The Tor Browser: gfx/skia/trunk/src/gpu/GrAAConvexPathRenderer.cpp@6474c204b198 (annotated)

gfx/skia/trunk/src/gpu/GrAAConvexPathRenderer.cpp@6474c204b198 (annotated)

gfx/skia/trunk/src/gpu/GrAAConvexPathRenderer.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "GrAAConvexPathRenderer.h"
 #include "GrContext.h"
 #include "GrDrawState.h"
 #include "GrDrawTargetCaps.h"
 #include "GrEffect.h"
 #include "GrPathUtils.h"
 #include "GrTBackendEffectFactory.h"
 #include "SkString.h"
 #include "SkStrokeRec.h"
 #include "SkTrace.h"
 #include "gl/GrGLEffect.h"
 #include "gl/GrGLSL.h"
 #include "gl/GrGLVertexEffect.h"
 #include "effects/GrVertexEffect.h"
 GrAAConvexPathRenderer::GrAAConvexPathRenderer() {
 }
 struct Segment {
     enum {
         // These enum values are assumed in member functions below.
         kLine = 0,
         kQuad = 1,
     } fType;
     // line uses one pt, quad uses 2 pts
     GrPoint fPts[2];
     // normal to edge ending at each pt
     GrVec fNorms[2];
     // is the corner where the previous segment meets this segment
     // sharp. If so, fMid is a normalized bisector facing outward.
     GrVec fMid;
     int countPoints() {
         GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
         return fType + 1;
     }
     const SkPoint& endPt() const {
         GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
         return fPts[fType];
     };
     const SkPoint& endNorm() const {
         GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
         return fNorms[fType];
     };
 };
 typedef SkTArray<Segment, true> SegmentArray;
 static void center_of_mass(const SegmentArray& segments, SkPoint* c) {
     SkScalar area = 0;
     SkPoint center = {0, 0};
     int count = segments.count();
     SkPoint p0 = {0, 0};
     if (count > 2) {
         // We translate the polygon so that the first point is at the origin.
         // This avoids some precision issues with small area polygons far away
         // from the origin.
         p0 = segments[0].endPt();
         SkPoint pi;
         SkPoint pj;
         // the first and last iteration of the below loop would compute
         // zeros since the starting / ending point is (0,0). So instead we start
         // at i=1 and make the last iteration i=count-2.
         pj = segments[1].endPt() - p0;
         for (int i = 1; i < count - 1; ++i) {
             pi = pj;
             const SkPoint pj = segments[i + 1].endPt() - p0;
             SkScalar t = SkScalarMul(pi.fX, pj.fY) - SkScalarMul(pj.fX, pi.fY);
             area += t;
             center.fX += (pi.fX + pj.fX) * t;
             center.fY += (pi.fY + pj.fY) * t;
         }
     }
     // If the poly has no area then we instead return the average of
     // its points.
     if (SkScalarNearlyZero(area)) {
         SkPoint avg;
         avg.set(0, 0);
         for (int i = 0; i < count; ++i) {
             const SkPoint& pt = segments[i].endPt();
             avg.fX += pt.fX;
             avg.fY += pt.fY;
         }
         SkScalar denom = SK_Scalar1 / count;
         avg.scale(denom);
         *c = avg;
     } else {
         area *= 3;
         area = SkScalarDiv(SK_Scalar1, area);
         center.fX = SkScalarMul(center.fX, area);
         center.fY = SkScalarMul(center.fY, area);
         // undo the translate of p0 to the origin.
         *c = center + p0;
     }
     SkASSERT(!SkScalarIsNaN(c->fX) && !SkScalarIsNaN(c->fY));
 }
 static void compute_vectors(SegmentArray* segments,
                             SkPoint* fanPt,
                             SkPath::Direction dir,
                             int* vCount,
                             int* iCount) {
     center_of_mass(*segments, fanPt);
     int count = segments->count();
     // Make the normals point towards the outside
     GrPoint::Side normSide;
     if (dir == SkPath::kCCW_Direction) {
         normSide = GrPoint::kRight_Side;
     } else {
         normSide = GrPoint::kLeft_Side;
     }
     *vCount = 0;
     *iCount = 0;
     // compute normals at all points
     for (int a = 0; a < count; ++a) {
         Segment& sega = (*segments)[a];
         int b = (a + 1) % count;
         Segment& segb = (*segments)[b];
         const GrPoint* prevPt = &sega.endPt();
         int n = segb.countPoints();
         for (int p = 0; p < n; ++p) {
             segb.fNorms[p] = segb.fPts[p] - *prevPt;
             segb.fNorms[p].normalize();
             segb.fNorms[p].setOrthog(segb.fNorms[p], normSide);
             prevPt = &segb.fPts[p];
         }
         if (Segment::kLine == segb.fType) {
             *vCount += 5;
             *iCount += 9;
         } else {
             *vCount += 6;
             *iCount += 12;
         }
     }
     // compute mid-vectors where segments meet. TODO: Detect shallow corners
     // and leave out the wedges and close gaps by stitching segments together.
     for (int a = 0; a < count; ++a) {
         const Segment& sega = (*segments)[a];
         int b = (a + 1) % count;
         Segment& segb = (*segments)[b];
         segb.fMid = segb.fNorms[0] + sega.endNorm();
         segb.fMid.normalize();
         // corner wedges
         *vCount += 4;
         *iCount += 6;
     }
 }
 struct DegenerateTestData {
     DegenerateTestData() { fStage = kInitial; }
     bool isDegenerate() const { return kNonDegenerate != fStage; }
     enum {
         kInitial,
         kPoint,
         kLine,
         kNonDegenerate
     }           fStage;
     GrPoint     fFirstPoint;
     GrVec       fLineNormal;
     SkScalar    fLineC;
 };
 static const SkScalar kClose = (SK_Scalar1 / 16);
 static const SkScalar kCloseSqd = SkScalarMul(kClose, kClose);
 static void update_degenerate_test(DegenerateTestData* data, const GrPoint& pt) {
     switch (data->fStage) {
         case DegenerateTestData::kInitial:
             data->fFirstPoint = pt;
             data->fStage = DegenerateTestData::kPoint;
             break;
         case DegenerateTestData::kPoint:
             if (pt.distanceToSqd(data->fFirstPoint) > kCloseSqd) {
                 data->fLineNormal = pt - data->fFirstPoint;
                 data->fLineNormal.normalize();
                 data->fLineNormal.setOrthog(data->fLineNormal);
                 data->fLineC = -data->fLineNormal.dot(data->fFirstPoint);
                 data->fStage = DegenerateTestData::kLine;
             }
             break;
         case DegenerateTestData::kLine:
             if (SkScalarAbs(data->fLineNormal.dot(pt) + data->fLineC) > kClose) {
                 data->fStage = DegenerateTestData::kNonDegenerate;
             }
         case DegenerateTestData::kNonDegenerate:
             break;
         default:
             GrCrash("Unexpected degenerate test stage.");
     }
 }
 static inline bool get_direction(const SkPath& path, const SkMatrix& m, SkPath::Direction* dir) {
     if (!path.cheapComputeDirection(dir)) {
         return false;
     }
     // check whether m reverses the orientation
     SkASSERT(!m.hasPerspective());
     SkScalar det2x2 = SkScalarMul(m.get(SkMatrix::kMScaleX), m.get(SkMatrix::kMScaleY)) -
                       SkScalarMul(m.get(SkMatrix::kMSkewX), m.get(SkMatrix::kMSkewY));
     if (det2x2 < 0) {
         *dir = SkPath::OppositeDirection(*dir);
     }
     return true;
 }
 static inline void add_line_to_segment(const SkPoint& pt,
                                        SegmentArray* segments,
                                        SkRect* devBounds) {
     segments->push_back();
     segments->back().fType = Segment::kLine;
     segments->back().fPts[0] = pt;
     devBounds->growToInclude(pt.fX, pt.fY);
 }
 #ifdef SK_DEBUG
 static inline bool contains_inclusive(const SkRect& rect, const SkPoint& p) {
     return p.fX >= rect.fLeft && p.fX <= rect.fRight && p.fY >= rect.fTop && p.fY <= rect.fBottom;
 }
 #endif
 static inline void add_quad_segment(const SkPoint pts[3],
                                     SegmentArray* segments,
                                     SkRect* devBounds) {
     if (pts[0].distanceToSqd(pts[1]) < kCloseSqd || pts[1].distanceToSqd(pts[2]) < kCloseSqd) {
         if (pts[0] != pts[2]) {
             add_line_to_segment(pts[2], segments, devBounds);
         }
     } else {
         segments->push_back();
         segments->back().fType = Segment::kQuad;
         segments->back().fPts[0] = pts[1];
         segments->back().fPts[1] = pts[2];
         SkASSERT(contains_inclusive(*devBounds, pts[0]));
         devBounds->growToInclude(pts + 1, 2);
     }
 }
 static inline void add_cubic_segments(const SkPoint pts[4],
                                       SkPath::Direction dir,
                                       SegmentArray* segments,
                                       SkRect* devBounds) {
     SkSTArray<15, SkPoint, true> quads;
     GrPathUtils::convertCubicToQuads(pts, SK_Scalar1, true, dir, &quads);
     int count = quads.count();
     for (int q = 0; q < count; q += 3) {
         add_quad_segment(&quads[q], segments, devBounds);
     }
 }
 static bool get_segments(const SkPath& path,
                          const SkMatrix& m,
                          SegmentArray* segments,
                          SkPoint* fanPt,
                          int* vCount,
                          int* iCount,
                          SkRect* devBounds) {
     SkPath::Iter iter(path, true);
     // This renderer over-emphasizes very thin path regions. We use the distance
     // to the path from the sample to compute coverage. Every pixel intersected
     // by the path will be hit and the maximum distance is sqrt(2)/2. We don't
     // notice that the sample may be close to a very thin area of the path and
     // thus should be very light. This is particularly egregious for degenerate
     // line paths. We detect paths that are very close to a line (zero area) and
     // draw nothing.
     DegenerateTestData degenerateData;
     SkPath::Direction dir;
     // get_direction can fail for some degenerate paths.
     if (!get_direction(path, m, &dir)) {
         return false;
     }
     for (;;) {
         GrPoint pts[4];
         SkPath::Verb verb = iter.next(pts);
         switch (verb) {
             case SkPath::kMove_Verb:
                 m.mapPoints(pts, 1);
                 update_degenerate_test(&degenerateData, pts[0]);
                 devBounds->set(pts->fX, pts->fY, pts->fX, pts->fY);
                 break;
             case SkPath::kLine_Verb: {
                 m.mapPoints(&pts[1], 1);
                 update_degenerate_test(&degenerateData, pts[1]);
                 add_line_to_segment(pts[1], segments, devBounds);
                 break;
             }
             case SkPath::kQuad_Verb:
                 m.mapPoints(pts, 3);
                 update_degenerate_test(&degenerateData, pts[1]);
                 update_degenerate_test(&degenerateData, pts[2]);
                 add_quad_segment(pts, segments, devBounds);
                 break;
             case SkPath::kCubic_Verb: {
                 m.mapPoints(pts, 4);
                 update_degenerate_test(&degenerateData, pts[1]);
                 update_degenerate_test(&degenerateData, pts[2]);
                 update_degenerate_test(&degenerateData, pts[3]);
                 add_cubic_segments(pts, dir, segments, devBounds);
                 break;
             };
             case SkPath::kDone_Verb:
                 if (degenerateData.isDegenerate()) {
                     return false;
                 } else {
                     compute_vectors(segments, fanPt, dir, vCount, iCount);
                     return true;
                 }
             default:
                 break;
         }
     }
 }
 struct QuadVertex {
     GrPoint  fPos;
     GrPoint  fUV;
     SkScalar fD0;
     SkScalar fD1;
 };
 struct Draw {
     Draw() : fVertexCnt(0), fIndexCnt(0) {}
     int fVertexCnt;
     int fIndexCnt;
 };
 typedef SkTArray<Draw, true> DrawArray;
 static void create_vertices(const SegmentArray&  segments,
                             const SkPoint& fanPt,
                             DrawArray*     draws,
                             QuadVertex*    verts,
                             uint16_t*      idxs) {
     Draw* draw = &draws->push_back();
     // alias just to make vert/index assignments easier to read.
     int* v = &draw->fVertexCnt;
     int* i = &draw->fIndexCnt;
     int count = segments.count();
     for (int a = 0; a < count; ++a) {
         const Segment& sega = segments[a];
         int b = (a + 1) % count;
         const Segment& segb = segments[b];
         // Check whether adding the verts for this segment to the current draw would cause index
         // values to overflow.
         int vCount = 4;
         if (Segment::kLine == segb.fType) {
             vCount += 5;
         } else {
             vCount += 6;
         }
         if (draw->fVertexCnt + vCount > (1 << 16)) {
             verts += *v;
             idxs += *i;
             draw = &draws->push_back();
             v = &draw->fVertexCnt;
             i = &draw->fIndexCnt;
         }
         // FIXME: These tris are inset in the 1 unit arc around the corner
         verts[*v + 0].fPos = sega.endPt();
         verts[*v + 1].fPos = verts[*v + 0].fPos + sega.endNorm();
         verts[*v + 2].fPos = verts[*v + 0].fPos + segb.fMid;
         verts[*v + 3].fPos = verts[*v + 0].fPos + segb.fNorms[0];
         verts[*v + 0].fUV.set(0,0);
         verts[*v + 1].fUV.set(0,-SK_Scalar1);
         verts[*v + 2].fUV.set(0,-SK_Scalar1);
         verts[*v + 3].fUV.set(0,-SK_Scalar1);
         verts[*v + 0].fD0 = verts[*v + 0].fD1 = -SK_Scalar1;
         verts[*v + 1].fD0 = verts[*v + 1].fD1 = -SK_Scalar1;
         verts[*v + 2].fD0 = verts[*v + 2].fD1 = -SK_Scalar1;
         verts[*v + 3].fD0 = verts[*v + 3].fD1 = -SK_Scalar1;
         idxs[*i + 0] = *v + 0;
         idxs[*i + 1] = *v + 2;
         idxs[*i + 2] = *v + 1;
         idxs[*i + 3] = *v + 0;
         idxs[*i + 4] = *v + 3;
         idxs[*i + 5] = *v + 2;
         *v += 4;
         *i += 6;
         if (Segment::kLine == segb.fType) {
             verts[*v + 0].fPos = fanPt;
             verts[*v + 1].fPos = sega.endPt();
             verts[*v + 2].fPos = segb.fPts[0];
             verts[*v + 3].fPos = verts[*v + 1].fPos + segb.fNorms[0];
             verts[*v + 4].fPos = verts[*v + 2].fPos + segb.fNorms[0];
             // we draw the line edge as a degenerate quad (u is 0, v is the
             // signed distance to the edge)
             SkScalar dist = fanPt.distanceToLineBetween(verts[*v + 1].fPos,
                                                         verts[*v + 2].fPos);
             verts[*v + 0].fUV.set(0, dist);
             verts[*v + 1].fUV.set(0, 0);
             verts[*v + 2].fUV.set(0, 0);
             verts[*v + 3].fUV.set(0, -SK_Scalar1);
             verts[*v + 4].fUV.set(0, -SK_Scalar1);
             verts[*v + 0].fD0 = verts[*v + 0].fD1 = -SK_Scalar1;
             verts[*v + 1].fD0 = verts[*v + 1].fD1 = -SK_Scalar1;
             verts[*v + 2].fD0 = verts[*v + 2].fD1 = -SK_Scalar1;
             verts[*v + 3].fD0 = verts[*v + 3].fD1 = -SK_Scalar1;
             verts[*v + 4].fD0 = verts[*v + 4].fD1 = -SK_Scalar1;
             idxs[*i + 0] = *v + 0;
             idxs[*i + 1] = *v + 2;
             idxs[*i + 2] = *v + 1;
             idxs[*i + 3] = *v + 3;
             idxs[*i + 4] = *v + 1;
             idxs[*i + 5] = *v + 2;
             idxs[*i + 6] = *v + 4;
             idxs[*i + 7] = *v + 3;
             idxs[*i + 8] = *v + 2;
             *v += 5;
             *i += 9;
         } else {
             GrPoint qpts[] = {sega.endPt(), segb.fPts[0], segb.fPts[1]};
             GrVec midVec = segb.fNorms[0] + segb.fNorms[1];
             midVec.normalize();
             verts[*v + 0].fPos = fanPt;
             verts[*v + 1].fPos = qpts[0];
             verts[*v + 2].fPos = qpts[2];
             verts[*v + 3].fPos = qpts[0] + segb.fNorms[0];
             verts[*v + 4].fPos = qpts[2] + segb.fNorms[1];
             verts[*v + 5].fPos = qpts[1] + midVec;
             SkScalar c = segb.fNorms[0].dot(qpts[0]);
             verts[*v + 0].fD0 =  -segb.fNorms[0].dot(fanPt) + c;
             verts[*v + 1].fD0 =  0.f;
             verts[*v + 2].fD0 =  -segb.fNorms[0].dot(qpts[2]) + c;
             verts[*v + 3].fD0 = -SK_ScalarMax/100;
             verts[*v + 4].fD0 = -SK_ScalarMax/100;
             verts[*v + 5].fD0 = -SK_ScalarMax/100;
             c = segb.fNorms[1].dot(qpts[2]);
             verts[*v + 0].fD1 =  -segb.fNorms[1].dot(fanPt) + c;
             verts[*v + 1].fD1 =  -segb.fNorms[1].dot(qpts[0]) + c;
             verts[*v + 2].fD1 =  0.f;
             verts[*v + 3].fD1 = -SK_ScalarMax/100;
             verts[*v + 4].fD1 = -SK_ScalarMax/100;
             verts[*v + 5].fD1 = -SK_ScalarMax/100;
             GrPathUtils::QuadUVMatrix toUV(qpts);
             toUV.apply<6, sizeof(QuadVertex), sizeof(GrPoint)>(verts + *v);
             idxs[*i + 0] = *v + 3;
             idxs[*i + 1] = *v + 1;
             idxs[*i + 2] = *v + 2;
             idxs[*i + 3] = *v + 4;
             idxs[*i + 4] = *v + 3;
             idxs[*i + 5] = *v + 2;
             idxs[*i + 6] = *v + 5;
             idxs[*i + 7] = *v + 3;
             idxs[*i + 8] = *v + 4;
             idxs[*i +  9] = *v + 0;
             idxs[*i + 10] = *v + 2;
             idxs[*i + 11] = *v + 1;
             *v += 6;
             *i += 12;
         }
     }
 }
 ///////////////////////////////////////////////////////////////////////////////
 /*
  * Quadratic specified by 0=u^2-v canonical coords. u and v are the first
  * two components of the vertex attribute. Coverage is based on signed
  * distance with negative being inside, positive outside. The edge is specified in
  * window space (y-down). If either the third or fourth component of the interpolated
  * vertex coord is > 0 then the pixel is considered outside the edge. This is used to
  * attempt to trim to a portion of the infinite quad.
  * Requires shader derivative instruction support.
  */
 class QuadEdgeEffect : public GrVertexEffect {
 public:
     static GrEffectRef* Create() {
         GR_CREATE_STATIC_EFFECT(gQuadEdgeEffect, QuadEdgeEffect, ());
         gQuadEdgeEffect->ref();
         return gQuadEdgeEffect;
     }
     virtual ~QuadEdgeEffect() {}
     static const char* Name() { return "QuadEdge"; }
     virtual void getConstantColorComponents(GrColor* color,
                                             uint32_t* validFlags) const SK_OVERRIDE {
         *validFlags = 0;
     }
     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE {
         return GrTBackendEffectFactory<QuadEdgeEffect>::getInstance();
     }
     class GLEffect : public GrGLVertexEffect {
     public:
         GLEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&)
             : INHERITED (factory) {}
         virtual void emitCode(GrGLFullShaderBuilder* builder,
                               const GrDrawEffect& drawEffect,
                               EffectKey key,
                               const char* outputColor,
                               const char* inputColor,
                               const TransformedCoordsArray&,
                               const TextureSamplerArray& samplers) SK_OVERRIDE {
             const char *vsName, *fsName;
             const SkString* attrName =
                 builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0]);
             builder->fsCodeAppendf("\t\tfloat edgeAlpha;\n");
             SkAssertResult(builder->enableFeature(
                                               GrGLShaderBuilder::kStandardDerivatives_GLSLFeature));
             builder->addVarying(kVec4f_GrSLType, "QuadEdge", &vsName, &fsName);
             // keep the derivative instructions outside the conditional
             builder->fsCodeAppendf("\t\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
             builder->fsCodeAppendf("\t\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
             builder->fsCodeAppendf("\t\tif (%s.z > 0.0 && %s.w > 0.0) {\n", fsName, fsName);
             // today we know z and w are in device space. We could use derivatives
             builder->fsCodeAppendf("\t\t\tedgeAlpha = min(min(%s.z, %s.w) + 0.5, 1.0);\n", fsName,
                                     fsName);
             builder->fsCodeAppendf ("\t\t} else {\n");
             builder->fsCodeAppendf("\t\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
                                    "\t\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
                                    fsName, fsName);
             builder->fsCodeAppendf("\t\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName,
                                     fsName);
             builder->fsCodeAppendf("\t\t\tedgeAlpha = "
                                    "clamp(0.5 - edgeAlpha / length(gF), 0.0, 1.0);\n\t\t}\n");
             builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
                                    (GrGLSLExpr4(inputColor) * GrGLSLExpr1("edgeAlpha")).c_str());
             builder->vsCodeAppendf("\t%s = %s;\n", vsName, attrName->c_str());
         }
         static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
             return 0x0;
         }
         virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE {}
     private:
         typedef GrGLVertexEffect INHERITED;
     };
 private:
     QuadEdgeEffect() {
         this->addVertexAttrib(kVec4f_GrSLType);
     }
     virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
         return true;
     }
     GR_DECLARE_EFFECT_TEST;
     typedef GrVertexEffect INHERITED;
 };
 GR_DEFINE_EFFECT_TEST(QuadEdgeEffect);
 GrEffectRef* QuadEdgeEffect::TestCreate(SkRandom* random,
                                         GrContext*,
                                         const GrDrawTargetCaps& caps,
                                         GrTexture*[]) {
     // Doesn't work without derivative instructions.
     return caps.shaderDerivativeSupport() ? QuadEdgeEffect::Create() : NULL;
 }
 ///////////////////////////////////////////////////////////////////////////////
 bool GrAAConvexPathRenderer::canDrawPath(const SkPath& path,
                                          const SkStrokeRec& stroke,
                                          const GrDrawTarget* target,
                                          bool antiAlias) const {
     return (target->caps()->shaderDerivativeSupport() && antiAlias &&
             stroke.isFillStyle() && !path.isInverseFillType() && path.isConvex());
 }
 namespace {
 // position + edge
 extern const GrVertexAttrib gPathAttribs[] = {
     {kVec2f_GrVertexAttribType, 0,               kPosition_GrVertexAttribBinding},
     {kVec4f_GrVertexAttribType, sizeof(GrPoint), kEffect_GrVertexAttribBinding}
 };
 };
 bool GrAAConvexPathRenderer::onDrawPath(const SkPath& origPath,
                                         const SkStrokeRec&,
                                         GrDrawTarget* target,
                                         bool antiAlias) {
     const SkPath* path = &origPath;
     if (path->isEmpty()) {
         return true;
     }
     SkMatrix viewMatrix = target->getDrawState().getViewMatrix();
     GrDrawTarget::AutoStateRestore asr;
     if (!asr.setIdentity(target, GrDrawTarget::kPreserve_ASRInit)) {
         return false;
     }
     GrDrawState* drawState = target->drawState();
     // We use the fact that SkPath::transform path does subdivision based on
     // perspective. Otherwise, we apply the view matrix when copying to the
     // segment representation.
     SkPath tmpPath;
     if (viewMatrix.hasPerspective()) {
         origPath.transform(viewMatrix, &tmpPath);
         path = &tmpPath;
         viewMatrix = SkMatrix::I();
     }
     QuadVertex *verts;
     uint16_t* idxs;
     int vCount;
     int iCount;
     enum {
         kPreallocSegmentCnt = 512 / sizeof(Segment),
         kPreallocDrawCnt = 4,
     };
     SkSTArray<kPreallocSegmentCnt, Segment, true> segments;
     SkPoint fanPt;
     // We can't simply use the path bounds because we may degenerate cubics to quads which produces
     // new control points outside the original convex hull.
     SkRect devBounds;
     if (!get_segments(*path, viewMatrix, &segments, &fanPt, &vCount, &iCount, &devBounds)) {
         return false;
     }
     // Our computed verts should all be within one pixel of the segment control points.
     devBounds.outset(SK_Scalar1, SK_Scalar1);
     drawState->setVertexAttribs<gPathAttribs>(SK_ARRAY_COUNT(gPathAttribs));
     static const int kEdgeAttrIndex = 1;
     GrEffectRef* quadEffect = QuadEdgeEffect::Create();
     drawState->addCoverageEffect(quadEffect, kEdgeAttrIndex)->unref();
     GrDrawTarget::AutoReleaseGeometry arg(target, vCount, iCount);
     if (!arg.succeeded()) {
         return false;
     }
     SkASSERT(sizeof(QuadVertex) == drawState->getVertexSize());
     verts = reinterpret_cast<QuadVertex*>(arg.vertices());
     idxs = reinterpret_cast<uint16_t*>(arg.indices());
     SkSTArray<kPreallocDrawCnt, Draw, true> draws;
     create_vertices(segments, fanPt, &draws, verts, idxs);
     // Check devBounds
 #ifdef SK_DEBUG
     SkRect tolDevBounds = devBounds;
     tolDevBounds.outset(SK_Scalar1 / 10000, SK_Scalar1 / 10000);
     SkRect actualBounds;
     actualBounds.set(verts[0].fPos, verts[1].fPos);
     for (int i = 2; i < vCount; ++i) {
         actualBounds.growToInclude(verts[i].fPos.fX, verts[i].fPos.fY);
     }
     SkASSERT(tolDevBounds.contains(actualBounds));
 #endif
     int vOffset = 0;
     for (int i = 0; i < draws.count(); ++i) {
         const Draw& draw = draws[i];
         target->drawIndexed(kTriangles_GrPrimitiveType,
                             vOffset,  // start vertex
 ,        // start index
                             draw.fVertexCnt,
                             draw.fIndexCnt,
                             &devBounds);
         vOffset += draw.fVertexCnt;
     }
     return true;
 }

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gfx/skia/trunk/src/gpu/GrAAConvexPathRenderer.cpp@6474c204b198 (annotated)

gfx/skia/trunk/src/gpu/GrAAConvexPathRenderer.cpp