Implement vertex buffer caching in the tessellated path renderer.

src/gpu/GrTessellatingPathRenderer.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrTessellatingPathRenderer.h"
 
 #include "GrBatch.h"
 #include "GrBatchTarget.h"
 #include "GrBatchTest.h"
 #include "GrDefaultGeoProcFactory.h"
 #include "GrPathUtils.h"
 #include "GrVertices.h"
+#include "GrResourceCache.h"
+#include "GrResourceProvider.h"
 #include "SkChunkAlloc.h"
 #include "SkGeometry.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.
  *
@@ skipping 505 matching lines @@
     const SkPoint s = { SkScalarAve(r[0].fX, r[1].fX), SkScalarAve(r[0].fY, r[1].fY) };
     pointsLeft >>= 1;
     prev = generate_cubic_points(p0, q[0], r[0], s, tolSqd, prev, head, pointsLeft, alloc);
     prev = generate_cubic_points(s, r[1], q[2], p3, tolSqd, prev, head, pointsLeft, alloc);
     return prev;
 }
 
 // Stage 1: convert the input path to a set of linear contours (linked list of Vertices).
 
 void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds,
-                      Vertex** contours, SkChunkAlloc& alloc) {
+                      Vertex** contours, SkChunkAlloc& alloc, bool *isLinear) {
 
     SkScalar toleranceSqd = tolerance * tolerance;
 
     SkPoint pts[4];
     bool done = false;
+    *isLinear = true;
     SkPath::Iter iter(path, false);
     Vertex* prev = NULL;
     Vertex* head = NULL;
     if (path.isInverseFillType()) {
         SkPoint quad[4];
         clipBounds.toQuad(quad);
         for (int i = 3; i >= 0; i--) {
             prev = append_point_to_contour(quad[i], prev, &head, alloc);
         }
         head->fPrev = prev;
         prev->fNext = head;
         *contours++ = head;
         head = prev = NULL;
     }
     SkAutoConicToQuads converter;
     while (!done) {
         SkPath::Verb verb = iter.next(pts);
         switch (verb) {
             case SkPath::kConic_Verb: {
                 SkScalar weight = iter.conicWeight();
                 const SkPoint* quadPts = converter.computeQuads(pts, weight, toleranceSqd);
                 for (int i = 0; i < converter.countQuads(); ++i) {
                     int pointsLeft = GrPathUtils::quadraticPointCount(quadPts, tolerance);
                     prev = generate_quadratic_points(quadPts[0], quadPts[1], quadPts[2],
                                                      toleranceSqd, prev, &head, pointsLeft, alloc);
                     quadPts += 2;
                 }
+                *isLinear = false;
                 break;
             }
             case SkPath::kMove_Verb:
                 if (head) {
                     head->fPrev = prev;
                     prev->fNext = head;
                     *contours++ = head;
                 }
                 head = prev = NULL;
                 prev = append_point_to_contour(pts[0], prev, &head, alloc);
                 break;
             case SkPath::kLine_Verb: {
                 prev = append_point_to_contour(pts[1], prev, &head, alloc);
                 break;
             }
             case SkPath::kQuad_Verb: {
                 int pointsLeft = GrPathUtils::quadraticPointCount(pts, tolerance);
                 prev = generate_quadratic_points(pts[0], pts[1], pts[2], toleranceSqd, prev,
                                                  &head, pointsLeft, alloc);
+                *isLinear = false;
                 break;
             }
             case SkPath::kCubic_Verb: {
                 int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance);
                 prev = generate_cubic_points(pts[0], pts[1], pts[2], pts[3],
                                 toleranceSqd, prev, &head, pointsLeft, alloc);
+                *isLinear = false;
                 break;
             }
             case SkPath::kClose_Verb:
                 if (head) {
                     head->fPrev = prev;
                     prev->fNext = head;
                     *contours++ = head;
                 }
                 head = prev = NULL;
                 break;
@@ skipping 713 matching lines @@
 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);
         }
     }
     return d;
 }
 
+struct TessInfo {
+    SkScalar  fTolerance;
+    int       fCount;
+};
+
+bool cache_match(GrVertexBuffer* vertexBuffer, SkScalar tol, int* actualCount) {
+    if (!vertexBuffer) {
+        return false;
+    }
+    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;
+    }
+    return false;
+}
+
 };
 
 GrTessellatingPathRenderer::GrTessellatingPathRenderer() {
 }
 
 GrPathRenderer::StencilSupport GrTessellatingPathRenderer::onGetStencilSupport(
                                                             const GrDrawTarget*,
                                                             const GrPipelineBuilder*,
                                                             const SkPath&,
                                                             const GrStrokeInfo&) const {
     return GrPathRenderer::kNoSupport_StencilSupport;
 }
 
+namespace {
+
+// 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;
+
+    void onChange() override {
+        SkMessageBus<GrUniqueKeyInvalidatedMessage>::Post(fMsg);
+    }
+};
+
+}  // namespace
+
 bool GrTessellatingPathRenderer::onCanDrawPath(const CanDrawPathArgs& args) const {
     // This path renderer can draw all fill styles, but does not do antialiasing. It can do convex
     // and concave paths, but we'll leave the convex ones to simpler algorithms.
     return args.fStroke->isFillStyle() && !args.fAntiAlias && !args.fPath->isConvex();
 }
 
 class TessellatingPathBatch : public GrBatch {
 public:
 
     static GrBatch* Create(const GrColor& color,
@@ skipping 15 matching lines @@
 
     void initBatchTracker(const GrPipelineInfo& init) override {
         // Handle any color overrides
         if (!init.readsColor()) {
             fColor = GrColor_ILLEGAL;
         }
         init.getOverrideColorIfSet(&fColor);
         fPipelineInfo = init;
     }
 
-    void generateGeometry(GrBatchTarget* batchTarget, const GrPipeline* pipeline) override {
+    int tessellate(GrUniqueKey* key,
+                   GrResourceProvider* resourceProvider,
+                   SkAutoTUnref<GrVertexBuffer>& vertexBuffer) {
         SkRect pathBounds = fPath.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(fPath, &contourCnt, tol);
         if (maxPts <= 0) {
-            return;
+            return 0;
         }
         if (maxPts > ((int)SK_MaxU16 + 1)) {
             SkDebugf("Path not rendered, too many verts (%d)\n", maxPts);
-            return;
+            return 0;
         }
         SkPath::FillType fillType = fPath.getFillType();
         if (SkPath::IsInverseFillType(fillType)) {
             contourCnt++;
         }
 
         LOG("got %d pts, %d contours\n", maxPts, contourCnt);
-        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));
-        }
-        batchTarget->initDraw(gp, pipeline);
-
         SkAutoTDeleteArray<Vertex*> contours(SkNEW_ARRAY(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)));
-        path_to_contours(fPath, tol, fClipBounds, contours.get(), alloc);
+        bool isLinear;
+        path_to_contours(fPath, 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;
+            return 0;
         }
 
-        size_t stride = gp->getVertexStride();
-        SkASSERT(stride == sizeof(SkPoint));
-        const GrVertexBuffer* vertexBuffer;
-        int firstVertex;
-        SkPoint* verts = static_cast<SkPoint*>(
-            batchTarget->makeVertSpace(stride, count, &vertexBuffer, &firstVertex));
-        if (!verts) {
+        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;
+            return 0;
         }
-
+        SkPoint* verts = static_cast<SkPoint*>(vertexBuffer->map());
         LOG("emitting %d verts\n", count);
         SkPoint* end = polys_to_triangles(polys, fillType, verts);
+        vertexBuffer->unmap();
         int actualCount = static_cast<int>(end - verts);
         LOG("actual count: %d\n", actualCount);
         SkASSERT(actualCount <= count);
 
+        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, SkNEW(PathInvalidator(*key)));
+        }
+        return actualCount;
+    }
+
+    void generateGeometry(GrBatchTarget* batchTarget, const GrPipeline* pipeline) 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;
+        GrUniqueKey::Builder builder(&key, kDomain, 2 + clipBoundsSize32);
+        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));
+        }
+        builder.finish();
+        GrResourceProvider* rp = batchTarget->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)) {
+            actualCount = tessellate(&key, rp, vertexBuffer);
+        }
+
+        if (actualCount == 0) {
+            return;
+        }
+
+        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));
+        }
+
+        batchTarget->initDraw(gp, pipeline);
+        SkASSERT(gp->getVertexStride() == sizeof(SkPoint));
+
         GrPrimitiveType primitiveType = WIREFRAME ? kLines_GrPrimitiveType
                                                   : kTriangles_GrPrimitiveType;
         GrVertices vertices;
-        vertices.init(primitiveType, vertexBuffer, firstVertex, actualCount);
+        vertices.init(primitiveType, vertexBuffer.get(), 0, actualCount);
         batchTarget->draw(vertices);
-
-        batchTarget->putBackVertices((size_t)(count - actualCount), stride);
-        return;
     }
 
     bool onCombineIfPossible(GrBatch*) override {
         return false;
     }
 
 private:
     TessellatingPathBatch(const GrColor& color,
                           const SkPath& path,
                           const SkMatrix& viewMatrix,
@@ skipping 49 matching lines @@
     SkMatrix vmi;
     bool result = viewMatrix.invert(&vmi);
     if (!result) {
         SkFAIL("Cannot invert matrix\n");
     }
     vmi.mapRect(&clipBounds);
     return TessellatingPathBatch::Create(color, path, viewMatrix, clipBounds);
 }
 
 #endif