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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/. */
#include "SampledAPZCState.h"
#include "APZUtils.h"
namespace mozilla {
namespace layers {
SampledAPZCState::SampledAPZCState() {}
SampledAPZCState::SampledAPZCState(const FrameMetrics& aMetrics)
: mLayoutViewport(aMetrics.GetLayoutViewport()),
mVisualScrollOffset(aMetrics.GetVisualScrollOffset()),
mZoom(aMetrics.GetZoom()) {
RemoveFractionalAsyncDelta();
}
SampledAPZCState::SampledAPZCState(const FrameMetrics& aMetrics,
Maybe<CompositionPayload>&& aPayload)
: mLayoutViewport(aMetrics.GetLayoutViewport()),
mVisualScrollOffset(aMetrics.GetVisualScrollOffset()),
mZoom(aMetrics.GetZoom()),
mScrollPayload(std::move(aPayload)) {
RemoveFractionalAsyncDelta();
}
bool SampledAPZCState::operator==(const SampledAPZCState& aOther) const {
// The payload doesn't factor into equality, that just comes along for
// the ride.
return mLayoutViewport.IsEqualEdges(aOther.mLayoutViewport) &&
mVisualScrollOffset == aOther.mVisualScrollOffset &&
mZoom == aOther.mZoom;
}
bool SampledAPZCState::operator!=(const SampledAPZCState& aOther) const {
return !(*this == aOther);
}
Maybe<CompositionPayload> SampledAPZCState::TakeScrollPayload() {
return std::move(mScrollPayload);
}
void SampledAPZCState::UpdateScrollProperties(const FrameMetrics& aMetrics) {
mLayoutViewport = aMetrics.GetLayoutViewport();
mVisualScrollOffset = aMetrics.GetVisualScrollOffset();
}
void SampledAPZCState::UpdateZoomProperties(const FrameMetrics& aMetrics) {
mZoom = aMetrics.GetZoom();
}
void SampledAPZCState::ClampVisualScrollOffset(const FrameMetrics& aMetrics) {
mVisualScrollOffset =
aMetrics.CalculateScrollRange().ClampPoint(mVisualScrollOffset);
FrameMetrics::KeepLayoutViewportEnclosingVisualViewport(
CSSRect(mVisualScrollOffset,
aMetrics.CalculateCompositedSizeInCssPixels()),
aMetrics.GetScrollableRect(), mLayoutViewport);
}
void SampledAPZCState::ZoomBy(const gfxSize& aScale) {
mZoom.xScale *= aScale.width;
mZoom.yScale *= aScale.height;
}
void SampledAPZCState::RemoveFractionalAsyncDelta() {
// This function is a performance hack. With non-WebRender, having small
// fractional deltas between the layout offset and scroll offset on
// container layers can trigger the creation of a temporary surface during
// composition, because it produces a non-integer translation that doesn't
// play well with layer clips. So we detect the case where the delta is
// uselessly small (0.01 parentlayer pixels or less) and tweak the sampled
// scroll offset to eliminate it. By doing this here at sample time rather
// than elsewhere in the pipeline we are least likely to break assumptions
// and invariants elsewhere in the code, since sampling effectively takes
// a snapshot of APZ state (decoupling it from APZ assumptions) and provides
// it as an input to the compositor (so all compositor state should be
// internally consistent based on this input).
if (mLayoutViewport.TopLeft() == mVisualScrollOffset) {
return;
}
ParentLayerPoint paintedOffset = mLayoutViewport.TopLeft() * mZoom;
ParentLayerPoint asyncOffset = mVisualScrollOffset * mZoom;
if (FuzzyEqualsAdditive(paintedOffset.x, asyncOffset.x, COORDINATE_EPSILON) &&
FuzzyEqualsAdditive(paintedOffset.y, asyncOffset.y, COORDINATE_EPSILON)) {
mVisualScrollOffset = mLayoutViewport.TopLeft();
}
}
} // namespace layers
} // namespace mozilla
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