void CCLayerTreeHostImpl::computePinchZoomDeltas(CCScrollAndScaleSet* scrollInfo)
{
if (!m_scrollLayerImpl)
return;
// Only send fake scroll/zoom deltas if we're pinch zooming out by a
// significant amount. This also ensures only one fake delta set will be
// sent.
const float pinchZoomOutSensitivity = 0.95;
if (m_pageScaleDelta > pinchZoomOutSensitivity)
return;
// Compute where the scroll offset/page scale would be if fully pinch-zoomed
// out from the anchor point.
FloatSize scrollBegin = toSize(m_scrollLayerImpl->scrollPosition() + m_scrollLayerImpl->scrollDelta());
scrollBegin.scale(m_pageScaleDelta);
float scaleBegin = m_pageScale * m_pageScaleDelta;
float pageScaleDeltaToSend = m_minPageScale / m_pageScale;
FloatSize scaledContentsSize = contentSize();
scaledContentsSize.scale(pageScaleDeltaToSend);
FloatSize anchor = toSize(m_previousPinchAnchor);
FloatSize scrollEnd = scrollBegin + anchor;
scrollEnd.scale(m_minPageScale / scaleBegin);
scrollEnd -= anchor;
scrollEnd = scrollEnd.shrunkTo(roundedIntSize(scaledContentsSize - m_viewportSize)).expandedTo(FloatSize(0, 0));
scrollEnd.scale(1 / pageScaleDeltaToSend);
makeScrollAndScaleSet(scrollInfo, roundedIntSize(scrollEnd), m_minPageScale);
}
FloatSize ImageBuffer::clampedSize(const FloatSize& size)
{
return size.shrunkTo(FloatSize(MaxClampedLength, MaxClampedLength));
}