Canvas2d: Implement rerouting event by hit region's control.

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp

Index: third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
diff --git a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
index ff96cb51b82b8ed1c31afd54261f3311c7d0e1ea..ead92561a4eb0d43e026d2b88f1fd62df3d908dc 100644
--- a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
+++ b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
@@ -41,6 +41,7 @@
 #include "core/dom/AXObjectCache.h"
 #include "core/dom/StyleEngine.h"
 #include "core/events/Event.h"
+#include "core/events/MouseEvent.h"
 #include "core/frame/Settings.h"
 #include "core/html/TextMetrics.h"
 #include "core/html/canvas/CanvasFontCache.h"
@@ -578,6 +579,27 @@ bool CanvasRenderingContext2D::parseColorOrCurrentColor(Color& color, const Stri
     return ::blink::parseColorOrCurrentColor(color, colorString, canvas());
 }
 
+std::pair<Element*, String> CanvasRenderingContext2D::getControlAndIdIfHitRegionExists(const LayoutPoint& location)
+{
+    if (hitRegionsCount() <= 0)
+        return std::make_pair(nullptr, String());
+
+    LayoutBox* box = canvas()->layoutBox();
+    FloatPoint localPos = box->absoluteToLocal(FloatPoint(location), UseTransforms);
+    if (box->hasBorderOrPadding())
+        localPos.move(-box->contentBoxOffset());
+    localPos.scale(canvas()->width() / box->contentWidth(), canvas()->height() / box->contentHeight());
+
+    HitRegion* hitRegion = hitRegionAtPoint(localPos);
+    if (hitRegion) {
+        Element* control = hitRegion->control();
+        if (control && canvas()->isSupportedInteractiveCanvasFallback(*control))
+            return std::make_pair(hitRegion->control(), hitRegion->id());
+        return std::make_pair(nullptr, hitRegion->id());
+    }
+    return std::make_pair(nullptr, String());
+}
+
 String CanvasRenderingContext2D::textAlign() const
 {
     return textAlignName(state().getTextAlign());