1 // Copyright 2013 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 CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_ 6 #define CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_ 7 8 #include "base/basictypes.h" 9 #include "ui/gfx/size_f.h" 10 #include "ui/gfx/vector2d_f.h" 11 12 namespace cc { 13 14 // The LayerScrollOffsetDelegate allows for the embedder to take ownership of 15 // the scroll offset of the root layer. 16 // 17 // The LayerScrollOffsetDelegate is only used on the impl thread. 18 class LayerScrollOffsetDelegate { 19 public: 20 // This is called by the compositor to notify the delegate what is the upper 21 // total scroll offset bound. 22 virtual void SetMaxScrollOffset(gfx::Vector2dF max_scroll_offset) = 0; 23 24 // This is called by the compositor when the scroll offset of the layer would 25 // have otherwise changed. 26 virtual void SetTotalScrollOffset(gfx::Vector2dF new_value) = 0; 27 28 // This is called by the compositor to query the current scroll offset of the 29 // layer. 30 // There is no requirement that the return values of this method are 31 // stable in time (two subsequent calls may yield different results). 32 // The return value is not required to be related to the values passed in to 33 // the SetTotalScrollOffset method in any way however it is required to be no 34 // more than the value passed to the most recent SetMaxScrollOffset call. 35 virtual gfx::Vector2dF GetTotalScrollOffset() = 0; 36 37 // This is called by the compositor to check whether a delegate-managed fling 38 // is active or not. 39 virtual bool IsExternalFlingActive() const = 0; 40 41 // This is called by the compositor to notify the delegate what is the current 42 // page scale factor is. 43 virtual void SetTotalPageScaleFactor(float page_scale_factor) = 0; 44 45 // This is called by the compositor to notify the delegate what is the layer's 46 // scrollable size is. 47 virtual void SetScrollableSize(gfx::SizeF scrollable_size) = 0; 48 49 protected: 50 LayerScrollOffsetDelegate() {} 51 virtual ~LayerScrollOffsetDelegate() {} 52 53 private: 54 DISALLOW_COPY_AND_ASSIGN(LayerScrollOffsetDelegate); 55 }; 56 57 } // namespace cc 58 59 #endif // CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_ 60
