Implemented swipe to close in overview mode.

ash/wm/overview/window_selector_item.cc

Index: ash/wm/overview/window_selector_item.cc
diff --git a/ash/wm/overview/window_selector_item.cc b/ash/wm/overview/window_selector_item.cc
index 0ec1a02858752cb7a358b6ae436ae0cf3de6a6fa..2440605d6762de9107d53ef5a3d37d9e467813f6 100644
--- a/ash/wm/overview/window_selector_item.cc
+++ b/ash/wm/overview/window_selector_item.cc
@@ -35,6 +35,19 @@ namespace ash {
 
 namespace {
 
+// The minimum opacity used during touch scroll gestures.
+const float kMinimumOpacity = 0.2f;

[flackr, 2014/11/07 19:10:52]

0.f seems like a decent close opacity. If you drag and the window becomes
invisible it's obvious that a release will kill it.

[bruthig, 2015/01/02 16:49:17]

I consulted with stevet@ with the 0.2f value. If we want to change it we should
loop him in to the conversation.  I would prefer that we don't delay getting
this CL in based on this and we can always change it later very easily.

+
+// The distance at which the minimum opacity should take effect.
+const float kMinimumOpacityDistance = 200.0f;

[flackr, 2014/11/07 19:10:52]

Shouldn't this be the same as the close distance?

[bruthig, 2015/01/02 16:49:17]

I agree, this should be in sync with the actual close distance.  I will defer
this until we agree on how that distance is calculated.

+
+// Calculates the window opacity from the given scroll |distance|.
+float CalculateOpacityFromScrollDistance(int distance) {
+  float opacity =
+      1.0 - static_cast<float>(abs(distance)) / kMinimumOpacityDistance;
+  return std::min(1.0f, std::max(kMinimumOpacity, opacity));
+}
+
 gfx::Rect GetTransformedBounds(aura::Window* window) {
   gfx::RectF bounds(ScreenUtil::ConvertRectToScreen(window->GetRootWindow(),
                                                     window->layer()->bounds()));
@@ -147,6 +160,38 @@ WindowSelectorItem::WindowListItem::WindowListItem(aura::Window* window)
 WindowSelectorItem::WindowListItem::~WindowListItem() {
 }
 
+void WindowSelectorItem::WindowListItem::Scroll(int delta_x) {
+  const float opacity = CalculateOpacityFromScrollDistance(delta_x);
+  ScopedTransformOverviewWindow::ScopedAnimationSettings animation_settings;
+  transform_window_->BeginScopedAnimation(
+      OverviewAnimationSettingsProvider::AnimationType::SELECTOR_ITEM_SCROLL,
+      &animation_settings);
+
+  gfx::Transform new_transform;
+  new_transform.Translate(delta_x, 0);
+  new_transform.PreconcatTransform(transform_window_->get_overview_transform());
+  transform_window_->SetTransform(transform_window_->window()->GetRootWindow(),
+                                  new_transform);
+
+  transform_window_->SetOpacity(opacity);
+}
+
+void WindowSelectorItem::WindowListItem::CancelScroll() {
+  aura::Window* window = transform_window_->window();
+  ScopedTransformOverviewWindow::ScopedAnimationSettings animation_settings;
+  transform_window_->BeginScopedAnimation(
+      OverviewAnimationSettingsProvider::AnimationType::
+          SELECTOR_ITEM_SCROLL_CANCEL,
+      &animation_settings);
+  // The target opacity is set before the transform so that the
+  // WindowSelectorItem::OnWindowTransformed handler can properly
+  // update the opacity of the close button to the window's target
+  // opacity.
+  transform_window_->SetOpacity(1.0);
+  transform_window_->SetTransform(window->GetRootWindow(),
+                                  transform_window_->get_overview_transform());
+}
+
 void WindowSelectorItem::WindowListItem::Select() {
   aura::Window* window = transform_window_->window();
   wm::GetWindowState(window)->Activate();
@@ -332,6 +377,7 @@ void WindowSelectorItem::SetBounds(aura::Window* root_window,
   // SetItemBounds is called before UpdateCloseButtonLayout so the close button
   // can properly use the updated windows bounds.
   UpdateCloseButtonLayout(animate);
+  SetCloseWindowDistanceMinimum(target_bounds_.size().width() / 2);
   UpdateSelectorButtons();
 }
 
@@ -400,12 +446,36 @@ void WindowSelectorItem::OnWindowTransformed(aura::Window* window) {
   }
 }
 
+void WindowSelectorItem::Scroll(int delta_x) {
+  for (WindowList::iterator iter = window_list_.begin();
+       iter != window_list_.end();
+       iter++) {
+    (*iter)->Scroll(delta_x);
+  }
+}
+
+void WindowSelectorItem::CancelScroll() {
+  for (WindowList::iterator iter = window_list_.begin();
+       iter != window_list_.end();
+       iter++) {
+    (*iter)->CancelScroll();
+  }
+}
+
 void WindowSelectorItem::Select() {
   aura::Window* selection_window = SelectionWindow();
   if (selection_window)
     wm::GetWindowState(selection_window)->Activate();
 }
 
+void WindowSelectorItem::Close() {
+  for (WindowList::iterator iter = window_list_.begin();
+       iter != window_list_.end();
+       iter++) {
+    (*iter)->Close();
+  }
+}
+
 void WindowSelectorItem::SetItemBounds(aura::Window* root_window,
                                        const gfx::Rect& target_bounds,
                                        bool animate) {
@@ -556,6 +626,16 @@ void WindowSelectorItem::CreateWindowLabel(const base::string16& title) {
   window_label_->Show();
 }
 
+void WindowSelectorItem::SetCloseWindowDistanceMinimum(int distance) {
+  selector_item_activate_window_button_->SetCloseWindowDistanceMinimum(
+      distance);
+  for (WindowList::iterator iter = window_list_.begin();
+       iter != window_list_.end();
+       ++iter) {
+    (*iter)->activate_button()->SetCloseWindowDistanceMinimum(distance);
+  }
+}
+
 void WindowSelectorItem::UpdateSelectorButtons() {
   selector_item_activate_window_button_->SetBounds(target_bounds());