cc: Support ClipRRect in SolidColorAnalyzer

We used to unconditionally return not_solid_color when analyzing the op
ClipRRect. This lead to huge memory usage of composited border-radius
scrolling because we need to store the texture for the whole mask layer.

This CL makes SolidColorAnalyzer capable of determining whether a tile
is fully covered by the clip rrect, so we can save memory by not storing
textures of solid color quads.

Bug: 567293, 567296, 740720
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I24b10a2d68c0c608aec8e5a8bafaabb9800cd466
Reviewed-on: https://chromium-review.googlesource.com/591913Reviewed-by: Robert Flack <flackr@chromium.org>
Reviewed-by: Walter Korman <wkorman@chromium.org>
Reviewed-by: Vladimir Levin <vmpstr@chromium.org>
Commit-Queue: Xianda Sun <sunxd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491732}

cc/paint/solid_color_analyzer.cc

@@ -45,9 +45,13 @@ bool IsSolidColorPaint(const PaintFlags& flags) {
          flags.getStyle() == PaintFlags::kFill_Style;
 }
 
-// Returns true if the specified drawn_rect will cover the entire canvas, and
-// that the canvas is not clipped (i.e. it covers ALL of the canvas).
-bool IsFullQuad(const SkCanvas& canvas, const SkRect& drawn_rect) {
+// Returns true if the specified |drawn_shape| will cover the entire canvas
+// and that the canvas is not clipped (i.e. it covers ALL of the canvas).
+template <typename T>
+bool IsFullQuad(const SkCanvas& canvas, const T& drawn_shape) {
+  if (!canvas.isClipRect())
+    return false;
+
   SkIRect clip_irect;
   if (!canvas.getDeviceClipBounds(&clip_irect))
     return false;
@@ -62,11 +66,13 @@ bool IsFullQuad(const SkCanvas& canvas, const SkRect& drawn_rect) {
   if (!matrix.rectStaysRect())
     return false;
 
-  SkRect device_rect;
-  matrix.mapRect(&device_rect, drawn_rect);
-  SkRect clip_rect;
-  clip_rect.set(clip_irect);
-  return device_rect.contains(clip_rect);
+  SkMatrix inverse;
+  if (!matrix.invert(&inverse))
+    return false;
+
+  SkRect clip_rect = SkRect::Make(clip_irect);
+  inverse.mapRect(&clip_rect, clip_rect);
+  return drawn_shape.contains(clip_rect);
 }
 
 void CheckIfSolidColor(const SkCanvas& canvas,
@@ -97,18 +103,19 @@ void CheckIfSolidColor(const SkCanvas& canvas,
   }
 }
 
-void CheckIfSolidRect(const SkCanvas& canvas,
-                      const SkRect& rect,
-                      const PaintFlags& flags,
-                      bool* is_solid_color,
-                      bool* is_transparent,
-                      SkColor* color) {
+template <typename T>
+void CheckIfSolidShape(const SkCanvas& canvas,
+                       const T& shape,
+                       const PaintFlags& flags,
+                       bool* is_solid_color,
+                       bool* is_transparent,
+                       SkColor* color) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
-               "SolidColorAnalyzer::HandleDrawRect");
+               "SolidColorAnalyzer::CheckIfSolidShape");
   if (flags.nothingToDraw())
     return;
 
-  bool does_cover_canvas = IsFullQuad(canvas, rect);
+  bool does_cover_canvas = IsFullQuad(canvas, shape);
   SkBlendMode blendmode = flags.getBlendMode();
   if (does_cover_canvas && ActsLikeClear(blendmode, flags.getAlpha()))
     *is_transparent = true;
@@ -123,6 +130,13 @@ void CheckIfSolidRect(const SkCanvas& canvas,
   }
 }
 
+bool CheckIfRRectClipCoversCanvas(const SkCanvas& canvas,
+                                  const SkRRect& rrect) {
+  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
+               "SolidColorAnalyzer::CheckIfRRectClipCoversCanvas");
+  return IsFullQuad(canvas, rrect);
+}
+
 }  // namespace
 
 base::Optional<SkColor> SolidColorAnalyzer::DetermineIfSolidColor(
@@ -160,7 +174,7 @@ base::Optional<SkColor> SolidColorAnalyzer::DetermineIfSolidColor(
   stack.emplace_back(PaintOpBuffer::CompositeIterator(buffer, offsets),
                      canvas.getTotalMatrix(), canvas.getSaveCount());
 
-  int num_ops = 0;
+  int num_draw_ops = 0;
   while (!stack.empty()) {
     auto& frame = stack.back();
     if (!frame.iter) {
@@ -193,7 +207,16 @@ base::Optional<SkColor> SolidColorAnalyzer::DetermineIfSolidColor(
       case PaintOpType::DrawOval:
       case PaintOpType::DrawPath:
       case PaintOpType::DrawPosText:
-      case PaintOpType::DrawRRect:
+        return base::nullopt;
+      // TODO(vmpstr): Add more tests on exceeding max_ops_to_analyze.
+      case PaintOpType::DrawRRect: {
+        if (++num_draw_ops > max_ops_to_analyze)
+          return base::nullopt;
+        const DrawRRectOp* rrect_op = static_cast<const DrawRRectOp*>(op);
+        CheckIfSolidShape(canvas, rrect_op->rrect, rrect_op->flags, &is_solid,
+                          &is_transparent, &color);
+        break;
+      }
       case PaintOpType::DrawText:
       case PaintOpType::DrawTextBlob:
       // Anything that has to do a save layer is probably not solid. As it will
@@ -205,19 +228,27 @@ base::Optional<SkColor> SolidColorAnalyzer::DetermineIfSolidColor(
       // cover the canvas.
       // TODO(vmpstr): We could investigate handling these.
       case PaintOpType::ClipPath:
-      case PaintOpType::ClipRRect:
         return base::nullopt;
-
+      case PaintOpType::ClipRRect: {
+        const ClipRRectOp* rrect_op = static_cast<const ClipRRectOp*>(op);
+        bool does_cover_canvas =
+            CheckIfRRectClipCoversCanvas(canvas, rrect_op->rrect);
+        // If the clip covers the full canvas, we can treat it as if there's no
+        // clip at all and continue, otherwise this is no longer a solid color.
+        if (!does_cover_canvas)
+          return base::nullopt;
+        break;
+      }
       case PaintOpType::DrawRect: {
-        if (++num_ops > max_ops_to_analyze)
+        if (++num_draw_ops > max_ops_to_analyze)
           return base::nullopt;
         const DrawRectOp* rect_op = static_cast<const DrawRectOp*>(op);
-        CheckIfSolidRect(canvas, rect_op->rect, rect_op->flags, &is_solid,
-                         &is_transparent, &color);
+        CheckIfSolidShape(canvas, rect_op->rect, rect_op->flags, &is_solid,
+                          &is_transparent, &color);
         break;
       }
       case PaintOpType::DrawColor: {
-        if (++num_ops > max_ops_to_analyze)
+        if (++num_draw_ops > max_ops_to_analyze)
           return base::nullopt;
         const DrawColorOp* color_op = static_cast<const DrawColorOp*>(op);
         CheckIfSolidColor(canvas, color_op->color, color_op->mode, &is_solid,

cc/paint/solid_color_analyzer_unittest.cc

@@ -29,6 +29,11 @@ class SolidColorAnalyzerTest : public testing::Test {
     buffer_ = nullptr;
   }
 
+  void Reset() {
+    TearDown();
+    SetUp();
+  }
+
   void Initialize(const gfx::Rect& rect = gfx::Rect(0, 0, 100, 100)) {
     canvas_.emplace(display_item_list_.get(), gfx::RectToSkRect(rect));
     rect_ = rect;
@@ -127,6 +132,21 @@ TEST_F(SolidColorAnalyzerTest, DrawRect) {
   EXPECT_EQ(color, GetColor());
 }
 
+// TODO(vmpstr): Generalize the DrawRect test cases so that we can test both
+// Rect and RRect.
+TEST_F(SolidColorAnalyzerTest, DrawRRect) {
+  SkRect rect = SkRect::MakeWH(200, 200);
+  SkRRect rrect;
+  rrect.setRectXY(rect, 5, 5);
+  gfx::Rect canvas_rect(5, 5, 190, 190);
+  Initialize(canvas_rect);
+  PaintFlags flags;
+  SkColor color = SkColorSetARGB(255, 11, 22, 33);
+  flags.setColor(color);
+  canvas()->drawRRect(rrect, flags);
+  EXPECT_EQ(color, GetColor());
+}
+
 TEST_F(SolidColorAnalyzerTest, DrawRectClipped) {
   Initialize();
   PaintFlags flags;
@@ -320,5 +340,85 @@ TEST_F(SolidColorAnalyzerTest, SaveLayer) {
   EXPECT_FALSE(IsSolidColor());
 }
 
+TEST_F(SolidColorAnalyzerTest, ClipRRectCoversCanvas) {
+  SkVector radii[4] = {
+      SkVector::Make(10.0, 15.0), SkVector::Make(20.0, 25.0),
+      SkVector::Make(30.0, 35.0), SkVector::Make(40.0, 45.0),
+  };
+
+  SkVector radii_scale[4] = {
+      SkVector::Make(100.0, 150.0), SkVector::Make(200.0, 250.0),
+      SkVector::Make(300.0, 350.0), SkVector::Make(400.0, 450.0),
+  };
+
+  int rr_size = 600;
+  int canvas_size = 255;
+  gfx::Rect canvas_rect(canvas_size, canvas_size);
+  PaintFlags flags;
+  flags.setColor(SK_ColorWHITE);
+
+  struct {
+    SkVector offset;
+    SkVector offset_scale;
+    bool expected;
+  } cases[] = {
+      // Not within bounding box of |rr|.
+      {SkVector::Make(100, 100), SkVector::Make(100, 100), false},
+
+      // Intersects UL corner.
+      {SkVector::Make(0, 0), SkVector::Make(0, 0), false},
+
+      // Between UL and UR.
+      {SkVector::Make(-50, 0), SkVector::Make(-50, -15), true},
+
+      // Intersects UR corner.
+      {SkVector::Make(canvas_size - rr_size, 0),
+       SkVector::Make(canvas_size - rr_size, 0), false},
+
+      // Between UR and LR.
+      {SkVector::Make(canvas_size - rr_size, -50), SkVector::Make(-305, -80),
+       true},
+
+      // Intersects LR corner.
+      {SkVector::Make(canvas_size - rr_size, canvas_size - rr_size),
+       SkVector::Make(canvas_size - rr_size, canvas_size - rr_size), false},
+
+      // Between LL and LR
+      {SkVector::Make(-50, canvas_size - rr_size), SkVector::Make(-205, -310),
+       true},
+
+      // Intersects LL corner
+      {SkVector::Make(0, canvas_size - rr_size),
+       SkVector::Make(0, canvas_size - rr_size), false},
+
+      // Between UL and LL
+      {SkVector::Make(0, -50), SkVector::Make(-15, -60), true},
+
+      // In center
+      {SkVector::Make(-100, -100), SkVector::Make(-100, -100), true},
+  };
+
+  for (int case_scale = 0; case_scale < 2; ++case_scale) {
+    bool scaled = case_scale > 0;
+    for (size_t i = 0; i < arraysize(cases); ++i) {
+      Reset();
+      Initialize(canvas_rect);
+
+      SkRect bounding_rect = SkRect::MakeXYWH(
+          scaled ? cases[i].offset_scale.x() : cases[i].offset.x(),
+          scaled ? cases[i].offset_scale.y() : cases[i].offset.y(), rr_size,
+          rr_size);
+
+      SkRRect rr;
+      rr.setRectRadii(bounding_rect, scaled ? radii_scale : radii);
+
+      canvas()->clipRRect(rr, SkClipOp::kIntersect, false);
+      canvas()->drawRect(RectToSkRect(canvas_rect), flags);
+      EXPECT_EQ(cases[i].expected, IsSolidColor())
+          << "Case " << i << ", " << scaled << " failed.";
+    }
+  }
+}
+
 }  // namespace
 }  // namespace cc