c06355c93e
Change-Id: Icecf6ab02846046af0baff2d49f3388a436370fb Reviewed-on: https://skia-review.googlesource.com/c/skia/+/276001 Reviewed-by: Nathaniel Nifong <nifong@google.com>
529 lines
16 KiB
Markdown
529 lines
16 KiB
Markdown
CanvasKit - Skia + WebAssembly
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==============================
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Skia now offers a WebAssembly build for easy deployment of our graphics APIs on
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the web.
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CanvasKit provides a playground for testing new Canvas and SVG platform APIs,
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enabling fast-paced development on the web platform.
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It can also be used as a deployment mechanism for custom web apps requiring
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cutting-edge features, like Skia's [Lottie
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animation](https://skia.org/user/modules/skottie) support.
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Features
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--------
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- WebGL context encapsulated as an SkSurface, allowing for direct drawing to
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an HTML canvas
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- Core set of Skia canvas/paint/path/text APIs available, see bindings
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- Draws to a hardware-accelerated backend
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- Security tested with Skia's fuzzers
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Samples
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-------
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<style>
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#demo canvas {
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border: 1px dashed #AAA;
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margin: 2px;
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}
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#patheffect, #ink, #shaping {
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width: 400px;
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height: 400px;
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}
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#sk_legos, #sk_drinks, #sk_party, #sk_onboarding, #shader1 {
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width: 300px;
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height: 300px;
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}
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figure {
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display: inline-block;
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margin: 0;
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}
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figcaption > a {
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margin: 2px 10px;
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}
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</style>
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<div id=demo>
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<h3>Go beyond the HTML Canvas2D</h3>
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<figure>
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<canvas id=patheffect width=400 height=400></canvas>
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<figcaption>
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<a href="https://jsfiddle.skia.org/canvaskit/43b38b83ca77dabe47f18f31cafe83f3018b3a24e569db27fe711c70bc3f7d62"
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target=_blank rel=noopener>
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Star JSFiddle</a>
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</figcaption>
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</figure>
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<figure>
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<canvas id=ink width=400 height=400></canvas>
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<figcaption>
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<a href="https://jsfiddle.skia.org/canvaskit/43475699d6d7d3d7dad1004c29f84015752a6a6dee2bb90f2e891b53e31d45cc"
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target=_blank rel=noopener>
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Ink JSFiddle</a>
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</figcaption>
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</figure>
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<h3>Skottie (click for fiddles)</h3>
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<a href="https://jsfiddle.skia.org/canvaskit/092690b273b41076d2f00f0d43d004893d6bb9992c387c0385efa8e6f6bc83d7"
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target=_blank rel=noopener>
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<canvas id=sk_legos width=300 height=300></canvas>
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</a>
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<a href="https://jsfiddle.skia.org/canvaskit/e7ac983d9859f89aff1b6d385190919202c2eb53d028a79992892cacceffd209"
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target=_blank rel=noopener>
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<canvas id=sk_drinks width=500 height=500></canvas>
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</a>
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<a href="https://jsfiddle.skia.org/canvaskit/0e06547181759731e7369d3e3613222a0826692f48c41b16504ed68d671583e1"
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target=_blank rel=noopener>
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<canvas id=sk_party width=500 height=500></canvas>
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</a>
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<a href="https://jsfiddle.skia.org/canvaskit/be3fc1c5c351e7f43cc2840033f80b44feb3475925264808f321bb9e2a21174a"
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target=_blank rel=noopener>
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<canvas id=sk_onboarding width=500 height=500></canvas>
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</a>
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<h3>SkParagraph (using ICU and Harfbuzz)</h3>
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<figure>
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<canvas id=shaping width=500 height=500></canvas>
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<figcaption>
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<a href="https://jsfiddle.skia.org/canvaskit/56cb197c724dfdfad0c3d8133d4fcab587e4c4e7f31576e62c17251637d3745c"
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target=_blank rel=noopener>
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SkParagraph JSFiddle</a>
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</figcaption>
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</figure>
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<h3>SKSL for writing custom shaders</h3>
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<a href="https://jsfiddle.skia.org/canvaskit/33ff9bed883cd5742b4770169da0b36fb0cbc18fd395ddd9563213e178362d30"
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target=_blank rel=noopener>
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<canvas id=shader1 width=512 height=512></canvas>
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</a>
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</div>
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<script type="text/javascript" charset="utf-8">
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(function() {
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// Tries to load the WASM version if supported, shows error otherwise
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let s = document.createElement('script');
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let locate_file = '';
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// Hey, if you are looking at this code for an example of how to do it yourself, please use
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// an actual CDN, such as https://unpkg.com/canvaskit-wasm - it will have better reliability
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// and niceties like brotli compression.
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if (window.WebAssembly && typeof window.WebAssembly.compile === 'function') {
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console.log('WebAssembly is supported!');
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locate_file = 'https://particles.skia.org/static/';
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} else {
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console.log('WebAssembly is not supported (yet) on this browser.');
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document.getElementById('demo').innerHTML = "<div>WASM not supported by your browser. Try a recent version of Chrome, Firefox, Edge, or Safari.</div>";
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return;
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}
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s.src = locate_file + 'canvaskit.js';
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s.onload = () => {
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let CanvasKit = null;
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let legoJSON = null;
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let drinksJSON = null;
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let confettiJSON = null;
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let onboardingJSON = null;
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let fullBounds = {fLeft: 0, fTop: 0, fRight: 500, fBottom: 500};
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CanvasKitInit({
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locateFile: (file) => locate_file + file,
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}).ready().then((CK) => {
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CanvasKit = CK;
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DrawingExample(CanvasKit);
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InkExample(CanvasKit);
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ShapingExample(CanvasKit);
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// Set bounds to fix the 4:3 resolution of the legos
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SkottieExample(CanvasKit, 'sk_legos', legoJSON, {fLeft: -50, fTop: 0, fRight: 350, fBottom: 300});
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// Re-size to fit
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SkottieExample(CanvasKit, 'sk_drinks', drinksJSON, fullBounds);
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SkottieExample(CanvasKit, 'sk_party', confettiJSON, fullBounds);
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SkottieExample(CanvasKit, 'sk_onboarding', onboardingJSON, fullBounds);
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ShaderExample1(CanvasKit);
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});
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fetch('https://storage.googleapis.com/skia-cdn/misc/lego_loader.json').then((resp) => {
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resp.text().then((str) => {
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legoJSON = str;
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SkottieExample(CanvasKit, 'sk_legos', legoJSON, {fLeft: -50, fTop: 0, fRight: 350, fBottom: 300});
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});
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});
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fetch('https://storage.googleapis.com/skia-cdn/misc/drinks.json').then((resp) => {
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resp.text().then((str) => {
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drinksJSON = str;
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SkottieExample(CanvasKit, 'sk_drinks', drinksJSON, fullBounds);
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});
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});
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fetch('https://storage.googleapis.com/skia-cdn/misc/confetti.json').then((resp) => {
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resp.text().then((str) => {
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confettiJSON = str;
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SkottieExample(CanvasKit, 'sk_party', confettiJSON, fullBounds);
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});
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});
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fetch('https://storage.googleapis.com/skia-cdn/misc/onboarding.json').then((resp) => {
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resp.text().then((str) => {
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onboardingJSON = str;
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SkottieExample(CanvasKit, 'sk_onboarding', onboardingJSON, fullBounds);
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});
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});
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function preventScrolling(canvas) {
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canvas.addEventListener('touchmove', (e) => {
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// Prevents touch events in the canvas from scrolling the canvas.
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e.preventDefault();
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e.stopPropagation();
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});
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}
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function DrawingExample(CanvasKit) {
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const surface = CanvasKit.MakeCanvasSurface('patheffect');
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if (!surface) {
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console.log('Could not make surface');
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}
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const context = CanvasKit.currentContext();
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const canvas = surface.getCanvas();
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const paint = new CanvasKit.SkPaint();
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const textPaint = new CanvasKit.SkPaint();
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textPaint.setColor(CanvasKit.Color(40, 0, 0, 1.0));
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textPaint.setAntiAlias(true);
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const textFont = new CanvasKit.SkFont(null, 30);
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let i = 0;
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let X = 200;
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let Y = 200;
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function drawFrame() {
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const path = starPath(CanvasKit, X, Y);
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CanvasKit.setCurrentContext(context);
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const dpe = CanvasKit.SkPathEffect.MakeDash([15, 5, 5, 10], i/5);
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i++;
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paint.setPathEffect(dpe);
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paint.setStyle(CanvasKit.PaintStyle.Stroke);
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paint.setStrokeWidth(5.0 + -3 * Math.cos(i/30));
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paint.setAntiAlias(true);
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paint.setColor(CanvasKit.Color(66, 129, 164, 1.0));
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canvas.clear(CanvasKit.Color(255, 255, 255, 1.0));
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canvas.drawPath(path, paint);
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canvas.drawText('Try Clicking!', 10, 380, textPaint, textFont);
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canvas.flush();
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dpe.delete();
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path.delete();
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window.requestAnimationFrame(drawFrame);
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}
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window.requestAnimationFrame(drawFrame);
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// Make animation interactive
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let interact = (e) => {
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if (!e.buttons) {
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return;
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}
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X = e.offsetX;
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Y = e.offsetY;
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};
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document.getElementById('patheffect').addEventListener('pointermove', interact);
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document.getElementById('patheffect').addEventListener('pointerdown', interact);
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preventScrolling(document.getElementById('patheffect'));
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// A client would need to delete this if it didn't go on forever.
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// font.delete();
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// paint.delete();
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}
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function InkExample(CanvasKit) {
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const surface = CanvasKit.MakeCanvasSurface('ink');
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if (!surface) {
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console.log('Could not make surface');
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}
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const context = CanvasKit.currentContext();
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const canvas = surface.getCanvas();
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let paint = new CanvasKit.SkPaint();
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paint.setAntiAlias(true);
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paint.setColor(CanvasKit.Color(0, 0, 0, 1.0));
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paint.setStyle(CanvasKit.PaintStyle.Stroke);
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paint.setStrokeWidth(4.0);
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// This effect smooths out the drawn lines a bit.
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paint.setPathEffect(CanvasKit.MakeSkCornerPathEffect(50));
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// Draw I N K
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let path = new CanvasKit.SkPath();
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path.moveTo(80, 30);
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path.lineTo(80, 80);
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path.moveTo(100, 80);
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path.lineTo(100, 15);
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path.lineTo(130, 95);
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path.lineTo(130, 30);
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path.moveTo(150, 30);
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path.lineTo(150, 80);
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path.moveTo(170, 30);
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path.lineTo(150, 55);
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path.lineTo(170, 80);
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let paths = [path];
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let paints = [paint];
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function drawFrame() {
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CanvasKit.setCurrentContext(context);
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for (let i = 0; i < paints.length && i < paths.length; i++) {
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canvas.drawPath(paths[i], paints[i]);
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}
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canvas.flush();
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window.requestAnimationFrame(drawFrame);
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}
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let hold = false;
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let interact = (e) => {
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let type = e.type;
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if (type === 'lostpointercapture' || type === 'pointerup' || !e.pressure ) {
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hold = false;
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return;
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}
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if (hold) {
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path.lineTo(e.offsetX, e.offsetY);
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} else {
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paint = paint.copy();
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paint.setColor(CanvasKit.Color(Math.random() * 255, Math.random() * 255, Math.random() * 255, Math.random() + .2));
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paints.push(paint);
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path = new CanvasKit.SkPath();
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paths.push(path);
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path.moveTo(e.offsetX, e.offsetY);
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}
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hold = true;
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};
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document.getElementById('ink').addEventListener('pointermove', interact);
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document.getElementById('ink').addEventListener('pointerdown', interact);
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document.getElementById('ink').addEventListener('lostpointercapture', interact);
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document.getElementById('ink').addEventListener('pointerup', interact);
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preventScrolling(document.getElementById('ink'));
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window.requestAnimationFrame(drawFrame);
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}
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function ShapingExample(CanvasKit) {
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const surface = CanvasKit.MakeCanvasSurface('shaping');
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if (!surface) {
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console.log('Could not make surface');
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return;
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}
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let robotoData = null;
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fetch('https://storage.googleapis.com/skia-cdn/google-web-fonts/Roboto-Regular.ttf').then((resp) => {
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resp.arrayBuffer().then((buffer) => {
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robotoData = buffer;
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requestAnimationFrame(drawFrame);
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});
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});
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let emojiData = null;
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fetch('https://storage.googleapis.com/skia-cdn/misc/NotoColorEmoji.ttf').then((resp) => {
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resp.arrayBuffer().then((buffer) => {
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emojiData = buffer;
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requestAnimationFrame(drawFrame);
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});
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});
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const skcanvas = surface.getCanvas();
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const font = new CanvasKit.SkFont(null, 18);
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const fontPaint = new CanvasKit.SkPaint();
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fontPaint.setStyle(CanvasKit.PaintStyle.Fill);
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fontPaint.setAntiAlias(true);
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skcanvas.drawText(`Fetching Font data...`, 5, 450, fontPaint, font);
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surface.flush();
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const context = CanvasKit.currentContext();
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let paragraph = null;
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let X = 10;
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let Y = 10;
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const str = 'The quick brown fox 🦊 ate a zesty hamburgerfons 🍔.\nThe 👩👩👧👧 laughed.';
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function drawFrame() {
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if (robotoData && emojiData && !paragraph) {
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const fontMgr = CanvasKit.SkFontMgr.FromData([robotoData, emojiData]);
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const paraStyle = new CanvasKit.ParagraphStyle({
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textStyle: {
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color: CanvasKit.BLACK,
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fontFamilies: ['Roboto', 'Noto Color Emoji'],
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fontSize: 50,
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},
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textAlign: CanvasKit.TextAlign.Left,
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maxLines: 7,
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ellipsis: '...',
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});
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const builder = CanvasKit.ParagraphBuilder.Make(paraStyle, fontMgr);
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builder.addText(str);
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paragraph = builder.build();
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}
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if (!paragraph) {
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requestAnimationFrame(drawFrame);
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return;
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}
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CanvasKit.setCurrentContext(context);
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skcanvas.clear(CanvasKit.WHITE);
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const wrapTo = 350 + 150 * Math.sin(Date.now() / 2000);
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paragraph.layout(wrapTo);
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skcanvas.drawParagraph(paragraph, 0, 0);
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skcanvas.drawLine(wrapTo, 0, wrapTo, 400, fontPaint);
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let posA = paragraph.getGlyphPositionAtCoordinate(X, Y);
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const cp = str.codePointAt(posA.pos);
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if (cp) {
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const glyph = String.fromCodePoint(cp);
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skcanvas.drawText(`At (${X.toFixed(2)}, ${Y.toFixed(2)}) glyph is '${glyph}'`, 5, 450, fontPaint, font);
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}
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surface.flush();
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requestAnimationFrame(drawFrame);
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}
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// Make animation interactive
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let interact = (e) => {
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// multiply by 4/5 to account for the difference in the canvas width and the CSS width.
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// The 10 accounts for where the mouse actually is compared to where it is drawn.
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X = (e.offsetX * 4/5) - 10;
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Y = e.offsetY * 4/5;
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};
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document.getElementById('shaping').addEventListener('pointermove', interact);
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document.getElementById('shaping').addEventListener('pointerdown', interact);
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document.getElementById('shaping').addEventListener('lostpointercapture', interact);
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document.getElementById('shaping').addEventListener('pointerup', interact);
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preventScrolling(document.getElementById('shaping'));
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window.requestAnimationFrame(drawFrame);
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}
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function starPath(CanvasKit, X=128, Y=128, R=116) {
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let p = new CanvasKit.SkPath();
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p.moveTo(X + R, Y);
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for (let i = 1; i < 8; i++) {
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let a = 2.6927937 * i;
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p.lineTo(X + R * Math.cos(a), Y + R * Math.sin(a));
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}
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return p;
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}
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function SkottieExample(CanvasKit, id, jsonStr, bounds) {
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if (!CanvasKit || !jsonStr) {
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return;
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}
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const animation = CanvasKit.MakeAnimation(jsonStr);
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const duration = animation.duration() * 1000;
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const size = animation.size();
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let c = document.getElementById(id);
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bounds = bounds || {fLeft: 0, fTop: 0, fRight: size.w, fBottom: size.h};
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const surface = CanvasKit.MakeCanvasSurface(id);
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if (!surface) {
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console.log('Could not make surface');
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}
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const context = CanvasKit.currentContext();
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const canvas = surface.getCanvas();
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let firstFrame = new Date().getTime();
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function drawFrame() {
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let now = new Date().getTime();
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let seek = ((now - firstFrame) / duration) % 1.0;
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CanvasKit.setCurrentContext(context);
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animation.seek(seek);
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animation.render(canvas, bounds);
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canvas.flush();
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window.requestAnimationFrame(drawFrame);
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}
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window.requestAnimationFrame(drawFrame);
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//animation.delete();
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}
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function ShaderExample1(CanvasKit) {
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if (!CanvasKit) {
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return;
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}
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const surface = CanvasKit.MakeCanvasSurface('shader1');
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if (!surface) {
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throw 'Could not make surface';
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}
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const skcanvas = surface.getCanvas();
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const paint = new CanvasKit.SkPaint();
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const prog = `
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uniform float rad_scale;
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uniform float2 in_center;
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uniform float4 in_colors0;
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uniform float4 in_colors1;
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void main(float2 p, inout half4 color) {
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float2 pp = p - in_center;
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float radius = sqrt(dot(pp, pp));
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radius = sqrt(radius);
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float angle = atan(pp.y / pp.x);
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float t = (angle + 3.1415926/2) / (3.1415926);
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t += radius * rad_scale;
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t = fract(t);
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color = half4(mix(in_colors0, in_colors1, t));
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}
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`;
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// If there are multiple contexts on the screen, we need to make sure
|
|
// we switch to this one before we draw.
|
|
const context = CanvasKit.currentContext();
|
|
const fact = CanvasKit.SkRuntimeEffect.Make(prog);
|
|
function drawFrame() {
|
|
CanvasKit.setCurrentContext(context);
|
|
skcanvas.clear(CanvasKit.WHITE);
|
|
const shader = fact.makeShader([
|
|
Math.sin(Date.now() / 2000) / 5,
|
|
256, 256,
|
|
1, 0, 0, 1,
|
|
0, 1, 0, 1],
|
|
true/*=opaque*/);
|
|
|
|
paint.setShader(shader);
|
|
skcanvas.drawRect(CanvasKit.LTRBRect(0, 0, 512, 512), paint);
|
|
surface.flush();
|
|
requestAnimationFrame(drawFrame);
|
|
shader.delete();
|
|
}
|
|
requestAnimationFrame(drawFrame);
|
|
}
|
|
|
|
}
|
|
document.head.appendChild(s);
|
|
})();
|
|
</script>
|
|
|
|
Lottie files courtesy of the lottiefiles.com community:
|
|
[Lego Loader](https://www.lottiefiles.com/410-lego-loader),
|
|
[I'm thirsty](https://www.lottiefiles.com/77-im-thirsty),
|
|
[Confetti](https://www.lottiefiles.com/1370-confetti),
|
|
[Onboarding](https://www.lottiefiles.com/1134-onboarding-1)
|
|
|
|
Test server
|
|
-----------
|
|
Test your code on our [CanvasKit Fiddle](https://jsfiddle.skia.org/canvaskit)
|
|
|
|
Download
|
|
--------
|
|
Get [CanvasKit on NPM](https://www.npmjs.com/package/canvaskit-wasm)
|