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Commit f352608a authored by Miguel Casas's avatar Miguel Casas Committed by Commit Bot
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Canvas LowLatency: make getContext() idempotent 

Canvas.getContext() method is idempotent, i.e. successive calls return
the same context over and over. When the context is lowLatency, however,
we think it's an OffscreenCanvas context and fail. This CL fixes
that and adds a LayoutTest to verify the new functionality.

Bug: 895551
Change-Id: I1ae140080915a277eb45ac01486e6c7c1464aefa
Reviewed-on: https://chromium-review.googlesource.com/c/1294090Reviewed-by: default avatarFernando Serboncini <fserb@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601652}
parent 916d7bb2
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Showing with 35 additions and 3 deletions
third_party/WebKit/LayoutTests/fast/canvas-api/canvas-lowlatency-getContext.html 0 → 100644
View file @ f352608a
<!DOCTYPE html>
<title>Tests that lowLatency Canvas getContext() calls are idempotent.</title>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script>
test(function() {
canvas = document.createElement('canvas');
var ctx_2d = canvas.getContext('2d', {lowLatency : true});
assert_true(ctx_2d instanceof CanvasRenderingContext2D);
// TODO(mcasas): Check ctx_2d.getContextAttributes().lowLatency after
// https://github.com/whatwg/html/issues/2563.
var ctx_2d_second = canvas.getContext('2d', {lowLatency : true});
assert_equals(ctx_2d, ctx_2d_second);
var ctx_2d_third = canvas.getContext('2d');
assert_equals(ctx_2d, ctx_2d_third);
}, '2D Canvas getContext() is idempotent');
test(function() {
canvas = document.createElement('canvas');
var ctx_3d = canvas.getContext('webgl', {lowLatency : true});
assert_true(ctx_3d instanceof WebGLRenderingContext);
// TODO(mcasas): Check ctx_3d.getContextAttributes().lowLatency after
// https://github.com/whatwg/html/issues/4087.
var ctx_3d_second = canvas.getContext('webgl', {lowLatency : true});
assert_equals(ctx_3d, ctx_3d_second);
var ctx_3d_third = canvas.getContext('webgl');
assert_equals(ctx_3d, ctx_3d_third);
}, 'WebGL Canvas getContext() is idempotent');
</script>
third_party/blink/renderer/modules/canvas/htmlcanvas/html_canvas_element_module.cc
View file @ f352608a
......@@ -19,7 +19,7 @@ void HTMLCanvasElementModule::getContext(
const CanvasContextCreationAttributesModule& attributes,
ExceptionState& exception_state,
RenderingContext& result) {
if (canvas.SurfaceLayerBridge()) {
if (canvas.SurfaceLayerBridge() && !canvas.LowLatencyEnabled()) {
// The existence of canvas surfaceLayerBridge indicates that
// HTMLCanvasElement.transferControlToOffscreen() has been called.
exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
......@@ -31,9 +31,8 @@ void HTMLCanvasElementModule::getContext(
CanvasRenderingContext* context = canvas.GetCanvasRenderingContext(
type, ToCanvasContextCreationAttributes(attributes));
if (context) {
if (context)
context->SetCanvasGetContextResult(result);
}
}
OffscreenCanvas* HTMLCanvasElementModule::transferControlToOffscreen(
......
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