Bug 1592739 - Stop clearing the background behind vibrant -moz-appearance items. r=mattwoodrow

Now that there is no Gecko-contributed background color in the window any more,
there's nothing that needs to be cleared away. This simplifies things.

Differential Revision: https://phabricator.services.mozilla.com/D51464

--HG--
extra : moz-landing-system : lando

gfx/src/nsITheme.h

@@ -168,11 +168,6 @@ class nsITheme : public nsISupports {
     return false;
   }
 
-  virtual bool NeedToClearBackgroundBehindWidget(nsIFrame* aFrame,
-                                                 StyleAppearance aWidgetType) {
-    return false;
-  }
-
   /**
    * ThemeGeometryType values are used for describing themed nsIFrames in
    * calls to nsIWidget::UpdateThemeGeometries. We don't simply pass the

layout/painting/nsDisplayItemTypesList.h

@@ -34,7 +34,6 @@ DECLARE_DISPLAY_ITEM_TYPE(CHECKED_CHECKBOX,
                           TYPE_RENDERS_NO_IMAGES | TYPE_IS_CONTENTFUL)
 DECLARE_DISPLAY_ITEM_TYPE(CHECKED_RADIOBUTTON,
                           TYPE_RENDERS_NO_IMAGES | TYPE_IS_CONTENTFUL)
-DECLARE_DISPLAY_ITEM_TYPE(CLEAR_BACKGROUND, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(COLUMN_RULE, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(COMBOBOX_FOCUS, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(COMPOSITOR_HITTEST_INFO, TYPE_RENDERS_NO_IMAGES)

layout/painting/nsDisplayList.cpp

@@ -1508,7 +1508,7 @@ void nsDisplayListBuilder::SetGlassDisplayItem(nsDisplayItem* aItem) {
 
 bool nsDisplayListBuilder::NeedToForceTransparentSurfaceForItem(
     nsDisplayItem* aItem) {
-  return aItem == mGlassDisplayItem || aItem->ClearsBackground();
+  return aItem == mGlassDisplayItem;
 }
 
 AnimatedGeometryRoot* nsDisplayListBuilder::WrapAGRForFrame(
@@ -4311,12 +4311,6 @@ bool nsDisplayBackgroundImage::AppendBackgroundItemsToTop(
   }
 
   if (isThemed) {
-    nsITheme* theme = presContext->GetTheme();
-    if (theme->NeedToClearBackgroundBehindWidget(
-            aFrame, aFrame->StyleDisplay()->mAppearance) &&
-        aBuilder->IsInChromeDocumentOrPopup() && !aBuilder->IsInTransform()) {
-      bgItemList.AppendNewToTop<nsDisplayClearBackground>(aBuilder, aFrame);
-    }
     if (aSecondaryReferenceFrame) {
       nsDisplayTableThemedBackground* bgItem =
           MakeDisplayItem<nsDisplayTableThemedBackground>(
@@ -5439,48 +5433,6 @@ void nsDisplayBackgroundColor::WriteDebugInfo(std::stringstream& aStream) {
   aStream << " backgroundRect" << mBackgroundRect;
 }
 
-already_AddRefed<Layer> nsDisplayClearBackground::BuildLayer(
-    nsDisplayListBuilder* aBuilder, LayerManager* aManager,
-    const ContainerLayerParameters& aParameters) {
-  RefPtr<ColorLayer> layer = static_cast<ColorLayer*>(
-      aManager->GetLayerBuilder()->GetLeafLayerFor(aBuilder, this));
-  if (!layer) {
-    layer = aManager->CreateColorLayer();
-    if (!layer) {
-      return nullptr;
-    }
-  }
-  layer->SetColor(Color());
-  layer->SetMixBlendMode(gfx::CompositionOp::OP_SOURCE);
-
-  bool snap;
-  nsRect bounds = GetBounds(aBuilder, &snap);
-  int32_t appUnitsPerDevPixel = mFrame->PresContext()->AppUnitsPerDevPixel();
-  layer->SetBounds(bounds.ToNearestPixels(appUnitsPerDevPixel));  // XXX Do we
-                                                                  // need to
-                                                                  // respect the
-                                                                  // parent
-                                                                  // layer's
-                                                                  // scale here?
-
-  return layer.forget();
-}
-
-bool nsDisplayClearBackground::CreateWebRenderCommands(
-    mozilla::wr::DisplayListBuilder& aBuilder,
-    mozilla::wr::IpcResourceUpdateQueue& aResources,
-    const StackingContextHelper& aSc,
-    mozilla::layers::RenderRootStateManager* aManager,
-    nsDisplayListBuilder* aDisplayListBuilder) {
-  LayoutDeviceRect bounds = LayoutDeviceRect::FromAppUnits(
-      nsRect(ToReferenceFrame(), mFrame->GetSize()),
-      mFrame->PresContext()->AppUnitsPerDevPixel());
-
-  aBuilder.PushClearRect(wr::ToLayoutRect(bounds));
-
-  return true;
-}
-
 nsRect nsDisplayOutline::GetBounds(nsDisplayListBuilder* aBuilder,
                                    bool* aSnap) const {
   *aSnap = false;

layout/painting/nsDisplayList.h

@@ -2764,8 +2764,6 @@ class nsDisplayItem : public nsDisplayItemBase {
     return false;
   }
 
-  virtual bool ClearsBackground() const { return false; }
-
   /**
    * Returns true if all layers that can be active should be forced to be
    * active. Requires setting the pref layers.force-active=true.
@@ -5107,49 +5105,6 @@ class nsDisplayTableBackgroundColor : public nsDisplayBackgroundColor {
   nsIFrame* mAncestorFrame;
 };
 
-class nsDisplayClearBackground : public nsPaintedDisplayItem {
- public:
-  nsDisplayClearBackground(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
-      : nsPaintedDisplayItem(aBuilder, aFrame) {}
-
-  NS_DISPLAY_DECL_NAME("ClearBackground", TYPE_CLEAR_BACKGROUND)
-
-  nsRect GetBounds(nsDisplayListBuilder* aBuilder, bool* aSnap) const override {
-    *aSnap = true;
-    return nsRect(ToReferenceFrame(), Frame()->GetSize());
-  }
-
-  nsRegion GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
-                           bool* aSnap) const override {
-    *aSnap = false;
-    return GetBounds(aBuilder, aSnap);
-  }
-
-  mozilla::Maybe<nscolor> IsUniform(
-      nsDisplayListBuilder* aBuilder) const override {
-    return mozilla::Some(NS_RGBA(0, 0, 0, 0));
-  }
-
-  bool ClearsBackground() const override { return true; }
-
-  LayerState GetLayerState(
-      nsDisplayListBuilder* aBuilder, LayerManager* aManager,
-      const ContainerLayerParameters& aParameters) override {
-    return mozilla::LayerState::LAYER_ACTIVE_FORCE;
-  }
-
-  already_AddRefed<Layer> BuildLayer(
-      nsDisplayListBuilder* aBuilder, LayerManager* aManager,
-      const ContainerLayerParameters& aContainerParameters) override;
-
-  bool CreateWebRenderCommands(
-      mozilla::wr::DisplayListBuilder& aBuilder,
-      mozilla::wr::IpcResourceUpdateQueue& aResources,
-      const StackingContextHelper& aSc,
-      mozilla::layers::RenderRootStateManager* aManager,
-      nsDisplayListBuilder* aDisplayListBuilder) override;
-};
-
 /**
  * The standard display item to paint the outer CSS box-shadows of a frame.
  */

widget/cocoa/nsNativeThemeCocoa.h

@@ -419,8 +419,6 @@ class nsNativeThemeCocoa : private nsNativeTheme, public nsITheme {
   bool ThemeDrawsFocusForWidget(StyleAppearance aAppearance) override;
   bool ThemeNeedsComboboxDropmarker() override;
   virtual bool WidgetAppearanceDependsOnWindowFocus(StyleAppearance aAppearance) override;
-  virtual bool NeedToClearBackgroundBehindWidget(nsIFrame* aFrame,
-                                                 StyleAppearance aAppearance) override;
   virtual ThemeGeometryType ThemeGeometryTypeForWidget(nsIFrame* aFrame,
                                                        StyleAppearance aAppearance) override;
   virtual Transparency GetWidgetTransparency(nsIFrame* aFrame,

widget/cocoa/nsNativeThemeCocoa.mm

@@ -3030,11 +3030,8 @@ Maybe<nsNativeThemeCocoa::WidgetInfo> nsNativeThemeCocoa::ComputeWidgetInfo(
 
     case StyleAppearance::MozMacSourceListSelection:
     case StyleAppearance::MozMacActiveSourceListSelection: {
-      // If we're in XUL tree, we need to rely on the source list's clear
-      // background display item. If we cleared the background behind the
-      // selections, the source list would not pick up the right font
-      // smoothing background. So, to simplify a bit, we only support vibrancy
-      // if we're in a source list.
+      // We only support vibrancy for source list selections if we're inside
+      // a source list.
       if (VibrancyManager::SystemSupportsVibrancy() && IsInSourceList(aFrame)) {
         return Nothing();
       }
@@ -4263,30 +4260,6 @@ bool nsNativeThemeCocoa::WidgetAppearanceDependsOnWindowFocus(StyleAppearance aA
   }
 }
 
-bool nsNativeThemeCocoa::NeedToClearBackgroundBehindWidget(nsIFrame* aFrame,
-                                                           StyleAppearance aAppearance) {
-  switch (aAppearance) {
-    case StyleAppearance::MozMacSourceList:
-    // If we're in a XUL tree, we don't want to clear the background behind the
-    // selections below, since that would make our source list to not pick up
-    // the right font smoothing background. But since we don't call this method
-    // in nsTreeBodyFrame::BuildDisplayList, we never get here.
-    case StyleAppearance::MozMacSourceListSelection:
-    case StyleAppearance::MozMacActiveSourceListSelection:
-    case StyleAppearance::MozMacVibrancyLight:
-    case StyleAppearance::MozMacVibrancyDark:
-    case StyleAppearance::MozMacVibrantTitlebarLight:
-    case StyleAppearance::MozMacVibrantTitlebarDark:
-    case StyleAppearance::Tooltip:
-    case StyleAppearance::Menupopup:
-    case StyleAppearance::Menuitem:
-    case StyleAppearance::Checkmenuitem:
-      return true;
-    default:
-      return false;
-  }
-}
-
 nsITheme::ThemeGeometryType nsNativeThemeCocoa::ThemeGeometryTypeForWidget(
     nsIFrame* aFrame, StyleAppearance aAppearance) {
   switch (aAppearance) {