Implement basic parts of hit regions on canvas2d.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

Index: Source/core/html/canvas/CanvasRenderingContext2D.cpp
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.cpp b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
index 1c92df5400c91c95558a8266871c7923bbed128c..7a65d41afb3d0a6b8db87390a9a4f9334dff14c1 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.cpp
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
@@ -37,7 +37,6 @@
 #include "bindings/v8/ExceptionMessages.h"
 #include "bindings/v8/ExceptionState.h"
 #include "bindings/v8/ExceptionStatePlaceholder.h"
-#include "core/accessibility/AXObjectCache.h"
 #include "core/css/CSSFontSelector.h"
 #include "core/css/parser/BisonCSSParser.h"
 #include "core/css/StylePropertySet.h"
@@ -168,6 +167,7 @@ void CanvasRenderingContext2D::trace(Visitor* visitor)
 #if ENABLE(OILPAN)
     visitor->trace(m_stateStack);
     visitor->trace(m_fetchedFonts);
+    visitor->trace(m_hitRegionManager);
 #endif
     CanvasRenderingContext::trace(visitor);
 }
@@ -1244,6 +1244,8 @@ void CanvasRenderingContext2D::clearRect(float x, float y, float width, float he
         context->setCompositeOperation(CompositeSourceOver);
     }
     context->clearRect(rect);
+    if (m_hitRegionManager)
+        m_hitRegionManager->removeHitRegionsInRect(rect, state().m_transform);
     if (saved)
         context->restore();
 
@@ -2356,4 +2358,83 @@ void CanvasRenderingContext2D::drawFocusRing(const Path& path)
     didDraw(dirtyRect);
 }
 
+void CanvasRenderingContext2D::addHitRegion(ExceptionState& exceptionState)
+{
+    addHitRegion(Dictionary(), exceptionState);
+}
+
+void CanvasRenderingContext2D::addHitRegion(const Dictionary& options, ExceptionState& exceptionState)
+{
+    HitRegionOptions passOptions;
+
+    options.getWithUndefinedOrNullCheck("id", passOptions.id);
+    options.getWithUndefinedOrNullCheck("control", passOptions.control);
+    if (passOptions.id.isEmpty() && !passOptions.control) {
+        exceptionState.throwDOMException(NotSupportedError, "Both id and control are null.");
+        return;
+    }
+
+    FloatRect clipBounds;
+    GraphicsContext* context = drawingContext();
+
+    if (m_path.isEmpty() || !context || !state().m_invertibleCTM
+        || !context->getTransformedClipBounds(&clipBounds)) {
+        exceptionState.throwDOMException(NotSupportedError, "The specified path has no pixels.");
+        return;
+    }
+
+    Path specifiedPath(m_path);
+    specifiedPath.transform(state().m_transform);
+    specifiedPath.intersectPath(context->getCurrentClipPath());

[fs, 2014/06/10 11:45:15]

The path could be "degenerate" after this operation, so I think that the
bounding-box of the path needs to checked at this step.

[zino, 2014/06/10 15:40:25]

Done.

+
+    passOptions.path = specifiedPath;
+
+    if (passOptions.path.isEmpty())
+        exceptionState.throwDOMException(NotSupportedError, "The specified path has no pixels.");
+    else
+        addHitRegionInternal(passOptions, exceptionState);
+}
+
+void CanvasRenderingContext2D::addHitRegionInternal(const HitRegionOptions& options, ExceptionState& exceptionState)
+{
+    if (!m_hitRegionManager)
+        m_hitRegionManager = HitRegionManager::create();
+
+    // Remove previous region (with id or control)
+    m_hitRegionManager->removeHitRegionById(options.id);
+    m_hitRegionManager->removeHitRegionByControl(options.control.get());
+
+    RefPtrWillBeRawPtr<HitRegion> hitRegion = HitRegion::create(options);
+    hitRegion->updateAccessibility(canvas());
+    m_hitRegionManager->addHitRegion(hitRegion.release());
+}
+
+void CanvasRenderingContext2D::removeHitRegion(const String& id)
+{
+    if (m_hitRegionManager)
+        m_hitRegionManager->removeHitRegionById(id);
+}
+
+void CanvasRenderingContext2D::clearHitRegions()
+{
+    if (m_hitRegionManager)
+        m_hitRegionManager->removeAllHitRegions();
+}
+
+HitRegion* CanvasRenderingContext2D::hitRegionAtPoint(const LayoutPoint& point)
+{
+    if (m_hitRegionManager)
+        return m_hitRegionManager->getHitRegionAtPoint(point);
+
+    return 0;
+}
+
+unsigned CanvasRenderingContext2D::hitRegionsCount() const
+{
+    if (m_hitRegionManager)
+        return m_hitRegionManager->getHitRegionsCount();
+
+    return 0;
+}
+
 } // namespace WebCore