cc: Apply the layer's initial CSS scale to the contentsScale to render text at the right resolution.

cc/CCLayerTreeHostCommon.cpp

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 #include "config.h"
 
 #include "CCLayerTreeHostCommon.h"
 
 #include "CCLayerImpl.h"
@@ skipping 315 matching lines @@
     // The adjustment allows us to continue using the scrollCompensation on the next surface.
     //  Step 1 (right-most in the math): transform from the new surface to the original ancestor surface
     //  Step 2: apply the scroll compensation
     //  Step 3: transform back to the new surface.
     if (layer->renderSurface() && !nextScrollCompensationMatrix.isIdentity())
         nextScrollCompensationMatrix = layer->renderSurface()->drawTransform().inverse() * nextScrollCompensationMatrix * layer->renderSurface()->drawTransform();
 
     return nextScrollCompensationMatrix;
 }
 
+// There is no contentsScale on impl thread.
+static inline void updateLayerContentsScale(CCLayerImpl*, const WebTransformationMatrix&, float, float) { }
+
+static inline void updateLayerContentsScale(LayerChromium* layer, const WebTransformationMatrix& combinedTransform, float deviceScaleFactor, float pageScaleFactor)
+{
+    float cssScale = layer->initialCssScale();
+    if (!cssScale) {
+        WebTransformationMatrix flatTransform = combinedTransform;

[enne (OOO), 2012/10/02 19:13:18]

Do you want the combinedTransform here or the screen space transform?

+        CCMathUtil::flattenTransformTo2d(flatTransform);
+
+        bool clipped;
+        FloatPoint origin = CCMathUtil::mapPoint(flatTransform, FloatPoint(0, 0), clipped);
+        FloatPoint xScale = CCMathUtil::mapPoint(flatTransform, FloatPoint(1, 0), clipped);
+        FloatPoint yScale = CCMathUtil::mapPoint(flatTransform, FloatPoint(0, 1), clipped);
+        float combinedScale = fmaxf(CCMathUtil::distanceBetweenPoints(xScale, origin), CCMathUtil::distanceBetweenPoints(yScale, origin));
+        cssScale = combinedScale / deviceScaleFactor;
+        if (!layer->boundsContainPageScale())
+            cssScale /= pageScaleFactor;
+        layer->setInitialCssScale(cssScale);
+    }
+
+    float contentsScale = cssScale * deviceScaleFactor;
+    if (!layer->boundsContainPageScale())
+        contentsScale *= pageScaleFactor;
+    layer->setContentsScale(contentsScale);
+
+    LayerChromium* maskLayer = layer->maskLayer();
+    if (maskLayer)
+        maskLayer->setContentsScale(contentsScale);
+
+    LayerChromium* replicaMaskLayer = layer->replicaLayer() ? layer->replicaLayer()->maskLayer() : 0;
+    if (replicaMaskLayer)
+        replicaMaskLayer->setContentsScale(contentsScale);
+}
+
 // Should be called just before the recursive calculateDrawTransformsInternal().
 template<typename LayerType, typename LayerList>
 void setupRootLayerAndSurfaceForRecursion(LayerType* rootLayer, LayerList& renderSurfaceLayerList, const IntSize& deviceViewportSize)
 {
     if (!rootLayer->renderSurface())
         rootLayer->createRenderSurface();
 
     rootLayer->renderSurface()->setContentRect(IntRect(IntPoint::zero(), deviceViewportSize));
     rootLayer->renderSurface()->clearLayerLists();
 
     ASSERT(renderSurfaceLayerList.isEmpty());
     renderSurfaceLayerList.append(rootLayer);
 }
 
 // Recursively walks the layer tree starting at the given node and computes all the
 // necessary transformations, clipRects, render surfaces, etc.
 template<typename LayerType, typename LayerList, typename RenderSurfaceType, typename LayerSorter>
 static void calculateDrawTransformsInternal(LayerType* layer, LayerType* rootLayer, const WebTransformationMatrix& parentMatrix,
     const WebTransformationMatrix& fullHierarchyMatrix, const WebTransformationMatrix& currentScrollCompensationMatrix,
     const IntRect& clipRectFromAncestor, bool ancestorClipsSubtree,
     RenderSurfaceType* nearestAncestorThatMovesPixels, LayerList& renderSurfaceLayerList, LayerList& layerList,
-    LayerSorter* layerSorter, int maxTextureSize, float deviceScaleFactor, IntRect& drawableContentRectOfSubtree)
+    LayerSorter* layerSorter, int maxTextureSize, float deviceScaleFactor, float pageScaleFactor, IntRect& drawableContentRectOfSubtree)

[enne (OOO), 2012/10/02 19:13:18]

How about an input struct to this function?

 {
     // This function computes the new matrix transformations recursively for this
     // layer and all its descendants. It also computes the appropriate render surfaces.
     // Some important points to remember:
     //
     // 0. Here, transforms are notated in Matrix x Vector order, and in words we describe what
     //    the transform does from left to right.
     //
     // 1. In our terminology, the "layer origin" refers to the top-left corner of a layer, and the
     //    positive Y-axis points downwards. This interpretation is valid because the orthographic
@@ skipping 112 matching lines @@
     WebTransformationMatrix combinedTransform = parentMatrix;
     combinedTransform.multiply(layerLocalTransform);
 
     if (layer->fixedToContainerLayer()) {
         // Special case: this layer is a composited fixed-position layer; we need to
         // explicitly compensate for all ancestors' nonzero scrollDeltas to keep this layer
         // fixed correctly.
         combinedTransform = currentScrollCompensationMatrix * combinedTransform;
     }
 
+    // The layer's contentsSize is determined from the combinedTransform, which then informs the
+    // layer's drawTransform.
+    updateLayerContentsScale(layer, combinedTransform, deviceScaleFactor, pageScaleFactor);
+
     // The drawTransform that gets computed below is effectively the layer's drawTransform, unless
     // the layer itself creates a renderSurface. In that case, the renderSurface re-parents the transforms.
     WebTransformationMatrix drawTransform = combinedTransform;
     // M[draw] = M[parent] * LT * Tr[anchor2center] * Tr[center2origin]
     drawTransform.translate(-layer->bounds().width() / 2.0, -layer->bounds().height() / 2.0);
     if (!layer->contentBounds().isEmpty() && !layer->bounds().isEmpty()) {
         // M[draw] = M[parent] * LT * Tr[anchor2origin] * S[layer2content]
         drawTransform.scaleNonUniform(layer->bounds().width() / static_cast<double>(layer->contentBounds().width()),
                                       layer->bounds().height() / static_cast<double>(layer->contentBounds().height()));
     }
@@ skipping 140 matching lines @@
         descendants.append(layer);
 
     WebTransformationMatrix nextScrollCompensationMatrix = computeScrollCompensationMatrixForChildren(layer, parentMatrix, currentScrollCompensationMatrix);;
 
     IntRect accumulatedDrawableContentRectOfChildren;
     for (size_t i = 0; i < layer->children().size(); ++i) {
         LayerType* child = CCLayerTreeHostCommon::getChildAsRawPtr(layer->children(), i);
         IntRect drawableContentRectOfChildSubtree;
         calculateDrawTransformsInternal<LayerType, LayerList, RenderSurfaceType, LayerSorter>(child, rootLayer, sublayerMatrix, nextHierarchyMatrix, nextScrollCompensationMatrix,
                                                                                               clipRectForSubtree, subtreeShouldBeClipped, nearestAncestorThatMovesPixels,
-                                                                                              renderSurfaceLayerList, descendants, layerSorter, maxTextureSize, deviceScaleFactor, drawableContentRectOfChildSubtree);
+                                                                                              renderSurfaceLayerList, descendants, layerSorter, maxTextureSize, deviceScaleFactor, pageScaleFactor, drawableContentRectOfChildSubtree);
         if (!drawableContentRectOfChildSubtree.isEmpty()) {
             accumulatedDrawableContentRectOfChildren.unite(drawableContentRectOfChildSubtree);
             if (child->renderSurface())
                 descendants.append(child);
         }
     }
 
     // Compute the total drawableContentRect for this subtree (the rect is in targetSurface space)
     IntRect localDrawableContentRectOfSubtree = accumulatedDrawableContentRectOfChildren;
     if (layer->drawsContent())
@@ skipping 114 matching lines @@
             LayerType* replicaMaskLayer = it->replicaLayer() ? it->replicaLayer()->maskLayer() : 0;
             if (replicaMaskLayer)
                 replicaMaskLayer->setVisibleContentRect(IntRect(IntPoint(), it->contentBounds()));
         } else if (it.representsItself()) {
             IntRect visibleContentRect = calculateVisibleContentRect(*it);
             it->setVisibleContentRect(visibleContentRect);
         }
     }
 }
 
-void CCLayerTreeHostCommon::calculateDrawTransforms(LayerChromium* rootLayer, const IntSize& deviceViewportSize, float deviceScaleFactor, int maxTextureSize, Vector<RefPtr<LayerChromium> >& renderSurfaceLayerList)
+void CCLayerTreeHostCommon::calculateDrawTransforms(LayerChromium* rootLayer, const IntSize& deviceViewportSize, float deviceScaleFactor, float pageScaleFactor, int maxTextureSize, Vector<RefPtr<LayerChromium> >& renderSurfaceLayerList)
 {
     IntRect totalDrawableContentRect;
     WebTransformationMatrix identityMatrix;
     WebTransformationMatrix deviceScaleTransform;
     deviceScaleTransform.scale(deviceScaleFactor);
 
     setupRootLayerAndSurfaceForRecursion<LayerChromium, Vector<RefPtr<LayerChromium> > >(rootLayer, renderSurfaceLayerList, deviceViewportSize);
 
     cc::calculateDrawTransformsInternal<LayerChromium, Vector<RefPtr<LayerChromium> >, RenderSurfaceChromium, void>(rootLayer, rootLayer, deviceScaleTransform, identityMatrix, identityMatrix,
-                                                                                                                         rootLayer->renderSurface()->contentRect(), true, 0, renderSurfaceLayerList,
-                                                                                                                         rootLayer->renderSurface()->layerList(), 0, maxTextureSize, deviceScaleFactor, totalDrawableContentRect);
+                                                                                                                    rootLayer->renderSurface()->contentRect(), true, 0, renderSurfaceLayerList,
+                                                                                                                    rootLayer->renderSurface()->layerList(), 0, maxTextureSize, deviceScaleFactor, pageScaleFactor, totalDrawableContentRect);
 }
 
-void CCLayerTreeHostCommon::calculateDrawTransforms(CCLayerImpl* rootLayer, const IntSize& deviceViewportSize, float deviceScaleFactor, CCLayerSorter* layerSorter, int maxTextureSize, Vector<CCLayerImpl*>& renderSurfaceLayerList)
+void CCLayerTreeHostCommon::calculateDrawTransforms(CCLayerImpl* rootLayer, const IntSize& deviceViewportSize, float deviceScaleFactor, float pageScaleFactor, CCLayerSorter* layerSorter, int maxTextureSize, Vector<CCLayerImpl*>& renderSurfaceLayerList)
 {
     IntRect totalDrawableContentRect;
     WebTransformationMatrix identityMatrix;
     WebTransformationMatrix deviceScaleTransform;
     deviceScaleTransform.scale(deviceScaleFactor);
 
     setupRootLayerAndSurfaceForRecursion<CCLayerImpl, Vector<CCLayerImpl*> >(rootLayer, renderSurfaceLayerList, deviceViewportSize);
 
     cc::calculateDrawTransformsInternal<CCLayerImpl, Vector<CCLayerImpl*>, CCRenderSurface, CCLayerSorter>(rootLayer, rootLayer, deviceScaleTransform, identityMatrix, identityMatrix,
-                                                                                                                rootLayer->renderSurface()->contentRect(), true, 0, renderSurfaceLayerList,
-                                                                                                                rootLayer->renderSurface()->layerList(), layerSorter, maxTextureSize, deviceScaleFactor, totalDrawableContentRect);
+                                                                                                           rootLayer->renderSurface()->contentRect(), true, 0, renderSurfaceLayerList,
+                                                                                                           rootLayer->renderSurface()->layerList(), layerSorter, maxTextureSize, deviceScaleFactor, pageScaleFactor, totalDrawableContentRect);
 }
 
 void CCLayerTreeHostCommon::calculateVisibleRects(Vector<RefPtr<LayerChromium> >& renderSurfaceLayerList)
 {
     calculateVisibleRectsInternal<LayerChromium, Vector<RefPtr<LayerChromium> >, RenderSurfaceChromium>(renderSurfaceLayerList);
 }
 
 void CCLayerTreeHostCommon::calculateVisibleRects(Vector<CCLayerImpl*>& renderSurfaceLayerList)
 {
     calculateVisibleRectsInternal<CCLayerImpl, Vector<CCLayerImpl*>, CCRenderSurface>(renderSurfaceLayerList);
@@ skipping 64 matching lines @@
 
         foundLayer = currentLayer;
         break;
     }
 
     // This can potentially return 0, which means the viewportPoint did not successfully hit test any layers, not even the root layer.
     return foundLayer;
 }
 
 } // namespace cc