src/third_party/skia/src/gpu/GrClipMaskManager.cpp

   1
   2 /*
   3  * Copyright 2012 Google Inc.
   4  *
   5  * Use of this source code is governed by a BSD-style license that can be
   6  * found in the LICENSE file.
   7  */
   8
   9 #include "GrClipMaskManager.h"
  10 #include "GrAAConvexPathRenderer.h"
  11 #include "GrAAHairLinePathRenderer.h"
  12 #include "GrAARectRenderer.h"
  13 #include "GrDrawTargetCaps.h"
  14 #include "GrPaint.h"
  15 #include "GrPathRenderer.h"
  16 #include "GrRenderTarget.h"
  17 #include "GrStencilBuffer.h"
  18 #include "GrSWMaskHelper.h"
  19 #include "SkRasterClip.h"
  20 #include "SkStrokeRec.h"
  21 #include "SkTLazy.h"
  22 #include "effects/GrTextureDomain.h"
  23 #include "effects/GrConvexPolyEffect.h"
  24 #include "effects/GrRRectEffect.h"
  25
  26 #define GR_AA_CLIP 1
  27
  28 typedef SkClipStack::Element Element;
  29
  30 ////////////////////////////////////////////////////////////////////////////////
  31 namespace {
  32 // set up the draw state to enable the aa clipping mask. Besides setting up the
  33 // stage matrix this also alters the vertex layout
  34 void setup_drawstate_aaclip(GrDrawTarget* gpu,
  35                             GrTexture* result,
  36                             const SkIRect &devBound) {
  37     GrDrawState* drawState = gpu->drawState();
  38     SkASSERT(drawState);
  39
  40     SkMatrix mat;
  41     // We want to use device coords to compute the texture coordinates. We set our matrix to be
  42     // equal to the view matrix followed by an offset to the devBound, and then a scaling matrix to
  43     // normalized coords. We apply this matrix to the vertex positions rather than local coords.
  44     mat.setIDiv(result->width(), result->height());
  45     mat.preTranslate(SkIntToScalar(-devBound.fLeft),
  46                      SkIntToScalar(-devBound.fTop));
  47     mat.preConcat(drawState->getViewMatrix());
  48
  49     SkIRect domainTexels = SkIRect::MakeWH(devBound.width(), devBound.height());
  50     // This could be a long-lived effect that is cached with the alpha-mask.
  51     drawState->addCoverageProcessor(
  52         GrTextureDomainEffect::Create(result,
  53                                       mat,
  54                                       GrTextureDomain::MakeTexelDomain(result, domainTexels),
  55                                       GrTextureDomain::kDecal_Mode,
  56                                       GrTextureParams::kNone_FilterMode,
  57                                       kPosition_GrCoordSet))->unref();
  58 }
  59
  60 bool path_needs_SW_renderer(GrContext* context,
  61                             GrDrawTarget* gpu,
  62                             const SkPath& origPath,
  63                             const SkStrokeRec& stroke,
  64                             bool doAA) {
  65     // the gpu alpha mask will draw the inverse paths as non-inverse to a temp buffer
  66     SkTCopyOnFirstWrite<SkPath> path(origPath);
  67     if (path->isInverseFillType()) {
  68         path.writable()->toggleInverseFillType();
  69     }
  70     // last (false) parameter disallows use of the SW path renderer
  71     GrPathRendererChain::DrawType type = doAA ?
  72                                          GrPathRendererChain::kColorAntiAlias_DrawType :
  73                                          GrPathRendererChain::kColor_DrawType;
  74
  75     return NULL == context->getPathRenderer(*path, stroke, gpu, false, type);
  76 }
  77
  78 }
  79
  80 /*
  81  * This method traverses the clip stack to see if the GrSoftwarePathRenderer
  82  * will be used on any element. If so, it returns true to indicate that the
  83  * entire clip should be rendered in SW and then uploaded en masse to the gpu.
  84  */
  85 bool GrClipMaskManager::useSWOnlyPath(const GrReducedClip::ElementList& elements) {
  86
  87     // TODO: generalize this function so that when
  88     // a clip gets complex enough it can just be done in SW regardless
  89     // of whether it would invoke the GrSoftwarePathRenderer.
  90     SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
  91
  92     for (GrReducedClip::ElementList::Iter iter(elements.headIter()); iter.get(); iter.next()) {
  93         const Element* element = iter.get();
  94         // rects can always be drawn directly w/o using the software path
  95         // Skip rrects once we're drawing them directly.
  96         if (Element::kRect_Type != element->getType()) {
  97             SkPath path;
  98             element->asPath(&path);
  99             if (path_needs_SW_renderer(this->getContext(), fClipTarget, path, stroke,
 100                                        element->isAA())) {
 101                 return true;
 102             }
 103         }
 104     }
 105     return false;
 106 }
 107
 108 bool GrClipMaskManager::installClipEffects(const GrReducedClip::ElementList& elements,
 109                                            GrDrawState::AutoRestoreEffects* are,
 110                                            const SkVector& clipToRTOffset,
 111                                            const SkRect* drawBounds) {
 112
 113     GrDrawState* drawState = fClipTarget->drawState();
 114     SkRect boundsInClipSpace;
 115     if (drawBounds) {
 116         boundsInClipSpace = *drawBounds;
 117         boundsInClipSpace.offset(-clipToRTOffset.fX, -clipToRTOffset.fY);
 118     }
 119
 120     are->set(drawState);
 121     GrRenderTarget* rt = drawState->getRenderTarget();
 122     GrReducedClip::ElementList::Iter iter(elements);
 123
 124     bool setARE = false;
 125     bool failed = false;
 126
 127     while (iter.get()) {
 128         SkRegion::Op op = iter.get()->getOp();
 129         bool invert;
 130         bool skip = false;
 131         switch (op) {
 132             case SkRegion::kReplace_Op:
 133                 SkASSERT(iter.get() == elements.head());
 134                 // Fallthrough, handled same as intersect.
 135             case SkRegion::kIntersect_Op:
 136                 invert = false;
 137                 if (drawBounds && iter.get()->contains(boundsInClipSpace)) {
 138                     skip = true;
 139                 }
 140                 break;
 141             case SkRegion::kDifference_Op:
 142                 invert = true;
 143                 // We don't currently have a cheap test for whether a rect is fully outside an
 144                 // element's primitive, so don't attempt to set skip.
 145                 break;
 146             default:
 147                 failed = true;
 148                 break;
 149         }
 150         if (failed) {
 151             break;
 152         }
 153
 154         if (!skip) {
 155             GrPrimitiveEdgeType edgeType;
 156             if (GR_AA_CLIP && iter.get()->isAA()) {
 157                 if (rt->isMultisampled()) {
 158                     // Coverage based AA clips don't place nicely with MSAA.
 159                     failed = true;
 160                     break;
 161                 }
 162                 edgeType =
 163                         invert ? kInverseFillAA_GrProcessorEdgeType : kFillAA_GrProcessorEdgeType;
 164             } else {
 165                 edgeType =
 166                         invert ? kInverseFillBW_GrProcessorEdgeType : kFillBW_GrProcessorEdgeType;
 167             }
 168             SkAutoTUnref<GrFragmentProcessor> fp;
 169             switch (iter.get()->getType()) {
 170                 case SkClipStack::Element::kPath_Type:
 171                     fp.reset(GrConvexPolyEffect::Create(edgeType, iter.get()->getPath(),
 172                         &clipToRTOffset));
 173                     break;
 174                 case SkClipStack::Element::kRRect_Type: {
 175                     SkRRect rrect = iter.get()->getRRect();
 176                     rrect.offset(clipToRTOffset.fX, clipToRTOffset.fY);
 177                     fp.reset(GrRRectEffect::Create(edgeType, rrect));
 178                     break;
 179                 }
 180                 case SkClipStack::Element::kRect_Type: {
 181                     SkRect rect = iter.get()->getRect();
 182                     rect.offset(clipToRTOffset.fX, clipToRTOffset.fY);
 183                     fp.reset(GrConvexPolyEffect::Create(edgeType, rect));
 184                     break;
 185                 }
 186                 default:
 187                     break;
 188             }
 189             if (fp) {
 190                 if (!setARE) {
 191                     are->set(fClipTarget->drawState());
 192                     setARE = true;
 193                 }
 194                 fClipTarget->drawState()->addCoverageProcessor(fp);
 195             } else {
 196                 failed = true;
 197                 break;
 198             }
 199         }
 200         iter.next();
 201     }
 202
 203     if (failed) {
 204         are->set(NULL);
 205     }
 206
 207     return !failed;
 208 }
 209
 210 ////////////////////////////////////////////////////////////////////////////////
 211 // sort out what kind of clip mask needs to be created: alpha, stencil,
 212 // scissor, or entirely software
 213 bool GrClipMaskManager::setupClipping(const GrClipData* clipDataIn,
 214                                       const SkRect* devBounds,
 215                                       GrDrawState::AutoRestoreEffects* are,
 216                                       GrDrawState::AutoRestoreStencil* ars,
 217                                       ScissorState* scissorState) {
 218     fCurrClipMaskType = kNone_ClipMaskType;
 219     if (kRespectClip_StencilClipMode == fClipMode) {
 220         fClipMode = kIgnoreClip_StencilClipMode;
 221     }
 222
 223     GrReducedClip::ElementList elements(16);
 224     int32_t genID;
 225     GrReducedClip::InitialState initialState;
 226     SkIRect clipSpaceIBounds;
 227     bool requiresAA;
 228
 229     GrDrawState* drawState = fClipTarget->drawState();
 230
 231     const GrRenderTarget* rt = drawState->getRenderTarget();
 232     // GrDrawTarget should have filtered this for us
 233     SkASSERT(rt);
 234
 235     bool ignoreClip = !drawState->isClipState() || clipDataIn->fClipStack->isWideOpen();
 236     if (!ignoreClip) {
 237         SkIRect clipSpaceRTIBounds = SkIRect::MakeWH(rt->width(), rt->height());
 238         clipSpaceRTIBounds.offset(clipDataIn->fOrigin);
 239         GrReducedClip::ReduceClipStack(*clipDataIn->fClipStack,
 240                                        clipSpaceRTIBounds,
 241                                        &elements,
 242                                        &genID,
 243                                        &initialState,
 244                                        &clipSpaceIBounds,
 245                                        &requiresAA);
 246         if (elements.isEmpty()) {
 247             if (GrReducedClip::kAllIn_InitialState == initialState) {
 248                 ignoreClip = clipSpaceIBounds == clipSpaceRTIBounds;
 249             } else {
 250                 return false;
 251             }
 252         }
 253     }
 254
 255     if (ignoreClip) {
 256         this->setDrawStateStencil(ars);
 257         return true;
 258     }
 259
 260     // An element count of 4 was chosen because of the common pattern in Blink of:
 261     //   isect RR
 262     //   diff  RR
 263     //   isect convex_poly
 264     //   isect convex_poly
 265     // when drawing rounded div borders. This could probably be tuned based on a
 266     // configuration's relative costs of switching RTs to generate a mask vs
 267     // longer shaders.
 268     if (elements.count() <= 4) {
 269         SkVector clipToRTOffset = { SkIntToScalar(-clipDataIn->fOrigin.fX),
 270                                     SkIntToScalar(-clipDataIn->fOrigin.fY) };
 271         if (elements.isEmpty() ||
 272             (requiresAA && this->installClipEffects(elements, are, clipToRTOffset, devBounds))) {
 273             SkIRect scissorSpaceIBounds(clipSpaceIBounds);
 274             scissorSpaceIBounds.offset(-clipDataIn->fOrigin);
 275             if (NULL == devBounds ||
 276                 !SkRect::Make(scissorSpaceIBounds).contains(*devBounds)) {
 277                 scissorState->set(scissorSpaceIBounds);
 278             }
 279             this->setDrawStateStencil(ars);
 280             return true;
 281         }
 282     }
 283
 284 #if GR_AA_CLIP
 285     // If MSAA is enabled we can do everything in the stencil buffer.
 286     if (0 == rt->numSamples() && requiresAA) {
 287         GrTexture* result = NULL;
 288
 289         if (this->useSWOnlyPath(elements)) {
 290             // The clip geometry is complex enough that it will be more efficient to create it
 291             // entirely in software
 292             result = this->createSoftwareClipMask(genID,
 293                                                   initialState,
 294                                                   elements,
 295                                                   clipSpaceIBounds);
 296         } else {
 297             result = this->createAlphaClipMask(genID,
 298                                                initialState,
 299                                                elements,
 300                                                clipSpaceIBounds);
 301         }
 302
 303         if (result) {
 304             // The mask's top left coord should be pinned to the rounded-out top left corner of
 305             // clipSpace bounds. We determine the mask's position WRT to the render target here.
 306             SkIRect rtSpaceMaskBounds = clipSpaceIBounds;
 307             rtSpaceMaskBounds.offset(-clipDataIn->fOrigin);
 308             are->set(fClipTarget->drawState());
 309             setup_drawstate_aaclip(fClipTarget, result, rtSpaceMaskBounds);
 310             this->setDrawStateStencil(ars);
 311             return true;
 312         }
 313         // if alpha clip mask creation fails fall through to the non-AA code paths
 314     }
 315 #endif // GR_AA_CLIP
 316
 317     // Either a hard (stencil buffer) clip was explicitly requested or an anti-aliased clip couldn't
 318     // be created. In either case, free up the texture in the anti-aliased mask cache.
 319     // TODO: this may require more investigation. Ganesh performs a lot of utility draws (e.g.,
 320     // clears, InOrderDrawBuffer playbacks) that hit the stencil buffer path. These may be
 321     // "incorrectly" clearing the AA cache.
 322     fAACache.reset();
 323
 324     // use the stencil clip if we can't represent the clip as a rectangle.
 325     SkIPoint clipSpaceToStencilSpaceOffset = -clipDataIn->fOrigin;
 326     this->createStencilClipMask(genID,
 327                                 initialState,
 328                                 elements,
 329                                 clipSpaceIBounds,
 330                                 clipSpaceToStencilSpaceOffset);
 331
 332     // This must occur after createStencilClipMask. That function may change the scissor. Also, it
 333     // only guarantees that the stencil mask is correct within the bounds it was passed, so we must
 334     // use both stencil and scissor test to the bounds for the final draw.
 335     SkIRect scissorSpaceIBounds(clipSpaceIBounds);
 336     scissorSpaceIBounds.offset(clipSpaceToStencilSpaceOffset);
 337     scissorState->set(scissorSpaceIBounds);
 338     this->setDrawStateStencil(ars);
 339     return true;
 340 }
 341
 342 #define VISUALIZE_COMPLEX_CLIP 0
 343
 344 #if VISUALIZE_COMPLEX_CLIP
 345     #include "SkRandom.h"
 346     SkRandom gRandom;
 347     #define SET_RANDOM_COLOR drawState->setColor(0xff000000 | gRandom.nextU());
 348 #else
 349     #define SET_RANDOM_COLOR
 350 #endif
 351
 352 namespace {
 353
 354 ////////////////////////////////////////////////////////////////////////////////
 355 // set up the OpenGL blend function to perform the specified
 356 // boolean operation for alpha clip mask creation
 357 void setup_boolean_blendcoeffs(GrDrawState* drawState, SkRegion::Op op) {
 358
 359     switch (op) {
 360         case SkRegion::kReplace_Op:
 361             drawState->setBlendFunc(kOne_GrBlendCoeff, kZero_GrBlendCoeff);
 362             break;
 363         case SkRegion::kIntersect_Op:
 364             drawState->setBlendFunc(kDC_GrBlendCoeff, kZero_GrBlendCoeff);
 365             break;
 366         case SkRegion::kUnion_Op:
 367             drawState->setBlendFunc(kOne_GrBlendCoeff, kISC_GrBlendCoeff);
 368             break;
 369         case SkRegion::kXOR_Op:
 370             drawState->setBlendFunc(kIDC_GrBlendCoeff, kISC_GrBlendCoeff);
 371             break;
 372         case SkRegion::kDifference_Op:
 373             drawState->setBlendFunc(kZero_GrBlendCoeff, kISC_GrBlendCoeff);
 374             break;
 375         case SkRegion::kReverseDifference_Op:
 376             drawState->setBlendFunc(kIDC_GrBlendCoeff, kZero_GrBlendCoeff);
 377             break;
 378         default:
 379             SkASSERT(false);
 380             break;
 381     }
 382 }
 383
 384 }
 385
 386 ////////////////////////////////////////////////////////////////////////////////
 387 bool GrClipMaskManager::drawElement(GrTexture* target,
 388                                     const SkClipStack::Element* element,
 389                                     GrPathRenderer* pr) {
 390     GrDrawState* drawState = fClipTarget->drawState();
 391
 392     drawState->setRenderTarget(target->asRenderTarget());
 393
 394     // TODO: Draw rrects directly here.
 395     switch (element->getType()) {
 396         case Element::kEmpty_Type:
 397             SkDEBUGFAIL("Should never get here with an empty element.");
 398             break;
 399         case Element::kRect_Type:
 400             // TODO: Do rects directly to the accumulator using a aa-rect GrProcessor that covers
 401             // the entire mask bounds and writes 0 outside the rect.
 402             if (element->isAA()) {
 403                 this->getContext()->getAARectRenderer()->fillAARect(fClipTarget,
 404                                                                     element->getRect(),
 405                                                                     SkMatrix::I(),
 406                                                                     element->getRect());
 407             } else {
 408                 fClipTarget->drawSimpleRect(element->getRect());
 409             }
 410             return true;
 411         default: {
 412             SkPath path;
 413             element->asPath(&path);
 414             path.setIsVolatile(true);
 415             if (path.isInverseFillType()) {
 416                 path.toggleInverseFillType();
 417             }
 418             SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
 419             if (NULL == pr) {
 420                 GrPathRendererChain::DrawType type;
 421                 type = element->isAA() ? GrPathRendererChain::kColorAntiAlias_DrawType :
 422                                          GrPathRendererChain::kColor_DrawType;
 423                 pr = this->getContext()->getPathRenderer(path, stroke, fClipTarget, false, type);
 424             }
 425             if (NULL == pr) {
 426                 return false;
 427             }
 428             pr->drawPath(path, stroke, fClipTarget, element->isAA());
 429             break;
 430         }
 431     }
 432     return true;
 433 }
 434
 435 bool GrClipMaskManager::canStencilAndDrawElement(GrTexture* target,
 436                                                  const SkClipStack::Element* element,
 437                                                  GrPathRenderer** pr) {
 438     GrDrawState* drawState = fClipTarget->drawState();
 439     drawState->setRenderTarget(target->asRenderTarget());
 440
 441     if (Element::kRect_Type == element->getType()) {
 442         return true;
 443     } else {
 444         // We shouldn't get here with an empty clip element.
 445         SkASSERT(Element::kEmpty_Type != element->getType());
 446         SkPath path;
 447         element->asPath(&path);
 448         if (path.isInverseFillType()) {
 449             path.toggleInverseFillType();
 450         }
 451         SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
 452         GrPathRendererChain::DrawType type = element->isAA() ?
 453             GrPathRendererChain::kStencilAndColorAntiAlias_DrawType :
 454             GrPathRendererChain::kStencilAndColor_DrawType;
 455         *pr = this->getContext()->getPathRenderer(path, stroke, fClipTarget, false, type);
 456         return SkToBool(*pr);
 457     }
 458 }
 459
 460 void GrClipMaskManager::mergeMask(GrTexture* dstMask,
 461                                   GrTexture* srcMask,
 462                                   SkRegion::Op op,
 463                                   const SkIRect& dstBound,
 464                                   const SkIRect& srcBound) {
 465     GrDrawState::AutoViewMatrixRestore avmr;
 466     GrDrawState* drawState = fClipTarget->drawState();
 467     SkAssertResult(avmr.setIdentity(drawState));
 468     GrDrawState::AutoRestoreEffects are(drawState);
 469
 470     drawState->setRenderTarget(dstMask->asRenderTarget());
 471
 472     setup_boolean_blendcoeffs(drawState, op);
 473
 474     SkMatrix sampleM;
 475     sampleM.setIDiv(srcMask->width(), srcMask->height());
 476
 477     drawState->addColorProcessor(
 478         GrTextureDomainEffect::Create(srcMask,
 479                                       sampleM,
 480                                       GrTextureDomain::MakeTexelDomain(srcMask, srcBound),
 481                                       GrTextureDomain::kDecal_Mode,
 482                                       GrTextureParams::kNone_FilterMode))->unref();
 483     fClipTarget->drawSimpleRect(SkRect::Make(dstBound));
 484 }
 485
 486 GrTexture* GrClipMaskManager::createTempMask(int width, int height) {
 487     GrSurfaceDesc desc;
 488     desc.fFlags = kRenderTarget_GrSurfaceFlag|kNoStencil_GrSurfaceFlag;
 489     desc.fWidth = width;
 490     desc.fHeight = height;
 491     desc.fConfig = kAlpha_8_GrPixelConfig;
 492
 493     return this->getContext()->refScratchTexture(desc, GrContext::kApprox_ScratchTexMatch);
 494 }
 495
 496 ////////////////////////////////////////////////////////////////////////////////
 497 // Return the texture currently in the cache if it exists. Otherwise, return NULL
 498 GrTexture* GrClipMaskManager::getCachedMaskTexture(int32_t elementsGenID,
 499                                                    const SkIRect& clipSpaceIBounds) {
 500     bool cached = fAACache.canReuse(elementsGenID, clipSpaceIBounds);
 501     if (!cached) {
 502         return NULL;
 503     }
 504
 505     return fAACache.getLastMask();
 506 }
 507
 508 ////////////////////////////////////////////////////////////////////////////////
 509 // Allocate a texture in the texture cache. This function returns the texture
 510 // allocated (or NULL on error).
 511 GrTexture* GrClipMaskManager::allocMaskTexture(int32_t elementsGenID,
 512                                                const SkIRect& clipSpaceIBounds,
 513                                                bool willUpload) {
 514     // Since we are setting up the cache we should free up the
 515     // currently cached mask so it can be reused.
 516     fAACache.reset();
 517
 518     GrSurfaceDesc desc;
 519     desc.fFlags = willUpload ? kNone_GrSurfaceFlags : kRenderTarget_GrSurfaceFlag;
 520     desc.fWidth = clipSpaceIBounds.width();
 521     desc.fHeight = clipSpaceIBounds.height();
 522     desc.fConfig = kRGBA_8888_GrPixelConfig;
 523     if (willUpload || this->getContext()->isConfigRenderable(kAlpha_8_GrPixelConfig, false)) {
 524         // We would always like A8 but it isn't supported on all platforms
 525         desc.fConfig = kAlpha_8_GrPixelConfig;
 526     }
 527
 528     fAACache.acquireMask(elementsGenID, desc, clipSpaceIBounds);
 529     return fAACache.getLastMask();
 530 }
 531
 532 ////////////////////////////////////////////////////////////////////////////////
 533 // Create a 8-bit clip mask in alpha
 534 GrTexture* GrClipMaskManager::createAlphaClipMask(int32_t elementsGenID,
 535                                                   GrReducedClip::InitialState initialState,
 536                                                   const GrReducedClip::ElementList& elements,
 537                                                   const SkIRect& clipSpaceIBounds) {
 538     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 539
 540     // First, check for cached texture
 541     GrTexture* result = this->getCachedMaskTexture(elementsGenID, clipSpaceIBounds);
 542     if (result) {
 543         fCurrClipMaskType = kAlpha_ClipMaskType;
 544         return result;
 545     }
 546
 547     // There's no texture in the cache. Let's try to allocate it then.
 548     result = this->allocMaskTexture(elementsGenID, clipSpaceIBounds, false);
 549     if (NULL == result) {
 550         fAACache.reset();
 551         return NULL;
 552     }
 553
 554     // The top-left of the mask corresponds to the top-left corner of the bounds.
 555     SkVector clipToMaskOffset = {
 556         SkIntToScalar(-clipSpaceIBounds.fLeft),
 557         SkIntToScalar(-clipSpaceIBounds.fTop)
 558     };
 559     // The texture may be larger than necessary, this rect represents the part of the texture
 560     // we populate with a rasterization of the clip.
 561     SkIRect maskSpaceIBounds = SkIRect::MakeWH(clipSpaceIBounds.width(), clipSpaceIBounds.height());
 562
 563     // Set the matrix so that rendered clip elements are transformed to mask space from clip space.
 564     SkMatrix translate;
 565     translate.setTranslate(clipToMaskOffset);
 566     GrDrawTarget::AutoGeometryAndStatePush agasp(fClipTarget, GrDrawTarget::kReset_ASRInit,
 567                                                  &translate);
 568
 569     GrDrawState* drawState = fClipTarget->drawState();
 570
 571     // We're drawing a coverage mask and want coverage to be run through the blend function.
 572     drawState->enableState(GrDrawState::kCoverageDrawing_StateBit);
 573
 574     // The scratch texture that we are drawing into can be substantially larger than the mask. Only
 575     // clear the part that we care about.
 576     fClipTarget->clear(&maskSpaceIBounds,
 577                        GrReducedClip::kAllIn_InitialState == initialState ? 0xffffffff : 0x00000000,
 578                        true,
 579                        result->asRenderTarget());
 580
 581     // When we use the stencil in the below loop it is important to have this clip installed.
 582     // The second pass that zeros the stencil buffer renders the rect maskSpaceIBounds so the first
 583     // pass must not set values outside of this bounds or stencil values outside the rect won't be
 584     // cleared.
 585     GrDrawTarget::AutoClipRestore acr(fClipTarget, maskSpaceIBounds);
 586     drawState->enableState(GrDrawState::kClip_StateBit);
 587
 588     SkAutoTUnref<GrTexture> temp;
 589     // walk through each clip element and perform its set op
 590     for (GrReducedClip::ElementList::Iter iter = elements.headIter(); iter.get(); iter.next()) {
 591         const Element* element = iter.get();
 592         SkRegion::Op op = element->getOp();
 593         bool invert = element->isInverseFilled();
 594
 595         if (invert || SkRegion::kIntersect_Op == op || SkRegion::kReverseDifference_Op == op) {
 596             GrPathRenderer* pr = NULL;
 597             bool useTemp = !this->canStencilAndDrawElement(result, element, &pr);
 598             GrTexture* dst;
 599             // This is the bounds of the clip element in the space of the alpha-mask. The temporary
 600             // mask buffer can be substantially larger than the actually clip stack element. We
 601             // touch the minimum number of pixels necessary and use decal mode to combine it with
 602             // the accumulator.
 603             SkIRect maskSpaceElementIBounds;
 604
 605             if (useTemp) {
 606                 if (invert) {
 607                     maskSpaceElementIBounds = maskSpaceIBounds;
 608                 } else {
 609                     SkRect elementBounds = element->getBounds();
 610                     elementBounds.offset(clipToMaskOffset);
 611                     elementBounds.roundOut(&maskSpaceElementIBounds);
 612                 }
 613
 614                 if (!temp) {
 615                     temp.reset(this->createTempMask(maskSpaceIBounds.fRight,
 616                                                     maskSpaceIBounds.fBottom));
 617                     if (!temp) {
 618                         fAACache.reset();
 619                         return NULL;
 620                     }
 621                 }
 622                 dst = temp;
 623                 // clear the temp target and set blend to replace
 624                 fClipTarget->clear(&maskSpaceElementIBounds,
 625                             invert ? 0xffffffff : 0x00000000,
 626                             true,
 627                             dst->asRenderTarget());
 628                 setup_boolean_blendcoeffs(drawState, SkRegion::kReplace_Op);
 629
 630             } else {
 631                 // draw directly into the result with the stencil set to make the pixels affected
 632                 // by the clip shape be non-zero.
 633                 dst = result;
 634                 GR_STATIC_CONST_SAME_STENCIL(kStencilInElement,
 635                                              kReplace_StencilOp,
 636                                              kReplace_StencilOp,
 637                                              kAlways_StencilFunc,
 638                                              0xffff,
 639                                              0xffff,
 640                                              0xffff);
 641                 drawState->setStencil(kStencilInElement);
 642                 setup_boolean_blendcoeffs(drawState, op);
 643             }
 644
 645             drawState->setAlpha(invert ? 0x00 : 0xff);
 646
 647             if (!this->drawElement(dst, element, pr)) {
 648                 fAACache.reset();
 649                 return NULL;
 650             }
 651
 652             if (useTemp) {
 653                 // Now draw into the accumulator using the real operation and the temp buffer as a
 654                 // texture
 655                 this->mergeMask(result,
 656                                 temp,
 657                                 op,
 658                                 maskSpaceIBounds,
 659                                 maskSpaceElementIBounds);
 660             } else {
 661                 // Draw to the exterior pixels (those with a zero stencil value).
 662                 drawState->setAlpha(invert ? 0xff : 0x00);
 663                 GR_STATIC_CONST_SAME_STENCIL(kDrawOutsideElement,
 664                                              kZero_StencilOp,
 665                                              kZero_StencilOp,
 666                                              kEqual_StencilFunc,
 667                                              0xffff,
 668                                              0x0000,
 669                                              0xffff);
 670                 drawState->setStencil(kDrawOutsideElement);
 671                 fClipTarget->drawSimpleRect(clipSpaceIBounds);
 672                 drawState->disableStencil();
 673             }
 674         } else {
 675             // all the remaining ops can just be directly draw into the accumulation buffer
 676             drawState->setAlpha(0xff);
 677             setup_boolean_blendcoeffs(drawState, op);
 678             this->drawElement(result, element);
 679         }
 680     }
 681
 682     fCurrClipMaskType = kAlpha_ClipMaskType;
 683     return result;
 684 }
 685
 686 ////////////////////////////////////////////////////////////////////////////////
 687 // Create a 1-bit clip mask in the stencil buffer. 'devClipBounds' are in device
 688 // (as opposed to canvas) coordinates
 689 bool GrClipMaskManager::createStencilClipMask(int32_t elementsGenID,
 690                                               GrReducedClip::InitialState initialState,
 691                                               const GrReducedClip::ElementList& elements,
 692                                               const SkIRect& clipSpaceIBounds,
 693                                               const SkIPoint& clipSpaceToStencilOffset) {
 694
 695     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 696
 697     GrDrawState* drawState = fClipTarget->drawState();
 698     SkASSERT(drawState->isClipState());
 699
 700     GrRenderTarget* rt = drawState->getRenderTarget();
 701     SkASSERT(rt);
 702
 703     // TODO: dynamically attach a SB when needed.
 704     GrStencilBuffer* stencilBuffer = rt->getStencilBuffer();
 705     if (NULL == stencilBuffer) {
 706         return false;
 707     }
 708
 709     if (stencilBuffer->mustRenderClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset)) {
 710         stencilBuffer->setLastClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset);
 711
 712         // Set the matrix so that rendered clip elements are transformed from clip to stencil space.
 713         SkVector translate = {
 714             SkIntToScalar(clipSpaceToStencilOffset.fX),
 715             SkIntToScalar(clipSpaceToStencilOffset.fY)
 716         };
 717         SkMatrix matrix;
 718         matrix.setTranslate(translate);
 719         GrDrawTarget::AutoGeometryAndStatePush agasp(fClipTarget, GrDrawTarget::kReset_ASRInit,
 720                                                      &matrix);
 721         drawState = fClipTarget->drawState();
 722
 723         drawState->setRenderTarget(rt);
 724
 725         // We set the current clip to the bounds so that our recursive draws are scissored to them.
 726         SkIRect stencilSpaceIBounds(clipSpaceIBounds);
 727         stencilSpaceIBounds.offset(clipSpaceToStencilOffset);
 728         GrDrawTarget::AutoClipRestore acr(fClipTarget, stencilSpaceIBounds);
 729         drawState->enableState(GrDrawState::kClip_StateBit);
 730
 731 #if !VISUALIZE_COMPLEX_CLIP
 732         drawState->enableState(GrDrawState::kNoColorWrites_StateBit);
 733 #endif
 734
 735         int clipBit = stencilBuffer->bits();
 736         SkASSERT((clipBit <= 16) && "Ganesh only handles 16b or smaller stencil buffers");
 737         clipBit = (1 << (clipBit-1));
 738
 739         fClipTarget->clearStencilClip(stencilSpaceIBounds,
 740                                       GrReducedClip::kAllIn_InitialState == initialState,
 741                                       rt);
 742
 743         // walk through each clip element and perform its set op
 744         // with the existing clip.
 745         for (GrReducedClip::ElementList::Iter iter(elements.headIter()); iter.get(); iter.next()) {
 746             const Element* element = iter.get();
 747             bool fillInverted = false;
 748             // enabled at bottom of loop
 749             fClipMode = kIgnoreClip_StencilClipMode;
 750             // if the target is MSAA then we want MSAA enabled when the clip is soft
 751             if (rt->isMultisampled()) {
 752                 drawState->setState(GrDrawState::kHWAntialias_StateBit, element->isAA());
 753             }
 754
 755             // This will be used to determine whether the clip shape can be rendered into the
 756             // stencil with arbitrary stencil settings.
 757             GrPathRenderer::StencilSupport stencilSupport;
 758
 759             SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
 760
 761             SkRegion::Op op = element->getOp();
 762
 763             GrPathRenderer* pr = NULL;
 764             SkPath clipPath;
 765             if (Element::kRect_Type == element->getType()) {
 766                 stencilSupport = GrPathRenderer::kNoRestriction_StencilSupport;
 767                 fillInverted = false;
 768             } else {
 769                 element->asPath(&clipPath);
 770                 fillInverted = clipPath.isInverseFillType();
 771                 if (fillInverted) {
 772                     clipPath.toggleInverseFillType();
 773                 }
 774                 pr = this->getContext()->getPathRenderer(clipPath,
 775                                                          stroke,
 776                                                          fClipTarget,
 777                                                          false,
 778                                                          GrPathRendererChain::kStencilOnly_DrawType,
 779                                                          &stencilSupport);
 780                 if (NULL == pr) {
 781                     return false;
 782                 }
 783             }
 784
 785             int passes;
 786             GrStencilSettings stencilSettings[GrStencilSettings::kMaxStencilClipPasses];
 787
 788             bool canRenderDirectToStencil =
 789                 GrPathRenderer::kNoRestriction_StencilSupport == stencilSupport;
 790             bool canDrawDirectToClip; // Given the renderer, the element,
 791                                       // fill rule, and set operation can
 792                                       // we render the element directly to
 793                                       // stencil bit used for clipping.
 794             canDrawDirectToClip = GrStencilSettings::GetClipPasses(op,
 795                                                                    canRenderDirectToStencil,
 796                                                                    clipBit,
 797                                                                    fillInverted,
 798                                                                    &passes,
 799                                                                    stencilSettings);
 800
 801             // draw the element to the client stencil bits if necessary
 802             if (!canDrawDirectToClip) {
 803                 GR_STATIC_CONST_SAME_STENCIL(gDrawToStencil,
 804                                              kIncClamp_StencilOp,
 805                                              kIncClamp_StencilOp,
 806                                              kAlways_StencilFunc,
 807                                              0xffff,
 808                                              0x0000,
 809                                              0xffff);
 810                 SET_RANDOM_COLOR
 811                 if (Element::kRect_Type == element->getType()) {
 812                     *drawState->stencil() = gDrawToStencil;
 813                     fClipTarget->drawSimpleRect(element->getRect());
 814                 } else {
 815                     if (!clipPath.isEmpty()) {
 816                         if (canRenderDirectToStencil) {
 817                             *drawState->stencil() = gDrawToStencil;
 818                             pr->drawPath(clipPath, stroke, fClipTarget, false);
 819                         } else {
 820                             pr->stencilPath(clipPath, stroke, fClipTarget);
 821                         }
 822                     }
 823                 }
 824             }
 825
 826             // now we modify the clip bit by rendering either the clip
 827             // element directly or a bounding rect of the entire clip.
 828             fClipMode = kModifyClip_StencilClipMode;
 829             for (int p = 0; p < passes; ++p) {
 830                 *drawState->stencil() = stencilSettings[p];
 831                 if (canDrawDirectToClip) {
 832                     if (Element::kRect_Type == element->getType()) {
 833                         SET_RANDOM_COLOR
 834                         fClipTarget->drawSimpleRect(element->getRect());
 835                     } else {
 836                         SET_RANDOM_COLOR
 837                         pr->drawPath(clipPath, stroke, fClipTarget, false);
 838                     }
 839                 } else {
 840                     SET_RANDOM_COLOR
 841                     // The view matrix is setup to do clip space -> stencil space translation, so
 842                     // draw rect in clip space.
 843                     fClipTarget->drawSimpleRect(SkRect::Make(clipSpaceIBounds));
 844                 }
 845             }
 846         }
 847     }
 848     // set this last because recursive draws may overwrite it back to kNone.
 849     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 850     fCurrClipMaskType = kStencil_ClipMaskType;
 851     fClipMode = kRespectClip_StencilClipMode;
 852     return true;
 853 }
 854
 855
 856 // mapping of clip-respecting stencil funcs to normal stencil funcs
 857 // mapping depends on whether stencil-clipping is in effect.
 858 static const GrStencilFunc
 859     gSpecialToBasicStencilFunc[2][kClipStencilFuncCount] = {
 860     {// Stencil-Clipping is DISABLED,  we are effectively always inside the clip
 861         // In the Clip Funcs
 862         kAlways_StencilFunc,          // kAlwaysIfInClip_StencilFunc
 863         kEqual_StencilFunc,           // kEqualIfInClip_StencilFunc
 864         kLess_StencilFunc,            // kLessIfInClip_StencilFunc
 865         kLEqual_StencilFunc,          // kLEqualIfInClip_StencilFunc
 866         // Special in the clip func that forces user's ref to be 0.
 867         kNotEqual_StencilFunc,        // kNonZeroIfInClip_StencilFunc
 868                                       // make ref 0 and do normal nequal.
 869     },
 870     {// Stencil-Clipping is ENABLED
 871         // In the Clip Funcs
 872         kEqual_StencilFunc,           // kAlwaysIfInClip_StencilFunc
 873                                       // eq stencil clip bit, mask
 874                                       // out user bits.
 875
 876         kEqual_StencilFunc,           // kEqualIfInClip_StencilFunc
 877                                       // add stencil bit to mask and ref
 878
 879         kLess_StencilFunc,            // kLessIfInClip_StencilFunc
 880         kLEqual_StencilFunc,          // kLEqualIfInClip_StencilFunc
 881                                       // for both of these we can add
 882                                       // the clip bit to the mask and
 883                                       // ref and compare as normal
 884         // Special in the clip func that forces user's ref to be 0.
 885         kLess_StencilFunc,            // kNonZeroIfInClip_StencilFunc
 886                                       // make ref have only the clip bit set
 887                                       // and make comparison be less
 888                                       // 10..0 < 1..user_bits..
 889     }
 890 };
 891
 892 namespace {
 893 // Sets the settings to clip against the stencil buffer clip while ignoring the
 894 // client bits.
 895 const GrStencilSettings& basic_apply_stencil_clip_settings() {
 896     // stencil settings to use when clip is in stencil
 897     GR_STATIC_CONST_SAME_STENCIL_STRUCT(gSettings,
 898         kKeep_StencilOp,
 899         kKeep_StencilOp,
 900         kAlwaysIfInClip_StencilFunc,
 901         0x0000,
 902         0x0000,
 903         0x0000);
 904     return *GR_CONST_STENCIL_SETTINGS_PTR_FROM_STRUCT_PTR(&gSettings);
 905 }
 906 }
 907
 908 void GrClipMaskManager::setDrawStateStencil(GrDrawState::AutoRestoreStencil* ars) {
 909     // We make two copies of the StencilSettings here (except in the early
 910     // exit scenario. One copy from draw state to the stack var. Then another
 911     // from the stack var to the gpu. We could make this class hold a ptr to
 912     // GrGpu's fStencilSettings and eliminate the stack copy here.
 913
 914     const GrDrawState& drawState = fClipTarget->getDrawState();
 915
 916     // use stencil for clipping if clipping is enabled and the clip
 917     // has been written into the stencil.
 918
 919     GrStencilSettings settings;
 920     // The GrGpu client may not be using the stencil buffer but we may need to
 921     // enable it in order to respect a stencil clip.
 922     if (drawState.getStencil().isDisabled()) {
 923         if (GrClipMaskManager::kRespectClip_StencilClipMode == fClipMode) {
 924             settings = basic_apply_stencil_clip_settings();
 925         } else {
 926             return;
 927         }
 928     } else {
 929         settings = drawState.getStencil();
 930     }
 931
 932     // TODO: dynamically attach a stencil buffer
 933     int stencilBits = 0;
 934     GrStencilBuffer* stencilBuffer = drawState.getRenderTarget()->getStencilBuffer();
 935     if (stencilBuffer) {
 936         stencilBits = stencilBuffer->bits();
 937     }
 938
 939     SkASSERT(fClipTarget->caps()->stencilWrapOpsSupport() || !settings.usesWrapOp());
 940     SkASSERT(fClipTarget->caps()->twoSidedStencilSupport() || !settings.isTwoSided());
 941     this->adjustStencilParams(&settings, fClipMode, stencilBits);
 942     ars->set(fClipTarget->drawState());
 943     fClipTarget->drawState()->setStencil(settings);
 944 }
 945
 946 void GrClipMaskManager::adjustStencilParams(GrStencilSettings* settings,
 947                                             StencilClipMode mode,
 948                                             int stencilBitCnt) {
 949     SkASSERT(stencilBitCnt > 0);
 950
 951     if (kModifyClip_StencilClipMode == mode) {
 952         // We assume that this clip manager itself is drawing to the GrGpu and
 953         // has already setup the correct values.
 954         return;
 955     }
 956
 957     unsigned int clipBit = (1 << (stencilBitCnt - 1));
 958     unsigned int userBits = clipBit - 1;
 959
 960     GrStencilSettings::Face face = GrStencilSettings::kFront_Face;
 961     bool twoSided = fClipTarget->caps()->twoSidedStencilSupport();
 962
 963     bool finished = false;
 964     while (!finished) {
 965         GrStencilFunc func = settings->func(face);
 966         uint16_t writeMask = settings->writeMask(face);
 967         uint16_t funcMask = settings->funcMask(face);
 968         uint16_t funcRef = settings->funcRef(face);
 969
 970         SkASSERT((unsigned) func < kStencilFuncCount);
 971
 972         writeMask &= userBits;
 973
 974         if (func >= kBasicStencilFuncCount) {
 975             int respectClip = kRespectClip_StencilClipMode == mode;
 976             if (respectClip) {
 977                 // The GrGpu class should have checked this
 978                 SkASSERT(this->isClipInStencil());
 979                 switch (func) {
 980                     case kAlwaysIfInClip_StencilFunc:
 981                         funcMask = clipBit;
 982                         funcRef = clipBit;
 983                         break;
 984                     case kEqualIfInClip_StencilFunc:
 985                     case kLessIfInClip_StencilFunc:
 986                     case kLEqualIfInClip_StencilFunc:
 987                         funcMask = (funcMask & userBits) | clipBit;
 988                         funcRef  = (funcRef  & userBits) | clipBit;
 989                         break;
 990                     case kNonZeroIfInClip_StencilFunc:
 991                         funcMask = (funcMask & userBits) | clipBit;
 992                         funcRef = clipBit;
 993                         break;
 994                     default:
 995                         SkFAIL("Unknown stencil func");
 996                 }
 997             } else {
 998                 funcMask &= userBits;
 999                 funcRef &= userBits;
1000             }
1001             const GrStencilFunc* table =
1002                 gSpecialToBasicStencilFunc[respectClip];
1003             func = table[func - kBasicStencilFuncCount];
1004             SkASSERT(func >= 0 && func < kBasicStencilFuncCount);
1005         } else {
1006             funcMask &= userBits;
1007             funcRef &= userBits;
1008         }
1009
1010         settings->setFunc(face, func);
1011         settings->setWriteMask(face, writeMask);
1012         settings->setFuncMask(face, funcMask);
1013         settings->setFuncRef(face, funcRef);
1014
1015         if (GrStencilSettings::kFront_Face == face) {
1016             face = GrStencilSettings::kBack_Face;
1017             finished = !twoSided;
1018         } else {
1019             finished = true;
1020         }
1021     }
1022     if (!twoSided) {
1023         settings->copyFrontSettingsToBack();
1024     }
1025 }
1026
1027 ////////////////////////////////////////////////////////////////////////////////
1028 GrTexture* GrClipMaskManager::createSoftwareClipMask(int32_t elementsGenID,
1029                                                      GrReducedClip::InitialState initialState,
1030                                                      const GrReducedClip::ElementList& elements,
1031                                                      const SkIRect& clipSpaceIBounds) {
1032     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
1033
1034     GrTexture* result = this->getCachedMaskTexture(elementsGenID, clipSpaceIBounds);
1035     if (result) {
1036         return result;
1037     }
1038
1039     // The mask texture may be larger than necessary. We round out the clip space bounds and pin
1040     // the top left corner of the resulting rect to the top left of the texture.
1041     SkIRect maskSpaceIBounds = SkIRect::MakeWH(clipSpaceIBounds.width(), clipSpaceIBounds.height());
1042
1043     GrSWMaskHelper helper(this->getContext());
1044
1045     SkMatrix matrix;
1046     matrix.setTranslate(SkIntToScalar(-clipSpaceIBounds.fLeft),
1047                         SkIntToScalar(-clipSpaceIBounds.fTop));
1048     helper.init(maskSpaceIBounds, &matrix, false);
1049
1050     helper.clear(GrReducedClip::kAllIn_InitialState == initialState ? 0xFF : 0x00);
1051
1052     SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
1053
1054     for (GrReducedClip::ElementList::Iter iter(elements.headIter()) ; iter.get(); iter.next()) {
1055
1056         const Element* element = iter.get();
1057         SkRegion::Op op = element->getOp();
1058
1059         if (SkRegion::kIntersect_Op == op || SkRegion::kReverseDifference_Op == op) {
1060             // Intersect and reverse difference require modifying pixels outside of the geometry
1061             // that is being "drawn". In both cases we erase all the pixels outside of the geometry
1062             // but leave the pixels inside the geometry alone. For reverse difference we invert all
1063             // the pixels before clearing the ones outside the geometry.
1064             if (SkRegion::kReverseDifference_Op == op) {
1065                 SkRect temp = SkRect::Make(clipSpaceIBounds);
1066                 // invert the entire scene
1067                 helper.draw(temp, SkRegion::kXOR_Op, false, 0xFF);
1068             }
1069
1070             SkPath clipPath;
1071             element->asPath(&clipPath);
1072             clipPath.toggleInverseFillType();
1073             helper.draw(clipPath, stroke, SkRegion::kReplace_Op, element->isAA(), 0x00);
1074
1075             continue;
1076         }
1077
1078         // The other ops (union, xor, diff) only affect pixels inside
1079         // the geometry so they can just be drawn normally
1080         if (Element::kRect_Type == element->getType()) {
1081             helper.draw(element->getRect(), op, element->isAA(), 0xFF);
1082         } else {
1083             SkPath path;
1084             element->asPath(&path);
1085             helper.draw(path, stroke, op, element->isAA(), 0xFF);
1086         }
1087     }
1088
1089     // Allocate clip mask texture
1090     result = this->allocMaskTexture(elementsGenID, clipSpaceIBounds, true);
1091     if (NULL == result) {
1092         fAACache.reset();
1093         return NULL;
1094     }
1095     helper.toTexture(result);
1096
1097     fCurrClipMaskType = kAlpha_ClipMaskType;
1098     return result;
1099 }
1100
1101 ////////////////////////////////////////////////////////////////////////////////
1102 void GrClipMaskManager::purgeResources() {
1103     fAACache.purgeResources();
1104 }
1105
1106 void GrClipMaskManager::setClipTarget(GrClipTarget* clipTarget) {
1107     fClipTarget = clipTarget;
1108     fAACache.setContext(clipTarget->getContext());
1109 }
1110
1111 void GrClipMaskManager::adjustPathStencilParams(GrStencilSettings* settings) {
1112     const GrDrawState& drawState = fClipTarget->getDrawState();
1113
1114     // TODO: dynamically attach a stencil buffer
1115     int stencilBits = 0;
1116     GrStencilBuffer* stencilBuffer = drawState.getRenderTarget()->getStencilBuffer();
1117     if (stencilBuffer) {
1118         stencilBits = stencilBuffer->bits();
1119         this->adjustStencilParams(settings, fClipMode, stencilBits);
1120     }
1121 }