| // 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 UI_COMPOSITOR_LAYER_OWNER_H_ |
| #define UI_COMPOSITOR_LAYER_OWNER_H_ |
| |
| #include <memory> |
| |
| #include "base/compiler_specific.h" |
| #include "base/macros.h" |
| #include "base/observer_list.h" |
| #include "ui/compositor/compositor_export.h" |
| #include "ui/compositor/layer.h" |
| |
| namespace ui { |
| |
| class COMPOSITOR_EXPORT LayerOwner { |
| public: |
| class Observer { |
| public: |
| // Called when the |layer()| of this LayerOwner has been recreated (i.e. |
| // RecreateLayer() was called). |old_layer| should not be retained after |
| // this as it may be destroyed soon. |
| // The new layer can be retrieved from LayerOwner::layer(). |
| virtual void OnLayerRecreated(ui::Layer* old_layer) = 0; |
| |
| protected: |
| virtual ~Observer() = default; |
| }; |
| |
| explicit LayerOwner(std::unique_ptr<Layer> layer = nullptr); |
| virtual ~LayerOwner(); |
| |
| void AddObserver(Observer* observer); |
| void RemoveObserver(Observer* observer); |
| |
| // Releases the owning reference to its layer, and returns it. |
| // This is used when you need to animate the presentation of the owner just |
| // prior to destroying it. The Owner can be destroyed soon after calling this |
| // function, and the caller is then responsible for disposing of the layer |
| // once any animation completes. Note that layer() will remain valid until the |
| // end of ~LayerOwner(). |
| std::unique_ptr<Layer> AcquireLayer(); |
| |
| // Similar to AcquireLayer(), but layer() will be set to nullptr immediately. |
| std::unique_ptr<Layer> ReleaseLayer(); |
| |
| // Releases the ownership of the current layer, and takes ownership of |
| // |layer|. |
| void Reset(std::unique_ptr<Layer> layer); |
| |
| // Asks the owner to recreate the layer, returning the old Layer. nullptr is |
| // returned if there is no existing layer, or recreate is not supported. |
| // |
| // This does not recurse. Existing children of the layer are moved to the new |
| // layer. |
| virtual std::unique_ptr<Layer> RecreateLayer(); |
| |
| ui::Layer* layer() { return layer_; } |
| const ui::Layer* layer() const { return layer_; } |
| |
| bool OwnsLayer() const; |
| |
| protected: |
| void SetLayer(std::unique_ptr<Layer> layer); |
| void DestroyLayer(); |
| |
| private: |
| // The LayerOwner owns its layer unless ownership is relinquished via a call |
| // to AcquireLayer(). After that moment |layer_| will still be valid but |
| // |layer_owner_| will be nullptr. The reason for releasing ownership is that |
| // the client may wish to animate the layer beyond the lifetime of the owner, |
| // e.g. fading it out when it is destroyed. |
| std::unique_ptr<Layer> layer_owner_; |
| Layer* layer_ = nullptr; |
| |
| base::ObserverList<Observer>::Unchecked observers_; |
| |
| DISALLOW_COPY_AND_ASSIGN(LayerOwner); |
| }; |
| |
| } // namespace ui |
| |
| #endif // UI_COMPOSITOR_LAYER_OWNER_H_ |