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 15 class COMPOSITOR_EXPORT LayerOwner { 16 public: 17 LayerOwner(); 18 virtual ~LayerOwner(); 19 20 // Releases the owning reference to its layer, and returns it. 21 // This is used when you need to animate the presentation of the owner just 22 // prior to destroying it. The Owner can be destroyed soon after calling this 23 // function, and the caller is then responsible for disposing of the layer 24 // once any animation completes. Note that layer() will remain valid until the 25 // end of ~LayerOwner(). 26 Layer* AcquireLayer() WARN_UNUSED_RESULT; 27 28 ui::Layer* layer() { return layer_; } 29 const ui::Layer* layer() const { return layer_; } 30 31 protected: 32 // The LayerOwner owns its layer unless ownership is relinquished via a call 33 // to AcquireLayer(). After that moment |layer_| will still be valid but 34 // |layer_owner_| will be NULL. The reason for releasing ownership is that 35 // the client may wish to animate the layer beyond the lifetime of the owner, 36 // e.g. fading it out when it is destroyed. 37 scoped_ptr<Layer> layer_owner_; 38 Layer* layer_; 39 40 private: 41 DISALLOW_COPY_AND_ASSIGN(LayerOwner); 42 }; 43 44 } // namespace ui 45 46 #endif // UI_COMPOSITOR_LAYER_OWNER_H_ 47
