Bug 1018845 - Make the fullscreen button easier to see on dark backgrounds. r=roc

dom/base/nsGkAtomList.h

@@ -160,6 +160,7 @@ GK_ATOM(browser, "browser")
 GK_ATOM(mozbrowser, "mozbrowser")
 GK_ATOM(bulletinboard, "bulletinboard")
 GK_ATOM(button, "button")
+GK_ATOM(brighttitlebarforeground, "brighttitlebarforeground")
 GK_ATOM(callTemplate, "call-template")
 GK_ATOM(cancel, "cancel")
 GK_ATOM(canvas, "canvas")

dom/xul/nsXULElement.cpp

@@ -1159,8 +1159,12 @@ nsXULElement::AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
                     nsCOMPtr<nsIXULDocument> xuldoc = do_QueryInterface(document);
                     if (xuldoc) {
                         xuldoc->ResetDocumentLWTheme();
+                        UpdateBrightTitlebarForeground(document);
                     }
                 }
+                else if (aName == nsGkAtoms::brighttitlebarforeground) {
+                    UpdateBrightTitlebarForeground(document);
+                }
             }
     
             if (aName == nsGkAtoms::src && document) {
@@ -1196,8 +1200,12 @@ nsXULElement::AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
                     nsCOMPtr<nsIXULDocument> xuldoc = do_QueryInterface(doc);
                     if (xuldoc) {
                         xuldoc->ResetDocumentLWTheme();
+                        UpdateBrightTitlebarForeground(doc);
                     }
                 }
+                else if (aName == nsGkAtoms::brighttitlebarforeground) {
+                    UpdateBrightTitlebarForeground(doc);
+                }
                 else if (aName == nsGkAtoms::drawintitlebar) {
                     SetDrawsInTitlebar(false);
                 }
@@ -1985,6 +1993,22 @@ nsXULElement::SetDrawsTitle(bool aState)
     }
 }
 
+void
+nsXULElement::UpdateBrightTitlebarForeground(nsIDocument* aDoc)
+{
+    nsIWidget* mainWidget = GetWindowWidget();
+    if (mainWidget) {
+        // We can do this synchronously because SetBrightTitlebarForeground doesn't have any
+        // synchronous effects apart from a harmless invalidation.
+        mainWidget->SetUseBrightTitlebarForeground(
+          aDoc->GetDocumentLWTheme() == nsIDocument::Doc_Theme_Bright ||
+          aDoc->GetRootElement()->AttrValueIs(kNameSpaceID_None,
+                                              nsGkAtoms::brighttitlebarforeground,
+                                              NS_LITERAL_STRING("true"),
+                                              eCaseMatters));
+    }
+}
+
 class MarginSetter : public nsRunnable
 {
 public:

dom/xul/nsXULElement.h

@@ -692,6 +692,7 @@ protected:
 
     void SetDrawsInTitlebar(bool aState);
     void SetDrawsTitle(bool aState);
+    void UpdateBrightTitlebarForeground(nsIDocument* aDocument);
 
     void RemoveBroadcaster(const nsAString & broadcasterId);
 

widget/cocoa/nsChildView.mm

@@ -2431,7 +2431,27 @@ nsChildView::UpdateTitlebarCGContext()
 
     [NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithGraphicsPort:ctx flipped:[view isFlipped]]];
 
-    [cell drawWithFrame:[button bounds] inView:button];
+    if ([window useBrightTitlebarForeground] && !nsCocoaFeatures::OnYosemiteOrLater() &&
+        view == [window standardWindowButton:NSWindowFullScreenButton]) {
+      // Make the fullscreen button visible on dark titlebar backgrounds by
+      // drawing it into a new transparency layer and turning it white.
+      CGRect r = NSRectToCGRect([view bounds]);
+      CGContextBeginTransparencyLayerWithRect(ctx, r, nullptr);
+
+      // Draw twice for double opacity.
+      [cell drawWithFrame:[button bounds] inView:button];
+      [cell drawWithFrame:[button bounds] inView:button];
+
+      // Make it white.
+      CGContextSetBlendMode(ctx, kCGBlendModeSourceIn);
+      CGContextSetRGBFillColor(ctx, 1, 1, 1, 1);
+      CGContextFillRect(ctx, r);
+      CGContextSetBlendMode(ctx, kCGBlendModeNormal);
+
+      CGContextEndTransparencyLayer(ctx);
+    } else {
+      [cell drawWithFrame:[button bounds] inView:button];
+    }
 
     [NSGraphicsContext setCurrentContext:context];
     CGContextRestoreGState(ctx);

widget/cocoa/nsCocoaWindow.h

@@ -79,6 +79,7 @@ typedef struct _nsCocoaWindowList {
 
   BOOL mBeingShown;
   BOOL mDrawTitle;
+  BOOL mBrightTitlebarForeground;
 }
 
 - (void)importState:(NSDictionary*)aState;
@@ -109,6 +110,9 @@ typedef struct _nsCocoaWindowList {
 - (void)setWantsTitleDrawn:(BOOL)aDrawTitle;
 - (BOOL)wantsTitleDrawn;
 
+- (void)setUseBrightTitlebarForeground:(BOOL)aBrightForeground;
+- (BOOL)useBrightTitlebarForeground;
+
 - (void)disableSetNeedsDisplay;
 - (void)enableSetNeedsDisplay;
 
@@ -302,6 +306,7 @@ public:
     virtual void SetShowsFullScreenButton(bool aShow);
     virtual void SetWindowAnimationType(WindowAnimationType aType);
     virtual void SetDrawsTitle(bool aDrawTitle);
+    virtual void SetUseBrightTitlebarForeground(bool aBrightForeground) MOZ_OVERRIDE;
     NS_IMETHOD SetNonClientMargins(nsIntMargin &margins);
     NS_IMETHOD SetWindowTitlebarColor(nscolor aColor, bool aActive);
     virtual void SetDrawsInTitlebar(bool aState);

widget/cocoa/nsCocoaWindow.mm

@@ -2000,6 +2000,16 @@ nsCocoaWindow::SetDrawsTitle(bool aDrawTitle)
   NS_OBJC_END_TRY_ABORT_BLOCK;
 }
 
+void
+nsCocoaWindow::SetUseBrightTitlebarForeground(bool aBrightForeground)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  [mWindow setUseBrightTitlebarForeground:aBrightForeground];
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
 NS_IMETHODIMP nsCocoaWindow::SetNonClientMargins(nsIntMargin &margins)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
@@ -2642,6 +2652,7 @@ static NSMutableSet *gSwizzledFrameViewClasses = nil;
   mTrackingArea = nil;
   mBeingShown = NO;
   mDrawTitle = NO;
+  mBrightTitlebarForeground = NO;
   [self updateTrackingArea];
 
   return self;
@@ -2740,6 +2751,17 @@ static const NSString* kStateShowsToolbarButton = @"showsToolbarButton";
   return mDrawTitle;
 }
 
+- (void)setUseBrightTitlebarForeground:(BOOL)aBrightForeground
+{
+  mBrightTitlebarForeground = aBrightForeground;
+  [[self standardWindowButton:NSWindowFullScreenButton] setNeedsDisplay:YES];
+}
+
+- (BOOL)useBrightTitlebarForeground
+{
+  return mBrightTitlebarForeground;
+}
+
 // Pass nil here to get the default appearance.
 - (void)setTitlebarColor:(NSColor*)aColor forActiveWindow:(BOOL)aActive
 {

widget/nsIWidget.h

@@ -98,8 +98,8 @@ typedef void* nsNativeWidget;
 #endif
 
 #define NS_IWIDGET_IID \
-{ 0x5b27abd6, 0x9e53, 0x4a0a, \
-  { 0x86, 0xf, 0x77, 0x5c, 0xc5, 0x69, 0x35, 0xf } };
+{ 0xcfe7543b, 0x8c0e, 0x40c3, \
+  { 0x9a, 0x6d, 0x77, 0x6e, 0x84, 0x8a, 0x7c, 0xfc } };
 
 /*
  * Window shadow styles
@@ -1366,6 +1366,12 @@ class nsIWidget : public nsISupports {
      */
     virtual void SetDrawsTitle(bool aDrawTitle) {}
 
+    /**
+     * Indicates whether the widget should attempt to make titlebar controls
+     * easier to see on dark titlebar backgrounds.
+     */
+    virtual void SetUseBrightTitlebarForeground(bool aBrightForeground) {}
+
     /** 
      * Hide window chrome (borders, buttons) for this widget.
      *