WIP: GPU-accelerated trapezoidal path renderer.

src/gpu/GrAAConcavePathRenderer.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrAAConcavePathRenderer.h"
+
+#include "GrDefaultGeoProcFactory.h"
+#include "GrPathUtils.h"
+#include "SkString.h"
+#include "SkStrokeRec.h"
+#include "SkTLazy.h"
+#include "SkTraceEvent.h"
+#include "SkScan.h"
+
+#include "batches/GrVertexBatch.h"
+#include "GrBatchFlushState.h"
+
+#include <stdio.h> // FIXME
+
+class AAConcavePathBatch : public GrVertexBatch {
+public:
+    struct Geometry {
+        GrColor fColor;
+        SkMatrix fViewMatrix;
+        SkPath fPath;
+        SkIRect fClipBounds;
+        bool fAntiAlias;
+    };
+
+    static GrDrawBatch* Create(const Geometry& geometry) {
+        return SkNEW_ARGS(AAConcavePathBatch, (geometry));
+    }
+
+    const char* name() const override { return "AAConcavePathBatch"; }
+
+    void getInvariantOutputColor(GrInitInvariantOutput* out) const override {
+        out->setKnownFourComponents(fGeometry.fColor);
+    }
+    void getInvariantOutputCoverage(GrInitInvariantOutput* out) const override {
+        out->setUnknownSingleComponent();
+    }
+
+private:
+    void initBatchTracker(const GrPipelineOptimizations& opt) override {
+        // Handle any color overrides
+        if (!opt.readsColor()) {
+            fGeometry.fColor = GrColor_ILLEGAL;
+        }
+        opt.getOverrideColorIfSet(&fGeometry.fColor);
+
+        fPipelineInfo = opt;
+    }
+    AAConcavePathBatch(const Geometry& geometry) {
+        this->initClassID<AAConcavePathBatch>();
+        fGeometry = geometry;
+        geometry.fViewMatrix.mapRect(&fBounds, geometry.fPath.getBounds());
+    }
+    void onPrepareDraws(Target* target) override;
+    bool onCombineIfPossible(GrBatch*, const GrCaps&) override { return false; }
+
+    Geometry fGeometry;
+    GrPipelineOptimizations fPipelineInfo;
+};
+
+GrAAConcavePathRenderer::GrAAConcavePathRenderer() {
+}
+
+
+GrPathRenderer::StencilSupport GrAAConcavePathRenderer::onGetStencilSupport(
+                                                            const SkPath&,
+                                                            const GrStrokeInfo&) const {
+    return GrPathRenderer::kNoSupport_StencilSupport;
+}
+
+bool GrAAConcavePathRenderer::onCanDrawPath(const CanDrawPathArgs& args) const {
+    const GrStrokeInfo& stroke = *args.fStroke;
+    return stroke.isFillStyle();
+}
+
+bool GrAAConcavePathRenderer::onDrawPath(const DrawPathArgs& args) {
+    GrDrawTarget* target = args.fTarget;
+
+    // compute bounds as intersection of rt size, clip, and path
+    const GrRenderTarget* rt = args.fPipelineBuilder->getRenderTarget();
+    if (NULL == rt) {
+        return false;
+    }
+
+    SkIRect clipBoundsI;
+    args.fPipelineBuilder->clip().getConservativeBounds(rt, &clipBoundsI);
+    AAConcavePathBatch::Geometry geometry;
+    geometry.fColor = args.fColor;
+    geometry.fPath = *args.fPath;
+    geometry.fViewMatrix = *args.fViewMatrix;
+    geometry.fClipBounds = clipBoundsI;
+    geometry.fAntiAlias = args.fAntiAlias;
+    SkAutoTUnref<GrDrawBatch> batch(AAConcavePathBatch::Create(geometry));
+    target->drawBatch(*args.fPipelineBuilder, batch.get());
+
+    return true;
+}
+
+void AAConcavePathBatch::onPrepareDraws(Target* target) {
+    const SkPath& path = fGeometry.fPath;
+    const SkIRect clipRect = fGeometry.fClipBounds;
+    const GrColor color = fGeometry.fColor;
+    const SkMatrix& viewMatrix = fGeometry.fViewMatrix;
+    bool antiAlias = fGeometry.fAntiAlias;
+    SkTDArray<SkPoint> points;
+    SkPath deviceSpacePath;
+    path.transform(viewMatrix, &deviceSpacePath);
+    SkScan::PathToTriangles(deviceSpacePath, clipRect, antiAlias, &points);
+    if (0 == points.count()) {
+        return;
+    }
+    const GrVertexBuffer* vertexBuffer;
+    int vertexStride = sizeof(SkPoint);
+    int firstVertex;
+    void* verts = target->makeVertexSpace(vertexStride, points.count(), &vertexBuffer, &firstVertex);
+    if (!verts) {
+        return;
+    }
+
+    // FIXME: avoid this memcpy by asking SkScan for worst-case size?
+    memcpy(verts, points.begin(), points.count() * sizeof(SkPoint));
+
+    // FIXME: pass devBounds here?
+    uint8_t coverage = 0xFF;
+    using namespace GrDefaultGeoProcFactory;
+    LocalCoords localCoords(fPipelineInfo.readsLocalCoords() ? LocalCoords::kUsePosition_Type
+                                                             : LocalCoords::kUnused_Type);
+
+    GrPrimitiveType primitiveType = SkScan::gWireframe ? kLines_GrPrimitiveType : kTriangles_GrPrimitiveType;
+    SkAutoTUnref<const GrGeometryProcessor> gp(
+            GrDefaultGeoProcFactory::Create(color, coverage, localCoords, SkMatrix::I()));
+
+    target->initDraw(gp, this->pipeline());
+    GrVertices vertices;
+    vertices.init(primitiveType, vertexBuffer, firstVertex, points.count());
+
+    target->draw(vertices);
+}