| // 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/canvas/HTMLCanvasElementModule.h" |
| |
| #include "core/dom/DOMNodeIds.h" |
| #include "core/html/canvas/CanvasContextCreationAttributes.h" |
| #include "core/html/canvas/CanvasRenderingContext.h" |
| #include "core/offscreencanvas/OffscreenCanvas.h" |
| |
| namespace blink { |
| |
| void HTMLCanvasElementModule::getContext( |
| HTMLCanvasElement& canvas, |
| const String& type, |
| const CanvasContextCreationAttributes& attributes, |
| ExceptionState& exceptionState, |
| RenderingContext& result) { |
| if (canvas.surfaceLayerBridge()) { |
| // The existence of canvas surfaceLayerBridge indicates that |
| // HTMLCanvasElement.transferControlToOffscreen() has been called. |
| exceptionState.throwDOMException(InvalidStateError, |
| "Cannot get context from a canvas that " |
| "has transferred its control to " |
| "offscreen."); |
| return; |
| } |
| |
| CanvasRenderingContext* context = |
| canvas.getCanvasRenderingContext(type, attributes); |
| if (context) { |
| context->setCanvasGetContextResult(result); |
| } |
| } |
| |
| OffscreenCanvas* HTMLCanvasElementModule::transferControlToOffscreen( |
| HTMLCanvasElement& canvas, |
| ExceptionState& exceptionState) { |
| if (canvas.surfaceLayerBridge()) { |
| exceptionState.throwDOMException( |
| InvalidStateError, |
| "Cannot transfer control from a canvas for more than one time."); |
| return nullptr; |
| } |
| |
| canvas.createLayer(); |
| |
| return transferControlToOffscreenInternal(canvas, exceptionState); |
| } |
| |
| OffscreenCanvas* HTMLCanvasElementModule::transferControlToOffscreenInternal( |
| HTMLCanvasElement& canvas, |
| ExceptionState& exceptionState) { |
| if (canvas.renderingContext()) { |
| exceptionState.throwDOMException( |
| InvalidStateError, |
| "Cannot transfer control from a canvas that has a rendering context."); |
| return nullptr; |
| } |
| OffscreenCanvas* offscreenCanvas = |
| OffscreenCanvas::create(canvas.width(), canvas.height()); |
| |
| int canvasId = DOMNodeIds::idForNode(&canvas); |
| offscreenCanvas->setPlaceholderCanvasId(canvasId); |
| canvas.registerPlaceholder(canvasId); |
| |
| CanvasSurfaceLayerBridge* bridge = canvas.surfaceLayerBridge(); |
| if (bridge) { |
| offscreenCanvas->setFrameSinkId(bridge->getFrameSinkId().client_id(), |
| bridge->getFrameSinkId().sink_id()); |
| } |
| return offscreenCanvas; |
| } |
| } |