && (borderImageRect.height() - topWidth - bottomWidth) > 0;
 937
 938     RefPtr<Image> image = styleImage->image(&obj, imageSize);
 939
 940     float destinationWidth = borderImageRect.width() - leftWidth - rightWidth;
 941     float destinationHeight = borderImageRect.height() - topWidth - bottomWidth;
 942
 943     float sourceWidth = imageWidth - leftSlice - rightSlice;
 944     float sourceHeight = imageHeight - topSlice - bottomSlice;
 945
 946     float leftSideScale = drawLeft ? (float)leftWidth / leftSlice : 1;
 947     float rightSideScale = drawRight ? (float)rightWidth / rightSlice : 1;
 948     float topSideScale = drawTop ? (float)topWidth / topSlice : 1;
 949     float bottomSideScale = drawBottom ? (float)bottomWidth / bottomSlice : 1;
 950
 951     if (drawLeft) {
 952         // Paint the top and bottom left corners.
 953
 954         // The top left corner rect is (tx, ty, leftWidth, topWidth)
 955         // The rect to use from within the image is obtained from our slice, and is (0, 0, leftSlice, topSlice)
 956         if (drawTop) {
 957             graphicsContext->drawImage(image.get(), IntRect(borderImageRect.location(), IntSize(leftWidth, topWidth)),
 958                 LayoutRect(0, 0, leftSlice, topSlice), op);
 959         }
 960
 961         // The bottom left corner rect is (tx, ty + h - bottomWidth, leftWidth, bottomWidth)
 962         // The rect to use from within the image is (0, imageHeight - bottomSlice, leftSlice, botomSlice)
 963         if (drawBottom) {
 964             graphicsContext->drawImage(image.get(), IntRect(borderImageRect.x(), borderImageRect.maxY() - bottomWidth, leftWidth, bottomWidth),
 965                 LayoutRect(0, imageHeight - bottomSlice, leftSlice, bottomSlice), op);
 966         }
 967
 968         // Paint the left edge.
 969         // Have to scale and tile into the border rect.
 970         if (sourceHeight > 0) {
 971             graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.x(), borderImageRect.y() + topWidth, leftWidth, destinationHeight),
 972                 IntRect(0, topSlice, leftSlice, sourceHeight), FloatSize(leftSideScale, leftSideScale), Image::StretchTile, (Image::TileRule)vRule, op);
 973         }
 974     }
 975
 976     if (drawRight) {
 977         // Paint the top and bottom right corners
 978         // The top right corner rect is (tx + w - rightWidth, ty, rightWidth, topWidth)
 979         // The rect to use from within the image is obtained from our slice, and is (imageWidth - rightSlice, 0, rightSlice, topSlice)
 980         if (drawTop) {
 981             graphicsContext->drawImage(image.get(), IntRect(borderImageRect.maxX() - rightWidth, borderImageRect.y(), rightWidth, topWidth),
 982                 LayoutRect(imageWidth - rightSlice, 0, rightSlice, topSlice), op);
 983         }
 984
 985         // The bottom right corner rect is (tx + w - rightWidth, ty + h - bottomWidth, rightWidth, bottomWidth)
 986         // The rect to use from within the image is (imageWidth - rightSlice, imageHeight - bottomSlice, rightSlice, bottomSlice)
 987         if (drawBottom) {
 988             graphicsContext->drawImage(image.get(), IntRect(borderImageRect.maxX() - rightWidth, borderImageRect.maxY() - bottomWidth, rightWidth, bottomWidth),
 989                 LayoutRect(imageWidth - rightSlice, imageHeight - bottomSlice, rightSlice, bottomSlice), op);
 990         }
 991
 992         // Paint the right edge.
 993         if (sourceHeight > 0) {
 994             graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.maxX() - rightWidth, borderImageRect.y() + topWidth, rightWidth,
 995                 destinationHeight),
 996                 IntRect(imageWidth - rightSlice, topSlice, rightSlice, sourceHeight),
 997                 FloatSize(rightSideScale, rightSideScale),
 998                 Image::StretchTile, (Image::TileRule)vRule, op);
 999         }
1000     }
1001
1002     // Paint the top edge.
1003     if (drawTop && sourceWidth > 0) {
1004         graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.x() + leftWidth, borderImageRect.y(), destinationWidth, topWidth),
1005             IntRect(leftSlice, 0, sourceWidth, topSlice),
1006             FloatSize(topSideScale, topSideScale), (Image::TileRule)hRule, Image::StretchTile, op);
1007     }
1008
1009     // Paint the bottom edge.
1010     if (drawBottom && sourceWidth > 0) {
1011         graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.x() + leftWidth, borderImageRect.maxY() - bottomWidth,
1012             destinationWidth, bottomWidth),
1013             IntRect(leftSlice, imageHeight - bottomSlice, sourceWidth, bottomSlice),
1014             FloatSize(bottomSideScale, bottomSideScale),
1015             (Image::TileRule)hRule, Image::StretchTile, op);
1016     }
1017
1018     // Paint the middle.
1019     if (drawMiddle) {
1020         FloatSize middleScaleFactor(1, 1);
1021         if (drawTop)
1022             middleScaleFactor.setWidth(topSideScale);
1023         else if (drawBottom)
1024             middleScaleFactor.setWidth(bottomSideScale);
1025         if (drawLeft)
1026             middleScaleFactor.setHeight(leftSideScale);
1027         else if (drawRight)
1028             middleScaleFactor.setHeight(rightSideScale);
1029
1030         // For "stretch" rules, just override the scale factor and replace. We only had to do this for the
1031         // center tile, since sides don't even use the scale factor unless they have a rule other than "stretch".
1032         // The middle however can have "stretch" specified in one axis but not the other, so we have to
1033         // correct the scale here.
1034         if (hRule == StretchImageRule)
1035             middleScaleFactor.setWidth(destinationWidth / sourceWidth);
1036
1037         if (vRule == StretchImageRule)
1038             middleScaleFactor.setHeight(destinationHeight / sourceHeight);
1039
1040         graphicsContext->drawTiledImage(image.get(),
1041             IntRect(borderImageRect.x() + leftWidth, borderImageRect.y() + topWidth, destinationWidth, destinationHeight),
1042             IntRect(leftSlice, topSlice, sourceWidth, sourceHeight),
1043             middleScaleFactor, (Image::TileRule)hRule, (Image::TileRule)vRule, op);
1044     }
1045
1046     return true;
1047 }
1048
1049 static IntRect calculateSideRect(const RoundedRect& outerBorder, const BorderEdge edges[], int side)
1050 {
1051     IntRect sideRect = outerBorder.rect();
1052     int width = edges[side].width;
1053
1054     if (side == BSTop)
1055         sideRect.setHeight(width);
1056     else if (side == BSBottom)
1057         sideRect.shiftYEdgeTo(sideRect.maxY() - width);
1058     else if (side == BSLeft)
1059         sideRect.setWidth(width);
1060     else
1061         sideRect.shiftXEdgeTo(sideRect.maxX() - width);
1062
1063     return sideRect;
1064 }
1065
1066 enum BorderEdgeFlag {
1067     TopBorderEdge = 1 << BSTop,
1068     RightBorderEdge = 1 << BSRight,
1069     BottomBorderEdge = 1 << BSBottom,
1070     LeftBorderEdge = 1 << BSLeft,
1071     AllBorderEdges = TopBorderEdge | BottomBorderEdge | LeftBorderEdge | RightBorderEdge
1072 };
1073
1074 static inline BorderEdgeFlag edgeFlagForSide(BoxSide side)
1075 {
1076     return static_cast<BorderEdgeFlag>(1 << side);
1077 }
1078
1079 static inline bool includesEdge(BorderEdgeFlags flags, BoxSide side)
1080 {
1081     return flags & edgeFlagForSide(side);
1082 }
1083
1084 inline bool styleRequiresClipPolygon(EBorderStyle style)
1085 {
1086     return style == DOTTED || style == DASHED; // These are drawn with a stroke, so we have to clip to get corner miters.
1087 }
1088
1089 static bool borderStyleFillsBorderArea(EBorderStyle style)
1090 {
1091     return !(style == DOTTED || style == DASHED || style == DOUBLE);
1092 }
1093
1094 static bool borderStyleHasInnerDetail(EBorderStyle style)
1095 {
1096     return style == GROOVE || style == RIDGE || style == DOUBLE;
1097 }
1098
1099 static bool borderStyleIsDottedOrDashed(EBorderStyle style)
1100 {
1101     return style == DOTTED || style == DASHED;
1102 }
1103
1104 // OUTSET darkens the bottom and right (and maybe lightens the top and left)
1105 // INSET darkens the top and left (and maybe lightens the bottom and right)
1106 static inline bool borderStyleHasUnmatchedColorsAtCorner(EBorderStyle style, BoxSide side, BoxSide adjacentSide)
1107 {
1108     // These styles match at the top/left and bottom/right.
1109     if (style == INSET || style == GROOVE || style == RIDGE || style == OUTSET) {
1110         const BorderEdgeFlags topRightFlags = edgeFlagForSide(BSTop) | edgeFlagForSide(BSRight);
1111         const BorderEdgeFlags bottomLeftFlags = edgeFlagForSide(BSBottom) | edgeFlagForSide(BSLeft);
1112
1113         BorderEdgeFlags flags = edgeFlagForSide(side) | edgeFlagForSide(adjacentSide);
1114         return flags == topRightFlags || flags == bottomLeftFlags;
1115     }
1116     return false;
1117 }
1118
1119 static inline bool colorsMatchAtCorner(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[])
1120 {
1121     if (edges[side].shouldRender() != edges[adjacentSide].shouldRender())
1122         return false;
1123
1124     if (!edges[side].sharesColorWith(edges[adjacentSide]))
1125         return false;
1126
1127     return !borderStyleHasUnmatchedColorsAtCorner(edges[side].borderStyle(), side, adjacentSide);
1128 }
1129
1130 static inline bool colorNeedsAntiAliasAtCorner(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[])
1131 {
1132     if (!edges[side].color.hasAlpha())
1133         return false;
1134
1135     if (edges[side].shouldRender() != edges[adjacentSide].shouldRender())
1136         return false;
1137
1138     if (!edges[side].sharesColorWith(edges[adjacentSide]))
1139         return true;
1140
1141     return borderStyleHasUnmatchedColorsAtCorner(edges[side].borderStyle(), side, adjacentSide);
1142 }
1143
1144 bool BoxPainter::shouldAntialiasLines(GraphicsContext* context)
1145 {
1146     // FIXME: We may want to not antialias when scaled by an integral value,
1147     // and we may want to antialias when translated by a non-integral value.
1148     // FIXME: See crbug.com/382491. getCTM does not include scale factors applied at raster time, such
1149     // as device zoom.
1150     return !context->getCTM().isIdentityOrTranslationOrFlipped();
1151 }
1152
1153 static bool borderWillArcInnerEdge(const LayoutSize& firstRadius, const FloatSize& secondRadius)
1154 {
1155     return !firstRadius.isZero() || !secondRadius.isZero();
1156 }
1157
1158 // This assumes that we draw in order: top, bottom, left, right.
1159 static inline bool willBeOverdrawn(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[])
1160 {
1161     switch (side) {
1162     case BSTop:
1163     case BSBottom:
1164         if (edges[adjacentSide].presentButInvisible())
1165             return false;
1166
1167         if (!edges[side].sharesColorWith(edges[adjacentSide]) && edges[adjacentSide].color.hasAlpha())
1168             return false;
1169
1170         if (!borderStyleFillsBorderArea(edges[adjacentSide].borderStyle()))
1171             return false;
1172
1173         return true;
1174
1175     case BSLeft:
1176     case BSRight:
1177         // These draw last, so are never overdrawn.
1178         return false;
1179     }
1180     return false;
1181 }
1182
1183 static inline bool borderStylesRequireMitre(BoxSide side, BoxSide adjacentSide, EBorderStyle style, EBorderStyle adjacentStyle)
1184 {
1185     if (style == DOUBLE || adjacentStyle == DOUBLE || adjacentStyle == GROOVE || adjacentStyle == RIDGE)
1186         return true;
1187
1188     if (borderStyleIsDottedOrDashed(style) != borderStyleIsDottedOrDashed(adjacentStyle))
1189         return true;
1190
1191     if (style != adjacentStyle)
1192         return true;
1193
1194     return borderStyleHasUnmatchedColorsAtCorner(style, side, adjacentSide);
1195 }
1196
1197 static bool joinRequiresMitre(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[], bool allowOverdraw)
1198 {
1199     if ((edges[side].isTransparent && edges[adjacentSide].isTransparent) || !edges[adjacentSide].isPresent)
1200         return false;
1201
1202     if (allowOverdraw && willBeOverdrawn(side, adjacentSide, edges))
1203         return false;
1204
1205     if (!edges[side].sharesColorWith(edges[adjacentSide]))
1206         return true;
1207
1208     if (borderStylesRequireMitre(side, adjacentSide, edges[side].borderStyle(), edges[adjacentSide].borderStyle()))
1209         return true;
1210
1211     return false;
1212 }
1213
1214 static IntRect calculateSideRectIncludingInner(const RoundedRect& outerBorder, const BorderEdge edges[], BoxSide side)
1215 {
1216     IntRect sideRect = outerBorder.rect();
1217     int width;
1218
1219     switch (side) {
1220     case BSTop:
1221         width = sideRect.height() - edges[BSBottom].width;
1222         sideRect.setHeight(width);
1223         break;
1224     case BSBottom:
1225         width = sideRect.height() - edges[BSTop].width;
1226         sideRect.shiftYEdgeTo(sideRect.maxY() - width);
1227         break;
1228     case BSLeft:
1229         width = sideRect.width() - edges[BSRight].width;
1230         sideRect.setWidth(width);
1231         break;
1232     case BSRight:
1233         width = sideRect.width() - edges[BSLeft].width;
1234         sideRect.shiftXEdgeTo(sideRect.maxX() - width);
1235         break;
1236     }
1237
1238     return sideRect;
1239 }
1240
1241 static RoundedRect calculateAdjustedInnerBorder(const RoundedRect&innerBorder, BoxSide side)
1242 {
1243     // Expand the inner border as necessary to make it a rounded rect (i.e. radii contained within each edge).
1244     // This function relies on the fact we only get radii not contained within each edge if one of the radii
1245     // for an edge is zero, so we can shift the arc towards the zero radius corner.
1246     RoundedRect::Radii newRadii = innerBorder.radii();
1247     IntRect newRect = innerBorder.rect();
1248
1249     float overshoot;
1250     float maxRadii;
1251
1252     switch (side) {
1253     case BSTop:
1254         overshoot = newRadii.topLeft().width() + newRadii.topRight().width() - newRect.width();
1255         if (overshoot > 0) {
1256             ASSERT(!(newRadii.topLeft().width() && newRadii.topRight().width()));
1257             newRect.setWidth(newRect.width() + overshoot);
1258             if (!newRadii.topLeft().width())
1259                 newRect.move(-overshoot, 0);
1260         }
1261         newRadii.setBottomLeft(IntSize(0, 0));
1262         newRadii.setBottomRight(IntSize(0, 0));
1263         maxRadii = std::max(newRadii.topLeft().height(), newRadii.topRight().height());
1264         if (maxRadii > newRect.height())
1265             newRect.setHeight(maxRadii);
1266         break;
1267
1268     case BSBottom:
1269         overshoot = newRadii.bottomLeft().width() + newRadii.bottomRight().width() - newRect.width();
1270         if (overshoot > 0) {
1271             ASSERT(!(newRadii.bottomLeft().width() && newRadii.bottomRight().width()));
1272             newRect.setWidth(newRect.width() + overshoot);
1273             if (!newRadii.bottomLeft().width())
1274                 newRect.move(-overshoot, 0);
1275         }
1276         newRadii.setTopLeft(IntSize(0, 0));
1277         newRadii.setTopRight(IntSize(0, 0));
1278         maxRadii = std::max(newRadii.bottomLeft().height(), newRadii.bottomRight().height());
1279         if (maxRadii > newRect.height()) {
1280             newRect.move(0, newRect.height() - maxRadii);
1281             newRect.setHeight(maxRadii);
1282         }
1283         break;
1284
1285     case BSLeft:
1286         overshoot = newRadii.topLeft().height() + newRadii.bottomLeft().height() - newRect.height();
1287         if (overshoot > 0) {
1288             ASSERT(!(newRadii.topLeft().height() && newRadii.bottomLeft().height()));
1289             newRect.setHeight(newRect.height() + overshoot);
1290             if (!newRadii.topLeft().height())
1291                 newRect.move(0, -overshoot);
1292         }
1293         newRadii.setTopRight(IntSize(0, 0));
1294         newRadii.setBottomRight(IntSize(0, 0));
1295         maxRadii = std::max(newRadii.topLeft().width(), newRadii.bottomLeft().width());
1296         if (maxRadii > newRect.width())
1297             newRect.setWidth(maxRadii);
1298         break;
1299
1300     case BSRight:
1301         overshoot = newRadii.topRight().height() + newRadii.bottomRight().height() - newRect.height();
1302         if (overshoot > 0) {
1303             ASSERT(!(newRadii.topRight().height() && newRadii.bottomRight().height()));
1304             newRect.setHeight(newRect.height() + overshoot);
1305             if (!newRadii.topRight().height())
1306                 newRect.move(0, -overshoot);
1307         }
1308         newRadii.setTopLeft(IntSize(0, 0));
1309         newRadii.setBottomLeft(IntSize(0, 0));
1310         maxRadii = std::max(newRadii.topRight().width(), newRadii.bottomRight().width());
1311         if (maxRadii > newRect.width()) {
1312             newRect.move(newRect.width() - maxRadii, 0);
1313             newRect.setWidth(maxRadii);
1314         }
1315         break;
1316     }
1317
1318     return RoundedRect(newRect, newRadii);
1319 }
1320
1321 void BoxPainter::clipBorderSideForComplexInnerPath(GraphicsContext* graphicsContext, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
1322     BoxSide side, const BorderEdge edges[])
1323 {
1324     graphicsContext->clip(calculateSideRectIncludingInner(outerBorder, edges, side));
1325     RoundedRect adjustedInnerRect = calculateAdjustedInnerBorder(innerBorder, side);
1326     if (!adjustedInnerRect.isEmpty())
1327         graphicsContext->clipOutRoundedRect(adjustedInnerRect);
1328 }
1329
1330 static bool allCornersClippedOut(const RoundedRect& border, const LayoutRect& clipRect)
1331 {
1332     LayoutRect boundingRect = border.rect();
1333     if (clipRect.contains(boundingRect))
1334         return false;
1335
1336     RoundedRect::Radii radii = border.radii();
1337
1338     LayoutRect topLeftRect(boundingRect.location(), radii.topLeft());
1339     if (clipRect.intersects(topLeftRect))
1340         return false;
1341
1342     LayoutRect topRightRect(boundingRect.location(), radii.topRight());
1343     topRightRect.setX(boundingRect.maxX() - topRightRect.width());
1344     if (clipRect.intersects(topRightRect))
1345         return false;
1346
1347     LayoutRect bottomLeftRect(boundingRect.location(), radii.bottomLeft());
1348     bottomLeftRect.setY(boundingRect.maxY() - bottomLeftRect.height());
1349     if (clipRect.intersects(bottomLeftRect))
1350         return false;
1351
1352     LayoutRect bottomRightRect(boundingRect.location(), radii.bottomRight());
1353     bottomRightRect.setX(boundingRect.maxX() - bottomRightRect.width());
1354     bottomRightRect.setY(boundingRect.maxY() - bottomRightRect.height());
1355     if (clipRect.intersects(bottomRightRect))
1356         return false;
1357
1358     return true;
1359 }
1360
1361 void BoxPainter::paintBorder(RenderBoxModelObject& obj, const PaintInfo& info, const LayoutRect& rect, const RenderStyle* style, BackgroundBleedAvoidance bleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
1362 {
1363     GraphicsContext* graphicsContext = info.context;
1364     // border-image is not affected by border-radius.
1365     if (paintNinePieceImage(obj, graphicsContext, rect, style, style->borderImage()))
1366         return;
1367
1368     BorderEdge edges[4];
1369     style->getBorderEdgeInfo(edges, includeLogicalLeftEdge, includeLogicalRightEdge);
1370     RoundedRect outerBorder = style->getRoundedBorderFor(rect, includeLogicalLeftEdge, includeLogicalRightEdge);
1371     RoundedRect innerBorder = style->getRoundedInnerBorderFor(borderInnerRectAdjustedForBleedAvoidance(graphicsContext, rect, bleedAvoidance), includeLogicalLeftEdge, includeLogicalRightEdge);
1372
1373     if (outerBorder.rect().isEmpty())
1374         return;
1375
1376     bool haveAlphaColor = false;
1377     bool haveAllSolidEdges = true;
1378     bool haveAllDoubleEdges = true;
1379     int numEdgesVisible = 4;
1380     bool allEdgesShareColor = true;
1381     bool allEdgesShareWidth = true;
1382     int firstVisibleEdge = -1;
1383     BorderEdgeFlags edgesToDraw = 0;
1384
1385     for (int i = BSTop; i <= BSLeft; ++i) {
1386         const BorderEdge& currEdge = edges[i];
1387
1388         if (edges[i].shouldRender())
1389             edgesToDraw |= edgeFlagForSide(static_cast<BoxSide>(i));
1390
1391         if (currEdge.presentButInvisible()) {
1392             --numEdgesVisible;
1393             allEdgesShareColor = false;
1394             allEdgesShareWidth = false;
1395             continue;
1396         }
1397
1398         if (!currEdge.shouldRender()) {
1399             --numEdgesVisible;
1400             continue;
1401         }
1402
1403         if (firstVisibleEdge == -1) {
1404             firstVisibleEdge = i;
1405         } else {
1406             if (currEdge.color != edges[firstVisibleEdge].color)
1407                 allEdgesShareColor = false;
1408             if (currEdge.width != edges[firstVisibleEdge].width)
1409                 allEdgesShareWidth = false;
1410         }
1411
1412         if (currEdge.color.hasAlpha())
1413             haveAlphaColor = true;
1414
1415         if (currEdge.borderStyle() != SOLID)
1416             haveAllSolidEdges = false;
1417
1418         if (currEdge.borderStyle() != DOUBLE)
1419             haveAllDoubleEdges = false;
1420     }
1421
1422     // If no corner intersects the clip region, we can pretend outerBorder is
1423     // rectangular to improve performance.
1424     if (haveAllSolidEdges && outerBorder.isRounded() && allCornersClippedOut(outerBorder, info.rect))
1425         outerBorder.setRadii(RoundedRect::Radii());
1426
1427     // isRenderable() check avoids issue described in https://bugs.webkit.org/show_bug.cgi?id=38787
1428     if ((haveAllSolidEdges || haveAllDoubleEdges) && allEdgesShareColor && innerBorder.isRenderable()) {
1429         // Fast path for drawing all solid edges and all unrounded double edges
1430
1431         if (numEdgesVisible == 4 && (outerBorder.isRounded() || haveAlphaColor)
1432             && (haveAllSolidEdges || (!outerBorder.isRounded() && !innerBorder.isRounded()))) {
1433             Path path;
1434
1435             if (outerBorder.isRounded() && allEdgesShareWidth) {
1436
1437                 // Very fast path for single stroked round rect with circular corners
1438
1439                 graphicsContext->fillBetweenRoundedRects(outerBorder, innerBorder, edges[firstVisibleEdge].color);
1440                 return;
1441             }
1442             if (outerBorder.isRounded() && bleedAvoidance != BackgroundBleedClipBackground)
1443                 path.addRoundedRect(outerBorder);
1444             else
1445                 path.addRect(outerBorder.rect());
1446
1447             if (haveAllDoubleEdges) {
1448                 IntRect innerThirdRect = outerBorder.rect();
1449                 IntRect outerThirdRect = outerBorder.rect();
1450                 for (int side = BSTop; side <= BSLeft; ++side) {
1451                     int outerWidth;
1452                     int innerWidth;
1453                     edges[side].getDoubleBorderStripeWidths(outerWidth, innerWidth);
1454
1455                     if (side == BSTop) {
1456                         innerThirdRect.shiftYEdgeTo(innerThirdRect.y() + innerWidth);
1457                         outerThirdRect.shiftYEdgeTo(outerThirdRect.y() + outerWidth);
1458                     } else if (side == BSBottom) {
1459                         innerThirdRect.setHeight(innerThirdRect.height() - innerWidth);
1460                         outerThirdRect.setHeight(outerThirdRect.height() - outerWidth);
1461                     } else if (side == BSLeft) {
1462                         innerThirdRect.shiftXEdgeTo(innerThirdRect.x() + innerWidth);
1463                         outerThirdRect.shiftXEdgeTo(outerThirdRect.x() + outerWidth);
1464                     } else {
1465                         innerThirdRect.setWidth(innerThirdRect.width() - innerWidth);
1466                         outerThirdRect.setWidth(outerThirdRect.width() - outerWidth);
1467                     }
1468                 }
1469
1470                 RoundedRect outerThird = outerBorder;
1471                 RoundedRect innerThird = innerBorder;
1472                 innerThird.setRect(innerThirdRect);
1473                 outerThird.setRect(outerThirdRect);
1474
1475                 if (outerThird.isRounded() && bleedAvoidance != BackgroundBleedClipBackground)
1476                     path.addRoundedRect(outerThird);
1477                 else
1478                     path.addRect(outerThird.rect());
1479
1480                 if (innerThird.isRounded() && bleedAvoidance != BackgroundBleedClipBackground)
1481                     path.addRoundedRect(innerThird);
1482                 else
1483                     path.addRect(innerThird.rect());
1484             }
1485
1486             if (innerBorder.isRounded())
1487                 path.addRoundedRect(innerBorder);
1488             else
1489                 path.addRect(innerBorder.rect());
1490
1491             graphicsContext->setFillRule(RULE_EVENODD);
1492             graphicsContext->setFillColor(edges[firstVisibleEdge].color);
1493             graphicsContext->fillPath(path);
1494             return;
1495         }
1496         // Avoid creating transparent layers
1497         if (haveAllSolidEdges && numEdgesVisible != 4 && !outerBorder.isRounded() && haveAlphaColor) {
1498             Path path;
1499
1500             for (int i = BSTop; i <= BSLeft; ++i) {
1501                 const BorderEdge& currEdge = edges[i];
1502                 if (currEdge.shouldRender()) {
1503                     IntRect sideRect = calculateSideRect(outerBorder, edges, i);
1504                     path.addRect(sideRect);
1505                 }
1506             }
1507
1508             graphicsContext->setFillRule(RULE_NONZERO);
1509             graphicsContext->setFillColor(edges[firstVisibleEdge].color);
1510             graphicsContext->fillPath(path);
1511             return;
1512         }
1513     }
1514
1515     bool clipToOuterBorder = outerBorder.isRounded();
1516     GraphicsContextStateSaver stateSaver(*graphicsContext, clipToOuterBorder);
1517     if (clipToOuterBorder) {
1518         // Clip to the inner and outer radii rects.
1519         if (bleedAvoidance != BackgroundBleedClipBackground)
1520             graphicsContext->clipRoundedRect(outerBorder);
1521         // isRenderable() check avoids issue described in https://bugs.webkit.org/show_bug.cgi?id=38787
1522         // The inside will be clipped out later (in clipBorderSideForComplexInnerPath)
1523         if (innerBorder.isRenderable() && !innerBorder.isEmpty())
1524             graphicsContext->clipOutRoundedRect(innerBorder);
1525     }
1526
1527     // If only one edge visible antialiasing doesn't create seams
1528     bool antialias = shouldAntialiasLines(graphicsContext) || numEdgesVisible == 1;
1529     RoundedRect unadjustedInnerBorder = (bleedAvoidance == BackgroundBleedBackgroundOverBorder) ? style->getRoundedInnerBorderFor(rect, includeLogicalLeftEdge, includeLogicalRightEdge) : innerBorder;
1530     IntPoint innerBorderAdjustment(innerBorder.rect().x() - unadjustedInnerBorder.rect().x(), innerBorder.rect().y() - unadjustedInnerBorder.rect().y());
1531     if (haveAlphaColor)
1532         paintTranslucentBorderSides(obj, graphicsContext, style, outerBorder, unadjustedInnerBorder, innerBorderAdjustment, edges, edgesToDraw, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
1533     else
1534         paintBorderSides(obj, graphicsContext, style, outerBorder, unadjustedInnerBorder, innerBorderAdjustment, edges, edgesToDraw, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
1535 }
1536
1537 static inline bool includesAdjacentEdges(BorderEdgeFlags flags)
1538 {
1539     return (flags & (TopBorderEdge | RightBorderEdge)) == (TopBorderEdge | RightBorderEdge)
1540         || (flags & (RightBorderEdge | BottomBorderEdge)) == (RightBorderEdge | BottomBorderEdge)
1541         || (flags & (BottomBorderEdge | LeftBorderEdge)) == (BottomBorderEdge | LeftBorderEdge)
1542         || (flags & (LeftBorderEdge | TopBorderEdge)) == (LeftBorderEdge | TopBorderEdge);
1543 }
1544
1545 void BoxPainter::paintTranslucentBorderSides(RenderObject& obj, GraphicsContext* graphicsContext, const RenderStyle* style, const RoundedRect& outerBorder, const RoundedRect& innerBorder, const IntPoint& innerBorderAdjustment,
1546     const BorderEdge edges[], BorderEdgeFlags edgesToDraw, BackgroundBleedAvoidance bleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias)
1547 {
1548     // willBeOverdrawn assumes that we draw in order: top, bottom, left, right.
1549     // This is different from BoxSide enum order.
1550     static const BoxSide paintOrder[] = { BSTop, BSBottom, BSLeft, BSRight };
1551
1552     while (edgesToDraw) {
1553         // Find undrawn edges sharing a color.
1554         Color commonColor;
1555
1556         BorderEdgeFlags commonColorEdgeSet = 0;
1557         for (size_t i = 0; i < sizeof(paintOrder) / sizeof(paintOrder[0]); ++i) {
1558             BoxSide currSide = paintOrder[i];
1559             if (!includesEdge(edgesToDraw, currSide))
1560                 continue;
1561
1562             bool includeEdge;
1563             if (!commonColorEdgeSet) {
1564                 commonColor = edges[currSide].color;
1565                 includeEdge = true;
1566             } else {
1567                 includeEdge = edges[currSide].color == commonColor;
1568             }
1569
1570             if (includeEdge)
1571                 commonColorEdgeSet |= edgeFlagForSide(currSide);
1572         }
1573
1574         bool useTransparencyLayer = includesAdjacentEdges(commonColorEdgeSet) && commonColor.hasAlpha();
1575         if (useTransparencyLayer) {
1576             graphicsContext->beginTransparencyLayer(static_cast<float>(commonColor.alpha()) / 255);
1577             commonColor = Color(commonColor.red(), commonColor.green(), commonColor.blue());
1578         }
1579
1580         paintBorderSides(obj, graphicsContext, style, outerBorder, innerBorder, innerBorderAdjustment, edges, commonColorEdgeSet, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, &commonColor);
1581
1582         if (useTransparencyLayer)
1583             graphicsContext->endLayer();
1584
1585         edgesToDraw &= ~commonColorEdgeSet;
1586     }
1587 }
1588
1589 LayoutRect BoxPainter::borderInnerRectAdjustedForBleedAvoidance(GraphicsContext* context, const LayoutRect& rect, BackgroundBleedAvoidance bleedAvoidance)
1590 {
1591     // We shrink the rectangle by one pixel on each side to make it fully overlap the anti-aliased background border
1592     return (bleedAvoidance == BackgroundBleedBackgroundOverBorder) ? shrinkRectByOnePixel(context, rect) : rect;
1593 }
1594
1595 void BoxPainter::paintOneBorderSide(RenderObject& obj, GraphicsContext* graphicsContext, const RenderStyle* style, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
1596     const IntRect& sideRect, BoxSide side, BoxSide adjacentSide1, BoxSide adjacentSide2, const BorderEdge edges[], const Path* path,
1597     BackgroundBleedAvoidance bleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias, const Color* overrideColor)
1598 {
1599     const BorderEdge& edgeToRender = edges[side];
1600     ASSERT(edgeToRender.width);
1601     const BorderEdge& adjacentEdge1 = edges[adjacentSide1];
1602     const BorderEdge& adjacentEdge2 = edges[adjacentSide2];
1603
1604     bool mitreAdjacentSide1 = joinRequiresMitre(side, adjacentSide1, edges, !antialias);
1605     bool mitreAdjacentSide2 = joinRequiresMitre(side, adjacentSide2, edges, !antialias);
1606
1607     bool adjacentSide1StylesMatch = colorsMatchAtCorner(side, adjacentSide1, edges);
1608     bool adjacentSide2StylesMatch = colorsMatchAtCorner(side, adjacentSide2, edges);
1609
1610     const Color& colorToPaint = overrideColor ? *overrideColor : edgeToRender.color;
1611
1612     if (path) {
1613         GraphicsContextStateSaver stateSaver(*graphicsContext);
1614         if (innerBorder.isRenderable())
1615             clipBorderSidePolygon(graphicsContext, outerBorder, innerBorder, side, adjacentSide1StylesMatch, adjacentSide2StylesMatch);
1616         else
1617             clipBorderSideForComplexInnerPath(graphicsContext, outerBorder, innerBorder, side, edges);
1618         float thickness = std::max(std::max(edgeToRender.width, adjacentEdge1.width), adjacentEdge2.width);
1619         drawBoxSideFromPath(graphicsContext, outerBorder.rect(), *path, edges, edgeToRender.width, thickness, side, style,
1620             colorToPaint, edgeToRender.borderStyle(), bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
1621     } else {
1622         bool clipForStyle = styleRequiresClipPolygon(edgeToRender.borderStyle()) && (mitreAdjacentSide1 || mitreAdjacentSide2);
1623         bool clipAdjacentSide1 = colorNeedsAntiAliasAtCorner(side, adjacentSide1, edges) && mitreAdjacentSide1;
1624         bool clipAdjacentSide2 = colorNeedsAntiAliasAtCorner(side, adjacentSide2, edges) && mitreAdjacentSide2;
1625         bool shouldClip = clipForStyle || clipAdjacentSide1 || clipAdjacentSide2;
1626
1627         GraphicsContextStateSaver clipStateSaver(*graphicsContext, shouldClip);
1628         if (shouldClip) {
1629             bool aliasAdjacentSide1 = clipAdjacentSide1 || (clipForStyle && mitreAdjacentSide1);
1630             bool aliasAdjacentSide2 = clipAdjacentSide2 || (clipForStyle && mitreAdjacentSide2);
1631             clipBorderSidePolygon(graphicsContext, outerBorder, innerBorder, side, !aliasAdjacentSide1, !aliasAdjacentSide2);
1632             // Since we clipped, no need to draw with a mitre.
1633             mitreAdjacentSide1 = false;
1634             mitreAdjacentSide2 = false;
1635         }
1636
1637         ObjectPainter::drawLineForBoxSide(graphicsContext, sideRect.x(), sideRect.y(), sideRect.maxX(), sideRect.maxY(), side, colorToPaint, edgeToRender.borderStyle(),
1638             mitreAdjacentSide1 ? adjacentEdge1.width : 0, mitreAdjacentSide2 ? adjacentEdge2.width : 0, antialias);
1639     }
1640 }
1641
1642 void BoxPainter::paintBorderSides(RenderObject& obj, GraphicsContext* graphicsContext, const RenderStyle* style, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
1643     const IntPoint& innerBorderAdjustment, const BorderEdge edges[], BorderEdgeFlags edgeSet, BackgroundBleedAvoidance bleedAvoidance,
1644     bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias, const Color* overrideColor)
1645 {
1646     bool renderRadii = outerBorder.isRounded();
1647
1648     Path roundedPath;
1649     if (renderRadii)
1650         roundedPath.addRoundedRect(outerBorder);
1651
1652     // The inner border adjustment for bleed avoidance mode BackgroundBleedBackgroundOverBorder
1653     // is only applied to sideRect, which is okay since BackgroundBleedBackgroundOverBorder
1654     // is only to be used for solid borders and the shape of the border painted by drawBoxSideFromPath
1655     // only depends on sideRect when painting solid borders.
1656
1657     if (edges[BSTop].shouldRender() && includesEdge(edgeSet, BSTop)) {
1658         IntRect sideRect = outerBorder.rect();
1659         sideRect.setHeight(edges[BSTop].width + innerBorderAdjustment.y());
1660
1661         bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSTop].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().topLeft(), innerBorder.radii().topRight()));
1662         paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSTop, BSLeft, BSRight, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
1663     }
1664
1665     if (edges[BSBottom].shouldRender() && includesEdge(edgeSet, BSBottom)) {
1666         IntRect sideRect = outerBorder.rect();
1667         sideRect.shiftYEdgeTo(sideRect.maxY() - edges[BSBottom].width - innerBorderAdjustment.y());
1668
1669         bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSBottom].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().bottomLeft(), innerBorder.radii().bottomRight()));
1670         paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSBottom, BSLeft, BSRight, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
1671     }
1672
1673     if (edges[BSLeft].shouldRender() && includesEdge(edgeSet, BSLeft)) {
1674         IntRect sideRect = outerBorder.rect();
1675         sideRect.setWidth(edges[BSLeft].width + innerBorderAdjustment.x());
1676
1677         bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSLeft].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().bottomLeft(), innerBorder.radii().topLeft()));
1678         paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSLeft, BSTop, BSBottom, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
1679     }
1680
1681     if (edges[BSRight].shouldRender() && includesEdge(edgeSet, BSRight)) {
1682         IntRect sideRect = outerBorder.rect();
1683         sideRect.shiftXEdgeTo(sideRect.maxX() - edges[BSRight].width - innerBorderAdjustment.x());
1684
1685         bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSRight].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().bottomRight(), innerBorder.radii().topRight()));
1686         paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSRight, BSTop, BSBottom, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
1687     }
1688 }
1689
1690 void BoxPainter::drawBoxSideFromPath(GraphicsContext* graphicsContext, const LayoutRect& borderRect, const Path& borderPath, const BorderEdge edges[],
1691     float thickness, float drawThickness, BoxSide side, const RenderStyle* style, Color color, EBorderStyle borderStyle, BackgroundBleedAvoidance bleedAvoidance,
1692     bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
1693 {
1694     if (thickness <= 0)
1695         return;
1696
1697     if (borderStyle == DOUBLE && thickness < 3)
1698         borderStyle = SOLID;
1699
1700     switch (borderStyle) {
1701     case BNONE:
1702     case BHIDDEN:
1703         return;
1704     case DOTTED:
1705     case DASHED: {
1706         graphicsContext->setStrokeColor(color);
1707
1708         // The stroke is doubled here because the provided path is the
1709         // outside edge of the border so half the stroke is clipped off.
1710         // The extra multiplier is so that the clipping mask can antialias
1711         // the edges to prevent jaggies.
1712         graphicsContext->setStrokeThickness(drawThickness * 2 * 1.1f);
1713         graphicsContext->setStrokeStyle(borderStyle == DASHED ? DashedStroke : DottedStroke);
1714
1715         // If the number of dashes that fit in the path is odd and non-integral then we
1716         // will have an awkwardly-sized dash at the end of the path. To try to avoid that
1717         // here, we simply make the whitespace dashes ever so slightly bigger.
1718         // FIXME: This could be even better if we tried to manipulate the dash offset
1719         // and possibly the gapLength to get the corners dash-symmetrical.
1720         float dashLength = thickness * ((borderStyle == DASHED) ? 3.0f : 1.0f);
1721         float gapLength = dashLength;
1722         float numberOfDashes = borderPath.length() / dashLength;
1723         // Don't try to show dashes if we have less than 2 dashes + 2 gaps.
1724         // FIXME: should do this test per side.
1725         if (numberOfDashes >= 4) {
1726             bool evenNumberOfFullDashes = !((int)numberOfDashes % 2);
1727             bool integralNumberOfDashes = !(numberOfDashes - (int)numberOfDashes);
1728             if (!evenNumberOfFullDashes && !integralNumberOfDashes) {
1729                 float numberOfGaps = numberOfDashes / 2;
1730                 gapLength += (dashLength  / numberOfGaps);
1731             }
1732
1733             DashArray lineDash;
1734             lineDash.append(dashLength);
1735             lineDash.append(gapLength);
1736             graphicsContext->setLineDash(lineDash, dashLength);
1737         }
1738
1739         // FIXME: stroking the border path causes issues with tight corners:
1740         // https://bugs.webkit.org/show_bug.cgi?id=58711
1741         // Also, to get the best appearance we should stroke a path between the two borders.
1742         graphicsContext->strokePath(borderPath);
1743         return;
1744     }
1745     case DOUBLE: {
1746         // Get the inner border rects for both the outer border line and the inner border line
1747         int outerBorderTopWidth;
1748         int innerBorderTopWidth;
1749         edges[BSTop].getDoubleBorderStripeWidths(outerBorderTopWidth, innerBorderTopWidth);
1750
1751         int outerBorderRightWidth;
1752         int innerBorderRightWidth;
1753         edges[BSRight].getDoubleBorderStripeWidths(outerBorderRightWidth, innerBorderRightWidth);
1754
1755         int outerBorderBottomWidth;
1756         int innerBorderBottomWidth;
1757         edges[BSBottom].getDoubleBorderStripeWidths(outerBorderBottomWidth, innerBorderBottomWidth);
1758
1759         int outerBorderLeftWidth;
1760         int innerBorderLeftWidth;
1761         edges[BSLeft].getDoubleBorderStripeWidths(outerBorderLeftWidth, innerBorderLeftWidth);
1762
1763         // Draw inner border line
1764         {
1765             GraphicsContextStateSaver stateSaver(*graphicsContext);
1766             RoundedRect innerClip = style->getRoundedInnerBorderFor(borderRect,
1767                 innerBorderTopWidth, innerBorderBottomWidth, innerBorderLeftWidth, innerBorderRightWidth,
1768                 includeLogicalLeftEdge, includeLogicalRightEdge);
1769
1770             graphicsContext->clipRoundedRect(innerClip);
1771             drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, SOLID, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
1772         }
1773
1774         // Draw outer border line
1775         {
1776             GraphicsContextStateSaver stateSaver(*graphicsContext);
1777             LayoutRect outerRect = borderRect;
1778             if (bleedAvoidance == BackgroundBleedClipBackground) {
1779                 outerRect.inflate(1);
1780                 ++outerBorderTopWidth;
1781                 ++outerBorderBottomWidth;
1782                 ++outerBorderLeftWidth;
1783                 ++outerBorderRightWidth;
1784             }
1785
1786             RoundedRect outerClip = style->getRoundedInnerBorderFor(outerRect,
1787                 outerBorderTopWidth, outerBorderBottomWidth, outerBorderLeftWidth, outerBorderRightWidth,
1788                 includeLogicalLeftEdge, includeLogicalRightEdge);
1789             graphicsContext->clipOutRoundedRect(outerClip);
1790             drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, SOLID, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
1791         }
1792         return;
1793     }
1794     case RIDGE:
1795     case GROOVE:
1796     {
1797         EBorderStyle s1;
1798         EBorderStyle s2;
1799         if (borderStyle == GROOVE) {
1800             s1 = INSET;
1801             s2 = OUTSET;
1802         } else {
1803             s1 = OUTSET;
1804             s2 = INSET;
1805         }
1806
1807         // Paint full border
1808         drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, s1, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
1809
1810         // Paint inner only
1811         GraphicsContextStateSaver stateSaver(*graphicsContext);
1812         LayoutUnit topWidth = edges[BSTop].usedWidth() / 2;
1813         LayoutUnit bottomWidth = edges[BSBottom].usedWidth() / 2;
1814         LayoutUnit leftWidth = edges[BSLeft].usedWidth() / 2;
1815         LayoutUnit rightWidth = edges[BSRight].usedWidth() / 2;
1816
1817         RoundedRect clipRect = style->getRoundedInnerBorderFor(borderRect,
1818             topWidth, bottomWidth, leftWidth, rightWidth,
1819             includeLogicalLeftEdge, includeLogicalRightEdge);
1820
1821         graphicsContext->clipRoundedRect(clipRect);
1822         drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, s2, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
1823         return;
1824     }
1825     case INSET:
1826         if (side == BSTop || side == BSLeft)
1827             color = color.dark();
1828         break;
1829     case OUTSET:
1830         if (side == BSBottom || side == BSRight)
1831             color = color.dark();
1832         break;
1833     default:
1834         break;
1835     }
1836
1837     graphicsContext->setStrokeStyle(NoStroke);
1838     graphicsContext->setFillColor(color);
1839     graphicsContext->drawRect(pixelSnappedIntRect(borderRect));
1840 }
1841
1842 void BoxPainter::paintBoxShadow(const PaintInfo& info, const LayoutRect& paintRect, const RenderStyle* s, ShadowStyle shadowStyle, bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
1843 {
1844     // FIXME: Deal with border-image. Would be great to use border-image as a mask.
1845     GraphicsContext* context = info.context;
1846     if (!s->boxShadow())
1847         return;
1848
1849     RoundedRect border = (shadowStyle == Inset) ? s->getRoundedInnerBorderFor(paintRect, includeLogicalLeftEdge, includeLogicalRightEdge)
1850         : s->getRoundedBorderFor(paintRect, includeLogicalLeftEdge, includeLogicalRightEdge);
1851
1852     bool hasBorderRadius = s->hasBorderRadius();
1853     bool isHorizontal = s->isHorizontalWritingMode();
1854     bool hasOpaqueBackground = s->visitedDependentColor(CSSPropertyBackgroundColor).alpha() == 255;
1855
1856     GraphicsContextStateSaver stateSaver(*context, false);
1857
1858     const ShadowList* shadowList = s->boxShadow();
1859     for (size_t i = shadowList->shadows().size(); i--; ) {
1860         const ShadowData& shadow = shadowList->shadows()[i];
1861         if (shadow.style() != shadowStyle)
1862             continue;
1863
1864         FloatSize shadowOffset(shadow.x(), shadow.y());
1865         float shadowBlur = shadow.blur();
1866         float shadowSpread = shadow.spread();
1867
1868         if (shadowOffset.isZero() && !shadowBlur && !shadowSpread)
1869             continue;
1870
1871         const Color& shadowColor = shadow.color();
1872
1873         if (shadow.style() == Normal) {
1874             FloatRect fillRect = border.rect();
1875             fillRect.inflate(shadowSpread);
1876             if (fillRect.isEmpty())
1877                 continue;
1878
1879             FloatRect shadowRect(border.rect());
1880             shadowRect.inflate(shadowBlur + shadowSpread);
1881             shadowRect.move(shadowOffset);
1882
1883             // Save the state and clip, if not already done.
1884             // The clip does not depend on any shadow-specific properties.
1885             if (!stateSaver.saved()) {
1886                 stateSaver.save();
1887                 if (hasBorderRadius) {
1888                     RoundedRect rectToClipOut = border;
1889
1890                     // If the box is opaque, it is unnecessary to clip it out. However, doing so saves time
1891                     // when painting the shadow. On the other hand, it introduces subpixel gaps along the
1892                     // corners. Those are avoided by insetting the clipping path by one pixel.
1893                     if (hasOpaqueBackground)
1894                         rectToClipOut.inflateWithRadii(-1);
1895
1896                     if (!rectToClipOut.isEmpty()) {
1897                         context->clipOutRoundedRect(rectToClipOut);
1898                     }
1899                 } else {
1900                     // This IntRect is correct even with fractional shadows, because it is used for the rectangle
1901                     // of the box itself, which is always pixel-aligned.
1902                     IntRect rectToClipOut = border.rect();
1903
1904                     // If the box is opaque, it is unnecessary to clip it out. However, doing so saves time
1905                     // when painting the shadow. On the other hand, it introduces subpixel gaps along the
1906                     // edges if they are not pixel-aligned. Those are avoided by insetting the clipping path
1907                     // by one pixel.
1908                     if (hasOpaqueBackground) {
1909                         // FIXME: The function to decide on the policy based on the transform should be a named function.
1910                         // FIXME: It's not clear if this check is right. What about integral scale factors?
1911                         // FIXME: See crbug.com/382491. The use of getCTM may also be wrong because it does not include
1912                         // device zoom applied at raster time.
1913                         AffineTransform transform = context->getCTM();
1914                         if (transform.a() != 1 || (transform.d() != 1 && transform.d() != -1) || transform.b() || transform.c())
1915                             rectToClipOut.inflate(-1);
1916                     }
1917
1918                     if (!rectToClipOut.isEmpty()) {
1919                         context->clipOut(rectToClipOut);
1920                     }
1921                 }
1922             }
1923
1924             // Draw only the shadow.
1925             OwnPtr<DrawLooperBuilder> drawLooperBuilder = DrawLooperBuilder::create();
1926             drawLooperBuilder->addShadow(shadowOffset, shadowBlur, shadowColor,
1927                 DrawLooperBuilder::ShadowRespectsTransforms, DrawLooperBuilder::ShadowIgnoresAlpha);
1928             context->setDrawLooper(drawLooperBuilder.release());
1929
1930             if (hasBorderRadius) {
1931                 RoundedRect influenceRect(pixelSnappedIntRect(LayoutRect(shadowRect)), border.radii());
1932                 influenceRect.expandRadii(2 * shadowBlur + shadowSpread);
1933                 if (allCornersClippedOut(influenceRect, info.rect)) {
1934                     context->fillRect(fillRect, Color::black);
1935                 } else {
1936                     // TODO: support non-integer shadows - crbug.com/334829
1937                     RoundedRect roundedFillRect = border;
1938                     roundedFillRect.inflate(shadowSpread);
1939
1940                     roundedFillRect.expandRadii(shadowSpread);
1941                     if (!roundedFillRect.isRenderable())
1942                         roundedFillRect.adjustRadii();
1943                     context->fillRoundedRect(roundedFillRect, Color::black);
1944                 }
1945             } else {
1946                 context->fillRect(fillRect, Color::black);
1947             }
1948         } else {
1949             // The inset shadow case.
1950             GraphicsContext::Edges clippedEdges = GraphicsContext::NoEdge;
1951             if (!includeLogicalLeftEdge) {
1952                 if (isHorizontal)
1953                     clippedEdges |= GraphicsContext::LeftEdge;
1954                 else
1955                     clippedEdges |= GraphicsContext::TopEdge;
1956             }
1957             if (!includeLogicalRightEdge) {
1958                 if (isHorizontal)
1959                     clippedEdges |= GraphicsContext::RightEdge;
1960                 else
1961                     clippedEdges |= GraphicsContext::BottomEdge;
1962             }
1963             // TODO: support non-integer shadows - crbug.com/334828
1964             context->drawInnerShadow(border, shadowColor, flooredIntSize(shadowOffset), shadowBlur, shadowSpread, clippedEdges);
1965         }
1966     }
1967 }
1968
1969 void BoxPainter::clipBorderSidePolygon(GraphicsContext* graphicsContext, const RoundedRect& outerBorder, const RoundedRect& innerBorder, BoxSide side, bool firstEdgeMatches, bool secondEdgeMatches)
1970 {
1971     FloatPoint quad[4];
1972
1973     const LayoutRect& outerRect = outerBorder.rect();
1974     const LayoutRect& innerRect = innerBorder.rect();
1975
1976     FloatPoint centerPoint(innerRect.location().x().toFloat() + innerRect.width().toFloat() / 2, innerRect.location().y().toFloat() + innerRect.height().toFloat() / 2);
1977
1978     // For each side, create a quad that encompasses all parts of that side that may draw,
1979     // including areas inside the innerBorder.
1980     //
1981     //         0----------------3
1982     //       0  \              /  0
1983     //       |\  1----------- 2  /|
1984     //       | 1                1 |
1985     //       | |                | |
1986     //       | |                | |
1987     //       | 2                2 |
1988     //       |/  1------------2  \|
1989     //       3  /              \  3
1990     //         0----------------3
1991     //
1992     switch (side) {
1993     case BSTop:
1994         quad[0] = outerRect.minXMinYCorner();
1995         quad[1] = innerRect.minXMinYCorner();
1996         quad[2] = innerRect.maxXMinYCorner();
1997         quad[3] = outerRect.maxXMinYCorner();
1998
1999         if (!innerBorder.radii().topLeft().isZero()) {
2000             findIntersection(quad[0], quad[1],
2001                 FloatPoint(
2002                     quad[1].x() + innerBorder.radii().topLeft().width(),
2003                     quad[1].y()),
2004                 FloatPoint(
2005                     quad[1].x(),
2006                     quad[1].y() + innerBorder.radii().topLeft().height()),
2007                 quad[1]);
2008         }
2009
2010         if (!innerBorder.radii().topRight().isZero()) {
2011             findIntersection(quad[3], quad[2],
2012                 FloatPoint(
2013                     quad[2].x() - innerBorder.radii().topRight().width(),
2014                     quad[2].y()),
2015                 FloatPoint(
2016                     quad[2].x(),
2017                     quad[2].y() + innerBorder.radii().topRight().height()),
2018                 quad[2]);
2019         }
2020         break;
2021
2022     case BSLeft:
2023         quad[0] = outerRect.minXMinYCorner();
2024         quad[1] = innerRect.minXMinYCorner();
2025         quad[2] = innerRect.minXMaxYCorner();
2026         quad[3] = outerRect.minXMaxYCorner();
2027
2028         if (!innerBorder.radii().topLeft().isZero()) {
2029             findIntersection(quad[0], quad[1],
2030                 FloatPoint(
2031                     quad[1].x() + innerBorder.radii().topLeft().width(),
2032                     quad[1].y()),
2033                 FloatPoint(
2034                     quad[1].x(),
2035                     quad[1].y() + innerBorder.radii().topLeft().height()),
2036                 quad[1]);
2037         }
2038
2039         if (!innerBorder.radii().bottomLeft().isZero()) {
2040             findIntersection(quad[3], quad[2],
2041                 FloatPoint(
2042                     quad[2].x() + innerBorder.radii().bottomLeft().width(),
2043                     quad[2].y()),
2044                 FloatPoint(
2045                     quad[2].x(),
2046                     quad[2].y() - innerBorder.radii().bottomLeft().height()),
2047                 quad[2]);
2048         }
2049         break;
2050
2051     case BSBottom:
2052         quad[0] = outerRect.minXMaxYCorner();
2053         quad[1] = innerRect.minXMaxYCorner();
2054         quad[2] = innerRect.maxXMaxYCorner();
2055         quad[3] = outerRect.maxXMaxYCorner();
2056
2057         if (!innerBorder.radii().bottomLeft().isZero()) {
2058             findIntersection(quad[0], quad[1],
2059                 FloatPoint(
2060                     quad[1].x() + innerBorder.radii().bottomLeft().width(),
2061                     quad[1].y()),
2062                 FloatPoint(
2063                     quad[1].x(),
2064                     quad[1].y() - innerBorder.radii().bottomLeft().height()),
2065                 quad[1]);
2066         }
2067
2068         if (!innerBorder.radii().bottomRight().isZero()) {
2069             findIntersection(quad[3], quad[2],
2070                 FloatPoint(
2071                     quad[2].x() - innerBorder.radii().bottomRight().width(),
2072                     quad[2].y()),
2073                 FloatPoint(
2074                     quad[2].x(),
2075                     quad[2].y() - innerBorder.radii().bottomRight().height()),
2076                 quad[2]);
2077         }
2078         break;
2079
2080     case BSRight:
2081         quad[0] = outerRect.maxXMinYCorner();
2082         quad[1] = innerRect.maxXMinYCorner();
2083         quad[2] = innerRect.maxXMaxYCorner();
2084         quad[3] = outerRect.maxXMaxYCorner();
2085
2086         if (!innerBorder.radii().topRight().isZero()) {
2087             findIntersection(quad[0], quad[1],
2088                 FloatPoint(
2089                     quad[1].x() - innerBorder.radii().topRight().width(),
2090                     quad[1].y()),
2091                 FloatPoint(
2092                     quad[1].x(),
2093                     quad[1].y() + innerBorder.radii().topRight().height()),
2094                 quad[1]);
2095         }
2096
2097         if (!innerBorder.radii().bottomRight().isZero()) {
2098             findIntersection(quad[3], quad[2],
2099                 FloatPoint(
2100                     quad[2].x() - innerBorder.radii().bottomRight().width(),
2101                     quad[2].y()),
2102                 FloatPoint(
2103                     quad[2].x(),
2104                     quad[2].y() - innerBorder.radii().bottomRight().height()),
2105                 quad[2]);
2106         }
2107         break;
2108     }
2109
2110     // If the border matches both of its adjacent sides, don't anti-alias the clip, and
2111     // if neither side matches, anti-alias the clip.
2112     if (firstEdgeMatches == secondEdgeMatches) {
2113         graphicsContext->clipConvexPolygon(4, quad, !firstEdgeMatches);
2114         return;
2115     }
2116
2117     // If antialiasing settings for the first edge and second edge is different,
2118     // they have to be addressed separately. We do this by breaking the quad into
2119     // two parallelograms, made by moving quad[1] and quad[2].
2120     float ax = quad[1].x() - quad[0].x();
2121     float ay = quad[1].y() - quad[0].y();
2122     float bx = quad[2].x() - quad[1].x();
2123     float by = quad[2].y() - quad[1].y();
2124     float cx = quad[3].x() - quad[2].x();
2125     float cy = quad[3].y() - quad[2].y();
2126
2127     const static float kEpsilon = 1e-2f;
2128     float r1, r2;
2129     if (fabsf(bx) < kEpsilon && fabsf(by) < kEpsilon) {
2130         // The quad was actually a triangle.
2131         r1 = r2 = 1.0f;
2132     } else {
2133         // Extend parallelogram a bit to hide calculation error
2134         const static float kExtendFill = 1e-2f;
2135
2136         r1 = (-ax * by + ay * bx) / (cx * by - cy * bx) + kExtendFill;
2137         r2 = (-cx * by + cy * bx) / (ax * by - ay * bx) + kExtendFill;
2138     }
2139
2140     FloatPoint firstQuad[4];
2141     firstQuad[0] = quad[0];
2142     firstQuad[1] = quad[1];
2143     firstQuad[2] = FloatPoint(quad[3].x() + r2 * ax, quad[3].y() + r2 * ay);
2144     firstQuad[3] = quad[3];
2145     graphicsContext->clipConvexPolygon(4, firstQuad, !firstEdgeMatches);
2146
2147     FloatPoint secondQuad[4];
2148     secondQuad[0] = quad[0];
2149     secondQuad[1] = FloatPoint(quad[0].x() - r1 * cx, quad[0].y() - r1 * cy);
2150     secondQuad[2] = quad[2];
2151     secondQuad[3] = quad[3];
2152     graphicsContext->clipConvexPolygon(4, secondQuad, !secondEdgeMatches);
2153 }
2154
2155 } // namespace blink