ui/compositor/layer_owner.h

   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
  13 namespace ui {
  14 class LayerOwnerDelegate;
  15
  16 class 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_