| // Copyright 2013 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 CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_ |
| #define CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_ |
| |
| #include "base/basictypes.h" |
| #include "ui/gfx/size_f.h" |
| #include "ui/gfx/vector2d_f.h" |
| |
| namespace cc { |
| |
| // The LayerScrollOffsetDelegate allows for the embedder to take ownership of |
| // the scroll offset of the root layer. |
| // |
| // The LayerScrollOffsetDelegate is only used on the impl thread. |
| class LayerScrollOffsetDelegate { |
| public: |
| // This is called by the compositor to notify the delegate what is the upper |
| // total scroll offset bound. |
| virtual void SetMaxScrollOffset(gfx::Vector2dF max_scroll_offset) = 0; |
| |
| // This is called by the compositor when the scroll offset of the layer would |
| // have otherwise changed. |
| virtual void SetTotalScrollOffset(gfx::Vector2dF new_value) = 0; |
| |
| // This is called by the compositor to query the current scroll offset of the |
| // layer. |
| // There is no requirement that the return values of this method are |
| // stable in time (two subsequent calls may yield different results). |
| // The return value is not required to be related to the values passed in to |
| // the SetTotalScrollOffset method in any way however it is required to be no |
| // more than the value passed to the most recent SetMaxScrollOffset call. |
| virtual gfx::Vector2dF GetTotalScrollOffset() = 0; |
| |
| // This is called by the compositor to check whether a delegate-managed fling |
| // is active or not. |
| virtual bool IsExternalFlingActive() const = 0; |
| |
| // This is called by the compositor to notify the delegate what is the current |
| // page scale factor is. |
| virtual void SetTotalPageScaleFactor(float page_scale_factor) = 0; |
| |
| // This is called by the compositor to notify the delegate what is the layer's |
| // scrollable size is. |
| virtual void SetScrollableSize(gfx::SizeF scrollable_size) = 0; |
| |
| protected: |
| LayerScrollOffsetDelegate() {} |
| virtual ~LayerScrollOffsetDelegate() {} |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(LayerScrollOffsetDelegate); |
| }; |
| |
| } // namespace cc |
| |
| #endif // CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_ |