Broke GrTessellatingPathRenderer's tessellator out into a separate file.

src/gpu/GrTessellator.cpp

Index: src/gpu/GrTessellator.cpp
diff --git a/src/gpu/batches/GrTessellatingPathRenderer.cpp b/src/gpu/GrTessellator.cpp
similarity index 79%
copy from src/gpu/batches/GrTessellatingPathRenderer.cpp
copy to src/gpu/GrTessellator.cpp
index 27e287e9c6bceb6b48c7e500ef338fcc7b259775..701e25679e9a370129ee5c9e2a73e09227811ba9 100644
--- a/src/gpu/batches/GrTessellatingPathRenderer.cpp
+++ b/src/gpu/GrTessellator.cpp
@@ -5,7 +5,7 @@
  * found in the LICENSE file.
  */
 
-#include "GrTessellatingPathRenderer.h"
+#include "GrTessellator.h"
 
 #include "GrBatchFlushState.h"
 #include "GrBatchTest.h"
@@ -14,18 +14,14 @@
 #include "GrVertices.h"
 #include "GrResourceCache.h"
 #include "GrResourceProvider.h"
-#include "SkChunkAlloc.h"
 #include "SkGeometry.h"
+#include "SkChunkAlloc.h"
 
 #include "batches/GrVertexBatch.h"
 
 #include <stdio.h>
 
 /*
- * This path renderer tessellates the path into triangles, uploads the triangles to a
- * vertex buffer, and renders them with a single draw call. It does not currently do
- * antialiasing, so it must be used in conjunction with multisampling.
- *
  * There are six stages to the algorithm:
  *
  * 1) Linearize the path contours into piecewise linear segments (path_to_contours()).
@@ -80,8 +76,8 @@
  * increasing in Y; edges to the right are decreasing in Y). That is, the setting rotates 90
  * degrees counterclockwise, rather that transposing.
  */
+
 #define LOGGING_ENABLED 0
-#define WIREFRAME 0
 
 #if LOGGING_ENABLED
 #define LOG printf
@@ -541,7 +537,6 @@ Vertex* generate_cubic_points(const SkPoint& p0,
 
 void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds,
                       Vertex** contours, SkChunkAlloc& alloc, bool *isLinear) {
-
     SkScalar toleranceSqd = tolerance * tolerance;
 
     SkPoint pts[4];
@@ -1293,7 +1288,16 @@ Poly* tessellate(Vertex* vertices, SkChunkAlloc& alloc) {
 
 // This is a driver function which calls stages 2-5 in turn.
 
-Poly* contours_to_polys(Vertex** contours, int contourCnt, Comparator& c, SkChunkAlloc& alloc) {
+Poly* contours_to_polys(Vertex** contours, int contourCnt, const SkRect& pathBounds, 
+                        SkChunkAlloc& alloc) {
+    Comparator c;
+    if (pathBounds.width() > pathBounds.height()) {
+        c.sweep_lt = sweep_lt_horiz;
+        c.sweep_gt = sweep_gt_horiz;
+    } else {
+        c.sweep_lt = sweep_lt_vert;
+        c.sweep_gt = sweep_gt_vert;
+    }
 #if LOGGING_ENABLED
     for (int i = 0; i < contourCnt; ++i) {
         Vertex* v = contours[i];
@@ -1323,349 +1327,143 @@ Poly* contours_to_polys(Vertex** contours, int contourCnt, Comparator& c, SkChun
     return tessellate(vertices, alloc);
 }
 
-// Stage 6: Triangulate the monotone polygons into a vertex buffer.
-
-SkPoint* polys_to_triangles(Poly* polys, SkPath::FillType fillType, SkPoint* data) {
-    SkPoint* d = data;
-    for (Poly* poly = polys; poly; poly = poly->fNext) {
-        if (apply_fill_type(fillType, poly->fWinding)) {
-            d = poly->emit(d);
-        }
+Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
+                    int contourCnt, SkChunkAlloc& alloc, bool* isLinear) {
+    SkPath::FillType fillType = path.getFillType();
+    if (SkPath::IsInverseFillType(fillType)) {
+        contourCnt++;
     }
-    return d;
-}
+    SkAutoTDeleteArray<Vertex*> contours(new Vertex* [contourCnt]);
 
-struct TessInfo {
-    SkScalar  fTolerance;
-    int       fCount;
-};
+    path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear);
+    return contours_to_polys(contours.get(), contourCnt, path.getBounds(), alloc);
+}
 
-bool cache_match(GrVertexBuffer* vertexBuffer, SkScalar tol, int* actualCount) {
-    if (!vertexBuffer) {
-        return false;
+void get_contour_count_and_size_estimate(const SkPath& path, SkScalar tolerance, int* contourCnt, 

[Stephen White, 2016/01/06 15:28:27]

The code might be slightly clearer (and less error-prone) if it returned the
contour count as return value. I leave it up to you, though.

+                                         int* sizeEstimate) {
+    int maxPts = GrPathUtils::worstCasePointCount(path, contourCnt, tolerance);
+    if (maxPts <= 0) {
+        *contourCnt = 0;
+        return;
     }
-    const SkData* data = vertexBuffer->getUniqueKey().getCustomData();
-    SkASSERT(data);
-    const TessInfo* info = static_cast<const TessInfo*>(data->data());
-    if (info->fTolerance == 0 || info->fTolerance < 3.0f * tol) {
-        *actualCount = info->fCount;
-        return true;
+    if (maxPts > ((int)SK_MaxU16 + 1)) {
+        SkDebugf("Path not rendered, too many verts (%d)\n", maxPts);
+        *contourCnt = 0;
+        return;
     }
-    return false;
+    // For the initial size of the chunk allocator, estimate based on the point count:
+    // one vertex per point for the initial passes, plus two for the vertices in the
+    // resulting Polys, since the same point may end up in two Polys.  Assume minimal
+    // connectivity of one Edge per Vertex (will grow for intersections).
+    *sizeEstimate = maxPts * (3 * sizeof(Vertex) + sizeof(Edge));
 }
 
-};
-
-GrTessellatingPathRenderer::GrTessellatingPathRenderer() {
 }
 
-namespace {
+namespace GrTessellator {
 
-// When the SkPathRef genID changes, invalidate a corresponding GrResource described by key.
-class PathInvalidator : public SkPathRef::GenIDChangeListener {
-public:
-    explicit PathInvalidator(const GrUniqueKey& key) : fMsg(key) {}
-private:
-    GrUniqueKeyInvalidatedMessage fMsg;
+// Stage 6: Triangulate the monotone polygons into a vertex buffer.
 
-    void onChange() override {
-        SkMessageBus<GrUniqueKeyInvalidatedMessage>::Post(fMsg);
+int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
+                    GrResourceProvider* resourceProvider, 
+                    SkAutoTUnref<GrVertexBuffer>& vertexBuffer, bool canMapVB, bool* isLinear) {
+    int contourCnt;
+    int sizeEstimate;
+    get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate);
+    if (contourCnt <= 0) {
+        return 0;
+    }
+    SkChunkAlloc alloc(sizeEstimate);
+    Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, isLinear);
+    SkPath::FillType fillType = path.getFillType();
+    int count = 0;
+    for (Poly* poly = polys; poly; poly = poly->fNext) {
+        if (apply_fill_type(fillType, poly->fWinding) && poly->fCount >= 3) {
+            count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3);
+        }
     }
-};
-
-}  // namespace
-
-bool GrTessellatingPathRenderer::onCanDrawPath(const CanDrawPathArgs& args) const {
-    // This path renderer can draw all fill styles, all stroke styles except hairlines, but does
-    // not do antialiasing. It can do convex and concave paths, but we'll leave the convex ones to
-    // simpler algorithms.
-    return !IsStrokeHairlineOrEquivalent(*args.fStroke, *args.fViewMatrix, nullptr) &&
-           !args.fAntiAlias && !args.fPath->isConvex();
-}
-
-class TessellatingPathBatch : public GrVertexBatch {
-public:
-    DEFINE_BATCH_CLASS_ID
-
-    static GrDrawBatch* Create(const GrColor& color,
-                               const SkPath& path,
-                               const GrStrokeInfo& stroke,
-                               const SkMatrix& viewMatrix,
-                               SkRect clipBounds) {
-        return new TessellatingPathBatch(color, path, stroke, viewMatrix, clipBounds);
+    if (0 == count) {
+        return 0;
     }
 
-    const char* name() const override { return "TessellatingPathBatch"; }
-
-    void computePipelineOptimizations(GrInitInvariantOutput* color, 
-                                      GrInitInvariantOutput* coverage,
-                                      GrBatchToXPOverrides* overrides) const override {
-        color->setKnownFourComponents(fColor);
-        coverage->setUnknownSingleComponent();
-        overrides->fUsePLSDstRead = false;
+    size_t size = count * sizeof(SkPoint);
+    if (!vertexBuffer.get() || vertexBuffer->gpuMemorySize() < size) {
+        vertexBuffer.reset(resourceProvider->createVertexBuffer(
+            size, GrResourceProvider::kStatic_BufferUsage, 0));
     }
-
-private:
-    void initBatchTracker(const GrXPOverridesForBatch& overrides) override {
-        // Handle any color overrides
-        if (!overrides.readsColor()) {
-            fColor = GrColor_ILLEGAL;
-        }
-        overrides.getOverrideColorIfSet(&fColor);
-        fPipelineInfo = overrides;
-    }
-
-    int tessellate(GrUniqueKey* key,
-                   GrResourceProvider* resourceProvider,
-                   SkAutoTUnref<GrVertexBuffer>& vertexBuffer,
-                   bool canMapVB) const {
-        SkPath path;
-        GrStrokeInfo stroke(fStroke);
-        if (stroke.isDashed()) {
-            if (!stroke.applyDashToPath(&path, &stroke, fPath)) {
-                return 0;
-            }
-        } else {
-            path = fPath;
-        }
-        if (!stroke.isFillStyle()) {
-            stroke.setResScale(SkScalarAbs(fViewMatrix.getMaxScale()));
-            if (!stroke.applyToPath(&path, path)) {
-                return 0;
-            }
-            stroke.setFillStyle();
-        }
-        SkRect pathBounds = path.getBounds();
-        Comparator c;
-        if (pathBounds.width() > pathBounds.height()) {
-            c.sweep_lt = sweep_lt_horiz;
-            c.sweep_gt = sweep_gt_horiz;
-        } else {
-            c.sweep_lt = sweep_lt_vert;
-            c.sweep_gt = sweep_gt_vert;
-        }
-        SkScalar screenSpaceTol = GrPathUtils::kDefaultTolerance;
-        SkScalar tol = GrPathUtils::scaleToleranceToSrc(screenSpaceTol, fViewMatrix, pathBounds);
-        int contourCnt;
-        int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tol);
-        if (maxPts <= 0) {
-            return 0;
-        }
-        if (maxPts > ((int)SK_MaxU16 + 1)) {
-            SkDebugf("Path not rendered, too many verts (%d)\n", maxPts);
-            return 0;
-        }
-        SkPath::FillType fillType = path.getFillType();
-        if (SkPath::IsInverseFillType(fillType)) {
-            contourCnt++;
-        }
-
-        LOG("got %d pts, %d contours\n", maxPts, contourCnt);
-        SkAutoTDeleteArray<Vertex*> contours(new Vertex* [contourCnt]);
-
-        // For the initial size of the chunk allocator, estimate based on the point count:
-        // one vertex per point for the initial passes, plus two for the vertices in the
-        // resulting Polys, since the same point may end up in two Polys.  Assume minimal
-        // connectivity of one Edge per Vertex (will grow for intersections).
-        SkChunkAlloc alloc(maxPts * (3 * sizeof(Vertex) + sizeof(Edge)));
-        bool isLinear;
-        path_to_contours(path, tol, fClipBounds, contours.get(), alloc, &isLinear);
-        Poly* polys;
-        polys = contours_to_polys(contours.get(), contourCnt, c, alloc);
-        int count = 0;
-        for (Poly* poly = polys; poly; poly = poly->fNext) {
-            if (apply_fill_type(fillType, poly->fWinding) && poly->fCount >= 3) {
-                count += (poly->fCount - 2) * (WIREFRAME ? 6 : 3);
-            }
-        }
-        if (0 == count) {
-            return 0;
-        }
-
-        size_t size = count * sizeof(SkPoint);
-        if (!vertexBuffer.get() || vertexBuffer->gpuMemorySize() < size) {
-            vertexBuffer.reset(resourceProvider->createVertexBuffer(
-                size, GrResourceProvider::kStatic_BufferUsage, 0));
-        }
-        if (!vertexBuffer.get()) {
-            SkDebugf("Could not allocate vertices\n");
-            return 0;
-        }
-        SkPoint* verts;
-        if (canMapVB) {
-            verts = static_cast<SkPoint*>(vertexBuffer->map());
-        } else {
-            verts = new SkPoint[count];
-        }
-        SkPoint* end = polys_to_triangles(polys, fillType, verts);
-        int actualCount = static_cast<int>(end - verts);
-        LOG("actual count: %d\n", actualCount);
-        SkASSERT(actualCount <= count);
-        if (canMapVB) {
-            vertexBuffer->unmap();
-        } else {
-            vertexBuffer->updateData(verts, actualCount * sizeof(SkPoint));
-            delete[] verts;
-        }
-
-
-        if (!fPath.isVolatile()) {
-            TessInfo info;
-            info.fTolerance = isLinear ? 0 : tol;
-            info.fCount = actualCount;
-            SkAutoTUnref<SkData> data(SkData::NewWithCopy(&info, sizeof(info)));
-            key->setCustomData(data.get());
-            resourceProvider->assignUniqueKeyToResource(*key, vertexBuffer.get());
-            SkPathPriv::AddGenIDChangeListener(fPath, new PathInvalidator(*key));
-        }
-        return actualCount;
-    }
-
-    void onPrepareDraws(Target* target) const override {
-        // construct a cache key from the path's genID and the view matrix
-        static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
-        GrUniqueKey key;
-        int clipBoundsSize32 =
-            fPath.isInverseFillType() ? sizeof(fClipBounds) / sizeof(uint32_t) : 0;
-        int strokeDataSize32 = fStroke.computeUniqueKeyFragmentData32Cnt();
-        GrUniqueKey::Builder builder(&key, kDomain, 2 + clipBoundsSize32 + strokeDataSize32);
-        builder[0] = fPath.getGenerationID();
-        builder[1] = fPath.getFillType();
-        // For inverse fills, the tessellation is dependent on clip bounds.
-        if (fPath.isInverseFillType()) {
-            memcpy(&builder[2], &fClipBounds, sizeof(fClipBounds));
-        }
-        fStroke.asUniqueKeyFragment(&builder[2 + clipBoundsSize32]);
-        builder.finish();
-        GrResourceProvider* rp = target->resourceProvider();
-        SkAutoTUnref<GrVertexBuffer> vertexBuffer(rp->findAndRefTByUniqueKey<GrVertexBuffer>(key));
-        int actualCount;
-        SkScalar screenSpaceTol = GrPathUtils::kDefaultTolerance;
-        SkScalar tol = GrPathUtils::scaleToleranceToSrc(
-            screenSpaceTol, fViewMatrix, fPath.getBounds());
-        if (!cache_match(vertexBuffer.get(), tol, &actualCount)) {
-            bool canMapVB = GrCaps::kNone_MapFlags != target->caps().mapBufferFlags();
-            actualCount = this->tessellate(&key, rp, vertexBuffer, canMapVB);
-        }
-
-        if (actualCount == 0) {
-            return;
+    if (!vertexBuffer.get()) {
+        SkDebugf("Could not allocate vertices\n");
+        return 0;
+    }
+    SkPoint* verts;
+    if (canMapVB) {
+        verts = static_cast<SkPoint*>(vertexBuffer->map());
+    } else {
+        verts = new SkPoint[count];
+    }
+    SkPoint* end = verts;
+    for (Poly* poly = polys; poly; poly = poly->fNext) {
+        if (apply_fill_type(fillType, poly->fWinding)) {
+            end = poly->emit(end);
         }
+    }
+    int actualCount = static_cast<int>(end - verts);
+    LOG("actual count: %d\n", actualCount);
+    SkASSERT(actualCount <= count);
+    if (canMapVB) {
+        vertexBuffer->unmap();
+    } else {
+        vertexBuffer->updateData(verts, actualCount * sizeof(SkPoint));
+        delete[] verts;
+    }
 
-        SkAutoTUnref<const GrGeometryProcessor> gp;
-        {
-            using namespace GrDefaultGeoProcFactory;
-
-            Color color(fColor);
-            LocalCoords localCoords(fPipelineInfo.readsLocalCoords() ?
-                                    LocalCoords::kUsePosition_Type :
-                                    LocalCoords::kUnused_Type);
-            Coverage::Type coverageType;
-            if (fPipelineInfo.readsCoverage()) {
-                coverageType = Coverage::kSolid_Type;
-            } else {
-                coverageType = Coverage::kNone_Type;
-            }
-            Coverage coverage(coverageType);
-            gp.reset(GrDefaultGeoProcFactory::Create(color, coverage, localCoords,
-                                                     fViewMatrix));
-        }
+    return actualCount;
+}
 
-        target->initDraw(gp, this->pipeline());
-        SkASSERT(gp->getVertexStride() == sizeof(SkPoint));
-
-        GrPrimitiveType primitiveType = WIREFRAME ? kLines_GrPrimitiveType
-                                                  : kTriangles_GrPrimitiveType;
-        GrVertices vertices;
-        vertices.init(primitiveType, vertexBuffer.get(), 0, actualCount);
-        target->draw(vertices);
-    }
-
-    bool onCombineIfPossible(GrBatch*, const GrCaps&) override { return false; }
-
-    TessellatingPathBatch(const GrColor& color,
-                          const SkPath& path,
-                          const GrStrokeInfo& stroke,
-                          const SkMatrix& viewMatrix,
-                          const SkRect& clipBounds)
-      : INHERITED(ClassID())
-      , fColor(color)
-      , fPath(path)
-      , fStroke(stroke)
-      , fViewMatrix(viewMatrix) {
-        const SkRect& pathBounds = path.getBounds();
-        fClipBounds = clipBounds;
-        // Because the clip bounds are used to add a contour for inverse fills, they must also
-        // include the path bounds.
-        fClipBounds.join(pathBounds);
-        if (path.isInverseFillType()) {
-            fBounds = fClipBounds;
-        } else {
-            fBounds = path.getBounds();
-        }
-        if (!stroke.isFillStyle()) {
-            SkScalar radius = SkScalarHalf(stroke.getWidth());
-            if (stroke.getJoin() == SkPaint::kMiter_Join) {
-                SkScalar scale = stroke.getMiter();
-                if (scale > SK_Scalar1) {
-                    radius = SkScalarMul(radius, scale);
-                }
-            }
-            fBounds.outset(radius, radius);
+int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
+                   GrTessellator::WindingVertex** verts) {
+    int contourCnt;
+    int sizeEstimate;
+    get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate);
+    if (contourCnt <= 0) {
+        return 0;
+    }
+    SkChunkAlloc alloc(sizeEstimate);
+    bool isLinear;
+    Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, &isLinear);
+    SkPath::FillType fillType = path.getFillType();
+    int count = 0;
+    for (Poly* poly = polys; poly; poly = poly->fNext) {

[Stephen White, 2016/01/06 15:28:27]

Nit: this could be refactored with the same code in PathToTriangles above.

+        if (apply_fill_type(fillType, poly->fWinding) && poly->fCount >= 3) {
+            count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3);
         }
-        viewMatrix.mapRect(&fBounds);
     }
-
-    GrColor                 fColor;
-    SkPath                  fPath;
-    GrStrokeInfo            fStroke;
-    SkMatrix                fViewMatrix;
-    SkRect                  fClipBounds; // in source space
-    GrXPOverridesForBatch   fPipelineInfo;
-
-    typedef GrVertexBatch INHERITED;
-};
-
-bool GrTessellatingPathRenderer::onDrawPath(const DrawPathArgs& args) {
-    SkASSERT(!args.fAntiAlias);
-    const GrRenderTarget* rt = args.fPipelineBuilder->getRenderTarget();
-    if (nullptr == rt) {
-        return false;
+    if (0 == count) {
+        *verts = nullptr;
+        return 0;
     }
 
-    SkIRect clipBoundsI;
-    args.fPipelineBuilder->clip().getConservativeBounds(rt->width(), rt->height(), &clipBoundsI);
-    SkRect clipBounds = SkRect::Make(clipBoundsI);
-    SkMatrix vmi;
-    if (!args.fViewMatrix->invert(&vmi)) {
-        return false;
+    *verts = new GrTessellator::WindingVertex[count];
+    GrTessellator::WindingVertex* vertsEnd = *verts;
+    SkPoint* points = new SkPoint[count];
+    SkPoint* pointsEnd = points;
+    for (Poly* poly = polys; poly; poly = poly->fNext) {
+        if (apply_fill_type(fillType, poly->fWinding)) {
+            SkPoint* start = pointsEnd;
+            pointsEnd = poly->emit(pointsEnd);
+            while (start != pointsEnd) {
+                vertsEnd->fPos = *start;
+                vertsEnd->fWinding = poly->fWinding;
+                ++start;
+                ++vertsEnd;
+            }
+        }
     }
-    vmi.mapRect(&clipBounds);
-    SkAutoTUnref<GrDrawBatch> batch(TessellatingPathBatch::Create(args.fColor, *args.fPath,
-                                                                  *args.fStroke, *args.fViewMatrix,
-                                                                  clipBounds));
-    args.fTarget->drawBatch(*args.fPipelineBuilder, batch);
-
-    return true;
+    int actualCount = static_cast<int>(vertsEnd - *verts);
+    SkASSERT(actualCount <= count);
+    SkASSERT(pointsEnd - points == actualCount);
+    delete[] points;
+    return actualCount;
 }
 
-///////////////////////////////////////////////////////////////////////////////////////////////////
-
-#ifdef GR_TEST_UTILS
-
-DRAW_BATCH_TEST_DEFINE(TesselatingPathBatch) {
-    GrColor color = GrRandomColor(random);
-    SkMatrix viewMatrix = GrTest::TestMatrixInvertible(random);
-    SkPath path = GrTest::TestPath(random);
-    SkRect clipBounds = GrTest::TestRect(random);
-    SkMatrix vmi;
-    bool result = viewMatrix.invert(&vmi);
-    if (!result) {
-        SkFAIL("Cannot invert matrix\n");
-    }
-    vmi.mapRect(&clipBounds);
-    GrStrokeInfo strokeInfo = GrTest::TestStrokeInfo(random);
-    return TessellatingPathBatch::Create(color, path, strokeInfo, viewMatrix, clipBounds);
 }
-
-#endif