Not submitted - Fixing invalid visibility states with layers which showed up in unittests ...

ash/wm/overview/window_overview.cc

 // Copyright 2013 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/overview/window_overview.h"
 
 #include <algorithm>
 
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/screen_util.h"
@@ skipping 31 matching lines @@
 // The minimum number of cards along the major axis (i.e. horizontally on a
 // landscape orientation).
 const int kMinCardsMajor = 3;
 
 // The duration of transition animations on the overview selector.
 const int kOverviewSelectorTransitionMilliseconds = 100;
 
 // The color and opacity of the overview selector.
 const SkColor kWindowOverviewSelectionColor = SK_ColorBLACK;
 const float kWindowOverviewSelectionOpacity = 0.5f;
+// When a window layer gets hidden, and the window remains "logically visible",
+// it is illegal to fade the layer to 0. We therefore use a fraction which is
+// resolving to an alpha of 0 but tells a comparison otherwise.
+const float kWindowLayerNotShown = 0.001f;

[sky, 2014/03/12 19:31:40]

Ugh. Why can't you actually hide here and evervy where?

 
 // The padding or amount of the window selector widget visible around the edges
 // of the currently selected window.
 const int kWindowOverviewSelectionPadding = 25;
 
 // A comparator for locating a given target window.
 struct WindowSelectorItemComparator
     : public std::unary_function<WindowSelectorItem*, bool> {
   explicit WindowSelectorItemComparator(const aura::Window* target_window)
       : target(target_window) {
@@ skipping 148 matching lines @@
       ui::ScopedLayerAnimationSettings animation_settings(
           old_selection->layer()->GetAnimator());
       animation_settings.SetTransitionDuration(
           base::TimeDelta::FromMilliseconds(
               kOverviewSelectorTransitionMilliseconds));
       animation_settings.SetPreemptionStrategy(
           ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
       old_selection->SetBoundsInScreen(
           GetSelectionBounds(selection_index_) + fade_out_direction,
           dst_display);
-      old_selection->layer()->SetOpacity(0);
+      old_selection->layer()->SetOpacity(kWindowLayerNotShown);
       InitializeSelectionWidget();
       selection_widget_->GetNativeWindow()->SetBoundsInScreen(
           target_bounds - fade_out_direction, dst_display);
     }
     ui::ScopedLayerAnimationSettings animation_settings(
         selection_widget_->GetNativeWindow()->layer()->GetAnimator());
     animation_settings.SetTransitionDuration(base::TimeDelta::FromMilliseconds(
         kOverviewSelectorTransitionMilliseconds));
     animation_settings.SetPreemptionStrategy(
         ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
@@ skipping 115 matching lines @@
     ui::ScopedLayerAnimationSettings settings(
         (*iter)->layer()->GetAnimator());
     settings.SetTransitionDuration(base::TimeDelta::FromMilliseconds(
         ScopedTransformOverviewWindow::kTransitionMilliseconds));
     settings.SetPreemptionStrategy(
         ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
     (*iter)->Hide();
     // Hiding the window can result in it being destroyed.
     if (!hidden_windows_.Contains(*iter))
       continue;
-    (*iter)->layer()->SetOpacity(0);
+    (*iter)->layer()->SetOpacity(kWindowLayerNotShown);
   }
 }
 
 void WindowOverview::PositionWindows() {
   if (single_root_window_) {
     std::vector<WindowSelectorItem*> windows;
     for (WindowSelectorItemList::iterator iter = windows_->begin();
          iter != windows_->end(); ++iter) {
       windows.push_back(*iter);
     }
@@ skipping 73 matching lines @@
   params.accept_events = false;
   selection_widget_->set_focus_on_creation(false);
   selection_widget_->Init(params);
   views::View* content_view = new views::View;
   content_view->set_background(
       views::Background::CreateSolidBackground(kWindowOverviewSelectionColor));
   selection_widget_->SetContentsView(content_view);
   selection_widget_->Show();
   selection_widget_->GetNativeWindow()->parent()->StackChildAtBottom(
       selection_widget_->GetNativeWindow());
-  selection_widget_->GetNativeWindow()->layer()->SetOpacity(0);
+  selection_widget_->GetNativeWindow()->layer()->SetOpacity(
+      kWindowLayerNotShown);
 }
 
 gfx::Rect WindowOverview::GetSelectionBounds(size_t index) {
   gfx::Rect bounds((*windows_)[index]->bounds());
   bounds.Inset(-kWindowOverviewSelectionPadding,
                -kWindowOverviewSelectionPadding);
   return bounds;
 }
 
 }  // namespace ash