Implement pinch-zoom scaling for main-frame scrollbars and pinch-zoom overlay scrollbars.

cc/layer_tree_host_impl.cc

Index: cc/layer_tree_host_impl.cc
diff --git a/cc/layer_tree_host_impl.cc b/cc/layer_tree_host_impl.cc
index 01c2d2847dfa3c86a2ee4e9006691343ebad4c81..60dc9d5cda4a2d6ea12a33dc57905c3662b11f56 100644
--- a/cc/layer_tree_host_impl.cc
+++ b/cc/layer_tree_host_impl.cc
@@ -24,6 +24,7 @@
 #include "cc/math_util.h"
 #include "cc/overdraw_metrics.h"
 #include "cc/page_scale_animation.h"
+#include "cc/pinch_zoom_scrollbars_manager.h"
 #include "cc/prioritized_resource_manager.h"
 #include "cc/quad_culler.h"
 #include "cc/render_pass_draw_quad.h"
@@ -380,10 +381,25 @@ void LayerTreeHostImpl::trackDamageForAllSurfaces(LayerImpl* rootDrawLayer, cons
     }
 }
 
-void LayerTreeHostImpl::updateRootScrollLayerImplTransform()
+void LayerTreeHostImpl::updateImplTransformOnRootChildren()
 {
     if (rootScrollLayer()) {
-        rootScrollLayer()->setImplTransform(implTransform());
+        for (size_t i = 0; i < rootLayer()->children().size(); ++i) {
+            LayerImpl* layerImpl = rootLayer()->children()[i];
+            if (layerImpl != static_cast<LayerImpl*>(activeTree()->pinch_zoom_scrollbar_vertical())
+                && layerImpl != static_cast<LayerImpl*>(activeTree()->pinch_zoom_scrollbar_horizontal()))
+                layerImpl->setImplTransform(implTransform());
+        }
+    }
+    // TODO(wjmaclean): make sure this is revised to work with multiple LayerTreeImpls.

[enne (OOO), 2012/12/13 17:43:38]

Whoa, why is the PinchZoomScrollbarsManager on the tree and not the host? It
seems to me that the layers from the main thread side have no state, so there's
no reason to have them on the pending tree.

Also, if you create them here and don't sync, then you don't need to do anything
on the layer side.  You can just create them here and hand them to the manager. 
(Or remove them from the previous tree and insert them in the next active tree
during tree swap.)

[wjmaclean, 2012/12/13 18:26:50]

OK, I will re-do with the manager on LTHI. I considered both options, but as I
was unaware of how the tree-swap mechanics would look I wasn't sure how easily
I'd be able to do the remove/insert.

+    PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+    if (pinchZoomScrollbars) {
+        pinchZoomScrollbars->setPinchZoomViewportPosition(m_pinchZoomViewport.zoomedViewportOffset(), m_pinchZoomViewport.totalPageScaleFactor());
+        if (rootScrollLayer())
+            pinchZoomScrollbars->setRootScrollLayerOffset(
+                rootScrollLayer()->scrollOffset(), rootScrollLayer()->maxScrollOffset());
+        else
+            pinchZoomScrollbars->setRootScrollLayerOffset(gfx::Vector2d(), gfx::Vector2d());
     }
 }
 
@@ -407,7 +423,7 @@ void LayerTreeHostImpl::calculateRenderSurfaceLayerList(LayerList& renderSurface
     DCHECK(rootLayer());
     DCHECK(m_renderer); // For maxTextureSize.
     {
-        updateRootScrollLayerImplTransform();
+        updateImplTransformOnRootChildren();
 
         TRACE_EVENT0("cc", "LayerTreeHostImpl::calcDrawEtc");
         float pageScaleFactor = m_pinchZoomViewport.pageScaleFactor();
@@ -555,6 +571,7 @@ bool LayerTreeHostImpl::calculateRenderPasses(FrameData& frame)
         } else if (it.representsItself() && !it->visibleContentRect().IsEmpty()) {
             bool hasOcclusionFromOutsideTargetSurface;
             bool implDrawTransformIsUnknown = false;
+
             if (occlusionTracker.occluded(it->renderTarget(), it->visibleContentRect(), it->drawTransform(), implDrawTransformIsUnknown, it->drawableContentRect(), &hasOcclusionFromOutsideTargetSurface))
                 appendQuadsData.hadOcclusionFromOutsideTargetSurface |= hasOcclusionFromOutsideTargetSurface;
             else {
@@ -884,6 +901,10 @@ void LayerTreeHostImpl::drawLayers(FrameData& frame)
     if (m_activeTree->hud_layer())
         m_activeTree->hud_layer()->updateHudTexture(m_resourceProvider.get());
 
+    PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();

[enne (OOO), 2012/12/13 17:43:38]

I would like nearly all the changes in this file to go away.  This adds way too
much complexity to the already overwhelming LTHI.  We already have abstractions
for updating layers.  You could give the manager an LTHI pointer or the layers
themselves could ask for their LTHI and then get the right device scale /
viewport / etc.

The pinch zoom scrollbar manager doesn't need to be special cased any time one
of these values changed.  You should just look them up when you need them.

[wjmaclean, 2012/12/13 18:26:50]

OK, I'll look into doing this. I had hoped this would minimize the number of
calls required to transfer the information.
OK.

+    if (pinchZoomScrollbars && m_pinchZoomViewport.pageScaleFactor() != 1)
+        pinchZoomScrollbars->updateThumbTextures(m_resourceProvider.get());
+
     m_renderer->drawFrame(frame.renderPasses, frame.renderPassesById);
 
     // The render passes should be consumed by the renderer.
@@ -1085,7 +1106,11 @@ void LayerTreeHostImpl::setViewportSize(const gfx::Size& layoutViewportSize, con
     m_layoutViewportSize = layoutViewportSize;
     m_deviceViewportSize = deviceViewportSize;
 
-    m_pinchZoomViewport.setLayoutViewportSize(layoutViewportSize);
+    m_pinchZoomViewport.setLayoutViewportSize(m_layoutViewportSize);
+    // TODO(wjmaclean): make sure this is revised to work with multiple LayerTreeImpls.
+    PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+    if (pinchZoomScrollbars)
+        pinchZoomScrollbars->setPinchZoomViewportBounds(layoutViewportSize);
 
     updateMaxScrollOffset();
 
@@ -1117,6 +1142,10 @@ void LayerTreeHostImpl::setDeviceScaleFactor(float deviceScaleFactor)
         return;
     m_deviceScaleFactor = deviceScaleFactor;
     m_pinchZoomViewport.setDeviceScaleFactor(m_deviceScaleFactor);
+    // TODO(wjmaclean): make sure this is revised to work with multiple LayerTreeImpls.
+    PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+    if (pinchZoomScrollbars)
+        pinchZoomScrollbars->setDeviceScaleFactor(m_deviceScaleFactor);
 
     updateMaxScrollOffset();
 }
@@ -1163,6 +1192,14 @@ void LayerTreeHostImpl::updateMaxScrollOffset()
 
     gfx::Size contentBounds = contentSize();
     if (m_settings.pageScalePinchZoomEnabled) {
+        // TODO(wjmaclean): make sure this is revised to work with multiple LayerTreeImpls.
+        PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+        if (pinchZoomScrollbars) {
+            if (!rootScrollLayer() || rootScrollLayer()->children().isEmpty())
+                pinchZoomScrollbars->setContentBounds(m_layoutViewportSize);
+            else
+                pinchZoomScrollbars->setContentBounds(contentSize());
+        }
         // 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.
@@ -1261,6 +1298,11 @@ InputHandlerClient::ScrollStatus LayerTreeHostImpl::scrollBegin(gfx::Point viewp
         m_scrollDeltaIsInViewportSpace = (type == Gesture);
         m_numImplThreadScrolls++;
         setNeedsUpdateDrawProperties();
+
+        PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+        if (type == Gesture && pinchZoomScrollbars)
+            pinchZoomScrollbars->setEnabled(m_pinchZoomViewport.totalPageScaleFactor() != 1);
+
         return ScrollStarted;
     }
     return ScrollIgnored;
@@ -1387,6 +1429,11 @@ void LayerTreeHostImpl::clearCurrentlyScrollingLayer()
 
 void LayerTreeHostImpl::scrollEnd()
 {
+    PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+    if (pinchZoomScrollbars) {
+        pinchZoomScrollbars->setEnabled(false);
+        m_client->setNeedsRedrawOnImplThread();
+    }
     clearCurrentlyScrollingLayer();
 }
 
@@ -1428,6 +1475,10 @@ void LayerTreeHostImpl::pinchGestureUpdate(float magnifyDelta, gfx::Point anchor
     if (rootScrollLayer()->scrollbarAnimationController())
         rootScrollLayer()->scrollbarAnimationController()->didPinchGestureUpdate();
 
+    PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+    if (pinchZoomScrollbars)
+        pinchZoomScrollbars->setEnabled(m_pinchZoomViewport.totalPageScaleFactor() != 1);
+
     m_client->setNeedsCommitOnImplThread();
     m_client->setNeedsRedrawOnImplThread();
     setNeedsUpdateDrawProperties();
@@ -1440,6 +1491,10 @@ void LayerTreeHostImpl::pinchGestureEnd()
     if (rootScrollLayer() && rootScrollLayer()->scrollbarAnimationController())
         rootScrollLayer()->scrollbarAnimationController()->didPinchGestureEnd();
 
+    PinchZoomScrollbarsManager* pinchZoomScrollbars = activeTree()->pinch_zoom_scrollbars_manager();
+    if (pinchZoomScrollbars)
+        pinchZoomScrollbars->setEnabled(false);
+
     m_client->setNeedsCommitOnImplThread();
 }