Separate contents_opaque logic on canvas cc::Layer from GraphicsLayer

contents_opaque on the canvas cc::Layer shouldn't depend on its host
GraphicsLayer; and the host GraphicsLayer shouldn't use any special
logic to determine contents_opaque.

This also fixes a CAP-specific bug where the paint code would emit a
background DisplayItem for a canvas even when the canvas has
responsibility for its own background.

As a side effect, this appears to fix a Mac-specific webgl bug that was
hidden due to bad test expectations files added by:

https://chromium-review.googlesource.com/c/chromium/src/+/1005017/

Bug: 1069546
Change-Id: I2a347a6d4a04d2d8b4e299dd0cb10a3c57acbfb1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2607423Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Stefan Zager <szager@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840071}

third_party/blink/renderer/core/layout/layout_html_canvas.cc

@@ -27,6 +27,7 @@
 
 #include "third_party/blink/renderer/core/frame/local_frame.h"
 #include "third_party/blink/renderer/core/frame/local_frame_view.h"
+#include "third_party/blink/renderer/core/html/canvas/canvas_rendering_context.h"
 #include "third_party/blink/renderer/core/html/canvas/html_canvas_element.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
 #include "third_party/blink/renderer/core/page/page.h"
@@ -68,6 +69,23 @@ void LayoutHTMLCanvas::CanvasSizeChanged() {
   SetNeedsLayout(layout_invalidation_reason::kSizeChanged);
 }
 
+bool LayoutHTMLCanvas::DrawsBackgroundOntoContentLayer() const {
+  auto* canvas = To<HTMLCanvasElement>(GetNode());
+  if (canvas->SurfaceLayerBridge())
+    return false;
+  CanvasRenderingContext* context = canvas->RenderingContext();
+  if (!context || !context->IsComposited() || !context->CcLayer())
+    return false;
+  if (StyleRef().HasBoxDecorations() || StyleRef().HasBackgroundImage())
+    return false;
+  // If there is no background, there is nothing to support.
+  if (!StyleRef().HasBackground())
+    return true;
+  // Simple background that is contained within the contents rect.
+  return ReplacedContentRect().Contains(
+      PhysicalBackgroundRect(kBackgroundClipRect));
+}
+
 void LayoutHTMLCanvas::InvalidatePaint(
     const PaintInvalidatorContext& context) const {
   NOT_DESTROYED();

third_party/blink/renderer/core/layout/layout_html_canvas.h

@@ -46,6 +46,8 @@ class CORE_EXPORT LayoutHTMLCanvas final : public LayoutReplaced {
 
   void CanvasSizeChanged();
 
+  bool DrawsBackgroundOntoContentLayer() const final;
+
   void StyleDidChange(StyleDifference, const ComputedStyle* old_style) override;
 
   const char* GetName() const override {

third_party/blink/renderer/core/layout/layout_replaced.h

@@ -81,6 +81,7 @@ class CORE_EXPORT LayoutReplaced : public LayoutBox {
     NOT_DESTROYED();
     return false;
   }
+  virtual bool DrawsBackgroundOntoContentLayer() const { return false; }
   virtual void PaintReplaced(const PaintInfo&,
                              const PhysicalOffset& paint_offset) const {
     NOT_DESTROYED();

third_party/blink/renderer/core/paint/compositing/composited_layer_mapping.cc

@@ -89,12 +89,6 @@ static PhysicalRect ContentsRect(const LayoutObject& layout_object) {
   return To<LayoutBox>(layout_object).PhysicalContentBoxRect();
 }
 
-static PhysicalRect BackgroundRect(const LayoutObject& layout_object) {
-  if (const auto* box = DynamicTo<LayoutBox>(layout_object))
-    return box->PhysicalBackgroundRect(kBackgroundClipRect);
-  return PhysicalRect();
-}
-
 static inline bool IsTextureLayerCanvas(const LayoutObject& layout_object) {
   if (layout_object.IsCanvas()) {
     auto* canvas = To<HTMLCanvasElement>(layout_object.GetNode());
@@ -106,33 +100,10 @@ static inline bool IsTextureLayerCanvas(const LayoutObject& layout_object) {
   return false;
 }
 
-static inline bool IsSurfaceLayerCanvas(const LayoutObject& layout_object) {
-  if (layout_object.IsCanvas()) {
-    auto* canvas = To<HTMLCanvasElement>(layout_object.GetNode());
-    return canvas->SurfaceLayerBridge();
-  }
-  return false;
-}
-
 static bool HasBoxDecorationsOrBackgroundImage(const ComputedStyle& style) {
   return style.HasBoxDecorations() || style.HasBackgroundImage();
 }
 
-static bool ContentLayerSupportsDirectBackgroundComposition(
-    const LayoutObject& layout_object) {
-  // No support for decorations - border, border-radius or outline.
-  // Only simple background - solid color or transparent.
-  if (HasBoxDecorationsOrBackgroundImage(layout_object.StyleRef()))
-    return false;
-
-  // If there is no background, there is nothing to support.
-  if (!layout_object.StyleRef().HasBackground())
-    return true;
-
-  // Simple background that is contained within the contents rect.
-  return ContentsRect(layout_object).Contains(BackgroundRect(layout_object));
-}
-
 static WebPluginContainerImpl* GetPluginContainer(LayoutObject& layout_object) {
   if (auto* embedded_object = DynamicTo<LayoutEmbeddedObject>(layout_object))
     return embedded_object->Plugin();
@@ -195,9 +166,7 @@ static bool NeedsDecorationOutlineLayer(const PaintLayer& paint_layer,
 }
 
 CompositedLayerMapping::CompositedLayerMapping(PaintLayer& layer)
-    : owning_layer_(layer),
-      pending_update_scope_(kGraphicsLayerUpdateNone),
-      draws_background_onto_content_layer_(false) {
+    : owning_layer_(layer), pending_update_scope_(kGraphicsLayerUpdateNone) {
   CreatePrimaryGraphicsLayer();
 }
 
@@ -273,30 +242,7 @@ void CompositedLayerMapping::UpdateContentsOpaque() {
   // not graphics_layer_, and so don't contribute to the opaqueness of the
   // latter.
   bool should_check_children = !foreground_layer_.get();
-  if (IsTextureLayerCanvas(GetLayoutObject())) {
-    CanvasRenderingContext* context =
-        To<HTMLCanvasElement>(GetLayoutObject().GetNode())->RenderingContext();
-    cc::Layer* layer = context ? context->CcLayer() : nullptr;
-    // Determine whether the external texture layer covers the whole graphics
-    // layer. This may not be the case if there are box decorations or
-    // shadows.
-    if (layer && layer->bounds() == graphics_layer_->CcLayer().bounds()) {
-      // Determine whether the rendering context's external texture layer is
-      // opaque.
-      if (!context->CreationAttributes().alpha) {
-        graphics_layer_->SetContentsOpaque(true);
-      } else {
-        graphics_layer_->SetContentsOpaque(
-            !Color(layer->background_color()).HasAlpha());
-      }
-    } else {
-      graphics_layer_->SetContentsOpaque(false);
-    }
-  } else if (IsSurfaceLayerCanvas(GetLayoutObject())) {
-    // TODO(crbug.com/705019): Contents could be opaque, but that cannot be
-    // determined from the main thread. Or can it?
-    graphics_layer_->SetContentsOpaque(false);
-  } else if (BackgroundPaintsOntoScrollingContentsLayer()) {
+  if (BackgroundPaintsOntoScrollingContentsLayer()) {
     DCHECK(scrolling_contents_layer_);
     // Backgrounds painted onto the foreground are clipped by the padding box
     // rect.
@@ -420,7 +366,7 @@ bool CompositedLayerMapping::UpdateGraphicsLayerConfiguration(
   } else if (layout_object.IsCanvas()) {
     graphics_layer_->SetContentsToCcLayer(
         To<HTMLCanvasElement>(layout_object.GetNode())->ContentsCcLayer(),
-        /*prevent_contents_opaque_changes=*/false);
+        /*prevent_contents_opaque_changes=*/true);
     layer_config_changed = true;
   }
 
@@ -986,21 +932,10 @@ void CompositedLayerMapping::UpdateDrawsContentAndPaintsHitTest() {
     scrolling_contents_layer_->SetPaintsHitTest(paints_hit_test);
   }
 
-  draws_background_onto_content_layer_ = false;
-  if (has_painted_content && IsTextureLayerCanvas(GetLayoutObject())) {
-    CanvasRenderingContext* context =
-        To<HTMLCanvasElement>(GetLayoutObject().GetNode())->RenderingContext();
-    // Content layer may be null if context is lost.
-    if (cc::Layer* content_layer = context->CcLayer()) {
-      if (ContentLayerSupportsDirectBackgroundComposition(GetLayoutObject())) {
-        has_painted_content = false;
-        draws_background_onto_content_layer_ = true;
-        Color contents_layer_background_color =
-            GetLayoutObject().ResolveColor(GetCSSPropertyBackgroundColor());
-        graphics_layer_->SetContentsLayerBackgroundColor(
-            contents_layer_background_color);
-      }
-    }
+  if (has_painted_content && GetLayoutObject().IsCanvas() &&
+      To<LayoutHTMLCanvas>(GetLayoutObject())
+          .DrawsBackgroundOntoContentLayer()) {
+    has_painted_content = false;
   }
 
   // FIXME: we could refine this to only allocate backings for one of these

third_party/blink/renderer/core/paint/compositing/composited_layer_mapping.h

@@ -247,10 +247,6 @@ class CORE_EXPORT CompositedLayerMapping final : public GraphicsLayerClient {
   bool AdjustForCompositedScrolling(const GraphicsLayer*,
                                     IntSize& offset) const;
 
-  bool DrawsBackgroundOntoContentLayer() const {
-    return draws_background_onto_content_layer_;
-  }
-
  private:
   // Returns true for layers with scrollable overflow which have a background
   // that can be painted into the composited scrolling contents layer (i.e.
@@ -460,8 +456,6 @@ class CORE_EXPORT CompositedLayerMapping final : public GraphicsLayerClient {
 
   unsigned pending_update_scope_ : 2;
 
-  bool draws_background_onto_content_layer_;
-
   friend class CompositedLayerMappingTest;
 };
 

third_party/blink/renderer/core/paint/html_canvas_painter.cc

@@ -46,9 +46,19 @@ void HTMLCanvasPainter::PaintReplaced(const PaintInfo& paint_info,
 
   bool flatten_composited_layers =
       paint_info.GetGlobalPaintFlags() & kGlobalPaintFlattenCompositingLayers;
-  if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled() &&
-      !flatten_composited_layers) {
-    if (auto* layer = canvas->ContentsCcLayer()) {
+
+  if (auto* layer = canvas->ContentsCcLayer()) {
+    // TODO(crbug.com/705019): For a texture layer canvas, setting the layer
+    // background color to an opaque color will cause the layer to be treated as
+    // opaque. For a surface layer canvas, contents could be opaque, but that
+    // cannot be determined from the main thread. Or can it?
+    if (layout_html_canvas_.DrawsBackgroundOntoContentLayer()) {
+      Color background_color =
+          layout_html_canvas_.ResolveColor(GetCSSPropertyBackgroundColor());
+      layer->SetBackgroundColor(background_color.Rgb());
+    }
+    if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled() &&
+        !flatten_composited_layers) {
       IntRect pixel_snapped_rect = PixelSnappedIntRect(paint_rect);
       layer->SetBounds(gfx::Size(pixel_snapped_rect.Size()));
       layer->SetIsDrawable(true);

third_party/blink/renderer/core/paint/replaced_painter.cc

@@ -109,12 +109,7 @@ void ReplacedPainter::Paint(const PaintInfo& paint_info) {
       }
     }
     if (should_paint_background) {
-      if (layout_replaced_.HasLayer() &&
-          layout_replaced_.Layer()->GetCompositingState() ==
-              kPaintsIntoOwnBacking &&
-          layout_replaced_.Layer()
-              ->GetCompositedLayerMapping()
-              ->DrawsBackgroundOntoContentLayer()) {
+      if (layout_replaced_.DrawsBackgroundOntoContentLayer()) {
         // If the background paints into the content layer, we can skip painting
         // the background but still need to paint the hit test rects.
         BoxPainter(layout_replaced_)

third_party/blink/renderer/platform/graphics/graphics_layer.cc

@@ -591,11 +591,6 @@ void GraphicsLayer::SetContentsVisible(bool contents_visible) {
   UpdateLayerIsDrawable();
 }
 
-void GraphicsLayer::SetContentsLayerBackgroundColor(Color color) {
-  if (contents_layer_)
-    contents_layer_->SetBackgroundColor(color.Rgb());
-}
-
 bool GraphicsLayer::ContentsOpaque() const {
   return CcLayer().contents_opaque();
 }

third_party/blink/renderer/platform/graphics/graphics_layer.h

@@ -139,8 +139,6 @@ class PLATFORM_EXPORT GraphicsLayer : public DisplayItemClient,
   bool ContentsAreVisible() const { return contents_visible_; }
   void SetContentsVisible(bool);
 
-  void SetContentsLayerBackgroundColor(Color color);
-
   // Opaque means that we know the layer contents have no alpha.
   bool ContentsOpaque() const;
   void SetContentsOpaque(bool);

third_party/blink/web_tests/compositing/draws-content/canvas-background-layer-expected.txt

@@ -15,7 +15,6 @@
     {
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [50, 50],
-      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 1
     },
@@ -33,6 +32,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-padding'",
       "bounds": [60, 60],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 3
     },
@@ -45,6 +45,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-border'",
       "bounds": [60, 60],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 4
     },
@@ -57,6 +58,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-image'",
       "bounds": [50, 50],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 5
     },
@@ -81,6 +83,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-opaque-border'",
       "bounds": [60, 60],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 7
     },
@@ -88,6 +91,7 @@
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-opaque-border'",
       "position": [5, 5],
       "bounds": [50, 50],
+      "contentsOpaque": true,
       "transform": 7
     },
     {
@@ -99,6 +103,7 @@
     {
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-opaque-box-shadow'",
       "bounds": [50, 50],
+      "contentsOpaque": true,
       "transform": 8
     }
   ],

third_party/blink/web_tests/compositing/draws-content/webgl-background-layer-expected.txt

@@ -15,13 +15,13 @@
     {
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [50, 50],
-      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 1
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-padding'",
       "bounds": [60, 60],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 2
     },
@@ -34,6 +34,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-border'",
       "bounds": [60, 60],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 3
     },
@@ -46,6 +47,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-image'",
       "bounds": [50, 50],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 4
     },

third_party/blink/web_tests/flag-specific/composite-after-paint/compositing/draws-content/canvas-background-layer-expected.txt

@@ -9,24 +9,25 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [50, 50],
-      "contentsOpaque": true,
-      "backgroundColor": "#008000",
+      "drawsContent": false,
       "transform": 1
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [50, 50],
+      "backgroundColor": "#008000",
       "transform": 1
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-transparent-background'",
       "bounds": [50, 50],
-      "backgroundColor": "#00FF0080",
+      "drawsContent": false,
       "transform": 2
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-transparent-background'",
       "bounds": [50, 50],
+      "backgroundColor": "#00FF0080",
       "transform": 2
     },
     {
@@ -70,14 +71,14 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-opaque'",
       "bounds": [50, 50],
-      "contentsOpaque": true,
-      "backgroundColor": "#008000",
+      "drawsContent": false,
       "transform": 6
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-opaque'",
       "bounds": [50, 50],
       "contentsOpaque": true,
+      "backgroundColor": "#008000",
       "transform": 6
     },
     {

third_party/blink/web_tests/flag-specific/composite-after-paint/compositing/draws-content/webgl-background-layer-expected.txt

@@ -9,13 +9,13 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [50, 50],
-      "contentsOpaque": true,
-      "backgroundColor": "#008000",
+      "drawsContent": false,
       "transform": 1
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [50, 50],
+      "backgroundColor": "#008000",
       "transform": 1
     },
     {
@@ -59,12 +59,13 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-transparent-background'",
       "bounds": [50, 50],
-      "backgroundColor": "#00FF0080",
+      "drawsContent": false,
       "transform": 5
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-transparent-background'",
       "bounds": [50, 50],
+      "backgroundColor": "#00FF0080",
       "transform": 5
     }
   ],

third_party/blink/web_tests/flag-specific/force-device-scale-factor=1.5/compositing/draws-content/canvas-background-layer-expected.txt

@@ -16,7 +16,6 @@
     {
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [75, 75],
-      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 1
     },
@@ -35,6 +34,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-padding'",
       "bounds": [90, 90],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 3
     },
@@ -47,6 +47,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-border'",
       "bounds": [90, 90],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 4
     },
@@ -59,6 +60,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-image'",
       "bounds": [75, 75],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 5
     },
@@ -84,6 +86,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-opaque-border'",
       "bounds": [90, 90],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 7
     },
@@ -91,6 +94,7 @@
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-opaque-border'",
       "position": [7, 8],
       "bounds": [75, 75],
+      "contentsOpaque": true,
       "transform": 7
     },
     {
@@ -102,6 +106,7 @@
     {
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-opaque-box-shadow'",
       "bounds": [75, 75],
+      "contentsOpaque": true,
       "transform": 8
     }
   ],

third_party/blink/web_tests/flag-specific/force-device-scale-factor=1.5/compositing/draws-content/webgl-background-layer-expected.txt

@@ -16,13 +16,13 @@
     {
       "name": "ContentsLayer for LayoutHTMLCanvas CANVAS id='canvas-simple'",
       "bounds": [75, 75],
-      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 1
     },
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-padding'",
       "bounds": [90, 90],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 2
     },
@@ -35,6 +35,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-border'",
       "bounds": [90, 90],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 3
     },
@@ -47,6 +48,7 @@
     {
       "name": "LayoutHTMLCanvas CANVAS id='canvas-image'",
       "bounds": [75, 75],
+      "contentsOpaque": true,
       "backgroundColor": "#008000",
       "transform": 4
     },