Bug 1062801 - Fill vibrant window regions with the correct vibrancy fill color. r=smichaud

widget/cocoa/VibrancyManager.h

@@ -75,6 +75,14 @@ public:
    */
   void ClearVibrantAreas() const;
 
+  /**
+   * Return the fill color that should be drawn on top of the cleared window
+   * parts. Usually this would be drawn by -[NSVisualEffectView drawRect:].
+   * The returned color is opaque if the system-wide "Reduce transparency"
+   * preference is set.
+   */
+  NSColor* VibrancyFillColorForType(VibrancyType aType);
+
   /**
    * Check whether the operating system supports vibrancy at all.
    * You may only create a VibrancyManager instance if this returns true.

widget/cocoa/VibrancyManager.mm

@@ -83,6 +83,26 @@ VibrancyManager::ClearVibrantRegion(const VibrantRegion& aVibrantRegion) const
   }
 }
 
+@interface NSView(CurrentFillColor)
+- (NSColor*)_currentFillColor;
+@end
+
+NSColor*
+VibrancyManager::VibrancyFillColorForType(VibrancyType aType)
+{
+  const nsTArray<NSView*>& views =
+    mVibrantRegions.LookupOrAdd(uint32_t(aType))->effectViews;
+
+  if (!views.IsEmpty() &&
+      [views[0] respondsToSelector:@selector(_currentFillColor)]) {
+    // -[NSVisualEffectView _currentFillColor] is the color that our view
+    // would draw during its drawRect implementation, if we hadn't
+    // disabled that.
+    return [views[0] _currentFillColor];
+  }
+  return [NSColor whiteColor];
+}
+
 static void
 DrawRectNothing(id self, SEL _cmd, NSRect aRect)
 {

widget/cocoa/nsChildView.h

@@ -329,6 +329,8 @@ typedef NSInteger NSEventGestureAxis;
 
 - (BOOL)isCoveringTitlebar;
 
+- (NSColor*)vibrancyFillColorForWidgetType:(uint8_t)aWidgetType;
+
 // Simple gestures support
 //
 // XXX - The swipeWithEvent, beginGestureWithEvent, magnifyWithEvent,
@@ -573,6 +575,7 @@ public:
 
   void              NotifyDirtyRegion(const nsIntRegion& aDirtyRegion);
   void              ClearVibrantAreas();
+  NSColor*          VibrancyFillColorForWidgetType(uint8_t aWidgetType);
 
   // unit conversion convenience functions
   int32_t           CocoaPointsToDevPixels(CGFloat aPts) const {

widget/cocoa/nsChildView.mm

@@ -2656,6 +2656,17 @@ nsChildView::ClearVibrantAreas()
   }
 }
 
+NSColor*
+nsChildView::VibrancyFillColorForWidgetType(uint8_t aWidgetType)
+{
+  if (VibrancyManager::SystemSupportsVibrancy()) {
+    return EnsureVibrancyManager().VibrancyFillColorForType(
+      aWidgetType == NS_THEME_MAC_VIBRANCY_LIGHT
+        ? VibrancyType::LIGHT : VibrancyType::DARK);
+  }
+  return [NSColor whiteColor];
+}
+
 mozilla::VibrancyManager&
 nsChildView::EnsureVibrancyManager()
 {
@@ -3639,6 +3650,14 @@ NSEvent* gLastDragMouseDownEvent = nil;
          [(BaseWindow*)[self window] drawsContentsIntoWindowFrame];
 }
 
+- (NSColor*)vibrancyFillColorForWidgetType:(uint8_t)aWidgetType
+{
+  if (!mGeckoChild) {
+    return [NSColor whiteColor];
+  }
+  return mGeckoChild->VibrancyFillColorForWidgetType(aWidgetType);
+}
+
 - (nsIntRegion)nativeDirtyRegionWithBoundingRect:(NSRect)aRect
 {
   nsIntRect boundingRect = mGeckoChild->CocoaPointsToDevPixels(aRect);

widget/cocoa/nsNativeThemeCocoa.mm

@@ -2858,6 +2858,23 @@ nsNativeThemeCocoa::DrawWidgetBackground(nsRenderingContext* aContext,
     case NS_THEME_RESIZER:
       DrawResizer(cgContext, macRect, aFrame);
       break;
+
+    case NS_THEME_MAC_VIBRANCY_LIGHT:
+    case NS_THEME_MAC_VIBRANCY_DARK:
+    {
+      NSWindow* win = NativeWindowForFrame(aFrame);
+      if ([win isKindOfClass:[ToolbarWindow class]]) {
+        NSGraphicsContext* savedContext = [NSGraphicsContext currentContext];
+        [NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithGraphicsPort:cgContext flipped:YES]];
+
+        ChildView* childView = [(ToolbarWindow*)win mainChildView];
+        [[childView vibrancyFillColorForWidgetType:aWidgetType] set];
+        NSRectFill(NSRectFromCGRect(macRect));
+
+        [NSGraphicsContext setCurrentContext:savedContext];
+      }
+      break;
+    }
   }
 
   if (hidpi) {