cc: Don't consider HUD layer for touches

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 e09233ddb8feeaf1323ba89df05d7f82971579fe..f546596c894770a73f39036406592fcf3c98e358 100644
--- a/cc/layer_tree_host_impl.cc
+++ b/cc/layer_tree_host_impl.cc
@@ -325,7 +325,7 @@ bool LayerTreeHostImpl::haveTouchEventHandlersAt(const gfx::Point& viewportPoint
 
     // First find out which layer was hit from the saved list of visible layers
     // in the most recent frame.
-    LayerImpl* layerImpl = LayerTreeHostCommon::findLayerThatIsHitByPoint(deviceViewportPoint, activeTree()->RenderSurfaceLayerList());
+    LayerImpl* layerImpl = findLayerThatIsHitByPoint(deviceViewportPoint, activeTree()->RenderSurfaceLayerList());
 
     // Walk up the hierarchy and look for a layer with a touch event handler region that the given point hits.
     for (; layerImpl; layerImpl = layerImpl->parent()) {
@@ -1189,7 +1189,7 @@ InputHandlerClient::ScrollStatus LayerTreeHostImpl::scrollBegin(gfx::Point viewp
 
     // First find out which layer was hit from the saved list of visible layers
     // in the most recent frame.
-    LayerImpl* layerImpl = LayerTreeHostCommon::findLayerThatIsHitByPoint(deviceViewportPoint, activeTree()->RenderSurfaceLayerList());
+    LayerImpl* layerImpl = findLayerThatIsHitByPoint(deviceViewportPoint, activeTree()->RenderSurfaceLayerList());
 
     // Walk up the hierarchy and look for a scrollable layer.
     LayerImpl* potentiallyScrollingLayerImpl = 0;
@@ -1230,6 +1230,42 @@ InputHandlerClient::ScrollStatus LayerTreeHostImpl::scrollBegin(gfx::Point viewp
     return ScrollIgnored;
 }
 
+LayerImpl* LayerTreeHostImpl::findLayerThatIsHitByPoint(const gfx::PointF& screenSpacePoint, const std::vector<LayerImpl*>& renderSurfaceLayerList)
+{
+    LayerImpl* foundLayer = 0;
+
+    typedef LayerIterator<LayerImpl, std::vector<LayerImpl*>, RenderSurfaceImpl, LayerIteratorActions::FrontToBack> LayerIteratorType;
+    LayerIteratorType end = LayerIteratorType::end(&renderSurfaceLayerList);
+    for (LayerIteratorType it = LayerIteratorType::begin(&renderSurfaceLayerList); it != end; ++it) {
+        // We don't want to consider renderSurfaces for hit testing.
+        if (!it.representsItself())
+            continue;
+
+        LayerImpl* currentLayer = (*it);
+
+        // Don't consider the hud layer as a viable target for hits.
+        if (currentLayer == activeTree()->hud_layer())

[danakj, 2013/02/18 19:18:49]

I don't understand why we would need to move around so much code to do this. We
do per-layer-type stuff in LayerTreeHostCommon all the time. See
updateLayerContentsScale for example.

You could just add a local bool IsHudLayer(LayerImpl*) { ... } method there to
deal with this.

That seems like it could be solved with 5 loc plus a test.

+            continue;
+
+        gfx::RectF contentRect(gfx::PointF(), currentLayer->contentBounds());
+        if (!MathUtil::pointHitsRect(screenSpacePoint, currentLayer->screenSpaceTransform(), contentRect))
+            continue;
+
+        // At this point, we think the point does hit the layer, but we need to walk up
+        // the parents to ensure that the layer was not clipped in such a way that the
+        // hit point actually should not hit the layer.
+        if (LayerTreeHostCommon::pointIsClippedBySurfaceOrClipRect(screenSpacePoint, currentLayer))
+            continue;
+
+        foundLayer = currentLayer;
+        break;
+    }
+
+    // This can potentially return 0, which means the screenSpacePoint did not successfully hit test any layers, not even the root layer.
+    return foundLayer;
+}
+
+
 gfx::Vector2dF LayerTreeHostImpl::scrollLayerWithViewportSpaceDelta(LayerImpl* layerImpl, float scaleFromViewportToScreenSpace, gfx::PointF viewportPoint, gfx::Vector2dF viewportDelta)
 {
     // Layers with non-invertible screen space transforms should not have passed the scroll hit