ui/v2/public/view_observer.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef UI_V2_PUBLIC_VIEW_OBSERVER_H_
   6 #define UI_V2_PUBLIC_VIEW_OBSERVER_H_
   7
   8 #include "ui/v2/public/v2_export.h"
   9
  10 namespace gfx {
  11 class Rect;
  12 }
  13
  14 namespace v2 {
  15
  16 class View;
  17
  18 // Observe View disposition changes. -ing methods are called before the change
  19 // is committed, -ed methods are called after.
  20 class V2_EXPORT ViewObserver {
  21  public:
  22   // Whether a notification is being sent before or after some property has
  23   // changed.
  24   enum DispositionChangePhase {
  25     DISPOSITION_CHANGING,
  26     DISPOSITION_CHANGED
  27   };
  28
  29   // Tree.
  30   struct TreeChangeParams {
  31     TreeChangeParams();
  32     View* target;
  33     View* old_parent;
  34     View* new_parent;
  35     View* receiver;
  36     DispositionChangePhase phase;
  37   };
  38
  39   // Called when a node is added or removed. Notifications are sent to the
  40   // following hierarchies in this order:
  41   // 1. |target|.
  42   // 2. |target|'s child hierarchy.
  43   // 3. |target|'s parent hierarchy in its |old_parent|
  44   //        (only for Changing notifications).
  45   // 3. |target|'s parent hierarchy in its |new_parent|.
  46   //        (only for Changed notifications).
  47   // This sequence is performed via the OnTreeChange notification below before
  48   // and after the change is committed.
  49   virtual void OnViewTreeChange(const TreeChangeParams& params) {}
  50
  51   // Disposition.
  52   virtual void OnViewDestroy(View* view, DispositionChangePhase phase) {}
  53   virtual void OnViewBoundsChanged(View* view,
  54                                    const gfx::Rect& old_bounds,
  55                                    const gfx::Rect& new_bounds) {}
  56   virtual void OnViewVisibilityChange(View* view,
  57                                       DispositionChangePhase phase) {}
  58
  59  protected:
  60   virtual ~ViewObserver() {}
  61 };
  62
  63 }  // namespace v2
  64
  65 #endif  // UI_V2_PUBLIC_VIEW_OBSERVER_H_