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December 8, 2021 22:42
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frame decode order skia vs webcodecs
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title>SkImage.readPixels</title> | |
| </head> | |
| <body> | |
| <canvas id=foo width=300 height=300></canvas> | |
| <script type="text/javascript" | |
| src="https://unpkg.com/[email protected]/bin/canvaskit.js"></script> | |
| <script type="text/javascript"> | |
| async function run() { | |
| /// An animated GIF image with 3 1x1 pixel frames (a red, green, and blue | |
| /// frames). The GIF animates forever, and each frame has a 100ms delay. | |
| let kAnimatedGif = Uint8Array.from([ | |
| 0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x01, 0x00, 0x01, 0x00, 0xa1, 0x03, 0x00, | |
| 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0xff, 0x00, 0xff, 0xff, 0xff, 0x21, | |
| 0xff, 0x0b, 0x4e, 0x45, 0x54, 0x53, 0x43, 0x41, 0x50, 0x45, 0x32, 0x2e, 0x30, | |
| 0x03, 0x01, 0x00, 0x00, 0x00, 0x21, 0xf9, 0x04, 0x00, 0x0a, 0x00, 0xff, 0x00, | |
| 0x2c, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x02, 0x02, 0x4c, | |
| 0x01, 0x00, 0x21, 0xf9, 0x04, 0x00, 0x0a, 0x00, 0xff, 0x00, 0x2c, 0x00, 0x00, | |
| 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x02, 0x02, 0x54, 0x01, 0x00, 0x21, | |
| 0xf9, 0x04, 0x00, 0x0a, 0x00, 0xff, 0x00, 0x2c, 0x00, 0x00, 0x00, 0x00, 0x01, | |
| 0x00, 0x01, 0x00, 0x00, 0x02, 0x02, 0x44, 0x01, 0x00, 0x3b, | |
| ]); | |
| let decoder = new ImageDecoder({ | |
| type: 'image/gif', | |
| data: kAnimatedGif.buffer, | |
| premultiplyAlpha: 'premultiply', | |
| colorSpaceConversion: 'default', | |
| preferAnimation: true | |
| }); | |
| await decoder.tracks.ready; | |
| await decoder.completed; | |
| console.log('WebCodecs:'); | |
| for (let i = 0; i < decoder.tracks.selectedTrack.frameCount; i++) { | |
| let decodeResult = await decoder.decode({frameIndex: i}); | |
| let videoFrame = decodeResult.image; | |
| let destination = new Uint8Array(videoFrame.allocationSize()); | |
| await videoFrame.copyTo(destination); | |
| console.log(`${videoFrame.format}: ${destination}`); | |
| } | |
| console.log('CanvasKit:'); | |
| const ckLoaded = CanvasKitInit({locateFile: (file) => 'https://unpkg.com/[email protected]/bin/'+file}); | |
| ckLoaded.then((CanvasKit) => { | |
| let animatedImage = CanvasKit.MakeAnimatedImageFromEncoded(kAnimatedGif); | |
| let frameCount = animatedImage.getFrameCount(); | |
| for (let i = 0; i < frameCount; i++) { | |
| animatedImage.decodeNextFrame(); | |
| let image = animatedImage.makeImageAtCurrentFrame(); | |
| let imageInfo = { | |
| alphaType: CanvasKit.AlphaType.Premul, | |
| colorType: CanvasKit.ColorType.RGBA_8888, | |
| colorSpace: CanvasKit.ColorSpace.SRGB, | |
| width: image.width(), | |
| height: image.height() | |
| }; | |
| console.log(`RGBA: ${image.readPixels(0, 0, imageInfo)}`); | |
| } | |
| }); | |
| } | |
| run(); | |
| </script> | |
| </body> | |
| </html> |
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