Upscaling demo
Change-Id: I22f26ff2a618f95f6f4f9ab0962a3fede509f1e6 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/379837 Auto-Submit: Mike Reed <reed@google.com> Reviewed-by: Mike Reed <reed@google.com> Commit-Queue: Mike Reed <reed@google.com>
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demos.skia.org/demos/up_scaling/index.html
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174
demos.skia.org/demos/up_scaling/index.html
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<!doctype HTML>
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<!DOCTYPE html>
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<title>Custom Image Upscaling</title>
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<meta charset="utf-8" />
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<meta http-equiv="X-UA-Compatible" content="IE=edge">
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<script type="text/javascript" src="https://unpkg.com/canvaskit-wasm@0.25.0/bin/full/canvaskit.js"></script>
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<style>
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canvas {
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border: 1px dashed grey;
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}
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</style>
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<body>
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<h1>Custom Image Upscaling</h1>
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<div id=scale_text></div>
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<div class="slidecontainer">
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<input type="range" min="100" max="500" value="100" class="slider" id="scale_slider">
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<input type="range" min="0" max="900" value="0" class="slider" id="sharpen">
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</div>
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<canvas id=draw width=1000 height=400></canvas>
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</body>
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<script type="text/javascript" charset="utf-8">
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let CanvasKit;
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onload = async () => {
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CanvasKit = await CanvasKitInit({ locateFile: (file) => "https://unpkg.com/canvaskit-wasm@0.25.0/bin/full/" + file });
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init();
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};
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function init() {
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if (!CanvasKit.RuntimeEffect) {
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console.log(CanvasKit.RuntimeEffect);
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throw "Need RuntimeEffect";
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}
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const surface = CanvasKit.MakeCanvasSurface('draw');
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if (!surface) {
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throw 'Could not make surface';
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}
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const prog = `
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uniform shader image;
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uniform float sharp; // slope of the lerp section of the kernel (steeper == sharper)
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float2 sharpen(float2 w) {
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return saturate(sharp * (w - 0.5) + 0.5);
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}
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bool nearly_center(float2 p) {
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float tolerance = 0.01; // not sure what to use here
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p = abs(fract(p) - 0.5);
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return p.x < tolerance && p.y < tolerance;
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}
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half4 main(float2 p) {
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float h = 0.5;
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if (nearly_center(p)) {
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return sample(image, p);
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} else {
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half4 pa = sample(image, float2(p.x-0.5, p.y-0.5));
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half4 pb = sample(image, float2(p.x+0.5, p.y-0.5));
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half4 pc = sample(image, float2(p.x-0.5, p.y+0.5));
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half4 pd = sample(image, float2(p.x+0.5, p.y+0.5));
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float2 w = sharpen(fract(p + 0.5));
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return mix(mix(pa, pb, w.x), mix(pc, pd, w.x), w.y);
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}
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}
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`;
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const effect = CanvasKit.RuntimeEffect.Make(prog);
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const size = 100;
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const shader_paint = new CanvasKit.Paint();
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const color_paint = new CanvasKit.Paint();
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const image = function() {
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let surf = CanvasKit.MakeSurface(size, size);
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let c = surf.getCanvas();
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color_paint.setColor([1, 1, 1, 1]);
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c.drawRect([0, 0, size, size], color_paint);
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color_paint.setColor([0, 0, 0, 1]);
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for (let x = 0; x < size; x += 2) {
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c.drawRect([x, 0, x+1, size], color_paint);
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}
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return surf.makeImageSnapshot();
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}();
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const imageShader = image.makeShaderOptions(CanvasKit.TileMode.Clamp,
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CanvasKit.TileMode.Clamp,
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CanvasKit.FilterMode.Nearest,
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CanvasKit.MipmapMode.None);
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sharpen.oninput = () => { surface.requestAnimationFrame(drawFrame); }
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scale_slider.oninput = () => { surface.requestAnimationFrame(drawFrame); }
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const fract = function(value) {
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return value - Math.floor(value);
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}
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drawFrame = function(canvas) {
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const scale = scale_slider.value / 100.0;
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scale_text.innerText = scale
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canvas.clear();
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// Draw the prog version.
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canvas.save();
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canvas.scale(scale, 1.0);
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shader_paint.setShader(effect.makeShaderWithChildren([scale], true, [imageShader], null));
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canvas.drawRect([0, 0, size, 100], shader_paint);
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canvas.restore();
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// magify
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drawMagnified(canvas, 0, 100);
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// Draw the two-pass version
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let intScale = Math.max(1, Math.floor(scale + 0.5));
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let intImage = imageAtScale(intScale);
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canvas.save();
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canvas.scale(scale / intScale, 1);
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canvas.drawImageOptions(intImage, 0, 200, CanvasKit.FilterMode.Linear, CanvasKit.MipmapMode.None, null);
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canvas.restore();
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// magnify
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drawMagnified(canvas, 200, 300);
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}
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function drawMagnified(canvas, sampleY, dstY) {
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let pixels = canvas.readPixels(
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0, sampleY,
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{ width: 50,
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height: 1,
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colorType: CanvasKit.ColorType.RGBA_8888,
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alphaType: CanvasKit.AlphaType.Premul,
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colorSpace: CanvasKit.ColorSpace.DISPLAY_P3
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}
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);
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for (let i = 0; i < 50; i++) {
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let color =
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[ pixels[i*4 + 0] / 255.0,
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pixels[i*4 + 1] / 255.0,
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pixels[i*4 + 2] / 255.0,
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pixels[i*4 + 3] / 255.0 ];
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color_paint.setColor(color);
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canvas.drawRect([i*20, dstY, (i+1)*20, dstY + 100], color_paint);
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}
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}
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function imageAtScale(s) {
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let surf = CanvasKit.MakeSurface(s * size, size);
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let c = surf.getCanvas();
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color_paint.setColor([1, 1, 1, 1]);
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c.drawRect([0, 0, s * size, size], color_paint);
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color_paint.setColor([0, 0, 0, 1]);
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for (let x = 0; x < size; x += 2) {
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c.drawRect([x * s, 0, (x+1) * s, size], color_paint);
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}
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return surf.makeImageSnapshot();
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}
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surface.requestAnimationFrame(drawFrame);
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}
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</script>
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