blob: 02ba011118dfb5621bf3a53c482b8ae8c1a40e67 [file] [log] [blame]
// 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.
#include "base/basictypes.h"
#include "ui/gfx/geometry/scroll_offset.h"
#include "ui/gfx/geometry/size_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 {
// 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::ScrollOffset GetTotalScrollOffset() = 0;
// This is called by the compositor to notify the delegate of any change to
// the following parameters:
// |total_scroll_offset| current scroll offset of the root layer,
// |max_scroll_offset| total scroll offset upper bound for the root layer,
// |scrollable_size| root layer scrollable size,
// |page_scale_factor| current page scale,
// |min_page_scale_factor| page scale lower limit,
// |max_page_scale_factor| page scale upper limit.
virtual void UpdateRootLayerState(
const gfx::ScrollOffset& total_scroll_offset,
const gfx::ScrollOffset& max_scroll_offset,
const gfx::SizeF& scrollable_size,
float page_scale_factor,
float min_page_scale_factor,
float max_page_scale_factor) = 0;
// This is called by the compositor to check whether a delegate-managed fling
// is active or not.
virtual bool IsExternalFlingActive() const = 0;
LayerScrollOffsetDelegate() {}
virtual ~LayerScrollOffsetDelegate() {}
} // namespace cc