Hook up CSSPaintValue::image to CSS Paint API callback.

third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp

 // Copyright 2016 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 "modules/csspaint/CSSPaintDefinition.h"
 
 #include "bindings/core/v8/ScriptState.h"
+#include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8BindingMacros.h"
+#include "bindings/core/v8/V8ObjectConstructor.h"
+#include "core/dom/ExecutionContext.h"
+#include "core/frame/ConsoleTypes.h"
+#include "core/inspector/ConsoleMessage.h"
+#include "modules/csspaint/Geometry.h"
+#include "modules/csspaint/PaintRenderingContext2D.h"
+#include "platform/ScriptForbiddenScope.h"
+#include "platform/graphics/ImageBuffer.h"
+#include "platform/graphics/PaintGeneratedImage.h"
+#include "platform/graphics/RecordingImageBufferSurface.h"
+#include "platform/graphics/UnacceleratedImageBufferSurface.h"
 
 namespace blink {
 
+namespace {
+
+// TODO(ikilpatrick): Modify RecordingImageBufferSurface so that it cannot
+// fallback to a UnacceleratedImageBufferSurface.
+class UnacceleratedSurfaceFactory : public RecordingImageBufferFallbackSurfaceFactory {
+public:
+    virtual PassOwnPtr<ImageBufferSurface> createSurface(const IntSize& size, OpacityMode opacityMode)
+    {
+        return adoptPtr(new UnacceleratedImageBufferSurface(size, opacityMode));
+    }
+
+    virtual ~UnacceleratedSurfaceFactory() { }
+};
+
+} // namespace
+
 CSSPaintDefinition* CSSPaintDefinition::create(ScriptState* scriptState, v8::Local<v8::Function> constructor, v8::Local<v8::Function> paint)
 {
     return new CSSPaintDefinition(scriptState, constructor, paint);
 }
 
 CSSPaintDefinition::CSSPaintDefinition(ScriptState* scriptState, v8::Local<v8::Function> constructor, v8::Local<v8::Function> paint)
     : m_scriptState(scriptState)
     , m_constructor(scriptState->isolate(), constructor)
     , m_paint(scriptState->isolate(), paint)
 {
 }
 
 CSSPaintDefinition::~CSSPaintDefinition()
 {
 }
 
+PassRefPtr<Image> CSSPaintDefinition::paint(const IntSize& size)
+{
+    ScriptState::Scope scope(m_scriptState.get());
+
+    maybeCreatePaintInstance();
+
+    v8::Isolate* isolate = m_scriptState->isolate();
+    v8::Local<v8::Object> instance = m_instance.newLocal(isolate);
+
+    // We may have failed to create an instance class, in which case produce an
+    // invalid image.
+    if (isUndefinedOrNull(instance))
+        return nullptr;
+
+    PaintRenderingContext2D* renderingContext = PaintRenderingContext2D::create(
+        ImageBuffer::create(adoptPtr(new RecordingImageBufferSurface(size, adoptPtr(new UnacceleratedSurfaceFactory())))));
+    Geometry* geometry = Geometry::create(size);
+
+    v8::Local<v8::Value> argv[] = {
+        toV8(renderingContext, m_scriptState->context()->Global(), isolate),
+        toV8(geometry, m_scriptState->context()->Global(), isolate)
+    };
+
+    v8::Local<v8::Function> paint = m_paint.newLocal(isolate);
+
+    v8::TryCatch block(isolate);
+    V8ScriptRunner::callFunction(paint, m_scriptState->getExecutionContext(), instance, 2, argv, isolate);
+
+    // The paint function may have produced an error, in which case produce an
+    // invalid image.
+    if (block.HasCaught()) {
+        return nullptr;
+    }
+
+    return PaintGeneratedImage::create(renderingContext->imageBuffer()->getPicture(), size);
+}
+
+void CSSPaintDefinition::maybeCreatePaintInstance()
+{
+    DCHECK(!m_invalidConstructor || !m_instance.isEmpty());
+
+    if (m_invalidConstructor)

[haraken, 2016/04/12 00:44:20]

I'd replace m_invalidConstructor with m_didCallConstructor, which just checks if
the constructor has been called or not.

Just to confirm: You don't need to call the constructor multiple times, right?
i.e., what happens if a user script updates the constructor function after
instantiating the CSSPaintDefinition object?

[ikilpatrick, 2016/04/12 03:08:09]

Yup we just call the constructor once. In the spec we'll explicitly say that we
grab the constructor function before using it. This is similar to the
web-components model of grabbing all the callbacks upon registration.

See: https://github.com/w3c/webcomponents/issues/417

Changed to m_didCallConstructor.

+        return;
+
+    if (!m_instance.isEmpty())
+        return;
+
+    v8::Isolate* isolate = m_scriptState->isolate();
+    v8::Local<v8::Function> constructor = m_constructor.newLocal(isolate);
+    DCHECK(!isUndefinedOrNull(constructor));
+
+    v8::Local<v8::Object> paintInstance;
+    if (!V8ObjectConstructor::newInstance(isolate, constructor).ToLocal(&paintInstance)) {
+        m_invalidConstructor = true;
+    } else {
+        m_instance.set(isolate, paintInstance);
+    }
+}
+
 } // namespace blink