[ash-md] Improves smoothness with many windows in overview

ash/common/wm/overview/window_selector_item.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/common/wm/overview/window_selector_item.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "ash/common/material_design/material_design_controller.h"
@@ skipping 88 matching lines @@
 
 // Duration of background opacity transition for the selected label.
 static const int kSelectorFadeInMilliseconds = 350;
 
 // Before closing a window animate both the window and the caption to shrink by
 // this fraction of size.
 static const float kPreCloseScale = 0.02f;
 
 // Calculates the |window| bounds after being transformed to the selector's
 // space. The returned Rect is in virtual screen coordinates.
-gfx::Rect GetTransformedBounds(WmWindow* window) {
+gfx::Rect GetTransformedBounds(WmWindow* window, bool hide_header) {
   gfx::RectF bounds(
       window->GetRootWindow()->ConvertRectToScreen(window->GetTargetBounds()));
   gfx::Transform new_transform = TransformAboutPivot(
       gfx::Point(bounds.x(), bounds.y()), window->GetTargetTransform());
   new_transform.TransformRect(&bounds);
 
   // With Material Design the preview title is shown above the preview window.
   // Hide the window header for apps or browser windows with no tabs (web apps)
   // to avoid showing both the window header and the preview title.
-  if (ash::MaterialDesignController::IsOverviewMaterial()) {
+  if (ash::MaterialDesignController::IsOverviewMaterial() && hide_header) {
     gfx::RectF header_bounds(bounds);
     header_bounds.set_height(
         window->GetIntProperty(WmWindowProperty::TOP_VIEW_INSET));
     new_transform.TransformRect(&header_bounds);
     bounds.Inset(0, gfx::ToCeiledInt(header_bounds.height()), 0, 0);
   }
   return ToEnclosingRect(bounds);
 }
 
 // Convenience method to fade in a Window with predefined animation settings.
@@ skipping 144 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(CaptionContainerView);
 };
 
 WindowSelectorItem::WindowSelectorItem(WmWindow* window,
                                        WindowSelector* window_selector)
     : dimmed_(false),
       root_window_(window->GetRootWindow()),
       transform_window_(window),
       in_bounds_update_(false),
+      hide_header_(false),

[tdanderson, 2016/07/18 16:26:58]

IIUC at any point in time, either all of the WindowSelectorItems should show
their header or all WSIs should hide their header. Rather than tracking
|hide_header_| on a per-window basis, perhaps this member should:

* Be static in WSI, or
* Be removed altogether and replaced with something like bool
WindowHeadersVisible() { return num_windows <= 10; } in WindowSelector or
WindowGrid, and queried when needed from WSI.

[varkha, 2016/07/19 00:29:07]

Done (made static and controlled by flags).

       caption_container_view_(nullptr),
       window_label_button_view_(nullptr),
       close_button_(new OverviewCloseButton(this)),
       window_selector_(window_selector) {
   CreateWindowLabel(window->GetTitle());
   if (!ash::MaterialDesignController::IsOverviewMaterial()) {
     views::Widget::InitParams params;
     params.type = views::Widget::InitParams::TYPE_POPUP;
     params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
     params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
@@ skipping 153 matching lines @@
 
 void WindowSelectorItem::OnWindowTitleChanged(WmWindow* window) {
   // TODO(flackr): Maybe add the new title to a vector of titles so that we can
   // filter any of the titles the window had while in the overview session.
   window_label_button_view_->SetText(window->GetTitle());
   UpdateCloseButtonAccessibilityName();
 }
 
 float WindowSelectorItem::GetItemScale(const gfx::Size& size) {
   gfx::Size inset_size(size.width(), size.height() - 2 * kWindowMarginMD);
+  const int header_inset =
+      hide_header_
+          ? GetWindow()->GetIntProperty(WmWindowProperty::TOP_VIEW_INSET)
+          : 0;
   return ScopedTransformOverviewWindow::GetItemScale(
-      GetWindow()->GetTargetBounds().size(), inset_size,
-      GetWindow()->GetIntProperty(WmWindowProperty::TOP_VIEW_INSET),
+      GetWindow()->GetTargetBounds().size(), inset_size, header_inset,
       close_button_->GetPreferredSize().height());
 }
 
 void WindowSelectorItem::SetItemBounds(const gfx::Rect& target_bounds,
                                        OverviewAnimationType animation_type) {
   DCHECK(root_window_ == GetWindow()->GetRootWindow());
   gfx::Rect screen_rect = transform_window_.GetTargetBoundsInScreen();
 
   // Avoid division by zero by ensuring screen bounds is not empty.
   gfx::Size screen_size(screen_rect.size());
   screen_size.SetToMax(gfx::Size(1, 1));
   screen_rect.set_size(screen_size);
 
   int top_view_inset = 0;
   int title_height = 0;
   if (ash::MaterialDesignController::IsOverviewMaterial()) {
-    top_view_inset =
-        GetWindow()->GetIntProperty(WmWindowProperty::TOP_VIEW_INSET);
+    if (hide_header_) {
+      top_view_inset =
+          GetWindow()->GetIntProperty(WmWindowProperty::TOP_VIEW_INSET);
+    }
     title_height = close_button_->GetPreferredSize().height();
   }
   gfx::Rect selector_item_bounds =
       ScopedTransformOverviewWindow::ShrinkRectToFitPreservingAspectRatio(
           screen_rect, target_bounds, top_view_inset, title_height);
   gfx::Transform transform = ScopedTransformOverviewWindow::GetTransformForRect(
       screen_rect, selector_item_bounds);
   ScopedTransformOverviewWindow::ScopedAnimationSettings animation_settings;
   transform_window_.BeginScopedAnimation(animation_type, &animation_settings);
   // Rounded corners are achieved by using a mask layer on the original window
   // before the transform. Dividing by scale factor obtains the corner radius
   // which when scaled will yield |kLabelBackgroundRadius|.
   transform_window_.SetTransform(
-      root_window_, transform,
+      root_window_, transform, hide_header_,
       (kLabelBackgroundRadius / GetItemScale(target_bounds.size())));
   transform_window_.set_overview_transform(transform);
 }
 
 void WindowSelectorItem::SetOpacity(float opacity) {
   window_label_->SetOpacity(opacity);
   if (!ash::MaterialDesignController::IsOverviewMaterial())
     close_button_widget_->SetOpacity(opacity);
 
   transform_window_.SetOpacity(opacity);
@@ skipping 71 matching lines @@
     window_label_selector_->set_focus_on_creation(false);
     window_label_selector_->SetContentsView(background_view);
     window_label_selector_->Show();
   } else {
     window_label_->SetContentsView(window_label_button_view_);
   }
 }
 
 void WindowSelectorItem::UpdateHeaderLayout(
     OverviewAnimationType animation_type) {
-  gfx::Rect transformed_window_bounds =
-      root_window_->ConvertRectFromScreen(GetTransformedBounds(GetWindow()));
+  gfx::Rect transformed_window_bounds = root_window_->ConvertRectFromScreen(
+      GetTransformedBounds(GetWindow(), hide_header_));
 
   if (ash::MaterialDesignController::IsOverviewMaterial()) {
     gfx::Rect label_rect(close_button_->GetPreferredSize());
     label_rect.set_y(-label_rect.height());
     label_rect.set_width(transformed_window_bounds.width());
 
     if (!window_label_button_view_->visible()) {
       window_label_button_view_->SetVisible(true);
       SetupFadeInAfterLayout(window_label_.get());
       SetupFadeInAfterLayout(window_label_selector_.get());
@@ skipping 72 matching lines @@
   window_label_selector_window->SetOpacity(opacity);
 }
 
 void WindowSelectorItem::UpdateCloseButtonAccessibilityName() {
   close_button_->SetAccessibleName(l10n_util::GetStringFUTF16(
       IDS_ASH_OVERVIEW_CLOSE_ITEM_BUTTON_ACCESSIBLE_NAME,
       GetWindow()->GetTitle()));
 }
 
 }  // namespace ash