canvaskit-wasm
Version:
A WASM version of Skia's Canvas API
1,294 lines (1,092 loc) • 40.6 kB
HTML
<title>CanvasKit (Skia via Web Assembly)</title>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
canvas, img {
border: 1px dashed #AAA;
}
#api5_c, #api6_c {
width: 300px;
height: 300px;
}
</style>
<h2> Drop in replacement for HTML Canvas (e.g. node.js)</h2>
<img id=api1 width=300 height=300>
<canvas id=api1_c width=300 height=300></canvas>
<img id=api2 width=300 height=300>
<canvas id=api2_c width=300 height=300></canvas>
<img id=api3 width=300 height=300>
<canvas id=api3_c width=300 height=300></canvas>
<img id=api4 width=300 height=300>
<canvas id=api4_c width=300 height=300></canvas>
<img id=api5 width=300 height=300>
<canvas id=api5_c width=300 height=300></canvas>
<img id=api6 width=300 height=300>
<canvas id=api6_c width=300 height=300></canvas>
<img id=api7 width=300 height=300>
<canvas id=api7_c width=300 height=300></canvas>
<img id=api8 width=300 height=300>
<canvas id=api8_c width=300 height=300></canvas>
<h2 id=title1> CanvasKit expands the functionality of a stock HTML canvas</h2>
<canvas id=vertex1 width=300 height=300></canvas>
<canvas id=gradient1 width=300 height=300></canvas>
<canvas id=patheffect width=300 height=300></canvas>
<canvas id=paths width=300 height=300></canvas>
<canvas id=pathperson width=300 height=300></canvas>
<canvas id=ink width=300 height=300></canvas>
<canvas id=surfaces width=300 height=300></canvas>
<canvas id=atlas width=300 height=300></canvas>
<canvas id=decode width=300 height=300></canvas>
<h2 id=title2> CanvasKit can allow for text measurement/placement (e.g. breaking, kerning)</h2>
<canvas id=textonpath width=300 height=300></canvas>
<canvas id=drawGlyphs width=300 height=300></canvas>
<h2 id=title3> Interactive drawPatch</h2>
<canvas id=interdrawpatch width=512 height=512></canvas>
<script type="text/javascript" src="/build/canvaskit.js"></script>
<script type="text/javascript" charset="utf-8" async>
var CanvasKit = null;
var cdn = 'https://storage.googleapis.com/skia-cdn/misc/';
const ckLoaded = CanvasKitInit({locateFile: (file) => '/build/'+file});
const loadRoboto = fetch(cdn + 'Roboto-Regular.ttf').then((response) => response.arrayBuffer());
const loadNotoSerif = fetch(cdn + 'NotoSerif-Regular.ttf').then((response) => response.arrayBuffer());
const loadTestImage = fetch(cdn + 'test.png').then((response) => response.arrayBuffer());
async function initWebGpu(CK) {
if (navigator.gpu && CK.webgpu) {
const adapter = await navigator.gpu.requestAdapter();
const device = await adapter.requestDevice();
var gpu = CK.MakeGPUDeviceContext(device);
if (!gpu) {
console.error('Failed to initialize WebGPU device context');
}
return gpu;
}
return null;
}
const ready = async function() {
let CK = await ckLoaded;
let gpu = await initWebGpu(CK);
return [CK, gpu];
}();
// Examples which only require canvaskit
ready.then((initData) => {
const [CK, gpu] = initData;
if (gpu) {
let titles = ['title1', 'title2', 'title3'];
titles.forEach((title) => document.getElementById(title).innerText += " (using WebGPU)");
}
CanvasKit = CK;
PathExample(CanvasKit);
InkExample(CanvasKit, gpu);
PathPersonExample(CanvasKit, gpu);
VertexAPI1(CanvasKit, gpu);
GradientAPI1(CanvasKit, gpu);
TextOnPathAPI1(CanvasKit, gpu);
DrawGlyphsAPI1(CanvasKit, gpu);
SurfaceAPI1(CanvasKit, gpu);
if (CanvasKit.MakeCanvas){
CanvasAPI1(CanvasKit);
CanvasAPI2(CanvasKit);
CanvasAPI3(CanvasKit);
CanvasAPI4(CanvasKit);
CanvasAPI5(CanvasKit);
CanvasAPI6(CanvasKit);
CanvasAPI7(CanvasKit);
CanvasAPI8(CanvasKit);
} else {
console.log("Skipping CanvasAPI1 because it's not compiled in");
}
InteractivePatch(CanvasKit, gpu);
});
// Examples requiring external resources
Promise.all([ready, loadRoboto]).then((results) => {DrawingExample(...results.flat())});
Promise.all([ready, loadTestImage]).then((results) => {AtlasAPI1(...results.flat())});
Promise.all([ckLoaded, loadTestImage]).then((results) => {DecodeAPI(...results)});
// Helper function to create an optional WebGPU canvas surface, if WebGPU is supported. Falls back
// to CanvasKit.MakeCanvasSurface for SW/WebGL otherwise.
function MakeCanvasSurface(CanvasKit, gpu, canvasId) {
if (gpu) {
const canvasContext = CanvasKit.MakeGPUCanvasContext(
gpu, document.getElementById(canvasId));
if (!canvasContext) {
console.error('Failed to configure WebGPU canvas context');
return;
}
const surface = CanvasKit.MakeGPUCanvasSurface(canvasContext);
if (!surface) {
console.error('Failed to initialize current swapchain Surface');
}
return surface;
}
return CanvasKit.MakeCanvasSurface(canvasId);
}
function DrawingExample(CanvasKit, gpu, robotoData) {
if (!robotoData || !CanvasKit) {
return;
}
const surface = MakeCanvasSurface(CanvasKit, gpu, 'patheffect');
if (!surface) {
console.error('Could not make surface');
return;
}
const paint = new CanvasKit.Paint();
const roboto = CanvasKit.Typeface.MakeFreeTypeFaceFromData(robotoData);
const textPaint = new CanvasKit.Paint();
textPaint.setColor(CanvasKit.RED);
textPaint.setAntiAlias(true);
const textFont = new CanvasKit.Font(roboto, 30);
let i = 0;
let X = 128;
let Y = 128;
function drawFrame(canvas) {
const path = starPath(CanvasKit, X, Y);
// Some animations see performance improvements by marking their
// paths as volatile.
path.setIsVolatile(true);
const dpe = CanvasKit.PathEffect.MakeDash([15, 5, 5, 10], i/5);
i++;
paint.setPathEffect(dpe);
paint.setStyle(CanvasKit.PaintStyle.Stroke);
paint.setStrokeWidth(5.0 + -3 * Math.cos(i/30));
paint.setAntiAlias(true);
paint.setColor(CanvasKit.Color(66, 129, 164, 1.0));
canvas.clear(CanvasKit.TRANSPARENT);
canvas.drawPath(path, paint);
canvas.drawText('Try Clicking!', 10, 280, textPaint, textFont);
dpe.delete();
path.delete();
surface.requestAnimationFrame(drawFrame);
}
surface.requestAnimationFrame(drawFrame);
// Make animation interactive
let interact = (e) => {
if (!e.pressure) {
return;
}
X = e.offsetX;
Y = e.offsetY;
};
document.getElementById('patheffect').addEventListener('pointermove', interact);
document.getElementById('patheffect').addEventListener('pointerdown', interact);
preventScrolling(document.getElementById('patheffect'));
// A client would need to delete this if it didn't go on for ever.
// paint.delete();
// textPaint.delete();
// textFont.delete();
}
function InteractivePatch(CanvasKit, gpu) {
const ELEM = 'interdrawpatch';
const surface = MakeCanvasSurface(CanvasKit, gpu, ELEM);
if (!surface) {
console.error('Could not make surface');
return;
}
let live_corner, live_index;
const paint = new CanvasKit.Paint();
const pts_paint = new CanvasKit.Paint();
pts_paint.setStyle(CanvasKit.PaintStyle.Stroke);
pts_paint.setStrokeWidth(9);
pts_paint.setStrokeCap(CanvasKit.StrokeCap.Round);
const line_paint = new CanvasKit.Paint();
line_paint.setStyle(CanvasKit.PaintStyle.Stroke);
line_paint.setStrokeWidth(2);
const colors = [CanvasKit.RED, CanvasKit.BLUE, CanvasKit.YELLOW, CanvasKit.CYAN];
const patch = [
[ 10,170, 10, 10, 170, 10], // prev_vector, point, next_vector
[340, 10, 500, 10, 500,170],
[500,340, 500,500, 340,500],
[170,500, 10,500, 10,340],
];
function get_corner(corner, index) {
return [corner[index*2+0], corner[index*2+1]];
}
function push_xy(array, xy) {
array.push(xy[0], xy[1]);
}
function patch_to_cubics(patch) {
const array = [];
push_xy(array, get_corner(patch[0],1));
push_xy(array, get_corner(patch[0],2));
for (let i = 1; i < 4; ++i) {
push_xy(array, get_corner(patch[i],0));
push_xy(array, get_corner(patch[i],1));
push_xy(array, get_corner(patch[i],2));
}
push_xy(array, get_corner(patch[0],0));
return array;
}
function drawFrame(canvas) {
const cubics = patch_to_cubics(patch);
canvas.drawColor(CanvasKit.WHITE);
canvas.drawPatch(cubics, colors, null, CanvasKit.BlendMode.Dst, paint);
if (live_corner) {
canvas.drawPoints(CanvasKit.PointMode.Polygon, live_corner, line_paint);
}
canvas.drawPoints(CanvasKit.PointMode.Points, cubics, pts_paint);
surface.requestAnimationFrame(drawFrame);
}
surface.requestAnimationFrame(drawFrame);
function length2(x, y) {
return x*x + y*y;
}
function hit_test(x,y, x1,y1) {
return length2(x-x1, y-y1) <= 10*10;
}
function pointer_up(e) {
live_corner = null;
live_index = null;
}
function pointer_down(e) {
live_corner = null;
live_index = null;
for (p of patch) {
for (let i = 0; i < 6; i += 2) {
if (hit_test(p[i], p[i+1], e.offsetX, e.offsetY)) {
live_corner = p;
live_index = i;
}
}
}
}
function pointer_move(e) {
if (e.pressure && live_corner) {
if (live_index == 2) {
// corner
const dx = e.offsetX - live_corner[2];
const dy = e.offsetY - live_corner[3];
for (let i = 0; i < 3; ++i) {
live_corner[i*2+0] += dx;
live_corner[i*2+1] += dy;
}
} else {
// control-point
live_corner[live_index+0] = e.offsetX;
live_corner[live_index+1] = e.offsetY;
}
}
}
document.getElementById(ELEM).addEventListener('pointermove', pointer_move);
document.getElementById(ELEM).addEventListener('pointerdown', pointer_down);
document.getElementById(ELEM).addEventListener('pointerup', pointer_up);
preventScrolling(document.getElementById(ELEM));
}
function PathPersonExample(CanvasKit, gpu) {
const surface = MakeCanvasSurface(CanvasKit, gpu, 'pathperson');
if (!surface) {
console.error('Could not make surface');
return;
}
function drawFrame(canvas) {
const paint = new CanvasKit.Paint();
paint.setStrokeWidth(1.0);
paint.setAntiAlias(true);
paint.setColor(CanvasKit.Color(0, 0, 0, 1.0));
paint.setStyle(CanvasKit.PaintStyle.Stroke);
const path = new CanvasKit.Path();
path.moveTo(10, 10);
path.lineTo(100, 10);
path.moveTo(10, 10);
path.lineTo(10, 200);
path.moveTo(10, 100);
path.lineTo(100,100);
path.moveTo(10, 200);
path.lineTo(100, 200);
canvas.drawPath(path, paint);
path.delete();
paint.delete();
}
// Intentionally just draw frame once
surface.drawOnce(drawFrame);
}
function PathExample(CanvasKit) {
const surface = CanvasKit.MakeSWCanvasSurface('paths');
if (!surface) {
console.error('Could not make surface');
return;
}
function drawFrame(canvas) {
const paint = new CanvasKit.Paint();
paint.setStrokeWidth(1.0);
paint.setAntiAlias(true);
paint.setColor(CanvasKit.Color(0, 0, 0, 1.0));
paint.setStyle(CanvasKit.PaintStyle.Stroke);
const path = new CanvasKit.Path();
path.moveTo(20, 5);
path.lineTo(30, 20);
path.lineTo(40, 10);
path.lineTo(50, 20);
path.lineTo(60, 0);
path.lineTo(20, 5);
path.moveTo(20, 80);
path.cubicTo(90, 10, 160, 150, 190, 10);
path.moveTo(36, 148);
path.quadTo(66, 188, 120, 136);
path.lineTo(36, 148);
path.moveTo(150, 180);
path.arcToTangent(150, 100, 50, 200, 20);
path.lineTo(160, 160);
path.moveTo(20, 120);
path.lineTo(20, 120);
canvas.drawPath(path, paint);
const rrect = CanvasKit.RRectXY([100, 10, 140, 62], 10, 4);
const rrectPath = new CanvasKit.Path().addRRect(rrect, true);
canvas.drawPath(rrectPath, paint);
rrectPath.delete();
path.delete();
paint.delete();
}
// Intentionally just draw frame once
surface.drawOnce(drawFrame);
}
function preventScrolling(canvas) {
canvas.addEventListener('touchmove', (e) => {
// Prevents touch events in the canvas from scrolling the canvas.
e.preventDefault();
e.stopPropagation();
});
}
function InkExample(CanvasKit, gpu) {
const surface = MakeCanvasSurface(CanvasKit, gpu, 'ink');
if (!surface) {
console.error('Could not make surface');
return;
}
let paint = new CanvasKit.Paint();
paint.setAntiAlias(true);
paint.setColor(CanvasKit.Color(0, 0, 0, 1.0));
paint.setStyle(CanvasKit.PaintStyle.Stroke);
paint.setStrokeWidth(4.0);
paint.setPathEffect(CanvasKit.PathEffect.MakeCorner(50));
// Draw I N K
let path = new CanvasKit.Path();
path.moveTo(80, 30);
path.lineTo(80, 80);
path.moveTo(100, 80);
path.lineTo(100, 15);
path.lineTo(130, 95);
path.lineTo(130, 30);
path.moveTo(150, 30);
path.lineTo(150, 80);
path.moveTo(170, 30);
path.lineTo(150, 55);
path.lineTo(170, 80);
let paths = [path];
let paints = [paint];
function drawFrame(canvas) {
canvas.clear(CanvasKit.Color(255, 255, 255, 1.0));
for (let i = 0; i < paints.length && i < paths.length; i++) {
canvas.drawPath(paths[i], paints[i]);
}
surface.requestAnimationFrame(drawFrame);
}
let hold = false;
let interact = (e) => {
let type = e.type;
if (type === 'lostpointercapture' || type === 'pointerup' || !e.pressure ) {
hold = false;
return;
}
if (hold) {
path.lineTo(e.offsetX, e.offsetY);
} else {
paint = paint.copy();
paint.setColor(CanvasKit.Color(Math.random() * 255, Math.random() * 255, Math.random() * 255, Math.random() + .2));
paints.push(paint);
path = new CanvasKit.Path();
paths.push(path);
path.moveTo(e.offsetX, e.offsetY);
}
hold = true;
};
document.getElementById('ink').addEventListener('pointermove', interact);
document.getElementById('ink').addEventListener('pointerdown', interact);
document.getElementById('ink').addEventListener('lostpointercapture', interact);
document.getElementById('ink').addEventListener('pointerup', interact);
preventScrolling(document.getElementById('ink'));
surface.requestAnimationFrame(drawFrame);
}
function starPath(CanvasKit, X=128, Y=128, R=116) {
let p = new CanvasKit.Path();
p.moveTo(X + R, Y);
for (let i = 1; i < 8; i++) {
let a = 2.6927937 * i;
p.lineTo(X + R * Math.cos(a), Y + R * Math.sin(a));
}
return p;
}
function CanvasAPI1(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(300, 300);
let realCanvas = document.getElementById('api1_c');
let skPromise = fetch(cdn + 'test.png')
// if clients want to use a Blob, they are responsible
// for reading it themselves.
.then((response) => response.arrayBuffer())
.then((buffer) => {
skcanvas._img = skcanvas.decodeImage(buffer);
});
let realPromise = fetch(cdn + 'test.png')
.then((response) => response.blob())
.then((blob) => createImageBitmap(blob))
.then((bitmap) => {
realCanvas._img = bitmap;
});
let realFontLoaded = new FontFace('Bungee', 'url(/tests/assets/Bungee-Regular.ttf)', {
'family': 'Bungee',
'style': 'normal',
'weight': '400',
}).load().then((font) => {
document.fonts.add(font);
});
let skFontLoaded = fetch('/tests/assets/Bungee-Regular.ttf').then(
(response) => response.arrayBuffer()).then(
(buffer) => {
// loadFont is synchronous
skcanvas.loadFont(buffer, {
'family': 'Bungee',
'style': 'normal',
'weight': '400',
});
});
Promise.all([realPromise, skPromise, realFontLoaded, skFontLoaded]).then(() => {
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
ctx.fillStyle = '#EEE';
ctx.fillRect(0, 0, 300, 300);
ctx.fillStyle = 'black';
ctx.font = '26px Bungee';
ctx.rotate(.1);
let text = ctx.measureText('Awesome');
ctx.fillText('Awesome ', 25, 100);
ctx.strokeText('Groovy!', 35 + text.width, 100);
// Draw line under Awesome
ctx.strokeStyle = 'rgba(125,0,0,0.5)';
ctx.beginPath();
ctx.lineWidth = 6;
ctx.moveTo(25, 105);
ctx.lineTo(200, 105);
ctx.stroke();
// squished vertically
ctx.globalAlpha = 0.7;
ctx.imageSmoothingQuality = 'medium';
ctx.drawImage(canvas._img, 150, 150, 150, 100);
ctx.rotate(-.2);
ctx.imageSmoothingEnabled = false;
ctx.drawImage(canvas._img, 100, 150, 400, 350, 10, 200, 150, 100);
let idata = ctx.getImageData(80, 220, 40, 45);
ctx.putImageData(idata, 250, 10);
ctx.putImageData(idata, 200, 10, 20, 10, 20, 30);
ctx.resetTransform();
ctx.strokeStyle = 'black';
ctx.lineWidth = 1;
ctx.strokeRect(200, 10, 40, 45);
idata = ctx.createImageData(10, 20);
ctx.putImageData(idata, 10, 10);
}
document.getElementById('api1').src = skcanvas.toDataURL();
skcanvas.dispose();
});
}
function CanvasAPI2(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(300, 300);
let realCanvas = document.getElementById('api2_c');
realCanvas.width = 300;
realCanvas.height = 300;
// svg data for a clock
skcanvas._path = skcanvas.makePath2D('M11.99 2C6.47 2 2 6.48 2 12s4.47 10 9.99 10C17.52 22 22 17.52 22 12S17.52 2 11.99 2zM12 20c-4.42 0-8-3.58-8-8s3.58-8 8-8 8 3.58 8 8-3.58 8-8 8zm.5-13H11v6l5.25 3.15.75-1.23-4.5-2.67z');
realCanvas._path = new Path2D('M11.99 2C6.47 2 2 6.48 2 12s4.47 10 9.99 10C17.52 22 22 17.52 22 12S17.52 2 11.99 2zM12 20c-4.42 0-8-3.58-8-8s3.58-8 8-8 8 3.58 8 8-3.58 8-8 8zm.5-13H11v6l5.25 3.15.75-1.23-4.5-2.67z');
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
ctx.scale(1.5, 1.5);
ctx.moveTo(20, 5);
ctx.lineTo(30, 20);
ctx.lineTo(40, 10);
ctx.lineTo(50, 20);
ctx.lineTo(60, 0);
ctx.lineTo(20, 5);
ctx.moveTo(20, 80);
ctx.bezierCurveTo(90, 10, 160, 150, 190, 10);
ctx.moveTo(36, 148);
ctx.quadraticCurveTo(66, 188, 120, 136);
ctx.lineTo(36, 148);
ctx.rect(5, 170, 20, 25);
ctx.moveTo(150, 180);
ctx.arcTo(150, 100, 50, 200, 20);
ctx.lineTo(160, 160);
ctx.moveTo(20, 120);
ctx.arc(20, 120, 18, 0, 1.75 * Math.PI);
ctx.lineTo(20, 120);
ctx.moveTo(150, 5);
ctx.ellipse(130, 25, 30, 10, -1*Math.PI/8, Math.PI/6, 1.5*Math.PI);
ctx.lineWidth = 4/3;
ctx.stroke();
// make a clock
ctx.stroke(canvas._path);
// Test edgecases and draw direction
ctx.beginPath();
ctx.arc(50, 100, 10, Math.PI, -Math.PI/2);
ctx.stroke();
ctx.beginPath();
ctx.arc(75, 100, 10, Math.PI, -Math.PI/2, true);
ctx.stroke();
ctx.beginPath();
ctx.arc(100, 100, 10, Math.PI, 100.1 * Math.PI, true);
ctx.stroke();
ctx.beginPath();
ctx.arc(125, 100, 10, Math.PI, 100.1 * Math.PI, false);
ctx.stroke();
ctx.beginPath();
ctx.ellipse(155, 100, 10, 15, Math.PI/8, 100.1 * Math.PI, Math.PI, true);
ctx.stroke();
ctx.beginPath();
ctx.ellipse(180, 100, 10, 15, Math.PI/8, Math.PI, 100.1 * Math.PI, true);
ctx.stroke();
}
document.getElementById('api2').src = skcanvas.toDataURL();
skcanvas.dispose();
}
function CanvasAPI3(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(300, 300);
let realCanvas = document.getElementById('api3_c');
realCanvas.width = 300;
realCanvas.height = 300;
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
ctx.rect(10, 10, 20, 20);
ctx.scale(2.0, 4.0);
ctx.rect(30, 10, 20, 20);
ctx.resetTransform();
ctx.rotate(Math.PI / 3);
ctx.rect(50, 10, 20, 20);
ctx.resetTransform();
ctx.translate(30, -2);
ctx.rect(70, 10, 20, 20);
ctx.resetTransform();
ctx.translate(60, 0);
ctx.rotate(Math.PI / 6);
ctx.transform(1.5, 0, 0, 0.5, 0, 0); // effectively scale
ctx.rect(90, 10, 20, 20);
ctx.resetTransform();
ctx.save();
ctx.setTransform(2, 0, -.5, 2.5, -40, 120);
ctx.rect(110, 10, 20, 20);
ctx.lineTo(110, 0);
ctx.restore();
ctx.lineTo(220, 120);
ctx.scale(3.0, 3.0);
ctx.font = '6pt Noto Mono';
ctx.fillText('This text should be huge', 10, 80);
ctx.resetTransform();
ctx.strokeStyle = 'black';
ctx.lineWidth = 2;
ctx.stroke();
ctx.beginPath();
ctx.moveTo(250, 30);
ctx.lineTo(250, 80);
ctx.scale(3.0, 3.0);
ctx.lineTo(280/3, 90/3);
ctx.closePath();
ctx.strokeStyle = 'black';
ctx.lineWidth = 5;
ctx.stroke();
}
document.getElementById('api3').src = skcanvas.toDataURL();
skcanvas.dispose();
}
function CanvasAPI4(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(300, 300);
let realCanvas = document.getElementById('api4_c');
realCanvas.width = 300;
realCanvas.height = 300;
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
ctx.strokeStyle = '#000';
ctx.fillStyle = '#CCC';
ctx.shadowColor = 'rebeccapurple';
ctx.shadowBlur = 1;
ctx.shadowOffsetX = 3;
ctx.shadowOffsetY = -8;
ctx.rect(10, 10, 30, 30);
ctx.save();
ctx.strokeStyle = '#C00';
ctx.fillStyle = '#00C';
ctx.shadowBlur = 0;
ctx.shadowColor = 'transparent';
ctx.stroke();
ctx.restore();
ctx.fill();
ctx.beginPath();
ctx.moveTo(36, 148);
ctx.quadraticCurveTo(66, 188, 120, 136);
ctx.closePath();
ctx.stroke();
ctx.beginPath();
ctx.shadowColor = '#993366AA';
ctx.shadowOffsetX = 8;
ctx.shadowBlur = 5;
ctx.setTransform(2, 0, -.5, 2.5, -40, 120);
ctx.rect(110, 10, 20, 20);
ctx.lineTo(110, 0);
ctx.resetTransform();
ctx.lineTo(220, 120);
ctx.stroke();
ctx.fillStyle = 'green';
ctx.font = '16pt Noto Mono';
ctx.fillText('This should be shadowed', 20, 80);
ctx.beginPath();
ctx.lineWidth = 6;
ctx.ellipse(10, 290, 30, 30, 0, 0, Math.PI * 2);
ctx.scale(2, 1);
ctx.moveTo(10, 290);
ctx.ellipse(10, 290, 30, 60, 0, 0, Math.PI * 2);
ctx.resetTransform();
ctx.scale(3, 1);
ctx.moveTo(10, 290);
ctx.ellipse(10, 290, 30, 90, 0, 0, Math.PI * 2);
ctx.stroke();
}
document.getElementById('api4').src = skcanvas.toDataURL();
skcanvas.dispose();
}
function CanvasAPI5(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(600, 600);
let realCanvas = document.getElementById('api5_c');
realCanvas.width = 600;
realCanvas.height = 600;
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
ctx.scale(1.1, 1.1);
ctx.translate(10, 10);
// Shouldn't impact the fillRect calls
ctx.setLineDash([5, 3]);
ctx.fillStyle = 'rgba(200, 0, 100, 0.81)';
ctx.fillRect(20, 30, 100, 100);
ctx.globalAlpha = 0.81;
ctx.fillStyle = 'rgba(200, 0, 100, 1.0)';
ctx.fillRect(120, 30, 100, 100);
// This shouldn't do anything
ctx.globalAlpha = 0.1;
ctx.fillStyle = 'rgba(200, 0, 100, 0.9)';
ctx.globalAlpha = 0.9;
// Intentional no-op to check ordering
ctx.clearRect(220, 30, 100, 100);
ctx.fillRect(220, 30, 100, 100);
ctx.fillRect(320, 30, 100, 100);
ctx.clearRect(330, 40, 80, 80);
ctx.strokeStyle = 'blue';
ctx.lineWidth = 3;
ctx.setLineDash([5, 3]);
ctx.strokeRect(20, 150, 100, 100);
ctx.setLineDash([50, 30]);
ctx.strokeRect(125, 150, 100, 100);
ctx.lineDashOffset = 25;
ctx.strokeRect(230, 150, 100, 100);
ctx.setLineDash([2, 5, 9]);
ctx.strokeRect(335, 150, 100, 100);
ctx.setLineDash([5, 2]);
ctx.moveTo(336, 400);
ctx.quadraticCurveTo(366, 488, 120, 450);
ctx.lineTo(300, 400);
ctx.stroke();
ctx.font = '36pt Noto Mono';
ctx.strokeText('Dashed', 20, 350);
ctx.fillText('Not Dashed', 20, 400);
}
document.getElementById('api5').src = skcanvas.toDataURL();
skcanvas.dispose();
}
function CanvasAPI6(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(600, 600);
let realCanvas = document.getElementById('api6_c');
realCanvas.width = 600;
realCanvas.height = 600;
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
let rgradient = ctx.createRadialGradient(200, 300, 10, 100, 100, 300);
// Add three color stops
rgradient.addColorStop(0, 'red');
rgradient.addColorStop(0.7, 'white');
rgradient.addColorStop(1, 'blue');
ctx.fillStyle = rgradient;
ctx.globalAlpha = 0.7;
ctx.fillRect(0, 0, 600, 600);
ctx.globalAlpha = 0.95;
ctx.beginPath();
ctx.arc(300, 100, 90, 0, Math.PI*1.66);
ctx.closePath();
ctx.strokeStyle = 'yellow';
ctx.lineWidth = 5;
ctx.stroke();
ctx.save();
ctx.clip();
let lgradient = ctx.createLinearGradient(200, 20, 420, 40);
// Add three color stops
lgradient.addColorStop(0, 'green');
lgradient.addColorStop(0.5, 'cyan');
lgradient.addColorStop(1, 'orange');
ctx.fillStyle = lgradient;
ctx.fillRect(200, 30, 200, 300);
ctx.restore();
ctx.fillRect(550, 550, 40, 40);
}
document.getElementById('api6').src = skcanvas.toDataURL();
skcanvas.dispose();
}
function CanvasAPI7(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(300, 300);
let realCanvas = document.getElementById('api7_c');
let skPromise = fetch(cdn + 'test.png')
// if clients want to use a Blob, they are responsible
// for reading it themselves.
.then((response) => response.arrayBuffer())
.then((buffer) => {
skcanvas._img = skcanvas.decodeImage(buffer);
});
let realPromise = fetch(cdn + 'test.png')
.then((response) => response.blob())
.then((blob) => createImageBitmap(blob))
.then((bitmap) => {
realCanvas._img = bitmap;
});
Promise.all([realPromise, skPromise]).then(() => {
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
ctx.fillStyle = '#EEE';
ctx.fillRect(0, 0, 300, 300);
ctx.lineWidth = 20;
ctx.scale(0.1, 0.2);
let pattern = ctx.createPattern(canvas._img, 'repeat');
ctx.fillStyle = pattern;
ctx.fillRect(0, 0, 1500, 750);
pattern = ctx.createPattern(canvas._img, 'repeat-x');
ctx.fillStyle = pattern;
ctx.fillRect(1500, 0, 3000, 750);
ctx.globalAlpha = 0.7;
pattern = ctx.createPattern(canvas._img, 'repeat-y');
ctx.fillStyle = pattern;
ctx.fillRect(0, 750, 1500, 1500);
ctx.strokeRect(0, 750, 1500, 1500);
pattern = ctx.createPattern(canvas._img, 'no-repeat');
ctx.fillStyle = pattern;
pattern.setTransform({a: 1, b: -.1, c:.1, d: 0.5, e: 1800, f:800});
ctx.fillRect(0, 0, 3000, 1500);
}
document.getElementById('api7').src = skcanvas.toDataURL();
skcanvas.dispose();
});
}
function CanvasAPI8(CanvasKit) {
let skcanvas = CanvasKit.MakeCanvas(300, 300);
let realCanvas = document.getElementById('api8_c');
function drawPoint(ctx, x, y, color) {
ctx.fillStyle = color;
ctx.fillRect(x, y, 1, 1);
}
const IN = 'purple';
const OUT = 'orange';
const SCALE = 4;
const pts = [[3, 3], [4, 4], [5, 5], [10, 10], [8, 10], [6, 10],
[6.5, 9], [15, 10], [17, 10], [17, 11], [24, 24],
[25, 25], [26, 26], [27, 27]];
const tests = [
{
xOffset: 0,
yOffset: 0,
fillType: 'nonzero',
strokeWidth: 0,
testFn: (ctx, x, y) => ctx.isPointInPath(x * SCALE, y * SCALE, 'nonzero'),
},
{
xOffset: 30,
yOffset: 0,
fillType: 'evenodd',
strokeWidth: 0,
testFn: (ctx, x, y) => ctx.isPointInPath(x * SCALE, y * SCALE, 'evenodd'),
},
{
xOffset: 0,
yOffset: 30,
fillType: null,
strokeWidth: 1,
testFn: (ctx, x, y) => ctx.isPointInStroke(x * SCALE, y * SCALE),
},
{
xOffset: 30,
yOffset: 30,
fillType: null,
strokeWidth: 2,
testFn: (ctx, x, y) => ctx.isPointInStroke(x * SCALE, y * SCALE),
},
];
for (let canvas of [skcanvas, realCanvas]) {
let ctx = canvas.getContext('2d');
ctx.font = '11px Noto Mono';
// Draw some visual aids
ctx.fillText('path-nonzero', 30, 15);
ctx.fillText('path-evenodd', 150, 15);
ctx.fillText('stroke-1px-wide', 30, 130);
ctx.fillText('stroke-2px-wide', 150, 130);
ctx.fillText('purple is IN, orange is OUT', 10, 280);
// Scale up to make single pixels easier to see
ctx.scale(SCALE, SCALE);
for (let test of tests) {
ctx.beginPath();
let xOffset = test.xOffset;
let yOffset = test.yOffset;
ctx.fillStyle = '#AAA';
ctx.lineWidth = test.strokeWidth;
ctx.rect(5+xOffset, 5+yOffset, 20, 20);
ctx.arc(15+xOffset, 15+yOffset, 8, 0, Math.PI*2, false);
if (test.fillType) {
ctx.fill(test.fillType);
} else {
ctx.stroke();
}
for (let pt of pts) {
let [x, y] = pt;
x += xOffset;
y += yOffset;
// naively apply transform when querying because the points queried
// ignore the CTM.
if (test.testFn(ctx, x, y)) {
drawPoint(ctx, x, y, IN);
} else {
drawPoint(ctx, x, y, OUT);
}
}
}
}
document.getElementById('api8').src = skcanvas.toDataURL();
skcanvas.dispose();
}
function VertexAPI1(CanvasKit, gpu) {
const surface = MakeCanvasSurface(CanvasKit, gpu, 'vertex1');
if (!surface) {
console.error('Could not make surface');
return;
}
const canvas = surface.getCanvas();
let paint = new CanvasKit.Paint();
// See https://fiddle.skia.org/c/f48b22eaad1bb7adcc3faaa321754af6
// for original c++ version.
let points = [0, 0, 250, 0, 100, 100, 0, 250];
let colors = [CanvasKit.RED, CanvasKit.BLUE,
CanvasKit.YELLOW, CanvasKit.CYAN];
let vertices = CanvasKit.MakeVertices(CanvasKit.VertexMode.TriangleFan,
points, null, colors,
false /*isVolatile*/);
canvas.drawVertices(vertices, CanvasKit.BlendMode.Dst, paint);
vertices.delete();
// See https://fiddle.skia.org/c/e8bdae9bea3227758989028424fcac3d
// for original c++ version.
points = [300, 300, 50, 300, 200, 200, 300, 50 ];
let texs = [ 0, 0, 0, 250, 250, 250, 250, 0 ];
vertices = CanvasKit.MakeVertices(CanvasKit.VertexMode.TriangleFan,
points, texs, colors);
let shader = CanvasKit.Shader.MakeLinearGradient([0, 0], [250, 0],
colors, null, CanvasKit.TileMode.Clamp);
paint.setShader(shader);
canvas.drawVertices(vertices, CanvasKit.BlendMode.Darken, paint);
surface.flush();
shader.delete();
paint.delete();
surface.delete();
vertices.delete();
}
function GradientAPI1(CanvasKit, gpu) {
const surface = MakeCanvasSurface(CanvasKit, gpu, 'gradient1');
if (!surface) {
console.error('Could not make surface');
return;
}
const canvas = surface.getCanvas();
let paint = new CanvasKit.Paint();
// See https://fiddle.skia.org/c/f48b22eaad1bb7adcc3faaa321754af6
// for original c++ version.
let colors = [CanvasKit.BLUE, CanvasKit.YELLOW, CanvasKit.RED];
let pos = [0, .7, 1.0];
let transform = [2, 0, 0,
0, 2, 0,
0, 0, 1];
let shader = CanvasKit.Shader.MakeRadialGradient([150, 150], 130, colors,
pos, CanvasKit.TileMode.Mirror, transform);
paint.setShader(shader);
const textFont = new CanvasKit.Font(null, 75);
const textBlob = CanvasKit.TextBlob.MakeFromText('Radial', textFont);
canvas.drawTextBlob(textBlob, 10, 200, paint);
surface.flush();
paint.delete();
textFont.delete();
textBlob.delete();
shader.delete();
surface.delete();
}
function TextOnPathAPI1(CanvasKit, gpu) {
const surface = MakeCanvasSurface(CanvasKit, gpu, 'textonpath');
if (!surface) {
console.error('Could not make surface');
return;
}
const canvas = surface.getCanvas();
const paint = new CanvasKit.Paint();
paint.setStyle(CanvasKit.PaintStyle.Stroke);
paint.setAntiAlias(true);
const font = new CanvasKit.Font(null, 24);
const fontPaint = new CanvasKit.Paint();
fontPaint.setStyle(CanvasKit.PaintStyle.Fill);
fontPaint.setAntiAlias(true);
const arc = new CanvasKit.Path();
arc.arcToOval(CanvasKit.LTRBRect(20, 40, 280, 300), -160, 140, true);
arc.lineTo(210, 140);
arc.arcToOval(CanvasKit.LTRBRect(20, 0, 280, 260), 160, -140, true);
const str = 'This téxt should follow the curve across contours...';
const textBlob = CanvasKit.TextBlob.MakeOnPath(str, arc, font);
canvas.drawPath(arc, paint);
canvas.drawTextBlob(textBlob, 0, 0, fontPaint);
surface.flush();
surface.delete();
textBlob.delete();
arc.delete();
paint.delete();
font.delete();
fontPaint.delete();
}
function DrawGlyphsAPI1(CanvasKit, gpu) {
const surface = MakeCanvasSurface(CanvasKit, gpu, 'drawGlyphs');
if (!surface) {
console.error('Could not make surface');
return;
}
const canvas = surface.getCanvas();
const paint = new CanvasKit.Paint();
const font = new CanvasKit.Font(null, 16);
paint.setAntiAlias(true);
let glyphs = [];
let positions = [];
for (let i = 0; i < 256; ++i) {
glyphs.push(i);
positions.push((i % 16) * 16);
positions.push(Math.round(i/16) * 16);
}
canvas.drawGlyphs(glyphs, positions, 16, 20, font, paint);
surface.flush();
surface.delete();
paint.delete();
font.delete();
}
function SurfaceAPI1(CanvasKit, gpu) {
const surface = MakeCanvasSurface(CanvasKit, gpu, 'surfaces');
if (!surface) {
console.error('Could not make surface');
return;
}
// create a subsurface as a temporary workspace.
const subSurface = surface.makeSurface({
width: 50,
height: 50,
alphaType: CanvasKit.AlphaType.Premul,
colorType: CanvasKit.ColorType.RGBA_8888,
colorSpace: CanvasKit.ColorSpace.SRGB,
});
if (!subSurface) {
console.error('Could not make subsurface');
return;
}
// draw a small "scene"
const paint = new CanvasKit.Paint();
paint.setColor(CanvasKit.Color(139, 228, 135, 0.95)); // greenish
paint.setStyle(CanvasKit.PaintStyle.Fill);
paint.setAntiAlias(true);
const subCanvas = subSurface.getCanvas();
subCanvas.clear(CanvasKit.BLACK);
subCanvas.drawRect(CanvasKit.LTRBRect(5, 15, 45, 40), paint);
paint.setColor(CanvasKit.Color(214, 93, 244)); // purplish
for (let i = 0; i < 10; i++) {
const x = Math.random() * 50;
const y = Math.random() * 50;
subCanvas.drawOval(CanvasKit.XYWHRect(x, y, 6, 6), paint);
}
// Snap it off as an Image - this image will be in the form the
// parent surface prefers (e.g. Texture for GPU / Raster for CPU).
const img = subSurface.makeImageSnapshot();
// clean up the temporary surface (which also cleans up subCanvas)
subSurface.delete();
paint.delete();
// Make it repeat a bunch with a shader
const pattern = img.makeShaderCubic(CanvasKit.TileMode.Repeat, CanvasKit.TileMode.Mirror,
1/3, 1/3);
const patternPaint = new CanvasKit.Paint();
patternPaint.setShader(pattern);
let i = 0;
function drawFrame(canvas) {
i++;
canvas.clear(CanvasKit.WHITE);
canvas.drawOval(CanvasKit.LTRBRect(i % 60, i % 60, 300 - (i% 60), 300 - (i % 60)), patternPaint);
surface.requestAnimationFrame(drawFrame);
}
surface.requestAnimationFrame(drawFrame);
}
function AtlasAPI1(CanvasKit, gpu, imgData) {
if (!CanvasKit || !imgData) {
return;
}
const surface = MakeCanvasSurface(CanvasKit, gpu, 'atlas');
if (!surface) {
console.error('Could not make surface');
return;
}
const img = CanvasKit.MakeImageFromEncoded(imgData);
const paint = new CanvasKit.Paint();
paint.setColor(CanvasKit.Color(0, 0, 0, 0.8));
// Allocate space for 2 rectangles.
const srcs = CanvasKit.Malloc(Float32Array, 8);
srcs.toTypedArray().set([
0, 0, 250, 250, // LTRB
250, 0, 500, 250
]);
// Allocate space for 2 RSXForms
const dsts = CanvasKit.Malloc(Float32Array, 8);
dsts.toTypedArray().set([
.5, 0, 0, 0, // scos, ssin, tx, ty
0, .8, 200, 100
]);
// Allocate space for 4 colors.
const colors = new CanvasKit.Malloc(Uint32Array, 2);
colors.toTypedArray().set([
CanvasKit.ColorAsInt( 85, 170, 10, 128), // light green
CanvasKit.ColorAsInt( 51, 51, 191, 128), // light blue
]);
let i = 0;
function drawFrame(canvas) {
canvas.clear(CanvasKit.WHITE);
i++;
let scale = 0.5 + Math.sin(i/40)/4;
// update the coordinates of existing sprites - note that this
// does not require a full re-copy of the full array; they are
// updated in-place.
dsts.toTypedArray().set([0.5, 0, (2*i)%200, (5*Math.round(i/200)) % 200], 0);
dsts.toTypedArray().set([scale*Math.sin(i/20), scale*Math.cos(i/20), 200, 100], 4);
canvas.drawAtlas(img, srcs, dsts, paint, CanvasKit.BlendMode.Plus, colors,
{filter: CanvasKit.FilterMode.Nearest});
surface.requestAnimationFrame(drawFrame);
}
surface.requestAnimationFrame(drawFrame);
}
async function DecodeAPI(CanvasKit, imgData) {
if (!CanvasKit || !imgData) {
return;
}
const surface = CanvasKit.MakeCanvasSurface('decode');
if (!surface) {
console.error('Could not make surface');
return;
}
const blob = new Blob([ imgData ]);
// ImageBitmap is not supported in Safari
const imageBitmap = await createImageBitmap(blob);
const img = await CanvasKit.MakeImageFromCanvasImageSource(imageBitmap);
surface.drawOnce((canvas) => {
canvas.drawImage(img, 0, 0, null);
});
}
</script>