WIP: <canvas> hit regions

Source/core/rendering/RenderHTMLCanvas.cpp

Index: Source/core/rendering/RenderHTMLCanvas.cpp
diff --git a/Source/core/rendering/RenderHTMLCanvas.cpp b/Source/core/rendering/RenderHTMLCanvas.cpp
index ae259126b0a17d8a719035d46a76f678ac8f673c..661fbd6af648312c3426af2fd760e24fa5bea44f 100644
--- a/Source/core/rendering/RenderHTMLCanvas.cpp
+++ b/Source/core/rendering/RenderHTMLCanvas.cpp
@@ -26,11 +26,13 @@
 #include "config.h"
 #include "core/rendering/RenderHTMLCanvas.h"
 
-#include "core/html/HTMLCanvasElement.h"
-#include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
+#include "core/html/HTMLCanvasElement.h"
+#include "core/html/canvas/CanvasRenderingContext.h"
+#include "core/html/canvas/CanvasRenderingContext2D.h"
 #include "core/page/Page.h"
+#include "core/rendering/HitTestLocation.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderView.h"
 
@@ -49,6 +51,29 @@ LayerType RenderHTMLCanvas::layerTypeRequired() const
     return NormalLayer;
 }
 
+bool RenderHTMLCanvas::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction hitTestAction)
+{
+    if (!RenderReplaced::nodeAtPoint(request, result, locationInContainer, accumulatedOffset, hitTestAction))
+        return false;
+
+    if (!visibleToHitTestRequest(request) || hitTestAction != HitTestForeground)
+        return true;
+
+    HTMLCanvasElement* canvas = toHTMLCanvasElement(node());
+    // Thread/plumb through HTMLCanvasElement instead?
+    if (!canvas->renderingContext() || !canvas->renderingContext()->is2d())
+        return true;
+
+    // Check for intersections with hit regions.
+    LayoutPoint adjustedLocation = accumulatedOffset + location();
+    LayoutPoint localPoint = locationInContainer.point() - toLayoutSize(adjustedLocation);
+    if (CanvasHitRegion* hitRegion = toCanvasRenderingContext2D(canvas->renderingContext())->hitRegionAtPoint(localPoint)) {
+        hitRegion = hitRegion;
+        updateHitTestResult(result, localPoint);
+    }
+    return true;
+}
+
 void RenderHTMLCanvas::paintReplaced(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     GraphicsContext* context = paintInfo.context;