CrOS Tablet Window management - Split Screen part I

ash/wm/overview/window_selector_item.h

Index: ash/wm/overview/window_selector_item.h
diff --git a/ash/wm/overview/window_selector_item.h b/ash/wm/overview/window_selector_item.h
index 6e77d73f8beff17812b244910bc405040c72af2f..e04b547e08005e5da6de5ae6f444552fdc8b5399 100644
--- a/ash/wm/overview/window_selector_item.h
+++ b/ash/wm/overview/window_selector_item.h
@@ -29,6 +29,7 @@ class ImageButton;
 namespace ash {
 
 class WindowSelector;
+class WindowGrid;
 
 // This class represents an item in overview mode.
 class ASH_EXPORT WindowSelectorItem : public views::ButtonListener,
@@ -47,7 +48,9 @@ class ASH_EXPORT WindowSelectorItem : public views::ButtonListener,
     DISALLOW_COPY_AND_ASSIGN(OverviewCloseButton);
   };
 
-  WindowSelectorItem(aura::Window* window, WindowSelector* window_selector);
+  WindowSelectorItem(aura::Window* window,
+                     WindowSelector* window_selector,
+                     WindowGrid* window_grid);
   ~WindowSelectorItem() override;
 
   aura::Window* GetWindow();
@@ -120,6 +123,11 @@ class ASH_EXPORT WindowSelectorItem : public views::ButtonListener,
   void OnWindowDestroying(aura::Window* window) override;
   void OnWindowTitleChanged(aura::Window* window) override;
 
+  // Handle the mouse/gesture event and facilitate dragging the item.
+  void HandlePressEvent(const gfx::Point& location_in_screen);
+  void HandleReleaseEvent(const gfx::Point& location_in_screen);
+  void HandleDragEvent(const gfx::Point& location_in_screen);
+
  private:
   class CaptionContainerView;
   class RoundedContainerView;
@@ -166,6 +174,15 @@ class ASH_EXPORT WindowSelectorItem : public views::ButtonListener,
 
   aura::Window* GetOverviewWindowForMinimizedStateForTest();
 
+  // Called before dragging. Scales up the window a little bit to indicate its
+  // selection and stacks the window at the top of the Z order in order to keep
+  // it visible while dragging around.
+  void StartDrag();
+
+  // Called after dragging. Inserts the window back to its original stack order
+  // so that the windows orders are the same as when they entering overview.

[varkha, 2017/06/26 16:40:08]

nit (I think): the windows are ordered in the same order
   or
     the window order is the same
   or
     the order of windows is the same

[xdai1, 2017/06/26 21:44:00]

Done.

+  void EndDrag();
+
   // True if the item is being shown in the overview, false if it's being
   // filtered.
   bool dimmed_;
@@ -215,6 +232,10 @@ class ASH_EXPORT WindowSelectorItem : public views::ButtonListener,
   // which is the only textured layer used by the |item_widget_|.
   RoundedContainerView* background_view_;
 
+  // Pointer to the WindowGrid that contains |this|. Guaranteed to be non-null
+  // for the lifetime of |this|.
+  WindowGrid* window_grid_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowSelectorItem);
 };