Layout panels on top of their launcher icons

ash/wm/panel_layout_manager.h

 // 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.
 
 #ifndef ASH_WM_PANEL_LAYOUT_MANAGER_H_
 #define ASH_WM_PANEL_LAYOUT_MANAGER_H_
 #pragma once
 
 #include <list>
 
 #include "ash/ash_export.h"
+#include "ash/launcher/launcher_icons_observer.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/aura/layout_manager.h"
 
 namespace aura {
 class Window;
 }
 
 namespace gfx {
 class Rect;
 }
 
 namespace ash {
+class Launcher;
+
 namespace internal {
 
 // PanelLayoutManager is responsible for organizing panels within the
 // workspace. It is associated with a specific container window (i.e.
 // kShellWindowId_PanelContainer) and controls the layout of any windows
 // added to that container.
 //
 // The constructor takes a |panel_container| argument which is expected to set
 // its layout manager to this instance, e.g.:
 // panel_container->SetLayoutManager(new PanelLayoutManager(panel_container));
 
 class ASH_EXPORT PanelLayoutManager : public aura::LayoutManager {
  public:
   explicit PanelLayoutManager(aura::Window* panel_container);
   virtual ~PanelLayoutManager();
 
   void StartDragging(aura::Window* panel);
   void FinishDragging();
 
   void ToggleMinimize(aura::Window* panel);
 
+  void SetLauncher(ash::Launcher* launcher);
+
   // Overridden from aura::LayoutManager:
   virtual void OnWindowResized() OVERRIDE;
   virtual void OnWindowAddedToLayout(aura::Window* child) OVERRIDE;
   virtual void OnWillRemoveWindowFromLayout(aura::Window* child) OVERRIDE;
   virtual void OnChildWindowVisibilityChanged(aura::Window* child,
                                               bool visibile) OVERRIDE;
   virtual void SetChildBounds(aura::Window* child,
                               const gfx::Rect& requested_bounds) OVERRIDE;
 
  private:
+  class LauncherIconsObserver : public ash::LauncherIconsObserver {

[sky, 2012/04/03 20:39:37]

Any reason you don't make PanelLayoutManager directly implement this as we do
everywhere else?

[Dmitry Lomov (no reviews), 2012/04/03 20:50:07]

The fact that PanelLayoutManager observes launcher icons is its implementation
detail, it is not a fact of its public interface.

[sky, 2012/04/03 20:57:18]

There are a plethora of classes in Chrome that fit this bill. As I mentioned, we
generally don't add another layer just to hide the interface. 

[Dmitry Lomov (no reviews), 2012/04/03 21:18:23]

Widespread use of errant practice does not make it commendable.

[stevenjb, 2012/04/03 22:09:29]

I have to agree with sky here - we make "correctness" vs. "simplicity" tradeoffs
all the time. In Chrome, Observer and Delegate interfaces are generally
inherited because it makes the code easier to follow.

On 2012/04/03 21:18:23, Dmitry Lomov (chromium) wrote:

+   public:
+    LauncherIconsObserver(PanelLayoutManager* layout_manager);
+
+    virtual void OnLauncherIconPositionsChanged() OVERRIDE;
+   private:
+    PanelLayoutManager* layout_manager_;
+  };
+
   typedef std::list<aura::Window*> PanelList;
 
   // Called whenever the panel layout might change.
   void Relayout();
 
   // Parent window associated with this layout manager.
   aura::Window* panel_container_;
   // Protect against recursive calls to Relayout().
   bool in_layout_;
   // Ordered list of unowned pointers to panel windows.
   PanelList panel_windows_;
 
   aura::Window* dragged_panel_;
 
+  LauncherIconsObserver launcher_icons_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(PanelLayoutManager);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_PANEL_LAYOUT_MANAGER_H_