1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
// 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;
}
}
|
