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Move parts to libraries (flutter#26054)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,98 @@ | ||
| // Copyright 2013 The Flutter Authors. All rights reserved. | ||
| // Use of this source code is governed by a BSD-style license that can be | ||
| // found in the LICENSE file. | ||
|
|
||
| import 'dart:async'; | ||
| import 'dart:html' as html; | ||
| import 'dart:js_util' as js_util; | ||
| import 'package:ui/src/engine.dart'; | ||
|
|
||
| /// Polyfill for html.OffscreenCanvas that is not supported on some browsers. | ||
| class OffScreenCanvas { | ||
| html.OffscreenCanvas? offScreenCanvas; | ||
| html.CanvasElement? canvasElement; | ||
| int width; | ||
| int height; | ||
| static bool? _supported; | ||
|
|
||
| OffScreenCanvas(this.width, this.height) { | ||
| if (OffScreenCanvas.supported) { | ||
| offScreenCanvas = html.OffscreenCanvas(width, height); | ||
| } else { | ||
| canvasElement = html.CanvasElement( | ||
| width: width, | ||
| height: height, | ||
| ); | ||
| canvasElement!.className = 'gl-canvas'; | ||
| final double cssWidth = width / EnginePlatformDispatcher.browserDevicePixelRatio; | ||
| final double cssHeight = height / EnginePlatformDispatcher.browserDevicePixelRatio; | ||
| canvasElement!.style | ||
| ..position = 'absolute' | ||
| ..width = '${cssWidth}px' | ||
| ..height = '${cssHeight}px'; | ||
| } | ||
| } | ||
|
|
||
| void dispose() { | ||
| offScreenCanvas = null; | ||
| canvasElement = null; | ||
| } | ||
|
|
||
| /// Returns CanvasRenderContext2D or OffscreenCanvasRenderingContext2D to | ||
| /// paint into. | ||
| Object? getContext2d() { | ||
| return (offScreenCanvas != null | ||
| ? offScreenCanvas!.getContext('2d') | ||
| : canvasElement!.getContext('2d')); | ||
| } | ||
|
|
||
| /// Feature detection for transferToImageBitmap on OffscreenCanvas. | ||
| bool get transferToImageBitmapSupported => | ||
| js_util.hasProperty(offScreenCanvas!, 'transferToImageBitmap'); | ||
|
|
||
| /// Creates an ImageBitmap object from the most recently rendered image | ||
| /// of the OffscreenCanvas. | ||
| /// | ||
| /// !Warning API still in experimental status, feature detect before using. | ||
| Object? transferToImageBitmap() { | ||
| return js_util.callMethod(offScreenCanvas!, 'transferToImageBitmap', | ||
| <dynamic>[]); | ||
| } | ||
|
|
||
| /// Draws canvas contents to a rendering context. | ||
| void transferImage(Object targetContext) { | ||
| // Actual size of canvas may be larger than viewport size. Use | ||
| // source/destination to draw part of the image data. | ||
| js_util.callMethod(targetContext, 'drawImage', | ||
| <dynamic>[offScreenCanvas ?? canvasElement!, 0, 0, width, height, | ||
| 0, 0, width, height]); | ||
| } | ||
|
|
||
| /// Converts canvas contents to an image and returns as data url. | ||
| Future<String> toDataUrl() { | ||
| final Completer<String> completer = Completer<String>(); | ||
| if (offScreenCanvas != null) { | ||
| offScreenCanvas!.convertToBlob().then((html.Blob value) { | ||
| final fileReader = html.FileReader(); | ||
| fileReader.onLoad.listen((event) { | ||
| completer.complete(js_util.getProperty( | ||
| js_util.getProperty(event, 'target')!, 'result')!); | ||
| }); | ||
| fileReader.readAsDataUrl(value); | ||
| }); | ||
| return completer.future; | ||
| } else { | ||
| return Future.value(canvasElement!.toDataUrl()); | ||
| } | ||
| } | ||
|
|
||
| /// Draws an image to canvas for both offscreen canvas canvas context2d. | ||
| void drawImage(Object image, int x, int y, int width, int height) { | ||
| js_util.callMethod( | ||
| getContext2d()!, 'drawImage', <dynamic>[image, x, y, width, height]); | ||
| } | ||
|
|
||
| /// Feature detects OffscreenCanvas. | ||
| static bool get supported => _supported ??= | ||
| js_util.hasProperty(html.window, 'OffscreenCanvas'); | ||
| } |
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