Fixing invalid visibility states with layers (opacity==0, visibility==true)

ash/wm/panels/panel_layout_manager.cc

 // Copyright (c) 2012 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 "ash/wm/panels/panel_layout_manager.h"
 
 #include <algorithm>
 #include <map>
 
 #include "ash/screen_util.h"
@@ skipping 830 matching lines @@
         callout_bounds.set_y(bounds.y() - callout_bounds.height());
         break;
     }
     callout_bounds = ScreenUtil::ConvertRectFromScreen(
         callout_widget->GetNativeWindow()->parent(),
         callout_bounds);
 
     SetChildBoundsDirect(callout_widget->GetNativeWindow(), callout_bounds);
     panel_container_->StackChildAbove(callout_widget->GetNativeWindow(),
                                       panel);
-    callout_widget->Show();
 
     ui::Layer* layer = callout_widget->GetNativeWindow()->layer();
     // If the panel is not over the callout position or has just become visible
     // then fade in the callout.
-    if ((distance_until_over_panel > 0 || layer->GetTargetOpacity() < 1) &&
-        panel->layer()->GetTargetTransform().IsIdentity()) {
+    if ((distance_until_over_panel > 0 || layer->GetTargetOpacity() < 1)) {
       if (distance_until_over_panel > 0 &&
           slide_distance >= distance_until_over_panel) {
-        layer->SetOpacity(0);
         // If the panel is not yet over the callout, then delay fading in
         // the callout until after the panel should be over it.
         int delay = kPanelSlideDurationMilliseconds *
             distance_until_over_panel / slide_distance;
         layer->SetOpacity(0);
         layer->GetAnimator()->StopAnimating();
         layer->GetAnimator()->SchedulePauseForProperties(
             base::TimeDelta::FromMilliseconds(delay),
             ui::LayerAnimationElement::OPACITY);
       }
-      {
-        ui::ScopedLayerAnimationSettings callout_settings(layer->GetAnimator());
-        callout_settings.SetPreemptionStrategy(
-            ui::LayerAnimator::REPLACE_QUEUED_ANIMATIONS);
-        callout_settings.SetTransitionDuration(
-            base::TimeDelta::FromMilliseconds(
-                kCalloutFadeDurationMilliseconds));
-        layer->SetOpacity(1);
-      }
+      ui::ScopedLayerAnimationSettings callout_settings(layer->GetAnimator());
+      callout_settings.SetPreemptionStrategy(
+          ui::LayerAnimator::REPLACE_QUEUED_ANIMATIONS);
+      callout_settings.SetTransitionDuration(
+          base::TimeDelta::FromMilliseconds(
+              kCalloutFadeDurationMilliseconds));
+      layer->SetOpacity(1);
     }
+
+    // Show the window after we have started the opacity animation.

[sky, 2014/03/18 20:13:11]

I'll say it again, don't document what the code does, document why, eg:

// Show after changing the opacity, this way we don't have a state
// where the widget is visible but the opacity is 0.

[Mr4D (OOO till 08-26), 2014/03/18 21:32:05]

Done. 

+    callout_widget->Show();
   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // keyboard::KeyboardControllerObserver implementation:
 
 void PanelLayoutManager::OnKeyboardBoundsChanging(
     const gfx::Rect& keyboard_bounds) {
   // This bounds change will have caused a change to the Shelf which does not
   // propogate automatically to this class, so manually recalculate bounds.
   OnWindowResized();
 }
 
 }  // namespace internal
 }  // namespace ash