Chromium compositor change implementing page-scale driven pinch-zoom.

cc/CCLayerTreeHostImpl.cpp

Index: cc/CCLayerTreeHostImpl.cpp
===================================================================
--- cc/CCLayerTreeHostImpl.cpp	(revision 157978)
+++ cc/CCLayerTreeHostImpl.cpp	(working copy)
@@ -48,6 +48,49 @@
 
 namespace cc {
 
+FloatRect CCPinchZoomViewport::bounds() const
+{
+    FloatSize scaledBounds = m_unpinchedBounds;
+    if (m_pageScaleFactor > 1)
+        scaledBounds.scale(1 / m_pageScaleFactor);
+
+    FloatRect bounds;
+    bounds.setSize(scaledBounds);
+    bounds.setLocation(m_pinchViewportScrollDelta);
+
+    return bounds;
+}
+
+FloatSize CCPinchZoomViewport::applyScroll(FloatSize& delta)
+{
+    FloatSize overflow;
+    FloatRect pinchedBounds = bounds();
+
+    pinchedBounds.move(delta);
+    if (pinchedBounds.x() < 0) {
+        pinchedBounds.setX(0);
+        overflow.setWidth(pinchedBounds.x());
+    }
+
+    if (pinchedBounds.y() < 0) {
+        pinchedBounds.setY(0);
+        overflow.setHeight(pinchedBounds.y());
+    }
+
+    if (pinchedBounds.maxX() > m_unpinchedBounds.width()) {
+        pinchedBounds.move(m_unpinchedBounds.width() - pinchedBounds.maxX(), 0);
+        overflow.setWidth(pinchedBounds.maxX() - m_unpinchedBounds.width());
+    }
+
+    if (pinchedBounds.maxY() > m_unpinchedBounds.height()) {
+        pinchedBounds.move(0, m_unpinchedBounds.height() - pinchedBounds.maxY());
+        overflow.setHeight(pinchedBounds.maxY() - m_unpinchedBounds.height());
+    }
+    m_pinchViewportScrollDelta = pinchedBounds.location();
+
+    return overflow;
+}
+
 class CCLayerTreeHostImplTimeSourceAdapter : public CCTimeSourceClient {
     WTF_MAKE_NONCOPYABLE(CCLayerTreeHostImplTimeSourceAdapter);
 public:
@@ -115,20 +158,23 @@
     , m_visible(true)
     , m_contentsTexturesPurged(false)
     , m_memoryAllocationLimitBytes(CCPrioritizedTextureManager::defaultMemoryAllocationLimit())
-    , m_pageScale(1)
+    , m_pageScaleFactor(1)
     , m_pageScaleDelta(1)
     , m_sentPageScaleDelta(1)
-    , m_minPageScale(0)
-    , m_maxPageScale(0)
+    , m_minPageScaleFactor(0)
+    , m_maxPageScaleFactor(0)
     , m_backgroundColor(0)
     , m_hasTransparentBackground(false)
     , m_needsAnimateLayers(false)
     , m_pinchGestureActive(false)
+    , m_applyPinchZoomInImpl(false)
     , m_fpsCounter(CCFrameRateCounter::create())
     , m_debugRectHistory(CCDebugRectHistory::create())
 {
     ASSERT(CCProxy::isImplThread());
     didVisibilityChange(this, m_visible);
+
+    m_applyPinchZoomInImpl = CCSettings::pageScalePinchZoomEnabled();
 }
 
 CCLayerTreeHostImpl::~CCLayerTreeHostImpl()
@@ -196,7 +242,7 @@
 
     IntSize scrollTotal = flooredIntSize(m_rootScrollLayerImpl->scrollPosition() + m_rootScrollLayerImpl->scrollDelta());
     scrollTotal.scale(m_pageScaleDelta);
-    float scaleTotal = m_pageScale * m_pageScaleDelta;
+    float scaleTotal = m_pageScaleFactor * m_pageScaleDelta;
     IntSize scaledContentSize = contentSize();
     scaledContentSize.scale(m_pageScaleDelta);
 
@@ -233,6 +279,13 @@
     }
 }
 
+void CCLayerTreeHostImpl::updateRootScrollLayerImplTransform()
+{
+    if (m_rootScrollLayerImpl) {
+        m_rootScrollLayerImpl->setImplTransform(implTransform());
+    }
+}
+
 void CCLayerTreeHostImpl::calculateRenderSurfaceLayerList(CCLayerList& renderSurfaceLayerList)
 {
     ASSERT(renderSurfaceLayerList.isEmpty());
@@ -240,6 +293,8 @@
     ASSERT(m_renderer); // For maxTextureSize.
 
     {
+        updateRootScrollLayerImplTransform();
+
         TRACE_EVENT0("cc", "CCLayerTreeHostImpl::calcDrawEtc");
         CCLayerTreeHostCommon::calculateDrawTransforms(m_rootLayerImpl.get(), deviceViewportSize(), m_deviceScaleFactor, &m_layerSorter, rendererCapabilities().maxTextureSize, renderSurfaceLayerList);
         CCLayerTreeHostCommon::calculateVisibleRects(renderSurfaceLayerList);
@@ -767,6 +822,8 @@
     m_layoutViewportSize = layoutViewportSize;
     m_deviceViewportSize = deviceViewportSize;
 
+    m_pinchZoomViewport.setUnpinchedBounds(FloatSize(layoutViewportSize));
+
     updateMaxScrollPosition();
 
     if (m_renderer)
@@ -801,38 +858,38 @@
 }
 
 
-void CCLayerTreeHostImpl::setPageScaleFactorAndLimits(float pageScale, float minPageScale, float maxPageScale)
+void CCLayerTreeHostImpl::setPageScaleFactorAndLimits(float pageScaleFactor, float minPageScaleFactor, float maxPageScaleFactor)
 {
-    if (!pageScale)
+    if (!pageScaleFactor)
         return;
 
-    if (m_sentPageScaleDelta == 1 && pageScale == m_pageScale && minPageScale == m_minPageScale && maxPageScale == m_maxPageScale)
+    if (m_sentPageScaleDelta == 1 && pageScaleFactor == m_pageScaleFactor && minPageScaleFactor == m_minPageScaleFactor && maxPageScaleFactor == m_maxPageScaleFactor)
         return;
 
-    m_minPageScale = minPageScale;
-    m_maxPageScale = maxPageScale;
+    m_minPageScaleFactor = minPageScaleFactor;
+    m_maxPageScaleFactor = maxPageScaleFactor;
 
-    float pageScaleChange = pageScale / m_pageScale;
-    m_pageScale = pageScale;
+    float pageScaleChange = pageScaleFactor / m_pageScaleFactor;
+    m_pageScaleFactor = pageScaleFactor;
 
-    if (pageScaleChange != 1)
-        adjustScrollsForPageScaleChange(m_rootScrollLayerImpl, pageScaleChange);
+    if (!m_applyPinchZoomInImpl) {
+        if (pageScaleChange != 1)
+            adjustScrollsForPageScaleChange(m_rootScrollLayerImpl, pageScaleChange);
+    }
 
     // Clamp delta to limits and refresh display matrix.
     setPageScaleDelta(m_pageScaleDelta / m_sentPageScaleDelta);
     m_sentPageScaleDelta = 1;
-    if (m_rootScrollLayerImpl)
-        m_rootScrollLayerImpl->setPageScaleDelta(m_pageScaleDelta);
 }
 
 void CCLayerTreeHostImpl::setPageScaleDelta(float delta)
 {
     // Clamp to the current min/max limits.
-    float finalMagnifyScale = m_pageScale * delta;
-    if (m_minPageScale && finalMagnifyScale < m_minPageScale)
-        delta = m_minPageScale / m_pageScale;
-    else if (m_maxPageScale && finalMagnifyScale > m_maxPageScale)
-        delta = m_maxPageScale / m_pageScale;
+    float finalMagnifyScale = m_pageScaleFactor * delta;
+    if (m_minPageScaleFactor && finalMagnifyScale < m_minPageScaleFactor)
+        delta = m_minPageScaleFactor / m_pageScaleFactor;
+    else if (m_maxPageScaleFactor && finalMagnifyScale > m_maxPageScaleFactor)
+        delta = m_maxPageScaleFactor / m_pageScaleFactor;
 
     if (delta == m_pageScaleDelta)
         return;
@@ -840,8 +897,6 @@
     m_pageScaleDelta = delta;
 
     updateMaxScrollPosition();
-    if (m_rootScrollLayerImpl)
-        m_rootScrollLayerImpl->setPageScaleDelta(m_pageScaleDelta);
 }
 
 void CCLayerTreeHostImpl::updateMaxScrollPosition()
@@ -859,9 +914,18 @@
     }
     viewBounds.scale(1 / m_pageScaleDelta);
 
-    // maxScroll is computed in physical pixels, but scroll positions are in layout pixels.
-    IntSize maxScroll = contentSize() - expandedIntSize(viewBounds);
+    IntSize contentBounds = contentSize();
+    if (m_applyPinchZoomInImpl) {
+        // Pinch with pageScale scrolls entirely in layout space.  contentSize
+        // returns the bounds including the page scale factor, so calculate the
+        // pre page-scale layout size here.
+        contentBounds.setWidth(contentBounds.width() / m_pageScaleFactor);
+        contentBounds.setHeight(contentBounds.height() / m_pageScaleFactor);
+    }
+
+    IntSize maxScroll = contentBounds - expandedIntSize(viewBounds);
     maxScroll.scale(1 / m_deviceScaleFactor);
+
     // The viewport may be larger than the contents in some cases, such as
     // having a vertical scrollbar but no horizontal overflow.
     maxScroll.clampNegativeToZero();
@@ -944,7 +1008,7 @@
     return ScrollIgnored;
 }
 
-static FloatSize scrollLayerWithScreenSpaceDelta(CCLayerImpl& layerImpl, const FloatPoint& screenSpacePoint, const FloatSize& screenSpaceDelta)
+static FloatSize scrollLayerWithScreenSpaceDelta(CCPinchZoomViewport* viewport, CCLayerImpl& layerImpl, const FloatPoint& screenSpacePoint, const FloatSize& screenSpaceDelta)
 {
     // Layers with non-invertible screen space transforms should not have passed the scroll hit
     // test in the first place.
@@ -966,8 +1030,11 @@
 
     // Apply the scroll delta.
     FloatSize previousDelta(layerImpl.scrollDelta());
-    layerImpl.scrollBy(localEndPoint - localStartPoint);
+    FloatSize unscrolled = layerImpl.scrollBy(localEndPoint - localStartPoint);
 
+    if (viewport)
+        viewport->applyScroll(unscrolled);
+
     // Calculate the applied scroll delta in screen space coordinates.
     FloatPoint actualLocalEndPoint = localStartPoint + layerImpl.scrollDelta() - previousDelta;
     FloatPoint actualScreenSpaceEndPoint = CCMathUtil::mapPoint(layerImpl.screenSpaceTransform(), actualLocalEndPoint, endClipped);
@@ -998,9 +1065,10 @@
         if (!layerImpl->scrollable())
             continue;
 
+        CCPinchZoomViewport* viewport = layerImpl == m_rootScrollLayerImpl ? &m_pinchZoomViewport : 0;
         FloatSize appliedDelta;
         if (m_scrollDeltaIsInScreenSpace)
-            appliedDelta = scrollLayerWithScreenSpaceDelta(*layerImpl, viewportPoint, pendingDelta);
+            appliedDelta = scrollLayerWithScreenSpaceDelta(viewport, *layerImpl, viewportPoint, pendingDelta);
         else
             appliedDelta = scrollLayerWithLocalDelta(*layerImpl, pendingDelta);
 
@@ -1071,9 +1139,16 @@
     FloatSize move = previousScaleAnchor - newScaleAnchor;
 
     m_previousPinchAnchor = anchor;
+    m_pinchZoomViewport.setTotalPageScaleFactor(m_pageScaleFactor * m_pageScaleDelta);
 
-    m_rootScrollLayerImpl->scrollBy(roundedIntSize(move));
+    if (m_applyPinchZoomInImpl) {
+        // Compute the application of the delta with respect to the current page zoom of the page.
+        move.scale(1 / (m_pageScaleFactor * m_deviceScaleFactor));
+    }
 
+    FloatSize scrollOverflow = m_applyPinchZoomInImpl? m_pinchZoomViewport.applyScroll(move) : move;
+    m_rootScrollLayerImpl->scrollBy(roundedIntSize(scrollOverflow));
+
     if (m_rootScrollLayerImpl->scrollbarAnimationController())
         m_rootScrollLayerImpl->scrollbarAnimationController()->didPinchGestureUpdate();
 
@@ -1095,7 +1170,7 @@
 {
     float pageScale = m_pageScaleAnimation->finalPageScale();
     IntSize scrollOffset = m_pageScaleAnimation->finalScrollOffset();
-    scrollOffset.scale(m_pageScale / pageScale);
+    scrollOffset.scale(m_pageScaleFactor / pageScale);
     makeScrollAndScaleSet(scrollInfo, scrollOffset, pageScale);
 }
 
@@ -1115,20 +1190,20 @@
     // out from the anchor point.
     IntSize scrollBegin = flooredIntSize(m_rootScrollLayerImpl->scrollPosition() + m_rootScrollLayerImpl->scrollDelta());
     scrollBegin.scale(m_pageScaleDelta);
-    float scaleBegin = m_pageScale * m_pageScaleDelta;
-    float pageScaleDeltaToSend = m_minPageScale / m_pageScale;
+    float scaleBegin = m_pageScaleFactor * m_pageScaleDelta;
+    float pageScaleDeltaToSend = m_minPageScaleFactor / m_pageScaleFactor;
     FloatSize scaledContentsSize = contentSize();
     scaledContentsSize.scale(pageScaleDeltaToSend);
 
     FloatSize anchor = toSize(m_previousPinchAnchor);
     FloatSize scrollEnd = scrollBegin + anchor;
-    scrollEnd.scale(m_minPageScale / scaleBegin);
+    scrollEnd.scale(m_minPageScaleFactor / scaleBegin);
     scrollEnd -= anchor;
     scrollEnd = scrollEnd.shrunkTo(roundedIntSize(scaledContentsSize - m_deviceViewportSize)).expandedTo(FloatSize(0, 0));
     scrollEnd.scale(1 / pageScaleDeltaToSend);
     scrollEnd.scale(m_deviceScaleFactor);
 
-    makeScrollAndScaleSet(scrollInfo, roundedIntSize(scrollEnd), m_minPageScale);
+    makeScrollAndScaleSet(scrollInfo, roundedIntSize(scrollEnd), m_minPageScaleFactor);
 }
 
 void CCLayerTreeHostImpl::makeScrollAndScaleSet(CCScrollAndScaleSet* scrollInfo, const IntSize& scrollOffset, float pageScale)
@@ -1141,7 +1216,7 @@
     scroll.scrollDelta = scrollOffset - toSize(m_rootScrollLayerImpl->scrollPosition());
     scrollInfo->scrolls.append(scroll);
     m_rootScrollLayerImpl->setSentScrollDelta(scroll.scrollDelta);
-    m_sentPageScaleDelta = scrollInfo->pageScaleDelta = pageScale / m_pageScale;
+    m_sentPageScaleDelta = scrollInfo->pageScaleDelta = pageScale / m_pageScaleFactor;
 }
 
 static void collectScrollDeltas(CCScrollAndScaleSet* scrollInfo, CCLayerImpl* layerImpl)
@@ -1168,10 +1243,14 @@
 
     if (m_pinchGestureActive || m_pageScaleAnimation) {
         m_sentPageScaleDelta = scrollInfo->pageScaleDelta = 1;
-        if (m_pinchGestureActive)
-            computePinchZoomDeltas(scrollInfo.get());
-        else if (m_pageScaleAnimation.get())
-            computeDoubleTapZoomDeltas(scrollInfo.get());
+        // If pinch zoom is applied in the impl thread, then there is no need to
+        // calculate these intermediate scale deltas.
+        if (!m_applyPinchZoomInImpl) {
+            if (m_pinchGestureActive)
+                computePinchZoomDeltas(scrollInfo.get());
+            else if (m_pageScaleAnimation.get())
+                computeDoubleTapZoomDeltas(scrollInfo.get());
+        }
         return scrollInfo.release();
     }
 
@@ -1181,6 +1260,22 @@
     return scrollInfo.release();
 }
 
+WebTransformationMatrix CCLayerTreeHostImpl::implTransform() const
+{
+    WebTransformationMatrix transform;
+    transform.scale(m_pageScaleDelta);
+
+    // If the pinch state is applied in the impl, then push it to the
+    // impl transform, otherwise the scale is handled by WebCore.
+    if (m_applyPinchZoomInImpl) {
+        transform.scale(m_pageScaleFactor);
+        transform.translate(-m_pinchZoomViewport.scrollDelta().x(),
+                            -m_pinchZoomViewport.scrollDelta().y());
+    }
+
+    return transform;
+}
+
 void CCLayerTreeHostImpl::setFullRootLayerDamage()
 {
     if (m_rootLayerImpl) {
@@ -1197,7 +1292,7 @@
 
     IntSize scrollTotal = flooredIntSize(m_rootScrollLayerImpl->scrollPosition() + m_rootScrollLayerImpl->scrollDelta());
 
-    setPageScaleDelta(m_pageScaleAnimation->pageScaleAtTime(monotonicTime) / m_pageScale);
+    setPageScaleDelta(m_pageScaleAnimation->pageScaleAtTime(monotonicTime) / m_pageScaleFactor);
     IntSize nextScroll = m_pageScaleAnimation->scrollOffsetAtTime(monotonicTime);
     nextScroll.scale(1 / m_pageScaleDelta);
     m_rootScrollLayerImpl->scrollBy(nextScroll - scrollTotal);