void CoordinatedGraphicsLayer::computePixelAlignment(FloatPoint& position, FloatSize& size, FloatPoint3D& anchorPoint, FloatSize& alignmentOffset)
{
if (isIntegral(effectiveContentsScale())) {
position = m_position;
size = m_size;
anchorPoint = m_anchorPoint;
alignmentOffset = FloatSize();
return;
}
FloatPoint positionRelativeToBase = computePositionRelativeToBase();
FloatRect baseRelativeBounds(positionRelativeToBase, m_size);
FloatRect scaledBounds = baseRelativeBounds;
// Scale by the effective scale factor to compute the screen-relative bounds.
scaledBounds.scale(effectiveContentsScale());
// Round to integer boundaries.
// NOTE: When using enclosingIntRect (as mac) it will have different sizes depending on position.
FloatRect alignedBounds = enclosingIntRect(scaledBounds);
// Convert back to layer coordinates.
alignedBounds.scale(1 / effectiveContentsScale());
// Convert back to layer coordinates.
alignmentOffset = baseRelativeBounds.location() - alignedBounds.location();
position = m_position - alignmentOffset;
size = alignedBounds.size();
// Now we have to compute a new anchor point which compensates for rounding.
float anchorPointX = m_anchorPoint.x();
float anchorPointY = m_anchorPoint.y();
if (alignedBounds.width())
anchorPointX = (baseRelativeBounds.width() * anchorPointX + alignmentOffset.width()) / alignedBounds.width();
if (alignedBounds.height())
anchorPointY = (baseRelativeBounds.height() * anchorPointY + alignmentOffset.height()) / alignedBounds.height();
anchorPoint = FloatPoint3D(anchorPointX, anchorPointY, m_anchorPoint.z() * effectiveContentsScale());
}
void CoordinatedGraphicsLayer::adjustContentsScale()
{
ASSERT(shouldHaveBackingStore());
if (!m_mainBackingStore || m_mainBackingStore->contentsScale() == effectiveContentsScale())
return;
// Between creating the new backing store and painting the content,
// we do not want to drop the previous one as that might result in
// briefly seeing flickering as the old tiles may be dropped before
// something replaces them.
m_previousBackingStore = std::move(m_mainBackingStore);
// No reason to save the previous backing store for non-visible areas.
m_previousBackingStore->removeAllNonVisibleTiles();
}
void WebGraphicsLayer::createBackingStore()
{
m_mainBackingStore = adoptPtr(new TiledBackingStore(this, TiledBackingStoreRemoteTileBackend::create(this)));
m_mainBackingStore->setSupportsAlpha(!contentsOpaque());
m_mainBackingStore->setContentsScale(effectiveContentsScale());
}
void CoordinatedGraphicsLayer::createBackingStore()
{
m_mainBackingStore = std::make_unique<TiledBackingStore>(this, std::make_unique<CoordinatedTileBackend>(this));
m_mainBackingStore->setSupportsAlpha(!contentsOpaque());
m_mainBackingStore->setContentsScale(effectiveContentsScale());
}
