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 "effects/GrConvexPolyEffect.h"
  22 #include "effects/GrRRectEffect.h"
  23 #include "SkRasterClip.h"
  24 #include "SkStrokeRec.h"
  25 #include "SkTLazy.h"
  26
  27 #define GR_AA_CLIP 1
  28
  29 typedef SkClipStack::Element Element;
  30
  31 using namespace GrReducedClip;
  32
  33 ////////////////////////////////////////////////////////////////////////////////
  34 namespace {
  35 // set up the draw state to enable the aa clipping mask. Besides setting up the
  36 // stage matrix this also alters the vertex layout
  37 void setup_drawstate_aaclip(GrGpu* gpu,
  38                             GrTexture* result,
  39                             const SkIRect &devBound) {
  40     GrDrawState* drawState = gpu->drawState();
  41     SkASSERT(drawState);
  42
  43     SkMatrix mat;
  44     // We want to use device coords to compute the texture coordinates. We set our matrix to be
  45     // equal to the view matrix followed by an offset to the devBound, and then a scaling matrix to
  46     // normalized coords. We apply this matrix to the vertex positions rather than local coords.
  47     mat.setIDiv(result->width(), result->height());
  48     mat.preTranslate(SkIntToScalar(-devBound.fLeft),
  49                      SkIntToScalar(-devBound.fTop));
  50     mat.preConcat(drawState->getViewMatrix());
  51
  52     SkIRect domainTexels = SkIRect::MakeWH(devBound.width(), devBound.height());
  53     // This could be a long-lived effect that is cached with the alpha-mask.
  54     drawState->addCoverageEffect(
  55         GrTextureDomainEffect::Create(result,
  56                                       mat,
  57                                       GrTextureDomain::MakeTexelDomain(result, domainTexels),
  58                                       GrTextureDomain::kDecal_Mode,
  59                                       GrTextureParams::kNone_FilterMode,
  60                                       kPosition_GrCoordSet))->unref();
  61 }
  62
  63 bool path_needs_SW_renderer(GrContext* context,
  64                             GrGpu* gpu,
  65                             const SkPath& origPath,
  66                             const SkStrokeRec& stroke,
  67                             bool doAA) {
  68     // the gpu alpha mask will draw the inverse paths as non-inverse to a temp buffer
  69     SkTCopyOnFirstWrite<SkPath> path(origPath);
  70     if (path->isInverseFillType()) {
  71         path.writable()->toggleInverseFillType();
  72     }
  73     // last (false) parameter disallows use of the SW path renderer
  74     GrPathRendererChain::DrawType type = doAA ?
  75                                          GrPathRendererChain::kColorAntiAlias_DrawType :
  76                                          GrPathRendererChain::kColor_DrawType;
  77
  78     return NULL == context->getPathRenderer(*path, stroke, gpu, false, type);
  79 }
  80
  81 }
  82
  83 /*
  84  * This method traverses the clip stack to see if the GrSoftwarePathRenderer
  85  * will be used on any element. If so, it returns true to indicate that the
  86  * entire clip should be rendered in SW and then uploaded en masse to the gpu.
  87  */
  88 bool GrClipMaskManager::useSWOnlyPath(const ElementList& elements) {
  89
  90     // TODO: generalize this function so that when
  91     // a clip gets complex enough it can just be done in SW regardless
  92     // of whether it would invoke the GrSoftwarePathRenderer.
  93     SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
  94
  95     for (ElementList::Iter iter(elements.headIter()); iter.get(); iter.next()) {
  96         const Element* element = iter.get();
  97         // rects can always be drawn directly w/o using the software path
  98         // Skip rrects once we're drawing them directly.
  99         if (Element::kRect_Type != element->getType()) {
 100             SkPath path;
 101             element->asPath(&path);
 102             if (path_needs_SW_renderer(this->getContext(), fGpu, path, stroke, element->isAA())) {
 103                 return true;
 104             }
 105         }
 106     }
 107     return false;
 108 }
 109
 110 bool GrClipMaskManager::installClipEffects(const ElementList& elements,
 111                                            GrDrawState::AutoRestoreEffects* are,
 112                                            const SkVector& clipToRTOffset,
 113                                            const SkRect* drawBounds) {
 114
 115     GrDrawState* drawState = fGpu->drawState();
 116     SkRect boundsInClipSpace;
 117     if (NULL != drawBounds) {
 118         boundsInClipSpace = *drawBounds;
 119         boundsInClipSpace.offset(-clipToRTOffset.fX, -clipToRTOffset.fY);
 120     }
 121
 122     are->set(drawState);
 123     GrRenderTarget* rt = drawState->getRenderTarget();
 124     ElementList::Iter iter(elements);
 125
 126     bool setARE = false;
 127     bool failed = false;
 128
 129     while (NULL != iter.get()) {
 130         SkRegion::Op op = iter.get()->getOp();
 131         bool invert;
 132         bool skip = false;
 133         switch (op) {
 134             case SkRegion::kReplace_Op:
 135                 SkASSERT(iter.get() == elements.head());
 136                 // Fallthrough, handled same as intersect.
 137             case SkRegion::kIntersect_Op:
 138                 invert = false;
 139                 if (NULL != drawBounds && iter.get()->contains(boundsInClipSpace)) {
 140                     skip = true;
 141                 }
 142                 break;
 143             case SkRegion::kDifference_Op:
 144                 invert = true;
 145                 // We don't currently have a cheap test for whether a rect is fully outside an
 146                 // element's primitive, so don't attempt to set skip.
 147                 break;
 148             default:
 149                 failed = true;
 150                 break;
 151         }
 152         if (failed) {
 153             break;
 154         }
 155
 156         if (!skip) {
 157             GrEffectEdgeType edgeType;
 158             if (GR_AA_CLIP && iter.get()->isAA()) {
 159                 if (rt->isMultisampled()) {
 160                     // Coverage based AA clips don't place nicely with MSAA.
 161                     failed = true;
 162                     break;
 163                 }
 164                 edgeType = invert ? kInverseFillAA_GrEffectEdgeType : kFillAA_GrEffectEdgeType;
 165             } else {
 166                 edgeType = invert ? kInverseFillBW_GrEffectEdgeType : kFillBW_GrEffectEdgeType;
 167             }
 168             SkAutoTUnref<GrEffectRef> effect;
 169             switch (iter.get()->getType()) {
 170                 case SkClipStack::Element::kPath_Type:
 171                     effect.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                     effect.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                     effect.reset(GrConvexPolyEffect::Create(edgeType, rect));
 184                     break;
 185                 }
 186                 default:
 187                     break;
 188             }
 189             if (effect) {
 190                 if (!setARE) {
 191                     are->set(fGpu->drawState());
 192                     setARE = true;
 193                 }
 194                 fGpu->drawState()->addCoverageEffect(effect);
 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                                       GrDrawState::AutoRestoreEffects* are,
 215                                       const SkRect* devBounds) {
 216     fCurrClipMaskType = kNone_ClipMaskType;
 217
 218     ElementList elements(16);
 219     int32_t genID;
 220     InitialState initialState;
 221     SkIRect clipSpaceIBounds;
 222     bool requiresAA;
 223
 224     GrDrawState* drawState = fGpu->drawState();
 225
 226     const GrRenderTarget* rt = drawState->getRenderTarget();
 227     // GrDrawTarget should have filtered this for us
 228     SkASSERT(NULL != rt);
 229
 230     bool ignoreClip = !drawState->isClipState() || clipDataIn->fClipStack->isWideOpen();
 231
 232     if (!ignoreClip) {
 233         SkIRect clipSpaceRTIBounds = SkIRect::MakeWH(rt->width(), rt->height());
 234         clipSpaceRTIBounds.offset(clipDataIn->fOrigin);
 235         ReduceClipStack(*clipDataIn->fClipStack,
 236                         clipSpaceRTIBounds,
 237                         &elements,
 238                         &genID,
 239                         &initialState,
 240                         &clipSpaceIBounds,
 241                         &requiresAA);
 242         if (elements.isEmpty()) {
 243             if (kAllIn_InitialState == initialState) {
 244                 ignoreClip = clipSpaceIBounds == clipSpaceRTIBounds;
 245             } else {
 246                 return false;
 247             }
 248         }
 249     }
 250
 251     if (ignoreClip) {
 252         fGpu->disableScissor();
 253         this->setGpuStencil();
 254         return true;
 255     }
 256
 257     // An element count of 4 was chosen because of the common pattern in Blink of:
 258     //   isect RR
 259     //   diff  RR
 260     //   isect convex_poly
 261     //   isect convex_poly
 262     // when drawing rounded div borders. This could probably be tuned based on a
 263     // configuration's relative costs of switching RTs to generate a mask vs
 264     // longer shaders.
 265     if (elements.count() <= 4) {
 266         SkVector clipToRTOffset = { SkIntToScalar(-clipDataIn->fOrigin.fX),
 267                                     SkIntToScalar(-clipDataIn->fOrigin.fY) };
 268         if (elements.isEmpty() ||
 269             (requiresAA && this->installClipEffects(elements, are, clipToRTOffset, devBounds))) {
 270             SkIRect scissorSpaceIBounds(clipSpaceIBounds);
 271             scissorSpaceIBounds.offset(-clipDataIn->fOrigin);
 272             if (NULL == devBounds ||
 273                 !SkRect::Make(scissorSpaceIBounds).contains(*devBounds)) {
 274                 fGpu->enableScissor(scissorSpaceIBounds);
 275             } else {
 276                 fGpu->disableScissor();
 277             }
 278             this->setGpuStencil();
 279             return true;
 280         }
 281     }
 282
 283 #if GR_AA_CLIP
 284     // If MSAA is enabled we can do everything in the stencil buffer.
 285     if (0 == rt->numSamples() && requiresAA) {
 286         GrTexture* result = NULL;
 287
 288         if (this->useSWOnlyPath(elements)) {
 289             // The clip geometry is complex enough that it will be more efficient to create it
 290             // entirely in software
 291             result = this->createSoftwareClipMask(genID,
 292                                                   initialState,
 293                                                   elements,
 294                                                   clipSpaceIBounds);
 295         } else {
 296             result = this->createAlphaClipMask(genID,
 297                                                initialState,
 298                                                elements,
 299                                                clipSpaceIBounds);
 300         }
 301
 302         if (NULL != result) {
 303             // The mask's top left coord should be pinned to the rounded-out top left corner of
 304             // clipSpace bounds. We determine the mask's position WRT to the render target here.
 305             SkIRect rtSpaceMaskBounds = clipSpaceIBounds;
 306             rtSpaceMaskBounds.offset(-clipDataIn->fOrigin);
 307             are->set(fGpu->drawState());
 308             setup_drawstate_aaclip(fGpu, result, rtSpaceMaskBounds);
 309             fGpu->disableScissor();
 310             this->setGpuStencil();
 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     fGpu->enableScissor(scissorSpaceIBounds);
 338     this->setGpuStencil();
 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 = fGpu->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 GrEffect that covers the
 401             // entire mask bounds and writes 0 outside the rect.
 402             if (element->isAA()) {
 403                 getContext()->getAARectRenderer()->fillAARect(fGpu,
 404                                                               fGpu,
 405                                                               element->getRect(),
 406                                                               SkMatrix::I(),
 407                                                               element->getRect(),
 408                                                               false);
 409             } else {
 410                 fGpu->drawSimpleRect(element->getRect(), NULL);
 411             }
 412             return true;
 413         default: {
 414             SkPath path;
 415             element->asPath(&path);
 416             if (path.isInverseFillType()) {
 417                 path.toggleInverseFillType();
 418             }
 419             SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
 420             if (NULL == pr) {
 421                 GrPathRendererChain::DrawType type;
 422                 type = element->isAA() ? GrPathRendererChain::kColorAntiAlias_DrawType :
 423                                          GrPathRendererChain::kColor_DrawType;
 424                 pr = this->getContext()->getPathRenderer(path, stroke, fGpu, false, type);
 425             }
 426             if (NULL == pr) {
 427                 return false;
 428             }
 429             pr->drawPath(path, stroke, fGpu, element->isAA());
 430             break;
 431         }
 432     }
 433     return true;
 434 }
 435
 436 bool GrClipMaskManager::canStencilAndDrawElement(GrTexture* target,
 437                                                  const SkClipStack::Element* element,
 438                                                  GrPathRenderer** pr) {
 439     GrDrawState* drawState = fGpu->drawState();
 440     drawState->setRenderTarget(target->asRenderTarget());
 441
 442     if (Element::kRect_Type == element->getType()) {
 443         return true;
 444     } else {
 445         // We shouldn't get here with an empty clip element.
 446         SkASSERT(Element::kEmpty_Type != element->getType());
 447         SkPath path;
 448         element->asPath(&path);
 449         if (path.isInverseFillType()) {
 450             path.toggleInverseFillType();
 451         }
 452         SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
 453         GrPathRendererChain::DrawType type = element->isAA() ?
 454             GrPathRendererChain::kStencilAndColorAntiAlias_DrawType :
 455             GrPathRendererChain::kStencilAndColor_DrawType;
 456         *pr = this->getContext()->getPathRenderer(path, stroke, fGpu, false, type);
 457         return NULL != *pr;
 458     }
 459 }
 460
 461 void GrClipMaskManager::mergeMask(GrTexture* dstMask,
 462                                   GrTexture* srcMask,
 463                                   SkRegion::Op op,
 464                                   const SkIRect& dstBound,
 465                                   const SkIRect& srcBound) {
 466     GrDrawState::AutoViewMatrixRestore avmr;
 467     GrDrawState* drawState = fGpu->drawState();
 468     SkAssertResult(avmr.setIdentity(drawState));
 469     GrDrawState::AutoRestoreEffects are(drawState);
 470
 471     drawState->setRenderTarget(dstMask->asRenderTarget());
 472
 473     setup_boolean_blendcoeffs(drawState, op);
 474
 475     SkMatrix sampleM;
 476     sampleM.setIDiv(srcMask->width(), srcMask->height());
 477
 478     drawState->addColorEffect(
 479         GrTextureDomainEffect::Create(srcMask,
 480                                       sampleM,
 481                                       GrTextureDomain::MakeTexelDomain(srcMask, srcBound),
 482                                       GrTextureDomain::kDecal_Mode,
 483                                       GrTextureParams::kNone_FilterMode))->unref();
 484     fGpu->drawSimpleRect(SkRect::Make(dstBound), NULL);
 485 }
 486
 487 // get a texture to act as a temporary buffer for AA clip boolean operations
 488 // TODO: given the expense of createTexture we may want to just cache this too
 489 void GrClipMaskManager::getTemp(int width, int height, GrAutoScratchTexture* temp) {
 490     if (NULL != temp->texture()) {
 491         // we've already allocated the temp texture
 492         return;
 493     }
 494
 495     GrTextureDesc desc;
 496     desc.fFlags = kRenderTarget_GrTextureFlagBit|kNoStencil_GrTextureFlagBit;
 497     desc.fWidth = width;
 498     desc.fHeight = height;
 499     desc.fConfig = kAlpha_8_GrPixelConfig;
 500
 501     temp->set(this->getContext(), desc);
 502 }
 503
 504 ////////////////////////////////////////////////////////////////////////////////
 505 // Return the texture currently in the cache if it exists. Otherwise, return NULL
 506 GrTexture* GrClipMaskManager::getCachedMaskTexture(int32_t elementsGenID,
 507                                                    const SkIRect& clipSpaceIBounds) {
 508     bool cached = fAACache.canReuse(elementsGenID, clipSpaceIBounds);
 509     if (!cached) {
 510         return NULL;
 511     }
 512
 513     return fAACache.getLastMask();
 514 }
 515
 516 ////////////////////////////////////////////////////////////////////////////////
 517 // Allocate a texture in the texture cache. This function returns the texture
 518 // allocated (or NULL on error).
 519 GrTexture* GrClipMaskManager::allocMaskTexture(int32_t elementsGenID,
 520                                                const SkIRect& clipSpaceIBounds,
 521                                                bool willUpload) {
 522     // Since we are setting up the cache we should free up the
 523     // currently cached mask so it can be reused.
 524     fAACache.reset();
 525
 526     GrTextureDesc desc;
 527     desc.fFlags = willUpload ? kNone_GrTextureFlags : kRenderTarget_GrTextureFlagBit;
 528     desc.fWidth = clipSpaceIBounds.width();
 529     desc.fHeight = clipSpaceIBounds.height();
 530     desc.fConfig = kRGBA_8888_GrPixelConfig;
 531     if (willUpload || this->getContext()->isConfigRenderable(kAlpha_8_GrPixelConfig, false)) {
 532         // We would always like A8 but it isn't supported on all platforms
 533         desc.fConfig = kAlpha_8_GrPixelConfig;
 534     }
 535
 536     fAACache.acquireMask(elementsGenID, desc, clipSpaceIBounds);
 537     return fAACache.getLastMask();
 538 }
 539
 540 ////////////////////////////////////////////////////////////////////////////////
 541 // Create a 8-bit clip mask in alpha
 542 GrTexture* GrClipMaskManager::createAlphaClipMask(int32_t elementsGenID,
 543                                                   InitialState initialState,
 544                                                   const ElementList& elements,
 545                                                   const SkIRect& clipSpaceIBounds) {
 546     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 547
 548     // First, check for cached texture
 549     GrTexture* result = this->getCachedMaskTexture(elementsGenID, clipSpaceIBounds);
 550     if (NULL != result) {
 551         fCurrClipMaskType = kAlpha_ClipMaskType;
 552         return result;
 553     }
 554
 555     // There's no texture in the cache. Let's try to allocate it then.
 556     result = this->allocMaskTexture(elementsGenID, clipSpaceIBounds, false);
 557     if (NULL == result) {
 558         fAACache.reset();
 559         return NULL;
 560     }
 561
 562     // The top-left of the mask corresponds to the top-left corner of the bounds.
 563     SkVector clipToMaskOffset = {
 564         SkIntToScalar(-clipSpaceIBounds.fLeft),
 565         SkIntToScalar(-clipSpaceIBounds.fTop)
 566     };
 567     // The texture may be larger than necessary, this rect represents the part of the texture
 568     // we populate with a rasterization of the clip.
 569     SkIRect maskSpaceIBounds = SkIRect::MakeWH(clipSpaceIBounds.width(), clipSpaceIBounds.height());
 570
 571     // Set the matrix so that rendered clip elements are transformed to mask space from clip space.
 572     SkMatrix translate;
 573     translate.setTranslate(clipToMaskOffset);
 574     GrDrawTarget::AutoGeometryAndStatePush agasp(fGpu, GrDrawTarget::kReset_ASRInit, &translate);
 575
 576     GrDrawState* drawState = fGpu->drawState();
 577
 578     // We're drawing a coverage mask and want coverage to be run through the blend function.
 579     drawState->enableState(GrDrawState::kCoverageDrawing_StateBit);
 580
 581     // The scratch texture that we are drawing into can be substantially larger than the mask. Only
 582     // clear the part that we care about.
 583     fGpu->clear(&maskSpaceIBounds,
 584                 kAllIn_InitialState == initialState ? 0xffffffff : 0x00000000,
 585                 true,
 586                 result->asRenderTarget());
 587
 588     // When we use the stencil in the below loop it is important to have this clip installed.
 589     // The second pass that zeros the stencil buffer renders the rect maskSpaceIBounds so the first
 590     // pass must not set values outside of this bounds or stencil values outside the rect won't be
 591     // cleared.
 592     GrDrawTarget::AutoClipRestore acr(fGpu, maskSpaceIBounds);
 593     drawState->enableState(GrDrawState::kClip_StateBit);
 594
 595     GrAutoScratchTexture temp;
 596     // walk through each clip element and perform its set op
 597     for (ElementList::Iter iter = elements.headIter(); iter.get(); iter.next()) {
 598         const Element* element = iter.get();
 599         SkRegion::Op op = element->getOp();
 600         bool invert = element->isInverseFilled();
 601
 602         if (invert || SkRegion::kIntersect_Op == op || SkRegion::kReverseDifference_Op == op) {
 603             GrPathRenderer* pr = NULL;
 604             bool useTemp = !this->canStencilAndDrawElement(result, element, &pr);
 605             GrTexture* dst;
 606             // This is the bounds of the clip element in the space of the alpha-mask. The temporary
 607             // mask buffer can be substantially larger than the actually clip stack element. We
 608             // touch the minimum number of pixels necessary and use decal mode to combine it with
 609             // the accumulator.
 610             SkIRect maskSpaceElementIBounds;
 611
 612             if (useTemp) {
 613                 if (invert) {
 614                     maskSpaceElementIBounds = maskSpaceIBounds;
 615                 } else {
 616                     SkRect elementBounds = element->getBounds();
 617                     elementBounds.offset(clipToMaskOffset);
 618                     elementBounds.roundOut(&maskSpaceElementIBounds);
 619                 }
 620
 621                 this->getTemp(maskSpaceIBounds.fRight, maskSpaceIBounds.fBottom, &temp);
 622                 if (NULL == temp.texture()) {
 623                     fAACache.reset();
 624                     return NULL;
 625                 }
 626                 dst = temp.texture();
 627                 // clear the temp target and set blend to replace
 628                 fGpu->clear(&maskSpaceElementIBounds,
 629                             invert ? 0xffffffff : 0x00000000,
 630                             true,
 631                             dst->asRenderTarget());
 632                 setup_boolean_blendcoeffs(drawState, SkRegion::kReplace_Op);
 633
 634             } else {
 635                 // draw directly into the result with the stencil set to make the pixels affected
 636                 // by the clip shape be non-zero.
 637                 dst = result;
 638                 GR_STATIC_CONST_SAME_STENCIL(kStencilInElement,
 639                                              kReplace_StencilOp,
 640                                              kReplace_StencilOp,
 641                                              kAlways_StencilFunc,
 642                                              0xffff,
 643                                              0xffff,
 644                                              0xffff);
 645                 drawState->setStencil(kStencilInElement);
 646                 setup_boolean_blendcoeffs(drawState, op);
 647             }
 648
 649             drawState->setAlpha(invert ? 0x00 : 0xff);
 650
 651             if (!this->drawElement(dst, element, pr)) {
 652                 fAACache.reset();
 653                 return NULL;
 654             }
 655
 656             if (useTemp) {
 657                 // Now draw into the accumulator using the real operation and the temp buffer as a
 658                 // texture
 659                 this->mergeMask(result,
 660                                 temp.texture(),
 661                                 op,
 662                                 maskSpaceIBounds,
 663                                 maskSpaceElementIBounds);
 664             } else {
 665                 // Draw to the exterior pixels (those with a zero stencil value).
 666                 drawState->setAlpha(invert ? 0xff : 0x00);
 667                 GR_STATIC_CONST_SAME_STENCIL(kDrawOutsideElement,
 668                                              kZero_StencilOp,
 669                                              kZero_StencilOp,
 670                                              kEqual_StencilFunc,
 671                                              0xffff,
 672                                              0x0000,
 673                                              0xffff);
 674                 drawState->setStencil(kDrawOutsideElement);
 675                 fGpu->drawSimpleRect(clipSpaceIBounds);
 676                 drawState->disableStencil();
 677             }
 678         } else {
 679             // all the remaining ops can just be directly draw into the accumulation buffer
 680             drawState->setAlpha(0xff);
 681             setup_boolean_blendcoeffs(drawState, op);
 682             this->drawElement(result, element);
 683         }
 684     }
 685
 686     fCurrClipMaskType = kAlpha_ClipMaskType;
 687     return result;
 688 }
 689
 690 ////////////////////////////////////////////////////////////////////////////////
 691 // Create a 1-bit clip mask in the stencil buffer. 'devClipBounds' are in device
 692 // (as opposed to canvas) coordinates
 693 bool GrClipMaskManager::createStencilClipMask(int32_t elementsGenID,
 694                                               InitialState initialState,
 695                                               const ElementList& elements,
 696                                               const SkIRect& clipSpaceIBounds,
 697                                               const SkIPoint& clipSpaceToStencilOffset) {
 698
 699     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 700
 701     GrDrawState* drawState = fGpu->drawState();
 702     SkASSERT(drawState->isClipState());
 703
 704     GrRenderTarget* rt = drawState->getRenderTarget();
 705     SkASSERT(NULL != rt);
 706
 707     // TODO: dynamically attach a SB when needed.
 708     GrStencilBuffer* stencilBuffer = rt->getStencilBuffer();
 709     if (NULL == stencilBuffer) {
 710         return false;
 711     }
 712
 713     if (stencilBuffer->mustRenderClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset)) {
 714
 715         stencilBuffer->setLastClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset);
 716
 717         // Set the matrix so that rendered clip elements are transformed from clip to stencil space.
 718         SkVector translate = {
 719             SkIntToScalar(clipSpaceToStencilOffset.fX),
 720             SkIntToScalar(clipSpaceToStencilOffset.fY)
 721         };
 722         SkMatrix matrix;
 723         matrix.setTranslate(translate);
 724         GrDrawTarget::AutoGeometryAndStatePush agasp(fGpu, GrDrawTarget::kReset_ASRInit, &matrix);
 725         drawState = fGpu->drawState();
 726
 727         drawState->setRenderTarget(rt);
 728
 729         // We set the current clip to the bounds so that our recursive draws are scissored to them.
 730         SkIRect stencilSpaceIBounds(clipSpaceIBounds);
 731         stencilSpaceIBounds.offset(clipSpaceToStencilOffset);
 732         GrDrawTarget::AutoClipRestore acr(fGpu, stencilSpaceIBounds);
 733         drawState->enableState(GrDrawState::kClip_StateBit);
 734
 735 #if !VISUALIZE_COMPLEX_CLIP
 736         drawState->enableState(GrDrawState::kNoColorWrites_StateBit);
 737 #endif
 738
 739         int clipBit = stencilBuffer->bits();
 740         SkASSERT((clipBit <= 16) && "Ganesh only handles 16b or smaller stencil buffers");
 741         clipBit = (1 << (clipBit-1));
 742
 743         fGpu->clearStencilClip(stencilSpaceIBounds, kAllIn_InitialState == initialState);
 744
 745         // walk through each clip element and perform its set op
 746         // with the existing clip.
 747         for (ElementList::Iter iter(elements.headIter()); NULL != iter.get(); iter.next()) {
 748             const Element* element = iter.get();
 749             bool fillInverted = false;
 750             // enabled at bottom of loop
 751             drawState->disableState(GrGpu::kModifyStencilClip_StateBit);
 752             // if the target is MSAA then we want MSAA enabled when the clip is soft
 753             if (rt->isMultisampled()) {
 754                 drawState->setState(GrDrawState::kHWAntialias_StateBit, element->isAA());
 755             }
 756
 757             // This will be used to determine whether the clip shape can be rendered into the
 758             // stencil with arbitrary stencil settings.
 759             GrPathRenderer::StencilSupport stencilSupport;
 760
 761             SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
 762
 763             SkRegion::Op op = element->getOp();
 764
 765             GrPathRenderer* pr = NULL;
 766             SkPath clipPath;
 767             if (Element::kRect_Type == element->getType()) {
 768                 stencilSupport = GrPathRenderer::kNoRestriction_StencilSupport;
 769                 fillInverted = false;
 770             } else {
 771                 element->asPath(&clipPath);
 772                 fillInverted = clipPath.isInverseFillType();
 773                 if (fillInverted) {
 774                     clipPath.toggleInverseFillType();
 775                 }
 776                 pr = this->getContext()->getPathRenderer(clipPath,
 777                                                          stroke,
 778                                                          fGpu,
 779                                                          false,
 780                                                          GrPathRendererChain::kStencilOnly_DrawType,
 781                                                          &stencilSupport);
 782                 if (NULL == pr) {
 783                     return false;
 784                 }
 785             }
 786
 787             int passes;
 788             GrStencilSettings stencilSettings[GrStencilSettings::kMaxStencilClipPasses];
 789
 790             bool canRenderDirectToStencil =
 791                 GrPathRenderer::kNoRestriction_StencilSupport == stencilSupport;
 792             bool canDrawDirectToClip; // Given the renderer, the element,
 793                                       // fill rule, and set operation can
 794                                       // we render the element directly to
 795                                       // stencil bit used for clipping.
 796             canDrawDirectToClip = GrStencilSettings::GetClipPasses(op,
 797                                                                    canRenderDirectToStencil,
 798                                                                    clipBit,
 799                                                                    fillInverted,
 800                                                                    &passes,
 801                                                                    stencilSettings);
 802
 803             // draw the element to the client stencil bits if necessary
 804             if (!canDrawDirectToClip) {
 805                 GR_STATIC_CONST_SAME_STENCIL(gDrawToStencil,
 806                                              kIncClamp_StencilOp,
 807                                              kIncClamp_StencilOp,
 808                                              kAlways_StencilFunc,
 809                                              0xffff,
 810                                              0x0000,
 811                                              0xffff);
 812                 SET_RANDOM_COLOR
 813                 if (Element::kRect_Type == element->getType()) {
 814                     *drawState->stencil() = gDrawToStencil;
 815                     fGpu->drawSimpleRect(element->getRect(), NULL);
 816                 } else {
 817                     if (!clipPath.isEmpty()) {
 818                         if (canRenderDirectToStencil) {
 819                             *drawState->stencil() = gDrawToStencil;
 820                             pr->drawPath(clipPath, stroke, fGpu, false);
 821                         } else {
 822                             pr->stencilPath(clipPath, stroke, fGpu);
 823                         }
 824                     }
 825                 }
 826             }
 827
 828             // now we modify the clip bit by rendering either the clip
 829             // element directly or a bounding rect of the entire clip.
 830             drawState->enableState(GrGpu::kModifyStencilClip_StateBit);
 831             for (int p = 0; p < passes; ++p) {
 832                 *drawState->stencil() = stencilSettings[p];
 833                 if (canDrawDirectToClip) {
 834                     if (Element::kRect_Type == element->getType()) {
 835                         SET_RANDOM_COLOR
 836                         fGpu->drawSimpleRect(element->getRect(), NULL);
 837                     } else {
 838                         SET_RANDOM_COLOR
 839                         pr->drawPath(clipPath, stroke, fGpu, false);
 840                     }
 841                 } else {
 842                     SET_RANDOM_COLOR
 843                     // The view matrix is setup to do clip space -> stencil space translation, so
 844                     // draw rect in clip space.
 845                     fGpu->drawSimpleRect(SkRect::Make(clipSpaceIBounds), NULL);
 846                 }
 847             }
 848         }
 849     }
 850     // set this last because recursive draws may overwrite it back to kNone.
 851     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 852     fCurrClipMaskType = kStencil_ClipMaskType;
 853     return true;
 854 }
 855
 856
 857 // mapping of clip-respecting stencil funcs to normal stencil funcs
 858 // mapping depends on whether stencil-clipping is in effect.
 859 static const GrStencilFunc
 860     gSpecialToBasicStencilFunc[2][kClipStencilFuncCount] = {
 861     {// Stencil-Clipping is DISABLED,  we are effectively always inside the clip
 862         // In the Clip Funcs
 863         kAlways_StencilFunc,          // kAlwaysIfInClip_StencilFunc
 864         kEqual_StencilFunc,           // kEqualIfInClip_StencilFunc
 865         kLess_StencilFunc,            // kLessIfInClip_StencilFunc
 866         kLEqual_StencilFunc,          // kLEqualIfInClip_StencilFunc
 867         // Special in the clip func that forces user's ref to be 0.
 868         kNotEqual_StencilFunc,        // kNonZeroIfInClip_StencilFunc
 869                                       // make ref 0 and do normal nequal.
 870     },
 871     {// Stencil-Clipping is ENABLED
 872         // In the Clip Funcs
 873         kEqual_StencilFunc,           // kAlwaysIfInClip_StencilFunc
 874                                       // eq stencil clip bit, mask
 875                                       // out user bits.
 876
 877         kEqual_StencilFunc,           // kEqualIfInClip_StencilFunc
 878                                       // add stencil bit to mask and ref
 879
 880         kLess_StencilFunc,            // kLessIfInClip_StencilFunc
 881         kLEqual_StencilFunc,          // kLEqualIfInClip_StencilFunc
 882                                       // for both of these we can add
 883                                       // the clip bit to the mask and
 884                                       // ref and compare as normal
 885         // Special in the clip func that forces user's ref to be 0.
 886         kLess_StencilFunc,            // kNonZeroIfInClip_StencilFunc
 887                                       // make ref have only the clip bit set
 888                                       // and make comparison be less
 889                                       // 10..0 < 1..user_bits..
 890     }
 891 };
 892
 893 namespace {
 894 // Sets the settings to clip against the stencil buffer clip while ignoring the
 895 // client bits.
 896 const GrStencilSettings& basic_apply_stencil_clip_settings() {
 897     // stencil settings to use when clip is in stencil
 898     GR_STATIC_CONST_SAME_STENCIL_STRUCT(gSettings,
 899         kKeep_StencilOp,
 900         kKeep_StencilOp,
 901         kAlwaysIfInClip_StencilFunc,
 902         0x0000,
 903         0x0000,
 904         0x0000);
 905     return *GR_CONST_STENCIL_SETTINGS_PTR_FROM_STRUCT_PTR(&gSettings);
 906 }
 907 }
 908
 909 void GrClipMaskManager::setGpuStencil() {
 910     // We make two copies of the StencilSettings here (except in the early
 911     // exit scenario. One copy from draw state to the stack var. Then another
 912     // from the stack var to the gpu. We could make this class hold a ptr to
 913     // GrGpu's fStencilSettings and eliminate the stack copy here.
 914
 915     const GrDrawState& drawState = fGpu->getDrawState();
 916
 917     // use stencil for clipping if clipping is enabled and the clip
 918     // has been written into the stencil.
 919     GrClipMaskManager::StencilClipMode clipMode;
 920     if (this->isClipInStencil() && drawState.isClipState()) {
 921         clipMode = GrClipMaskManager::kRespectClip_StencilClipMode;
 922         // We can't be modifying the clip and respecting it at the same time.
 923         SkASSERT(!drawState.isStateFlagEnabled(
 924                     GrGpu::kModifyStencilClip_StateBit));
 925     } else if (drawState.isStateFlagEnabled(
 926                     GrGpu::kModifyStencilClip_StateBit)) {
 927         clipMode = GrClipMaskManager::kModifyClip_StencilClipMode;
 928     } else {
 929         clipMode = GrClipMaskManager::kIgnoreClip_StencilClipMode;
 930     }
 931
 932     GrStencilSettings settings;
 933     // The GrGpu client may not be using the stencil buffer but we may need to
 934     // enable it in order to respect a stencil clip.
 935     if (drawState.getStencil().isDisabled()) {
 936         if (GrClipMaskManager::kRespectClip_StencilClipMode == clipMode) {
 937             settings = basic_apply_stencil_clip_settings();
 938         } else {
 939             fGpu->disableStencil();
 940             return;
 941         }
 942     } else {
 943         settings = drawState.getStencil();
 944     }
 945
 946     // TODO: dynamically attach a stencil buffer
 947     int stencilBits = 0;
 948     GrStencilBuffer* stencilBuffer =
 949         drawState.getRenderTarget()->getStencilBuffer();
 950     if (NULL != stencilBuffer) {
 951         stencilBits = stencilBuffer->bits();
 952     }
 953
 954     SkASSERT(fGpu->caps()->stencilWrapOpsSupport() || !settings.usesWrapOp());
 955     SkASSERT(fGpu->caps()->twoSidedStencilSupport() || !settings.isTwoSided());
 956     this->adjustStencilParams(&settings, clipMode, stencilBits);
 957     fGpu->setStencilSettings(settings);
 958 }
 959
 960 void GrClipMaskManager::adjustStencilParams(GrStencilSettings* settings,
 961                                             StencilClipMode mode,
 962                                             int stencilBitCnt) {
 963     SkASSERT(stencilBitCnt > 0);
 964
 965     if (kModifyClip_StencilClipMode == mode) {
 966         // We assume that this clip manager itself is drawing to the GrGpu and
 967         // has already setup the correct values.
 968         return;
 969     }
 970
 971     unsigned int clipBit = (1 << (stencilBitCnt - 1));
 972     unsigned int userBits = clipBit - 1;
 973
 974     GrStencilSettings::Face face = GrStencilSettings::kFront_Face;
 975     bool twoSided = fGpu->caps()->twoSidedStencilSupport();
 976
 977     bool finished = false;
 978     while (!finished) {
 979         GrStencilFunc func = settings->func(face);
 980         uint16_t writeMask = settings->writeMask(face);
 981         uint16_t funcMask = settings->funcMask(face);
 982         uint16_t funcRef = settings->funcRef(face);
 983
 984         SkASSERT((unsigned) func < kStencilFuncCount);
 985
 986         writeMask &= userBits;
 987
 988         if (func >= kBasicStencilFuncCount) {
 989             int respectClip = kRespectClip_StencilClipMode == mode;
 990             if (respectClip) {
 991                 // The GrGpu class should have checked this
 992                 SkASSERT(this->isClipInStencil());
 993                 switch (func) {
 994                     case kAlwaysIfInClip_StencilFunc:
 995                         funcMask = clipBit;
 996                         funcRef = clipBit;
 997                         break;
 998                     case kEqualIfInClip_StencilFunc:
 999                     case kLessIfInClip_StencilFunc:
1000                     case kLEqualIfInClip_StencilFunc:
1001                         funcMask = (funcMask & userBits) | clipBit;
1002                         funcRef  = (funcRef  & userBits) | clipBit;
1003                         break;
1004                     case kNonZeroIfInClip_StencilFunc:
1005                         funcMask = (funcMask & userBits) | clipBit;
1006                         funcRef = clipBit;
1007                         break;
1008                     default:
1009                         SkFAIL("Unknown stencil func");
1010                 }
1011             } else {
1012                 funcMask &= userBits;
1013                 funcRef &= userBits;
1014             }
1015             const GrStencilFunc* table =
1016                 gSpecialToBasicStencilFunc[respectClip];
1017             func = table[func - kBasicStencilFuncCount];
1018             SkASSERT(func >= 0 && func < kBasicStencilFuncCount);
1019         } else {
1020             funcMask &= userBits;
1021             funcRef &= userBits;
1022         }
1023
1024         settings->setFunc(face, func);
1025         settings->setWriteMask(face, writeMask);
1026         settings->setFuncMask(face, funcMask);
1027         settings->setFuncRef(face, funcRef);
1028
1029         if (GrStencilSettings::kFront_Face == face) {
1030             face = GrStencilSettings::kBack_Face;
1031             finished = !twoSided;
1032         } else {
1033             finished = true;
1034         }
1035     }
1036     if (!twoSided) {
1037         settings->copyFrontSettingsToBack();
1038     }
1039 }
1040
1041 ////////////////////////////////////////////////////////////////////////////////
1042 GrTexture* GrClipMaskManager::createSoftwareClipMask(int32_t elementsGenID,
1043                                                      GrReducedClip::InitialState initialState,
1044                                                      const GrReducedClip::ElementList& elements,
1045                                                      const SkIRect& clipSpaceIBounds) {
1046     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
1047
1048     GrTexture* result = this->getCachedMaskTexture(elementsGenID, clipSpaceIBounds);
1049     if (NULL != result) {
1050         return result;
1051     }
1052
1053     // The mask texture may be larger than necessary. We round out the clip space bounds and pin
1054     // the top left corner of the resulting rect to the top left of the texture.
1055     SkIRect maskSpaceIBounds = SkIRect::MakeWH(clipSpaceIBounds.width(), clipSpaceIBounds.height());
1056
1057     GrSWMaskHelper helper(this->getContext());
1058
1059     SkMatrix matrix;
1060     matrix.setTranslate(SkIntToScalar(-clipSpaceIBounds.fLeft),
1061                         SkIntToScalar(-clipSpaceIBounds.fTop));
1062     helper.init(maskSpaceIBounds, &matrix);
1063
1064     helper.clear(kAllIn_InitialState == initialState ? 0xFF : 0x00);
1065
1066     SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
1067
1068     for (ElementList::Iter iter(elements.headIter()) ; NULL != iter.get(); iter.next()) {
1069
1070         const Element* element = iter.get();
1071         SkRegion::Op op = element->getOp();
1072
1073         if (SkRegion::kIntersect_Op == op || SkRegion::kReverseDifference_Op == op) {
1074             // Intersect and reverse difference require modifying pixels outside of the geometry
1075             // that is being "drawn". In both cases we erase all the pixels outside of the geometry
1076             // but leave the pixels inside the geometry alone. For reverse difference we invert all
1077             // the pixels before clearing the ones outside the geometry.
1078             if (SkRegion::kReverseDifference_Op == op) {
1079                 SkRect temp = SkRect::Make(clipSpaceIBounds);
1080                 // invert the entire scene
1081                 helper.draw(temp, SkRegion::kXOR_Op, false, 0xFF);
1082             }
1083
1084             SkPath clipPath;
1085             element->asPath(&clipPath);
1086             clipPath.toggleInverseFillType();
1087             helper.draw(clipPath, stroke, SkRegion::kReplace_Op, element->isAA(), 0x00);
1088
1089             continue;
1090         }
1091
1092         // The other ops (union, xor, diff) only affect pixels inside
1093         // the geometry so they can just be drawn normally
1094         if (Element::kRect_Type == element->getType()) {
1095             helper.draw(element->getRect(), op, element->isAA(), 0xFF);
1096         } else {
1097             SkPath path;
1098             element->asPath(&path);
1099             helper.draw(path, stroke, op, element->isAA(), 0xFF);
1100         }
1101     }
1102
1103     // Allocate clip mask texture
1104     result = this->allocMaskTexture(elementsGenID, clipSpaceIBounds, true);
1105     if (NULL == result) {
1106         fAACache.reset();
1107         return NULL;
1108     }
1109     helper.toTexture(result);
1110
1111     fCurrClipMaskType = kAlpha_ClipMaskType;
1112     return result;
1113 }
1114
1115 ////////////////////////////////////////////////////////////////////////////////
1116 void GrClipMaskManager::releaseResources() {
1117     fAACache.releaseResources();
1118 }
1119
1120 void GrClipMaskManager::setGpu(GrGpu* gpu) {
1121     fGpu = gpu;
1122     fAACache.setContext(gpu->getContext());
1123 }
1124
1125 void GrClipMaskManager::adjustPathStencilParams(GrStencilSettings* settings) {
1126     const GrDrawState& drawState = fGpu->getDrawState();
1127     GrClipMaskManager::StencilClipMode clipMode;
1128     if (this->isClipInStencil() && drawState.isClipState()) {
1129         clipMode = GrClipMaskManager::kRespectClip_StencilClipMode;
1130         // We can't be modifying the clip and respecting it at the same time.
1131         SkASSERT(!drawState.isStateFlagEnabled(
1132                     GrGpu::kModifyStencilClip_StateBit));
1133     } else if (drawState.isStateFlagEnabled(
1134                     GrGpu::kModifyStencilClip_StateBit)) {
1135         clipMode = GrClipMaskManager::kModifyClip_StencilClipMode;
1136     } else {
1137         clipMode = GrClipMaskManager::kIgnoreClip_StencilClipMode;
1138     }
1139
1140     // TODO: dynamically attach a stencil buffer
1141     int stencilBits = 0;
1142     GrStencilBuffer* stencilBuffer =
1143         drawState.getRenderTarget()->getStencilBuffer();
1144     if (NULL != stencilBuffer) {
1145         stencilBits = stencilBuffer->bits();
1146         this->adjustStencilParams(settings, clipMode, stencilBits);
1147     }
1148 }