src/third_party/skia/src/gpu/GrStencilAndCoverPathRenderer.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
  10 #include "GrStencilAndCoverPathRenderer.h"
  11 #include "GrContext.h"
  12 #include "GrDrawTargetCaps.h"
  13 #include "GrGpu.h"
  14 #include "GrPath.h"
  15 #include "SkStrokeRec.h"
  16
  17 /*
  18  * For now paths only natively support winding and even odd fill types
  19  */
  20 static GrPathRendering::FillType convert_skpath_filltype(SkPath::FillType fill) {
  21     switch (fill) {
  22         default:
  23             SkFAIL("Incomplete Switch\n");
  24         case SkPath::kWinding_FillType:
  25         case SkPath::kInverseWinding_FillType:
  26             return GrPathRendering::kWinding_FillType;
  27         case SkPath::kEvenOdd_FillType:
  28         case SkPath::kInverseEvenOdd_FillType:
  29             return GrPathRendering::kEvenOdd_FillType;
  30     }
  31 }
  32
  33 GrPathRenderer* GrStencilAndCoverPathRenderer::Create(GrContext* context) {
  34     SkASSERT(context);
  35     SkASSERT(context->getGpu());
  36     if (context->getGpu()->caps()->pathRenderingSupport()) {
  37         return SkNEW_ARGS(GrStencilAndCoverPathRenderer, (context->getGpu()));
  38     } else {
  39         return NULL;
  40     }
  41 }
  42
  43 GrStencilAndCoverPathRenderer::GrStencilAndCoverPathRenderer(GrGpu* gpu) {
  44     SkASSERT(gpu->caps()->pathRenderingSupport());
  45     fGpu = gpu;
  46     gpu->ref();
  47 }
  48
  49 GrStencilAndCoverPathRenderer::~GrStencilAndCoverPathRenderer() {
  50     fGpu->unref();
  51 }
  52
  53 bool GrStencilAndCoverPathRenderer::canDrawPath(const SkPath& path,
  54                                                 const SkStrokeRec& stroke,
  55                                                 const GrDrawTarget* target,
  56                                                 bool antiAlias) const {
  57     return !stroke.isHairlineStyle() &&
  58            !antiAlias && // doesn't do per-path AA, relies on the target having MSAA
  59            target->getDrawState().getRenderTarget()->getStencilBuffer() &&
  60            target->getDrawState().getStencil().isDisabled();
  61 }
  62
  63 GrPathRenderer::StencilSupport
  64 GrStencilAndCoverPathRenderer::onGetStencilSupport(const SkPath&,
  65                                                    const SkStrokeRec& ,
  66                                                    const GrDrawTarget*) const {
  67     return GrPathRenderer::kStencilOnly_StencilSupport;
  68 }
  69
  70 static GrPath* get_gr_path(GrGpu* gpu, const SkPath& skPath, const SkStrokeRec& stroke) {
  71     GrContext* ctx = gpu->getContext();
  72     GrResourceKey resourceKey = GrPath::ComputeKey(skPath, stroke);
  73     SkAutoTUnref<GrPath> path(static_cast<GrPath*>(ctx->findAndRefCachedResource(resourceKey)));
  74     if (NULL == path || !path->isEqualTo(skPath, stroke)) {
  75         path.reset(gpu->pathRendering()->createPath(skPath, stroke));
  76         ctx->addResourceToCache(resourceKey, path);
  77     }
  78     return path.detach();
  79 }
  80
  81 void GrStencilAndCoverPathRenderer::onStencilPath(const SkPath& path,
  82                                                   const SkStrokeRec& stroke,
  83                                                   GrDrawTarget* target) {
  84     SkASSERT(!path.isInverseFillType());
  85     SkAutoTUnref<GrPath> p(get_gr_path(fGpu, path, stroke));
  86     target->stencilPath(p, convert_skpath_filltype(path.getFillType()));
  87 }
  88
  89 bool GrStencilAndCoverPathRenderer::onDrawPath(const SkPath& path,
  90                                                const SkStrokeRec& stroke,
  91                                                GrDrawTarget* target,
  92                                                bool antiAlias) {
  93     SkASSERT(!antiAlias);
  94     SkASSERT(!stroke.isHairlineStyle());
  95
  96     GrDrawState* drawState = target->drawState();
  97     SkASSERT(drawState->getStencil().isDisabled());
  98
  99     SkAutoTUnref<GrPath> p(get_gr_path(fGpu, path, stroke));
 100
 101     if (path.isInverseFillType()) {
 102         GR_STATIC_CONST_SAME_STENCIL(kInvertedStencilPass,
 103             kZero_StencilOp,
 104             kZero_StencilOp,
 105             // We know our rect will hit pixels outside the clip and the user bits will be 0
 106             // outside the clip. So we can't just fill where the user bits are 0. We also need to
 107             // check that the clip bit is set.
 108             kEqualIfInClip_StencilFunc,
 109             0xffff,
 110             0x0000,
 111             0xffff);
 112
 113         drawState->setStencil(kInvertedStencilPass);
 114
 115         // fake inverse with a stencil and cover
 116         target->stencilPath(p, convert_skpath_filltype(path.getFillType()));
 117
 118         GrDrawState::AutoViewMatrixRestore avmr;
 119         SkRect bounds = SkRect::MakeLTRB(0, 0,
 120                                          SkIntToScalar(drawState->getRenderTarget()->width()),
 121                                          SkIntToScalar(drawState->getRenderTarget()->height()));
 122         SkMatrix vmi;
 123         // mapRect through persp matrix may not be correct
 124         if (!drawState->getViewMatrix().hasPerspective() && drawState->getViewInverse(&vmi)) {
 125             vmi.mapRect(&bounds);
 126             // theoretically could set bloat = 0, instead leave it because of matrix inversion
 127             // precision.
 128             SkScalar bloat = drawState->getViewMatrix().getMaxScale() * SK_ScalarHalf;
 129             bounds.outset(bloat, bloat);
 130         } else {
 131             avmr.setIdentity(drawState);
 132         }
 133         target->drawSimpleRect(bounds);
 134     } else {
 135         GR_STATIC_CONST_SAME_STENCIL(kStencilPass,
 136             kZero_StencilOp,
 137             kZero_StencilOp,
 138             kNotEqual_StencilFunc,
 139             0xffff,
 140             0x0000,
 141             0xffff);
 142
 143         drawState->setStencil(kStencilPass);
 144         target->drawPath(p, convert_skpath_filltype(path.getFillType()));
 145     }
 146
 147     target->drawState()->stencil()->setDisabled();
 148     return true;
 149 }