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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_layers_ScrollThumbUtils_h
#define mozilla_layers_ScrollThumbUtils_h
#include "LayersTypes.h"
#include "Units.h"
namespace mozilla {
namespace layers {
class AsyncPanZoomController;
struct FrameMetrics;
struct ScrollbarData;
namespace apz {
/**
* Compute the updated shadow transform for a scroll thumb layer that
* reflects async scrolling of the associated scroll frame.
*
* @param aCurrentTransform The current shadow transform on the scroll thumb
* layer, as returned by Layer::GetLocalTransform() or similar.
* @param aScrollableContentTransform The current content transform on the
* scrollable content, as returned by Layer::GetTransform().
* @param aApzc The APZC that scrolls the scroll frame.
* @param aMetrics The metrics associated with the scroll frame, reflecting
* the last paint of the associated content. Note: this metrics should
* NOT reflect async scrolling, i.e. they should be the layer tree's
* copy of the metrics, or APZC's last-content-paint metrics.
* @param aScrollbarData The scrollbar data for the the scroll thumb layer.
* @param aScrollbarIsDescendant True iff. the scroll thumb layer is a
* descendant of the layer bearing the scroll frame's metrics.
* @return The new shadow transform for the scroll thumb layer, including
* any pre- or post-scales.
*/
LayerToParentLayerMatrix4x4 ComputeTransformForScrollThumb(
const LayerToParentLayerMatrix4x4& aCurrentTransform,
const gfx::Matrix4x4& aScrollableContentTransform,
AsyncPanZoomController* aApzc, const FrameMetrics& aMetrics,
const ScrollbarData& aScrollbarData, bool aScrollbarIsDescendant);
} // namespace apz
} // namespace layers
} // namespace mozilla
#endif // mozilla_layers_ScrollThumbUtils_h