Implement vertex buffer caching in the tessellated path renderer.

src/gpu/GrTessellatingPathRenderer.cpp

Index: src/gpu/GrTessellatingPathRenderer.cpp
diff --git a/src/gpu/GrTessellatingPathRenderer.cpp b/src/gpu/GrTessellatingPathRenderer.cpp
index f420372ca516c708c89d1ea6152ea02b94903f11..b767a63a7276339165bd265fb27138770e15ac3b 100644
--- a/src/gpu/GrTessellatingPathRenderer.cpp
+++ b/src/gpu/GrTessellatingPathRenderer.cpp
@@ -13,6 +13,8 @@
 #include "GrDefaultGeoProcFactory.h"
 #include "GrPathUtils.h"
 #include "GrVertices.h"
+#include "GrResourceCache.h"
+#include "GrResourceProvider.h"
 #include "SkChunkAlloc.h"
 #include "SkGeometry.h"
 
@@ -538,12 +540,13 @@ Vertex* generate_cubic_points(const SkPoint& p0,
 // 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;
@@ -571,6 +574,7 @@ void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clip
                                                      toleranceSqd, prev, &head, pointsLeft, alloc);
                     quadPts += 2;
                 }
+                *isLinear = false;
                 break;
             }
             case SkPath::kMove_Verb:
@@ -590,12 +594,14 @@ void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clip
                 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:
@@ -1329,9 +1335,30 @@ SkPoint* polys_to_triangles(Poly* polys, SkPath::FillType fillType, SkPoint* dat
     return d;
 }
 
+bool cacheMatch(GrVertexBuffer* vertexBuffer, const SkMatrix& newMatrix) {
+    if (!vertexBuffer) {
+        return false;
+    }
+    const SkData* data = vertexBuffer->getCustomData();
+    if (!data || !data->data()) { // path is linear; matches any scale
+        return true;
+    }
+    const SkSize* cachedScale = static_cast<const SkSize*>(data->data());
+    SkASSERT(cachedScale);
+    SkSize newScale;
+    if (!newMatrix.decomposeScale(&newScale)) {
+        return false;
+    }
+    if (newScale.width() > 0.01f * cachedScale->width() && newScale.width() < 3.0f * cachedScale->width()
+     && newScale.height() > 0.01f * cachedScale->height() && newScale.height() < 3.0f * cachedScale->height()) {
+        return true;
+    }
+    return false;
+}
+
 };
 
-GrTessellatingPathRenderer::GrTessellatingPathRenderer() {
+GrTessellatingPathRenderer::GrTessellatingPathRenderer(GrContext* context) : fContext(context) {
 }
 
 GrPathRenderer::StencilSupport GrTessellatingPathRenderer::onGetStencilSupport(
@@ -1342,6 +1369,23 @@ GrPathRenderer::StencilSupport GrTessellatingPathRenderer::onGetStencilSupport(
     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::canDrawPath(const GrDrawTarget* target,
                                              const GrPipelineBuilder* pipelineBuilder,
                                              const SkMatrix& viewMatrix,
@@ -1359,8 +1403,9 @@ public:
     static GrBatch* Create(const GrColor& color,
                            const SkPath& path,
                            const SkMatrix& viewMatrix,
-                           SkRect clipBounds) {
-        return SkNEW_ARGS(TessellatingPathBatch, (color, path, viewMatrix, clipBounds));
+                           SkRect clipBounds,
+                           GrContext* context) {
+        return SkNEW_ARGS(TessellatingPathBatch, (color, path, viewMatrix, clipBounds, context));
     }
 
     const char* name() const override { return "TessellatingPathBatch"; }
@@ -1382,7 +1427,7 @@ public:
         fPipelineInfo = init;
     }
 
-    void generateGeometry(GrBatchTarget* batchTarget, const GrPipeline* pipeline) override {
+    int tessellate(const GrUniqueKey& key, SkAutoTUnref<GrVertexBuffer>& vertexBuffer) {
         SkRect pathBounds = fPath.getBounds();
         Comparator c;
         if (pathBounds.width() > pathBounds.height()) {
@@ -1397,11 +1442,11 @@ public:
         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)) {
@@ -1409,13 +1454,6 @@ public:
         }
 
         LOG("got %d pts, %d contours\n", maxPts, contourCnt);
-        uint32_t flags = GrDefaultGeoProcFactory::kPosition_GPType;
-        SkAutoTUnref<const GrGeometryProcessor> gp(
-            GrDefaultGeoProcFactory::Create(flags, fColor, fPipelineInfo.readsLocalCoords(),
-                                            !fPipelineInfo.readsCoverage(), fViewMatrix,
-                                            SkMatrix::I()));
-        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:
@@ -1423,7 +1461,8 @@ public:
         // 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;
@@ -1433,34 +1472,65 @@ public:
             }
         }
         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) {
+        vertexBuffer.reset(fContext->getGpu()->createVertexBuffer(count * sizeof(SkPoint), false));
+        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()) {
+            SkSize scale;
+            if (!isLinear && fViewMatrix.decomposeScale(&scale)) {
+                vertexBuffer->setCustomData(SkData::NewWithCopy(&scale, sizeof(scale)));
+            }
+            fContext->resourceProvider()->assignUniqueKeyToResource(key, vertexBuffer.get());
+            fPath.pathRef()->addGenIDChangeListener(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;
+        GrUniqueKey::Builder builder(&key, kDomain, 1);
+        builder[0] = fPath.getGenerationID();
+        builder.finish();
+        SkAutoTUnref<GrVertexBuffer> vertexBuffer(fContext->resourceProvider()->findAndRefTByUniqueKey<GrVertexBuffer>(key));
+        int actualCount;
+        if (cacheMatch(vertexBuffer.get(), fViewMatrix)) {
+            actualCount = static_cast<int>(vertexBuffer->gpuMemorySize() / sizeof(SkPoint));
+        } else {
+            actualCount = tessellate(key, vertexBuffer);
+        }
+
+        if (actualCount == 0) {
+            return;
+        }
+
+        uint32_t flags = GrDefaultGeoProcFactory::kPosition_GPType;
+        SkAutoTUnref<const GrGeometryProcessor> gp(
+            GrDefaultGeoProcFactory::Create(flags, fColor, fPipelineInfo.readsLocalCoords(),
+                                            !fPipelineInfo.readsCoverage(), fViewMatrix,
+                                            SkMatrix::I()));
+        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 {
@@ -1471,11 +1541,13 @@ private:
     TessellatingPathBatch(const GrColor& color,
                           const SkPath& path,
                           const SkMatrix& viewMatrix,
-                          const SkRect& clipBounds)
+                          const SkRect& clipBounds,
+                          GrContext* context)
       : fColor(color)
       , fPath(path)
       , fViewMatrix(viewMatrix)
-      , fClipBounds(clipBounds) {
+      , fClipBounds(clipBounds)
+      , fContext(context) {
         this->initClassID<TessellatingPathBatch>();
 
         fBounds = path.getBounds();
@@ -1486,6 +1558,7 @@ private:
     SkPath         fPath;
     SkMatrix       fViewMatrix;
     SkRect         fClipBounds; // in source space
+    GrContext*     fContext;
     GrPipelineInfo fPipelineInfo;
 };
 
@@ -1510,7 +1583,7 @@ bool GrTessellatingPathRenderer::onDrawPath(GrDrawTarget* target,
         return false;
     }
     vmi.mapRect(&clipBounds);
-    SkAutoTUnref<GrBatch> batch(TessellatingPathBatch::Create(color, path, viewM, clipBounds));
+    SkAutoTUnref<GrBatch> batch(TessellatingPathBatch::Create(color, path, viewM, clipBounds, fContext));
     target->drawBatch(*pipelineBuilder, batch);
 
     return true;
@@ -1531,7 +1604,7 @@ BATCH_TEST_DEFINE(TesselatingPathBatch) {
         SkFAIL("Cannot invert matrix\n");
     }
     vmi.mapRect(&clipBounds);
-    return TessellatingPathBatch::Create(color, path, viewMatrix, clipBounds);
+    return TessellatingPathBatch::Create(color, path, viewMatrix, clipBounds, context);
 }
 
 #endif