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