Subpixel rendering: Enable compositing RenderLayer painting on device pixel position.
https://bugs.webkit.org/show_bug.cgi?id=128509
Reviewed by Simon Fraser.
GraphicsLayer is now positioned on device pixel boundary. This enables us to put
compositing layers on a subpixel position and animate them with device pixel
precision.
Source/WebCore:
Tests: fast/sub-pixel/compositing-layers-on-subpixel-position.html
fast/sub-pixel/simple-clipping.html
* platform/LayoutUnit.h:
(WebCore::ceilToDevicePixel):
* platform/graphics/LayoutPoint.h:
(WebCore::flooredForPainting):
(WebCore::ceiledForPainting):
* platform/graphics/LayoutRect.cpp:
(WebCore::enclosingRectForPainting):
* platform/graphics/LayoutRect.h:
* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::clipToRect):
* rendering/RenderLayerBacking.cpp:
(WebCore::clipBox):
(WebCore::pixelFractionForLayerPainting):
(WebCore::calculateDevicePixelOffsetFromRenderer):
(WebCore::RenderLayerBacking::updateGraphicsLayerGeometry):
(WebCore::RenderLayerBacking::paintIntoLayer):
* rendering/RenderLayerBacking.h:
LayoutTests:
* TestExpectations:
* fast/sub-pixel/compositing-layers-on-subpixel-position-expected.html: Added.
* fast/sub-pixel/compositing-layers-on-subpixel-position.html: Added.
* fast/sub-pixel/simple-clipping-expected.html: Added.
* fast/sub-pixel/simple-clipping.html: Added.
* platform/mac/compositing/layer-creation/overlap-animation-container-expected.txt:
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@164449 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/WebCore/rendering/RenderLayerBacking.cpp b/Source/WebCore/rendering/RenderLayerBacking.cpp
index 079a4fd..0f4b2ba 100644
--- a/Source/WebCore/rendering/RenderLayerBacking.cpp
+++ b/Source/WebCore/rendering/RenderLayerBacking.cpp
@@ -642,7 +642,23 @@
if (renderer.hasClip())
result.intersect(renderer.clipRect(LayoutPoint(), 0)); // FIXME: Incorrect for CSS regions.
- return pixelSnappedIntRect(result);
+ return result;
+}
+
+static FloatSize pixelFractionForLayerPainting(const LayoutPoint& point, float pixelSnappingFactor)
+{
+ LayoutUnit x = point.x();
+ LayoutUnit y = point.y();
+ x = x >= 0 ? floorToDevicePixel(x, pixelSnappingFactor) : ceilToDevicePixel(x, pixelSnappingFactor);
+ y = y >= 0 ? floorToDevicePixel(y, pixelSnappingFactor) : ceilToDevicePixel(y, pixelSnappingFactor);
+ return point - LayoutPoint(x, y);
+}
+
+static void calculateDevicePixelOffsetFromRenderer(const LayoutSize& rendererOffsetFromGraphicsLayer, FloatSize& devicePixelOffsetFromRenderer,
+ LayoutSize& devicePixelFractionFromRenderer, float deviceScaleFactor)
+{
+ devicePixelFractionFromRenderer = LayoutSize(pixelFractionForLayerPainting(toLayoutPoint(rendererOffsetFromGraphicsLayer), deviceScaleFactor));
+ devicePixelOffsetFromRenderer = rendererOffsetFromGraphicsLayer - devicePixelFractionFromRenderer;
}
void RenderLayerBacking::updateGraphicsLayerGeometry()
@@ -689,20 +705,49 @@
LayoutRect ancestorCompositingBounds;
if (compAncestor) {
ASSERT(compAncestor->backing());
- ancestorCompositingBounds = pixelSnappedIntRect(compAncestor->backing()->compositedBounds());
+ ancestorCompositingBounds = compAncestor->backing()->compositedBounds();
}
- LayoutRect localRawCompositingBounds = compositedBounds();
- LayoutPoint rawDelta;
- m_owningLayer.convertToLayerCoords(compAncestor, rawDelta, RenderLayer::AdjustForColumns);
- IntPoint delta = flooredIntPoint(rawDelta);
- m_subpixelAccumulation = toLayoutSize(rawDelta.fraction());
- // Move the bounds by the subpixel accumulation so that it pixel-snaps relative to absolute pixels instead of local coordinates.
- localRawCompositingBounds.move(m_subpixelAccumulation);
-
- LayoutRect localCompositingBounds = pixelSnappedIntRect(localRawCompositingBounds);
+ /*
+ * GraphicsLayer: device pixel positioned. Floored, enclosing rect.
+ * RenderLayer: subpixel positioned.
+ * Offset from renderer (GraphicsLayer <-> RenderLayer::renderer()): subpixel based offset.
+ *
+ * relativeCompositingBounds
+ * _______________________________________
+ * |\ GraphicsLayer |
+ * | \ |
+ * | \ offset from renderer: (device pixel + subpixel)
+ * | \ |
+ * | \______________________________ |
+ * | | localCompositingBounds | |
+ * | | | |
+ * | | RenderLayer::renderer() | |
+ * | | | |
+ *
+ * localCompositingBounds: this RenderLayer relative to its renderer().
+ * relativeCompositingBounds: this RenderLayer relative to its parent compositing layer.
+ * enclosingRelativeCompositingBounds: this RenderLayer relative to its parent but floored to device pixel position.
+ * rendererOffsetFromGraphicsLayer: RenderLayer::renderer()'s offset from its enclosing GraphicsLayer.
+ * devicePixelOffsetFromRenderer: rendererOffsetFromGraphicsLayer's device pixel part. (6.9px -> 6.5px in case of 2x display)
+ * devicePixelFractionFromRenderer: rendererOffsetFromGraphicsLayer's fractional part (6.9px -> 0.4px in case of 2x display)
+ */
+ float deviceScaleFactor = this->deviceScaleFactor();
+ LayoutRect localCompositingBounds = compositedBounds();
LayoutRect relativeCompositingBounds(localCompositingBounds);
- relativeCompositingBounds.moveBy(delta);
+
+ LayoutPoint offsetFromParent;
+ m_owningLayer.convertToLayerCoords(compAncestor, offsetFromParent, RenderLayer::AdjustForColumns);
+ relativeCompositingBounds.moveBy(offsetFromParent);
+
+ LayoutRect enclosingRelativeCompositingBounds = LayoutRect(enclosingRectForPainting(relativeCompositingBounds, deviceScaleFactor));
+ LayoutSize subpixelOffsetAdjustment = enclosingRelativeCompositingBounds.location() - relativeCompositingBounds.location();
+ LayoutSize rendererOffsetFromGraphicsLayer = toLayoutSize(localCompositingBounds.location()) + subpixelOffsetAdjustment;
+
+ FloatSize devicePixelOffsetFromRenderer;
+ LayoutSize devicePixelFractionFromRenderer;
+ calculateDevicePixelOffsetFromRenderer(rendererOffsetFromGraphicsLayer, devicePixelOffsetFromRenderer, devicePixelFractionFromRenderer, deviceScaleFactor);
+ m_devicePixelFractionFromRenderer = LayoutSize(fabs(devicePixelFractionFromRenderer.width().toFloat()), fabs(devicePixelFractionFromRenderer.height().toFloat()));
adjustAncestorCompositingBoundsForFlowThread(ancestorCompositingBounds, compAncestor);
@@ -741,40 +786,39 @@
// layer. Note that we call it with temporaryClipRects = true because normally when computing clip rects
// for a compositing layer, rootLayer is the layer itself.
RenderLayer::ClipRectsContext clipRectsContext(compAncestor, 0, TemporaryClipRects, IgnoreOverlayScrollbarSize, IgnoreOverflowClip);
- LayoutRect parentClipRect = pixelSnappedIntRect(m_owningLayer.backgroundClipRect(clipRectsContext).rect()); // FIXME: Incorrect for CSS regions.
+ LayoutRect parentClipRect = m_owningLayer.backgroundClipRect(clipRectsContext).rect(); // FIXME: Incorrect for CSS regions.
ASSERT(parentClipRect != LayoutRect::infiniteRect());
m_ancestorClippingLayer->setPosition(FloatPoint(parentClipRect.location() - graphicsLayerParentLocation));
m_ancestorClippingLayer->setSize(parentClipRect.size());
// backgroundRect is relative to compAncestor, so subtract deltaX/deltaY to get back to local coords.
- m_ancestorClippingLayer->setOffsetFromRenderer(parentClipRect.location() - delta);
+ m_ancestorClippingLayer->setOffsetFromRenderer(parentClipRect.location() - offsetFromParent);
// The primary layer is then parented in, and positioned relative to this clipping layer.
graphicsLayerParentLocation = parentClipRect.location();
}
- LayoutSize contentsSize = relativeCompositingBounds.size();
+ LayoutSize contentsSize = enclosingRelativeCompositingBounds.size();
if (m_contentsContainmentLayer) {
m_contentsContainmentLayer->setPreserves3D(preserves3D);
- m_contentsContainmentLayer->setPosition(FloatPoint(relativeCompositingBounds.location() - graphicsLayerParentLocation));
+ m_contentsContainmentLayer->setPosition(FloatPoint(enclosingRelativeCompositingBounds.location() - graphicsLayerParentLocation));
// Use the same size as m_graphicsLayer so transforms behave correctly.
m_contentsContainmentLayer->setSize(contentsSize);
- graphicsLayerParentLocation = relativeCompositingBounds.location();
+ graphicsLayerParentLocation = enclosingRelativeCompositingBounds.location();
}
- m_graphicsLayer->setPosition(FloatPoint(relativeCompositingBounds.location() - graphicsLayerParentLocation));
+ m_graphicsLayer->setPosition(FloatPoint(enclosingRelativeCompositingBounds.location() - graphicsLayerParentLocation));
m_graphicsLayer->setSize(contentsSize);
- FloatSize offsetFromRenderer = toLayoutSize(localCompositingBounds.location());
- if (offsetFromRenderer != m_graphicsLayer->offsetFromRenderer()) {
- m_graphicsLayer->setOffsetFromRenderer(offsetFromRenderer);
+ if (devicePixelOffsetFromRenderer != m_graphicsLayer->offsetFromRenderer()) {
+ m_graphicsLayer->setOffsetFromRenderer(devicePixelOffsetFromRenderer);
positionOverflowControlsLayers();
}
if (!m_isMainFrameRenderViewLayer) {
// For non-root layers, background is always painted by the primary graphics layer.
ASSERT(!m_backgroundLayer);
- bool hadSubpixelRounding = relativeCompositingBounds.size() != localRawCompositingBounds.size();
+ bool hadSubpixelRounding = !m_devicePixelFractionFromRenderer.isEmpty();
m_graphicsLayer->setContentsOpaque(!hadSubpixelRounding && m_owningLayer.backgroundIsKnownToBeOpaqueInRect(localCompositingBounds));
}
@@ -797,14 +841,14 @@
const LayoutRect borderBox = toRenderBox(renderer()).pixelSnappedBorderBoxRect();
// Get layout bounds in the coords of compAncestor to match relativeCompositingBounds.
- LayoutRect layerBounds(delta, borderBox.size());
+ LayoutRect layerBounds(offsetFromParent, borderBox.size());
// Update properties that depend on layer dimensions
FloatPoint3D transformOrigin = computeTransformOrigin(borderBox);
// Compute the anchor point, which is in the center of the renderer box unless transform-origin is set.
- FloatPoint3D anchor(relativeCompositingBounds.width() != 0.0f ? ((layerBounds.x() - relativeCompositingBounds.x()) + transformOrigin.x()) / relativeCompositingBounds.width() : 0.5f,
- relativeCompositingBounds.height() != 0.0f ? ((layerBounds.y() - relativeCompositingBounds.y()) + transformOrigin.y()) / relativeCompositingBounds.height() : 0.5f,
- transformOrigin.z());
+ FloatPoint3D anchor(enclosingRelativeCompositingBounds.width() != 0.0f ? ((layerBounds.x() - enclosingRelativeCompositingBounds.x()) + transformOrigin.x())
+ / enclosingRelativeCompositingBounds.width() : 0.5f, enclosingRelativeCompositingBounds.height() != 0.0f ? ((layerBounds.y() - enclosingRelativeCompositingBounds.y())
+ + transformOrigin.y()) / enclosingRelativeCompositingBounds.height() : 0.5f, transformOrigin.z());
if (m_contentsContainmentLayer)
m_contentsContainmentLayer->setAnchorPoint(anchor);
else
@@ -876,15 +920,15 @@
if (m_scrollingLayer) {
ASSERT(m_scrollingContentsLayer);
RenderBox& renderBox = toRenderBox(renderer());
- IntRect paddingBox(renderBox.borderLeft(), renderBox.borderTop(), renderBox.width() - renderBox.borderLeft() - renderBox.borderRight(), renderBox.height() - renderBox.borderTop() - renderBox.borderBottom());
- IntSize scrollOffset = m_owningLayer.scrollOffset();
+ LayoutRect paddingBox(renderBox.borderLeft(), renderBox.borderTop(), renderBox.width() - renderBox.borderLeft() - renderBox.borderRight(), renderBox.height() - renderBox.borderTop() - renderBox.borderBottom());
+ LayoutSize scrollOffset = m_owningLayer.scrollOffset();
m_scrollingLayer->setPosition(FloatPoint(paddingBox.location() - localCompositingBounds.location()));
m_scrollingLayer->setSize(paddingBox.size());
#if PLATFORM(IOS)
FloatSize oldScrollingLayerOffset = m_scrollingLayer->offsetFromRenderer();
- m_scrollingLayer->setOffsetFromRenderer(IntPoint() - paddingBox.location());
+ m_scrollingLayer->setOffsetFromRenderer(FloatPoint() - paddingBox.location());
bool paddingBoxOffsetChanged = oldScrollingLayerOffset != m_scrollingLayer->offsetFromRenderer();
if (m_owningLayer.isInUserScroll()) {
@@ -914,7 +958,7 @@
m_scrollingContentsLayer->setPosition(FloatPoint(-scrollOffset.width(), -scrollOffset.height()));
FloatSize oldScrollingLayerOffset = m_scrollingLayer->offsetFromRenderer();
- m_scrollingLayer->setOffsetFromRenderer(-toIntSize(paddingBox.location()));
+ m_scrollingLayer->setOffsetFromRenderer(-toFloatSize(paddingBox.location()));
bool paddingBoxOffsetChanged = oldScrollingLayerOffset != m_scrollingLayer->offsetFromRenderer();
@@ -922,7 +966,7 @@
if (scrollSize != m_scrollingContentsLayer->size() || paddingBoxOffsetChanged)
m_scrollingContentsLayer->setNeedsDisplay();
- IntSize scrollingContentsOffset = toIntSize(paddingBox.location() - scrollOffset);
+ LayoutSize scrollingContentsOffset = toLayoutSize(paddingBox.location() - scrollOffset);
if (scrollingContentsOffset != m_scrollingContentsLayer->offsetFromRenderer() || scrollSize != m_scrollingContentsLayer->size())
compositor().scrollingLayerDidChange(m_owningLayer);
@@ -938,7 +982,7 @@
}
// If this layer was created just for clipping or to apply perspective, it doesn't need its own backing store.
- setRequiresOwnBackingStore(compositor().requiresOwnBackingStore(m_owningLayer, compAncestor, relativeCompositingBounds, ancestorCompositingBounds));
+ setRequiresOwnBackingStore(compositor().requiresOwnBackingStore(m_owningLayer, compAncestor, enclosingRelativeCompositingBounds, ancestorCompositingBounds));
bool didUpdateContentsRect = false;
updateDirectlyCompositedContents(isSimpleContainer, didUpdateContentsRect);
@@ -2161,7 +2205,7 @@
paintFlags |= RenderLayer::PaintLayerPaintingSkipRootBackground;
// FIXME: GraphicsLayers need a way to split for RenderRegions.
- RenderLayer::LayerPaintingInfo paintingInfo(&m_owningLayer, paintDirtyRect, paintBehavior, m_subpixelAccumulation);
+ RenderLayer::LayerPaintingInfo paintingInfo(&m_owningLayer, paintDirtyRect, paintBehavior, m_devicePixelFractionFromRenderer);
m_owningLayer.paintLayerContents(context, paintingInfo, paintFlags);
if (m_owningLayer.containsDirtyOverlayScrollbars())
