Add rendering context and rendering 2D context to OffscreenCanvas

third_party/WebKit/Source/core/html/canvas/OffscreenCanvas.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/html/canvas/OffscreenCanvas.h"
 
+#include "core/html/canvas/CanvasContextCreationAttributes.h"
+#include "core/html/canvas/OffscreenCanvasRenderingContext.h"
+#include "core/html/canvas/OffscreenCanvasRenderingContextFactory.h"
 #include "wtf/MathExtras.h"
 
 namespace blink {
 
 OffscreenCanvas* OffscreenCanvas::create(unsigned width, unsigned height)
 {
     return new OffscreenCanvas(IntSize(clampTo<int>(width), clampTo<int>(height)));
 }
 
 void OffscreenCanvas::setWidth(unsigned width)
 {
     m_size.setWidth(clampTo<int>(width));
 }
 
 void OffscreenCanvas::setHeight(unsigned height)
 {
     m_size.setHeight(clampTo<int>(height));
 }
 
 OffscreenCanvas::OffscreenCanvas(const IntSize& size)
     : m_size(size)
 {
 }
 
+OffscreenCanvasRenderingContext* OffscreenCanvas::getContext(const String& id, const CanvasContextCreationAttributes& attributes)
+{
+    OffscreenCanvasRenderingContext::ContextType contextType = OffscreenCanvasRenderingContext::contextTypeFromId(id);
+
+    // Unknown type.
+    if (contextType == OffscreenCanvasRenderingContext::ContextTypeCount)
+        return nullptr;
+
+    OffscreenCanvasRenderingContextFactory* factory = getRenderingContextFactory(contextType);
+    if (!factory)
+        return nullptr;

[Justin Novosad, 2016/03/02 15:41:50]

This is correct, but it needs to be tested in a layout test. Should check that
getContext does not throw and returns null.  I know the spec is not written yet,
but let's base ourselved on the canvas element spec for this, for now.

[xlai (Olivia), 2016/03/03 22:50:06]

Done for here and elsewhere.

+
+    if (m_context) {
+        if (m_context->contextType() == contextType)
+            return m_context.get();

[Justin Novosad, 2016/03/02 15:41:50]

This case needs to be covered in a layout test.

+
+        factory->onError(this, "OffscreenCanvas has an existing context of a different type");
+        return nullptr;

[Justin Novosad, 2016/03/02 15:41:50]

This case need to be covered in a layout test.

+    }
+
+    m_context = factory->create(this, attributes);
+    if (!m_context)
+        return nullptr;

[Justin Novosad, 2016/03/02 15:41:50]

This is not necessary. The return statement below is already going to return
null if m_context is null.

+
+    return m_context.get();
+}
+
+OffscreenCanvas::ContextFactoryVector& OffscreenCanvas::renderingContextFactories()
+{
+    DEFINE_STATIC_LOCAL(ContextFactoryVector, s_contextFactories, (OffscreenCanvasRenderingContext::ContextTypeCount));
+    return s_contextFactories;
+}
+
+OffscreenCanvasRenderingContextFactory* OffscreenCanvas::getRenderingContextFactory(int type)
+{
+    ASSERT(type < OffscreenCanvasRenderingContext::ContextTypeCount);
+    return renderingContextFactories()[type].get();
+}
+
+void OffscreenCanvas::registerRenderingContextFactory(PassOwnPtr<OffscreenCanvasRenderingContextFactory> renderingContextFactory)
+{
+    OffscreenCanvasRenderingContext::ContextType type = renderingContextFactory->contextType();
+    ASSERT(type < OffscreenCanvasRenderingContext::ContextTypeCount);
+    ASSERT(!renderingContextFactories()[type]);
+    renderingContextFactories()[type] = renderingContextFactory;
+}
+
 DEFINE_TRACE(OffscreenCanvas)
 {
+    visitor->trace(m_context);
 }
 
 } // namespace blink