Implement canvas focus ring methods.

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 b2701331d1dffccff104b5be49378965be011792..6aa11cc8f3c779c16b73352258768bb6f29fbf9d 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.cpp
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
@@ -34,6 +34,7 @@
 #include "core/html/canvas/CanvasRenderingContext2D.h"
 
 #include "CSSPropertyNames.h"
+#include "core/accessibility/AXObjectCache.h"

[Stephen White, 2013/07/19 14:37:11]

It seems unfortunate to add this dependency directly. Is there a way this could
be avoided, perhaps by adding methods to Element to set its accessibility
bounding box?

 #include "core/css/CSSFontSelector.h"
 #include "core/css/CSSParser.h"
 #include "core/css/StylePropertySet.h"
@@ -2307,4 +2308,68 @@ PassRefPtr<Canvas2DContextAttributes> CanvasRenderingContext2D::getContextAttrib
     return attributes.release();
 }
 
+void CanvasRenderingContext2D::drawSystemFocusRing(Element* element)
+{
+    drawFocusRing(m_path, element, false);
+}
+
+void CanvasRenderingContext2D::drawSystemFocusRing(DOMPath* path, Element* element)
+{
+    drawFocusRing(path->path(), element, false);
+}
+
+bool CanvasRenderingContext2D::drawCustomFocusRing(Element* element)
+{
+    drawFocusRing(m_path, element, true);
+    // Blink doesn't draw a custom focus ring; we always return false to inform the web app it should draw it.
+    return false;
+}
+
+bool CanvasRenderingContext2D::drawCustomFocusRing(DOMPath* path, Element* element)
+{
+    drawFocusRing(path->path(), element, true);
+    // Blink doesn't draw a custom focus ring; we always return false to inform the web app it should draw it.
+    return false;
+}
+
+void CanvasRenderingContext2D::drawFocusRing(const Path& path, Element* element, bool custom)
+{
+    GraphicsContext* c = drawingContext();
+    if (!c)
+        return;
+    if (!state().m_invertibleCTM)
+        return;
+    if (path.isEmpty())
+        return;
+    FloatRect boundingRect = path.boundingRect();
+
+    // If accessibility is enabled, associate this bounding box with the element.
+    if (AXObjectCache* axObjectCache = element->document()->existingAXObjectCache()) {
+        if (AccessibilityObject* obj = axObjectCache->getOrCreate(element)) {
+            IntRect canvasRect = canvas()->renderer()->absoluteBoundingBoxRect();
+            LayoutRect rect = LayoutRect(boundingRect);
+            rect.moveBy(canvasRect.location());
+            obj->setElementRect(rect);
+        }
+    }
+
+    // Only draw if the element is focused and if the function called wasn't drawCustomFocusRing.
+    if (custom || !element->focused())
+        return;
+
+    // Get the outline style from the element and use it to draw the focus ring on the canvas.
+    RenderStyle* style = element->computedStyle();
+    if (!style)
+        return;
+
+    c->save();
+    c->setAlpha(1.0);
+    c->clearShadow();
+    Vector<IntRect> rects;
+    rects.append(pixelSnappedIntRect(LayoutRect(boundingRect)));
+    c->drawFocusRing(rects, style->outlineWidth(), style->outlineOffset(), style->visitedDependentColor(CSSPropertyOutlineColor));
+    c->restore();
+    didDraw(boundingRect);
+}
+
 } // namespace WebCore