cc/input/layer_scroll_offset_delegate.h

   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 "base/callback_forward.h"
  10 #include "base/time/time.h"
  11 #include "ui/gfx/geometry/scroll_offset.h"
  12 #include "ui/gfx/geometry/size_f.h"
  13
  14 namespace cc {
  15
  16 // The LayerScrollOffsetDelegate allows for the embedder to take ownership of
  17 // the scroll offset of the root layer.
  18 //
  19 // The LayerScrollOffsetDelegate is only used on the impl thread.
  20 class LayerScrollOffsetDelegate {
  21  public:
  22   // This is called by the compositor to notify the delegate of any change to
  23   // the following parameters:
  24   // |total_scroll_offset| current scroll offset of the root layer,
  25   // |max_scroll_offset| total scroll offset upper bound for the root layer,
  26   // |scrollable_size| root layer scrollable size,
  27   // |page_scale_factor| current page scale,
  28   // |min_page_scale_factor| page scale lower limit,
  29   // |max_page_scale_factor| page scale upper limit.
  30   virtual void UpdateRootLayerState(
  31       const gfx::ScrollOffset& total_scroll_offset,
  32       const gfx::ScrollOffset& max_scroll_offset,
  33       const gfx::SizeF& scrollable_size,
  34       float page_scale_factor,
  35       float min_page_scale_factor,
  36       float max_page_scale_factor) = 0;
  37
  38  protected:
  39   LayerScrollOffsetDelegate() {}
  40   virtual ~LayerScrollOffsetDelegate() {}
  41
  42  private:
  43   DISALLOW_COPY_AND_ASSIGN(LayerScrollOffsetDelegate);
  44 };
  45
  46 }  // namespace cc
  47
  48 #endif  // CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_