Add optional sw generated path coverage mask caching

src/gpu/GrSoftwarePathRenderer.cpp

Index: src/gpu/GrSoftwarePathRenderer.cpp
diff --git a/src/gpu/GrSoftwarePathRenderer.cpp b/src/gpu/GrSoftwarePathRenderer.cpp
index 05b3ef8853bc42ded0f52972466e16c7462be75d..c22ce66005478ae7cce4f2665af99f8209ceee96 100644
--- a/src/gpu/GrSoftwarePathRenderer.cpp
+++ b/src/gpu/GrSoftwarePathRenderer.cpp
@@ -9,6 +9,7 @@
 #include "GrAuditTrail.h"
 #include "GrClip.h"
 #include "GrPipelineBuilder.h"
+#include "GrGpuResourcePriv.h"
 #include "GrSWMaskHelper.h"
 #include "GrTextureProvider.h"
 #include "batches/GrRectBatchFactory.h"
@@ -20,39 +21,38 @@ bool GrSoftwarePathRenderer::onCanDrawPath(const CanDrawPathArgs& args) const {
     return !args.fShape->style().applies() && SkToBool(fTexProvider);
 }
 
-namespace {
-
 ////////////////////////////////////////////////////////////////////////////////
-// gets device coord bounds of path (not considering the fill) and clip. The
-// path bounds will be a subset of the clip bounds. returns false if
-// path bounds would be empty.
-bool get_shape_and_clip_bounds(int width, int height,
-                               const GrClip& clip,
-                               const GrShape& shape,
-                               const SkMatrix& matrix,
-                               SkIRect* devShapeBounds,
-                               SkIRect* devClipBounds) {
+static bool get_unclipped_shape_dev_bounds(const GrShape& shape, const SkMatrix& matrix,
+                                           SkIRect* devBounds) {
+    SkRect shapeBounds = shape.styledBounds();
+    if (shapeBounds.isEmpty()) {
+        return false;
+    }
+    SkRect shapeDevBounds;
+    matrix.mapRect(&shapeDevBounds, shapeBounds);
+    shapeDevBounds.roundOut(devBounds);
+    return true;
+}
+
+// Gets the shape bounds, the clip bounds, and the intersection (if any). Returns false if there
+// is no intersection.
+static bool get_shape_and_clip_bounds(int width, int height,
+                                      const GrClip& clip,
+                                      const GrShape& shape,
+                                      const SkMatrix& matrix,
+                                      SkIRect* unclippedDevShapeBounds,
+                                      SkIRect* clippedDevShapeBounds,
+                                      SkIRect* devClipBounds) {
     // compute bounds as intersection of rt size, clip, and path
     clip.getConservativeBounds(width, height, devClipBounds);
 
-    if (devClipBounds->isEmpty()) {
-        *devShapeBounds = SkIRect::MakeWH(width, height);
+    if (!get_unclipped_shape_dev_bounds(shape, matrix, unclippedDevShapeBounds)) {
+        *unclippedDevShapeBounds = SkIRect::EmptyIRect();
+        *clippedDevShapeBounds = SkIRect::EmptyIRect();
         return false;
     }
-    SkRect shapeBounds = shape.styledBounds();
-    if (!shapeBounds.isEmpty()) {
-        SkRect shapeSBounds;
-        matrix.mapRect(&shapeSBounds, shapeBounds);
-        SkIRect shapeIBounds;
-        shapeSBounds.roundOut(&shapeIBounds);
-        *devShapeBounds = *devClipBounds;
-        if (!devShapeBounds->intersect(shapeIBounds)) {
-            // set the correct path bounds, as this would be used later.
-            *devShapeBounds = shapeIBounds;
-            return false;
-        }
-    } else {
-        *devShapeBounds = SkIRect::EmptyIRect();
+    if (!clippedDevShapeBounds->intersect(*devClipBounds, *unclippedDevShapeBounds)) {
+        *clippedDevShapeBounds = SkIRect::EmptyIRect();
         return false;
     }
     return true;
@@ -60,8 +60,6 @@ bool get_shape_and_clip_bounds(int width, int height,
 
 ////////////////////////////////////////////////////////////////////////////////
 
-}
-
 void GrSoftwarePathRenderer::DrawNonAARect(GrDrawContext* drawContext,
                                            const GrPaint& paint,
                                            const GrUserStencilSettings& userStencilSettings,
@@ -133,35 +131,97 @@ bool GrSoftwarePathRenderer::onDrawPath(const DrawPathArgs& args) {
     SkASSERT(!args.fShape->style().applies());
     inverseFilled = args.fShape->inverseFilled();
 
-    SkIRect devShapeBounds, devClipBounds;
+    SkIRect unclippedDevShapeBounds, clippedDevShapeBounds, devClipBounds;
+    // To prevent overloading the cache with entries during animations we limit the cache of masks
+    // to cases where the matrix preserves axis alignment.
+    bool useCache = fAllowCaching && !inverseFilled && args.fViewMatrix->preservesAxisAlignment() &&
+                    args.fShape->hasUnstyledKey() && args.fAntiAlias;
+
     if (!get_shape_and_clip_bounds(args.fDrawContext->width(), args.fDrawContext->height(),
                                    *args.fClip, *args.fShape,
-                                   *args.fViewMatrix, &devShapeBounds, &devClipBounds)) {
+                                   *args.fViewMatrix, &unclippedDevShapeBounds,
+                                   &clippedDevShapeBounds,
+                                   &devClipBounds)) {
         if (inverseFilled) {
             DrawAroundInvPath(args.fDrawContext, *args.fPaint, *args.fUserStencilSettings,
                               *args.fClip,
-                              *args.fViewMatrix, devClipBounds, devShapeBounds);
+                              *args.fViewMatrix, devClipBounds, unclippedDevShapeBounds);
 
         }
         return true;
     }
 
-    SkAutoTUnref<GrTexture> texture(
-            GrSWMaskHelper::DrawShapeMaskToTexture(fTexProvider, *args.fShape, devShapeBounds,
-                                                   args.fAntiAlias, args.fViewMatrix));
+    const SkIRect* boundsForMask = &clippedDevShapeBounds;
+    if (useCache) {
+        // Use the cache only if >50% of the path is visible.
+        int unclippedWidth = unclippedDevShapeBounds.width();
+        int unclippedHeight = unclippedDevShapeBounds.height();
+        int unclippedArea = unclippedWidth * unclippedHeight;
+        int clippedArea = clippedDevShapeBounds.width() * clippedDevShapeBounds.height();
+        int maxTextureSize = args.fDrawContext->caps()->maxTextureSize();
+        if (unclippedArea > 2 * clippedArea || unclippedWidth > maxTextureSize ||
+            unclippedHeight > maxTextureSize) {
+            useCache = false;
+        } else {
+            boundsForMask = &unclippedDevShapeBounds;
+        }
+    }
+
+    GrUniqueKey maskKey;
+    struct KeyData {
+        SkScalar fFractionalTranslateX;
+        SkScalar fFractionalTranslateY;
+    };
+
+    if (useCache) {
+        // We require the upper left 2x2 of the matrix to match exactly for a cache hit.
+        SkScalar sx = args.fViewMatrix->get(SkMatrix::kMScaleX);
+        SkScalar sy = args.fViewMatrix->get(SkMatrix::kMScaleY);
+        SkScalar kx = args.fViewMatrix->get(SkMatrix::kMSkewX);
+        SkScalar ky = args.fViewMatrix->get(SkMatrix::kMSkewY);
+        SkScalar tx = args.fViewMatrix->get(SkMatrix::kMTransX);
+        SkScalar ty = args.fViewMatrix->get(SkMatrix::kMTransY);
+        // Allow 8 bits each in x and y of subpixel positioning.
+        SkFixed fracX = SkScalarToFixed(SkScalarFraction(tx)) & 0x0000FF00;
+        SkFixed fracY = SkScalarToFixed(SkScalarFraction(ty)) & 0x0000FF00;
+        static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
+        GrUniqueKey::Builder builder(&maskKey, kDomain, 5 + args.fShape->unstyledKeySize());
+        builder[0] = SkFloat2Bits(sx);
+        builder[1] = SkFloat2Bits(sy);
+        builder[2] = SkFloat2Bits(kx);
+        builder[3] = SkFloat2Bits(ky);
+        builder[4] = fracX | (fracY >> 8);
+        args.fShape->writeUnstyledKey(&builder[5]);
+    }
+
+    sk_sp<GrTexture> texture;
+    if (useCache) {
+        texture.reset(args.fResourceProvider->findAndRefTextureByUniqueKey(maskKey));
+    }
     if (!texture) {
-        return false;
+         GrSWMaskHelper::TextureType type = useCache ? GrSWMaskHelper::TextureType::kExactFit
+                                                     : GrSWMaskHelper::TextureType::kApproximateFit;
+         texture.reset(GrSWMaskHelper::DrawShapeMaskToTexture(fTexProvider, *args.fShape,
+                                                              *boundsForMask, args.fAntiAlias,
+                                                              type, args.fViewMatrix));
+         if (!texture) {
+             return false;
+         }
+         if (useCache) {
+             texture->resourcePriv().setUniqueKey(maskKey);
+         }
     }
 
-    GrSWMaskHelper::DrawToTargetWithShapeMask(texture, args.fDrawContext, *args.fPaint,
+    GrSWMaskHelper::DrawToTargetWithShapeMask(texture.get(), args.fDrawContext, *args.fPaint,
                                               *args.fUserStencilSettings,
                                               *args.fClip, *args.fViewMatrix,
-                                              devShapeBounds);
+                                              SkIPoint {boundsForMask->fLeft, boundsForMask->fTop},
+                                              *boundsForMask);
 
     if (inverseFilled) {
         DrawAroundInvPath(args.fDrawContext, *args.fPaint, *args.fUserStencilSettings,
                           *args.fClip,
-                          *args.fViewMatrix, devClipBounds, devShapeBounds);
+                          *args.fViewMatrix, devClipBounds, unclippedDevShapeBounds);
     }
 
     return true;