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// 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 "third_party/blink/renderer/modules/canvas/htmlcanvas/html_canvas_element_module.h"
#include "third_party/blink/renderer/core/dom/dom_node_ids.h"
#include "third_party/blink/renderer/core/frame/local_frame.h"
#include "third_party/blink/renderer/core/html/canvas/canvas_rendering_context.h"
#include "third_party/blink/renderer/core/offscreencanvas/offscreen_canvas.h"
#include "third_party/blink/renderer/modules/canvas/htmlcanvas/canvas_context_creation_attributes_helpers.h"
#include "third_party/blink/renderer/modules/canvas/htmlcanvas/canvas_context_creation_attributes_module.h"
#include "third_party/blink/renderer/platform/instrumentation/histogram.h"
namespace blink {
void HTMLCanvasElementModule::getContext(
HTMLCanvasElement& canvas,
const String& type,
const CanvasContextCreationAttributesModule* attributes,
ExceptionState& exception_state,
RenderingContext& result) {
if (canvas.SurfaceLayerBridge() && !canvas.LowLatencyEnabled()) {
// The existence of canvas surfaceLayerBridge indicates that
// HTMLCanvasElement.transferControlToOffscreen() has been called.
exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
"Cannot get context from a canvas that "
"has transferred its control to "
"offscreen.");
return;
}
CanvasRenderingContext* context = canvas.GetCanvasRenderingContext(
type, ToCanvasContextCreationAttributes(attributes));
if (context)
context->SetCanvasGetContextResult(result);
}
OffscreenCanvas* HTMLCanvasElementModule::transferControlToOffscreen(
ExecutionContext* execution_context,
HTMLCanvasElement& canvas,
ExceptionState& exception_state) {
OffscreenCanvas* offscreen_canvas = nullptr;
if (canvas.SurfaceLayerBridge()) {
exception_state.ThrowDOMException(
DOMExceptionCode::kInvalidStateError,
"Cannot transfer control from a canvas for more than one time.");
} else {
canvas.CreateLayer();
offscreen_canvas = TransferControlToOffscreenInternal(
execution_context, canvas, exception_state);
}
UMA_HISTOGRAM_BOOLEAN("Blink.OffscreenCanvas.TransferControlToOffscreen",
bool(offscreen_canvas));
return offscreen_canvas;
}
OffscreenCanvas* HTMLCanvasElementModule::TransferControlToOffscreenInternal(
ExecutionContext* execution_context,
HTMLCanvasElement& canvas,
ExceptionState& exception_state) {
if (canvas.RenderingContext()) {
exception_state.ThrowDOMException(
DOMExceptionCode::kInvalidStateError,
"Cannot transfer control from a canvas that has a rendering context.");
return nullptr;
}
OffscreenCanvas* offscreen_canvas = OffscreenCanvas::Create(
execution_context, canvas.width(), canvas.height());
offscreen_canvas->SetFilterQuality(canvas.FilterQuality());
// If this canvas is cross-origin, then the associated offscreen canvas
// should prefer using the low-power GPU.
LocalFrame* frame = canvas.GetDocument().GetFrame();
if (!(frame && frame->IsCrossOriginSubframe()))
offscreen_canvas->AllowHighPerformancePowerPreference();
DOMNodeId canvas_id = DOMNodeIds::IdForNode(&canvas);
offscreen_canvas->SetPlaceholderCanvasId(canvas_id);
canvas.RegisterPlaceholderCanvas(static_cast<int>(canvas_id));
SurfaceLayerBridge* bridge = canvas.SurfaceLayerBridge();
if (bridge) {
offscreen_canvas->SetFrameSinkId(bridge->GetFrameSinkId().client_id(),
bridge->GetFrameSinkId().sink_id());
}
return offscreen_canvas;
}
} // namespace blink
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