1// Copyright (c) 2012 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_COMPOSITOR_LAYER_OWNER_H_
6#define UI_COMPOSITOR_LAYER_OWNER_H_
7
8#include "base/compiler_specific.h"
9#include "base/memory/scoped_ptr.h"
10#include "ui/compositor/compositor_export.h"
11#include "ui/compositor/layer.h"
12
13namespace ui {
14class LayerOwnerDelegate;
15
16class COMPOSITOR_EXPORT LayerOwner {
17 public:
18  LayerOwner();
19  virtual ~LayerOwner();
20
21  void SetLayer(Layer* layer);
22
23  // Releases the owning reference to its layer, and returns it.
24  // This is used when you need to animate the presentation of the owner just
25  // prior to destroying it. The Owner can be destroyed soon after calling this
26  // function, and the caller is then responsible for disposing of the layer
27  // once any animation completes. Note that layer() will remain valid until the
28  // end of ~LayerOwner().
29  scoped_ptr<Layer> AcquireLayer();
30
31  // Asks the owner to recreate the layer, returning the old Layer. NULL is
32  // returned if there is no existing layer, or recreate is not supported.
33  //
34  // This does not recurse. Existing children of the layer are moved to the new
35  // layer.
36  scoped_ptr<Layer> RecreateLayer();
37
38  ui::Layer* layer() { return layer_; }
39  const ui::Layer* layer() const { return layer_; }
40
41  void set_layer_owner_delegate(LayerOwnerDelegate* delegate) {
42    layer_owner_delegate_ = delegate;
43  }
44
45 protected:
46  void DestroyLayer();
47
48  bool OwnsLayer() const;
49
50 private:
51  // The LayerOwner owns its layer unless ownership is relinquished via a call
52  // to AcquireLayer(). After that moment |layer_| will still be valid but
53  // |layer_owner_| will be NULL. The reason for releasing ownership is that
54  // the client may wish to animate the layer beyond the lifetime of the owner,
55  // e.g. fading it out when it is destroyed.
56  scoped_ptr<Layer> layer_owner_;
57  Layer* layer_;
58
59  LayerOwnerDelegate* layer_owner_delegate_;
60
61  DISALLOW_COPY_AND_ASSIGN(LayerOwner);
62};
63
64}  // namespace ui
65
66#endif  // UI_COMPOSITOR_LAYER_OWNER_H_
67