Imageresizing using a canvas
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a91230f614
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@ -4,13 +4,14 @@ export const resize = (imageUrl: string, maxSize: number) => {
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img.onload = () => {
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img.onload = () => {
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const currentMaxSize = Math.max(img.width, img.height);
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const currentMaxSize = Math.max(img.width, img.height);
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const ratio = currentMaxSize / maxSize;
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const ratio = currentMaxSize / maxSize;
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const targetWidth = img.width / ratio;
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const targetHeight = img.height / ratio;
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const nbStepsReal = Math.log2(ratio);
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const nbStepsReal = Math.log2(ratio);
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const nbSteps = Math.floor(nbStepsReal);
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const nbSteps = Math.floor(nbStepsReal);
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const reminder = maxSize - currentMaxSize / 2 ** nbSteps;
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const canvas = document.createElement('canvas');
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const canvas = document.createElement('canvas');
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canvas.width = img.width / 2;
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canvas.width = img.width;
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canvas.height = img.height / 2;
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canvas.height = img.height;
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const canvasCtx = canvas.getContext('2d');
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const canvasCtx = canvas.getContext('2d');
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let src: any = img;
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let src: any = img;
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@ -19,27 +20,39 @@ export const resize = (imageUrl: string, maxSize: number) => {
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for (let i = 0; i < nbSteps; i++) {
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for (let i = 0; i < nbSteps; i++) {
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width = width / 2;
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width = width / 2;
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height = height / 2;
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height = height / 2;
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canvasCtx?.drawImage(src, 0, 0, width, height);
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canvasCtx?.drawImage(src, 0, 0, canvas.width / 2, canvas.height / 2);
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src = canvas;
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src = canvas;
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console.log({
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caller: 'resize',
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width,
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height,
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targetHeight,
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targetWidth,
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i,
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});
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}
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}
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const finalCanvas = document.createElement('canvas');
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const finalCanvas = document.createElement('canvas');
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finalCanvas.height = height;
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finalCanvas.height = targetHeight;
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finalCanvas.width = width;
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finalCanvas.width = targetWidth;
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const finalCanvasCtx = finalCanvas.getContext('2d');
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const finalCanvasCtx = finalCanvas.getContext('2d');
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finalCanvasCtx?.drawImage(
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finalCanvasCtx?.drawImage(
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canvas,
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canvas,
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0,
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0,
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0,
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0,
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width * 4,
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height * 4,
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0,
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0,
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width,
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width,
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height
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height,
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0,
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0,
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targetWidth,
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targetHeight
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);
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);
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resolver(finalCanvas.toDataURL('image/jpeg'));
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const imageUrl = finalCanvas.toDataURL('image/jpeg');
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canvas.remove();
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finalCanvas.remove();
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resolver(imageUrl);
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};
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};
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img.src = imageUrl;
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img.src = imageUrl;
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return new Promise((resolve, reject) => {
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return new Promise((resolve, reject) => {
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