Mac: improve apparent z-order problems when switching Spaces.

chrome/browser/cocoa/status_bubble_mac.mm

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/cocoa/status_bubble_mac.h"
 
 #include <limits>
 
 #include "app/gfx/text_elider.h"
 #include "base/compiler_specific.h"
@@ skipping 89 matching lines @@
       url_text_(nil),
       state_(kBubbleHidden),
       immediate_(false) {
 }
 
 StatusBubbleMac::~StatusBubbleMac() {
   Hide();
 
   if (window_) {
     [[[window_ animationForKey:kFadeAnimationKey] delegate] invalidate];
-    [parent_ removeChildWindow:window_];
+    Detach();
     [window_ release];
     window_ = nil;
   }
 }
 
 void StatusBubbleMac::SetStatus(const std::wstring& status) {
   Create();
 
   SetText(status, false);
 }
@@ skipping 205 matching lines @@
   [animation autorelease];
   StatusBubbleAnimationDelegate* animation_delegate =
       [[StatusBubbleAnimationDelegate alloc] initWithStatusBubble:this];
   [animation_delegate autorelease];
   [animation setDelegate:animation_delegate];
   NSMutableDictionary* animation_dictionary =
       [NSMutableDictionary dictionaryWithDictionary:[window_ animations]];
   [animation_dictionary setObject:animation forKey:kFadeAnimationKey];
   [window_ setAnimations:animation_dictionary];
 
-  Attach();
+  // Don't |Attach()| since we don't know the appropriate state; let the
+  // |SetState()| call do that.
 
   [view setCornerFlags:kRoundedTopRightCorner];
   MouseMoved(gfx::Point(), false);
 }
 
 void StatusBubbleMac::Attach() {
-  // If the parent window is offscreen when the child is added, the child will
-  // never be displayed, even when the parent moves on-screen.  This method
-  // may be called several times during the process of creating or showing a
-  // status bubble to attach the bubble to its parent window.
-  if (![window_ parentWindow] && [parent_ isVisible])
+  // This method may be called several times during the process of creating or
+  // showing a status bubble to attach the bubble to its parent window.
+  if (!is_attached())
     [parent_ addChildWindow:window_ ordered:NSWindowAbove];
 }
 
+void StatusBubbleMac::Detach() {
+  // This method may be called several times in the process of hiding or
+  // destroying a status bubble.
+  if (is_attached())
+    [parent_ removeChildWindow:window_];
+}
+
 void StatusBubbleMac::AnimationDidStop(CAAnimation* animation, bool finished) {
   DCHECK([NSThread isMainThread]);
   DCHECK(state_ == kBubbleShowingFadeIn || state_ == kBubbleHidingFadeOut);
+  DCHECK(is_attached());
 
   if (finished) {
     // Because of the mechanism used to interrupt animations, this is never
     // actually called with finished set to false.  If animations ever become
     // directly interruptible, the check will ensure that state_ remains
     // properly synchronized.
     if (state_ == kBubbleShowingFadeIn) {
       DCHECK_EQ([[window_ animator] alphaValue], kBubbleOpacity);
       SetState(kBubbleShown);
     } else {
       DCHECK_EQ([[window_ animator] alphaValue], 0.0);
       SetState(kBubbleHidden);
     }
   }
 }
 
 void StatusBubbleMac::SetState(StatusBubbleState state) {
+  // We must be hidden or attached, but not both.
+  DCHECK((state_ == kBubbleHidden) ^ is_attached());
+
   if (state == state_)
     return;
 
+  if (state == kBubbleHidden)
+    Detach();
+  else
+    Attach();
+
   if ([delegate_ respondsToSelector:@selector(statusBubbleWillEnterState:)])
     [delegate_ statusBubbleWillEnterState:state];
 
   state_ = state;
 }
 
 void StatusBubbleMac::Fade(bool show) {
   DCHECK([NSThread isMainThread]);
 
   StatusBubbleState fade_state = kBubbleShowingFadeIn;
   StatusBubbleState target_state = kBubbleShown;
   NSTimeInterval full_duration = kShowFadeInDurationSeconds;
   CGFloat opacity = kBubbleOpacity;
 
   if (!show) {
     fade_state = kBubbleHidingFadeOut;
     target_state = kBubbleHidden;
     full_duration = kHideFadeOutDurationSeconds;
     opacity = 0.0;
   }
 
   DCHECK(state_ == fade_state || state_ == target_state);
 
   if (state_ == target_state)
     return;
 
-  Attach();
-
   if (immediate_) {
     [window_ setAlphaValue:opacity];
     SetState(target_state);
     return;
   }
 
   // If an incomplete transition has left the opacity somewhere between 0 and
   // kBubbleOpacity, the fade rate is kept constant by shortening the duration.
   NSTimeInterval duration =
       full_duration *
@@ skipping 42 matching lines @@
   if (state_ == kBubbleShowingTimer) {
     SetState(kBubbleShowingFadeIn);
     Fade(true);
   } else {
     SetState(kBubbleHidingFadeOut);
     Fade(false);
   }
 }
 
 void StatusBubbleMac::StartShowing() {
-  Attach();
+  // Note that |SetState()| will |Attach()| or |Detach()| as required.
 
   if (state_ == kBubbleHidden) {
     // Arrange to begin fading in after a delay.
     SetState(kBubbleShowingTimer);
     StartTimer(kShowDelayMilliseconds);
   } else if (state_ == kBubbleHidingFadeOut) {
     // Cancel the fade-out in progress and replace it with a fade in.
     SetState(kBubbleShowingFadeIn);
     Fade(true);
   } else if (state_ == kBubbleHidingTimer) {
@@ skipping 44 matching lines @@
 }
 
 NSRect StatusBubbleMac::CalculateWindowFrame() {
   DCHECK(parent_);
 
   NSRect rect = [parent_ frame];
   rect.size.height = kWindowHeight;
   rect.size.width = static_cast<int>(kWindowWidthPercent * rect.size.width);
   return rect;
 }