src/third_party/skia/modules/pathkit/npm-wasm/example.html - cobalt - Git at Google

 <!DOCTYPE html>
 <title>PathKit (Skia's Geometry + WASM)</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>
   svg, canvas {
     border: 1px dashed #AAA;
   }

   canvas {
     width: 200px;
     height: 200px;
   }

   canvas.big {
     width: 300px;
     height: 300px;
   }

 </style>

 <h2> Can output to an SVG Path, a Canvas, or a Path2D object </h2>
 <svg id=svg1 xmlns='http://www.w3.org/2000/svg' width=200 height=200></svg>
 <canvas id=canvas1></canvas>
 <canvas id=canvas2></canvas>

 <h2> Interact with NewPath() just like a Path2D Object </h2>
 <canvas class=big id=canvas3></canvas>
 <canvas class=big id=canvas4></canvas>

 <h2> Has various Path Effects </h2>
 <canvas class=big id=canvas5></canvas>
 <canvas class=big id=canvas6></canvas>
 <canvas class=big id=canvas7></canvas>
 <canvas class=big id=canvas8></canvas>
 <canvas class=big id=canvas9></canvas>
 <canvas class=big id=canvas10></canvas>
 <canvas class=big id=canvas11></canvas>
 <canvas class=big id=canvasTransform></canvas>

 <h2> Supports fill-rules of nonzero and evenodd </h2>
 <svg id=svg2 xmlns='http://www.w3.org/2000/svg' width=200 height=200></svg>
 <svg id=svg3 xmlns='http://www.w3.org/2000/svg' width=200 height=200></svg>

 <h2> Solves Cubics for Y given X </h2>
 <canvas class=big id=cubics></canvas>

 <script type="text/javascript" src="/node_modules/pathkit-wasm/bin/pathkit.js"></script>

 <script type="text/javascript" charset="utf-8">

   PathKitInit({
     locateFile: (file) => '/node_modules/pathkit-wasm/bin/'+file,
   }).ready().then((PathKit) => {
     window.PathKit = PathKit;
     OutputsExample(PathKit);
     Path2DExample(PathKit);
     PathEffectsExample(PathKit);
     MatrixTransformExample(PathKit);
     FilledSVGExample(PathKit);
     CubicSolverExample(PathKit);
   });

   function setCanvasSize(ctx, width, height) {
     ctx.canvas.width = width;
     ctx.canvas.height = height;
   }

   function OutputsExample(PathKit) {
     let firstPath = PathKit.FromSVGString('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');

     let secondPath = PathKit.NewPath();
     // Acts somewhat like the Canvas API, except can be chained
     secondPath.moveTo(1, 1)
               .lineTo(20, 1)
               .lineTo(10, 30)
               .closePath();

     // Join the two paths together (mutating firstPath in the process)
     firstPath.op(secondPath, PathKit.PathOp.INTERSECT);

     let simpleStr = firstPath.toSVGString();

     let newSVG = document.createElementNS('http://www.w3.org/2000/svg', 'path');
     newSVG.setAttribute('stroke', 'rgb(0,0,200)');
     newSVG.setAttribute('fill', 'white');
     newSVG.setAttribute('transform', 'scale(8,8)');
     newSVG.setAttribute('d', simpleStr);
     document.getElementById('svg1').appendChild(newSVG);

     // Draw directly to Canvas
     let ctx = document.getElementById('canvas1').getContext('2d');
     setCanvasSize(ctx, 200, 200);
     ctx.strokeStyle = 'green';
     ctx.fillStyle = 'white';
     ctx.scale(8, 8);
     ctx.beginPath();
     firstPath.toCanvas(ctx);
     ctx.stroke();

     // create Path2D object and use it in a Canvas.
     let path2D = firstPath.toPath2D();
     ctx = document.getElementById('canvas2').getContext('2d');
     setCanvasSize(ctx, 200, 200);
     ctx.canvas.width = 200
     ctx.scale(8, 8);
     ctx.fillStyle = 'purple';
     ctx.strokeStyle = 'orange';
     ctx.fill(path2D);
     ctx.stroke(path2D);

     // clean up WASM memory
     // See http://kripken.github.io/emscripten-site/docs/porting/connecting_cpp_and_javascript/embind.html?highlight=memory#memory-management
     firstPath.delete();
     secondPath.delete();
   }

   function Path2DExample(PathKit) {
     let objs = [new Path2D(), PathKit.NewPath(), new Path2D(), PathKit.NewPath()];
     let canvases = [
       document.getElementById('canvas3').getContext('2d'),
       document.getElementById('canvas4').getContext('2d')
     ];

     for (i = 0; i <= 1; i++) {
       let path = objs[i];

       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.bezierCurveTo(90, 10, 160, 150, 190, 10);

       path.moveTo(36, 148);
       path.quadraticCurveTo(66, 188, 120, 136);
       path.lineTo(36, 148);

       path.rect(5, 170, 20, 20);

       path.moveTo(150, 180);
       path.arcTo(150, 100, 50, 200, 20);
       path.lineTo(160, 160);

       path.moveTo(20, 120);
       path.arc(20, 120, 18, 0, 1.75 * Math.PI);
       path.lineTo(20, 120);

       let secondPath = objs[i+2];
       secondPath.ellipse(130, 25, 30, 10, -1*Math.PI/8, Math.PI/6, 1.5*Math.PI, false);

       path.addPath(secondPath);

       let m = document.createElementNS('http://www.w3.org/2000/svg', 'svg').createSVGMatrix();
       m.a = 1; m.b = 0;
       m.c = 0; m.d = 1;
       m.e = 0; m.f = 20.5;

       path.addPath(secondPath, m);
       // With PathKit, one can also just provide the 6 params as floats, to avoid
       // the overhead of making an SVGMatrix
       // path.addPath(secondPath, 1, 0, 0, 1, 0, 20.5);

       canvasCtx = canvases[i];
       canvasCtx.fillStyle = 'blue';
       setCanvasSize(canvasCtx, 300, 300);
       canvasCtx.scale(1.5, 1.5);
       if (path.toPath2D) {
         canvasCtx.stroke(path.toPath2D());
       } else {
         canvasCtx.stroke(path);
       }
     }


     objs[1].delete();
   }

   // see https://fiddle.skia.org/c/@discrete_path
   function drawStar(path) {
     let R = 115.2, C = 128.0;
     path.moveTo(C + R + 22, C);
     for (let i = 1; i < 8; i++) {
       let a = 2.6927937 * i;
       path.lineTo(C + R * Math.cos(a) + 22, C + R * Math.sin(a));
     }
     path.closePath();
     return path;
   }

   function PathEffectsExample(PathKit) {
     let effects = [
       // no-op
       (path) => path,
       // dash
       (path, counter) => path.dash(10, 3, counter/5),
       // trim (takes optional 3rd param for returning the trimmed part
       // or the complement)
       (path, counter) => path.trim((counter/100) % 1, 0.8, false),
       // simplify
       (path) => path.simplify(),
       // stroke
       (path, counter) => path.stroke({
         width: 10 * (Math.sin(counter/30) + 1),
         join: PathKit.StrokeJoin.BEVEL,
         cap: PathKit.StrokeCap.BUTT,
         miter_limit: 1,
       }),
       // "offset effect", that is, making a border around the shape.
       (path, counter) => {
         let orig = path.copy();
         path.stroke({
           width: 10 + (counter / 4) % 50,
           join: PathKit.StrokeJoin.ROUND,
           cap: PathKit.StrokeCap.SQUARE,
         })
           .op(orig, PathKit.PathOp.DIFFERENCE);
         orig.delete();
       },
       (path, counter) => {
         let simplified = path.simplify().copy();
         path.stroke({
           width: 2 + (counter / 2) % 100,
           join: PathKit.StrokeJoin.BEVEL,
           cap: PathKit.StrokeCap.BUTT,
         })
           .op(simplified, PathKit.PathOp.REVERSE_DIFFERENCE);
         simplified.delete();
       }
     ];

     let names = ["(plain)", "Dash", "Trim", "Simplify", "Stroke", "Grow", "Shrink"];

     let counter = 0;
     function frame() {
       counter++;
       for (let i = 0; i < effects.length; i++) {
         let path = PathKit.NewPath();
         drawStar(path);

         // The transforms apply directly to the path.
         effects[i](path, counter);

         let ctx = document.getElementById(`canvas${i+5}`).getContext('2d');
         setCanvasSize(ctx, 300, 300);
         ctx.strokeStyle = '#3c597a';
         ctx.fillStyle = '#3c597a';
         if (i >=4 ) {
           ctx.fill(path.toPath2D(), path.getFillTypeString());
         } else {
           ctx.stroke(path.toPath2D());
         }

         ctx.font = '42px monospace';

         let x = 150-ctx.measureText(names[i]).width/2;
         ctx.strokeText(names[i], x, 290);

         path.delete();
       }
       window.requestAnimationFrame(frame);
     }
     window.requestAnimationFrame(frame);
   }

   function MatrixTransformExample(PathKit) {
     // Creates an animated star that twists and moves.
     let ctx = document.getElementById('canvasTransform').getContext('2d');
     setCanvasSize(ctx, 300, 300);
     ctx.strokeStyle = '#3c597a';

     let path = drawStar(PathKit.NewPath());
     // TODO(kjlubick): Perhaps expose some matrix helper functions to allow
     // clients to build their own matrices like this?
     // These matrices represent a 2 degree rotation and a 1% scale factor.
     let scaleUp = [1.0094, -0.0352,  3.1041,
                    0.0352,  1.0094, -6.4885,
                    0     ,  0      , 1];

     let scaleDown = [ 0.9895, 0.0346, -2.8473,
                      -0.0346, 0.9895,  6.5276,
                       0     , 0     ,  1];

     let i = 0;
     function frame(){
       i++;
       if (Math.round(i/100) % 2) {
         path.transform(scaleDown);
       } else {
         path.transform(scaleUp);
       }

       ctx.clearRect(0, 0, 300, 300);
       ctx.stroke(path.toPath2D());

       ctx.font = '42px monospace';
       let x = 150-ctx.measureText('Transform').width/2;
       ctx.strokeText('Transform', x, 290);

       window.requestAnimationFrame(frame);
     }
     window.requestAnimationFrame(frame);
   }

   function FilledSVGExample(PathKit) {
     let innerRect = PathKit.NewPath();
     innerRect.rect(80, 100, 40, 40);

     let outerRect = PathKit.NewPath();
     outerRect.rect(50, 10, 100, 100)
              .op(innerRect, PathKit.PathOp.XOR);

     let str = outerRect.toSVGString();

     let diffSVG = document.createElementNS('http://www.w3.org/2000/svg', 'path');
     diffSVG.setAttribute('stroke', 'red');
     diffSVG.setAttribute('fill', 'black');
     // force fill-rule to nonzero to demonstrate difference
     diffSVG.setAttribute('fill-rule', 'nonzero');
     diffSVG.setAttribute('d', str);
     document.getElementById('svg2').appendChild(diffSVG);

     let unionSVG = document.createElementNS('http://www.w3.org/2000/svg', 'path');
     unionSVG.setAttribute('stroke', 'red');
     unionSVG.setAttribute('fill', 'black');
     // ask what the path thinks fill-rule should be ('evenodd')
     // SVG and Canvas both use the same keys ('nonzero' and 'evenodd') and both
     // default to 'nonzero', so one call supports both.
     unionSVG.setAttribute('fill-rule', outerRect.getFillTypeString());
     unionSVG.setAttribute('d', str);
     document.getElementById('svg3').appendChild(unionSVG);

     outerRect.delete();
     innerRect.delete();
   }

   function CubicSolverExample(PathKit) {
     let ctx = document.getElementById('cubics').getContext('2d');
     setCanvasSize(ctx, 300, 300);
     // Draw lines between cp0 (0, 0) and cp1 and then cp2 and cp3 (1, 1)
     // scaled up to be on a 300x300 grid instead of unit square
     ctx.strokeStyle = 'black';
     ctx.beginPath();
     ctx.moveTo(0, 0);
     ctx.lineTo(0.1 * 300, 0.5*300);

     ctx.moveTo(0.5 * 300, 0.1*300);
     ctx.lineTo(300, 300);
     ctx.stroke();


     ctx.strokeStyle = 'green';
     ctx.beginPath();

     for (let x = 0; x < 300; x++) {
       // scale X into unit square
       let y = PathKit.cubicYFromX(0.1, 0.5, 0.5, 0.1, x/300);
       ctx.arc(x, y*300, 2, 0, 2*Math.PI);
     }
     ctx.stroke();
   }

 </script>
	<!DOCTYPE html>
	<title>PathKit (Skia's Geometry + WASM)</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>
	svg, canvas {
	border: 1px dashed #AAA;
	}

	canvas {
	width: 200px;
	height: 200px;
	}

	canvas.big {
	width: 300px;
	height: 300px;
	}

	</style>

	<h2> Can output to an SVG Path, a Canvas, or a Path2D object </h2>
	<svg id=svg1 xmlns='http://www.w3.org/2000/svg' width=200 height=200></svg>
	<canvas id=canvas1></canvas>
	<canvas id=canvas2></canvas>

	<h2> Interact with NewPath() just like a Path2D Object </h2>
	<canvas class=big id=canvas3></canvas>
	<canvas class=big id=canvas4></canvas>

	<h2> Has various Path Effects </h2>
	<canvas class=big id=canvas5></canvas>
	<canvas class=big id=canvas6></canvas>
	<canvas class=big id=canvas7></canvas>
	<canvas class=big id=canvas8></canvas>
	<canvas class=big id=canvas9></canvas>
	<canvas class=big id=canvas10></canvas>
	<canvas class=big id=canvas11></canvas>
	<canvas class=big id=canvasTransform></canvas>

	<h2> Supports fill-rules of nonzero and evenodd </h2>
	<svg id=svg2 xmlns='http://www.w3.org/2000/svg' width=200 height=200></svg>
	<svg id=svg3 xmlns='http://www.w3.org/2000/svg' width=200 height=200></svg>

	<h2> Solves Cubics for Y given X </h2>
	<canvas class=big id=cubics></canvas>

	<script type="text/javascript" src="/node_modules/pathkit-wasm/bin/pathkit.js"></script>

	<script type="text/javascript" charset="utf-8">

	PathKitInit({
	locateFile: (file) => '/node_modules/pathkit-wasm/bin/'+file,
	}).ready().then((PathKit) => {
	window.PathKit = PathKit;
	OutputsExample(PathKit);
	Path2DExample(PathKit);
	PathEffectsExample(PathKit);
	MatrixTransformExample(PathKit);
	FilledSVGExample(PathKit);
	CubicSolverExample(PathKit);
	});

	function setCanvasSize(ctx, width, height) {
	ctx.canvas.width = width;
	ctx.canvas.height = height;
	}

	function OutputsExample(PathKit) {
	let firstPath = PathKit.FromSVGString('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');

	let secondPath = PathKit.NewPath();
	// Acts somewhat like the Canvas API, except can be chained
	secondPath.moveTo(1, 1)
	.lineTo(20, 1)
	.lineTo(10, 30)
	.closePath();

	// Join the two paths together (mutating firstPath in the process)
	firstPath.op(secondPath, PathKit.PathOp.INTERSECT);

	let simpleStr = firstPath.toSVGString();

	let newSVG = document.createElementNS('http://www.w3.org/2000/svg', 'path');
	newSVG.setAttribute('stroke', 'rgb(0,0,200)');
	newSVG.setAttribute('fill', 'white');
	newSVG.setAttribute('transform', 'scale(8,8)');
	newSVG.setAttribute('d', simpleStr);
	document.getElementById('svg1').appendChild(newSVG);

	// Draw directly to Canvas
	let ctx = document.getElementById('canvas1').getContext('2d');
	setCanvasSize(ctx, 200, 200);
	ctx.strokeStyle = 'green';
	ctx.fillStyle = 'white';
	ctx.scale(8, 8);
	ctx.beginPath();
	firstPath.toCanvas(ctx);
	ctx.stroke();

	// create Path2D object and use it in a Canvas.
	let path2D = firstPath.toPath2D();
	ctx = document.getElementById('canvas2').getContext('2d');
	setCanvasSize(ctx, 200, 200);
	ctx.canvas.width = 200
	ctx.scale(8, 8);
	ctx.fillStyle = 'purple';
	ctx.strokeStyle = 'orange';
	ctx.fill(path2D);
	ctx.stroke(path2D);

	// clean up WASM memory
	// See http://kripken.github.io/emscripten-site/docs/porting/connecting_cpp_and_javascript/embind.html?highlight=memory#memory-management
	firstPath.delete();
	secondPath.delete();
	}

	function Path2DExample(PathKit) {
	let objs = [new Path2D(), PathKit.NewPath(), new Path2D(), PathKit.NewPath()];
	let canvases = [
	document.getElementById('canvas3').getContext('2d'),
	document.getElementById('canvas4').getContext('2d')
	];

	for (i = 0; i <= 1; i++) {
	let path = objs[i];

	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.bezierCurveTo(90, 10, 160, 150, 190, 10);

	path.moveTo(36, 148);
	path.quadraticCurveTo(66, 188, 120, 136);
	path.lineTo(36, 148);

	path.rect(5, 170, 20, 20);

	path.moveTo(150, 180);
	path.arcTo(150, 100, 50, 200, 20);
	path.lineTo(160, 160);

	path.moveTo(20, 120);
	path.arc(20, 120, 18, 0, 1.75 * Math.PI);
	path.lineTo(20, 120);

	let secondPath = objs[i+2];
	secondPath.ellipse(130, 25, 30, 10, -1Math.PI/8, Math.PI/6, 1.5Math.PI, false);

	path.addPath(secondPath);

	let m = document.createElementNS('http://www.w3.org/2000/svg', 'svg').createSVGMatrix();
	m.a = 1; m.b = 0;
	m.c = 0; m.d = 1;
	m.e = 0; m.f = 20.5;

	path.addPath(secondPath, m);
	// With PathKit, one can also just provide the 6 params as floats, to avoid
	// the overhead of making an SVGMatrix
	// path.addPath(secondPath, 1, 0, 0, 1, 0, 20.5);

	canvasCtx = canvases[i];
	canvasCtx.fillStyle = 'blue';
	setCanvasSize(canvasCtx, 300, 300);
	canvasCtx.scale(1.5, 1.5);
	if (path.toPath2D) {
	canvasCtx.stroke(path.toPath2D());
	} else {
	canvasCtx.stroke(path);
	}
	}


	objs[1].delete();
	}

	// see https://fiddle.skia.org/c/@discrete_path
	function drawStar(path) {
	let R = 115.2, C = 128.0;
	path.moveTo(C + R + 22, C);
	for (let i = 1; i < 8; i++) {
	let a = 2.6927937 * i;
	path.lineTo(C + R * Math.cos(a) + 22, C + R * Math.sin(a));
	}
	path.closePath();
	return path;
	}

	function PathEffectsExample(PathKit) {
	let effects = [
	// no-op
	(path) => path,
	// dash
	(path, counter) => path.dash(10, 3, counter/5),
	// trim (takes optional 3rd param for returning the trimmed part
	// or the complement)
	(path, counter) => path.trim((counter/100) % 1, 0.8, false),
	// simplify
	(path) => path.simplify(),
	// stroke
	(path, counter) => path.stroke({
	width: 10 * (Math.sin(counter/30) + 1),
	join: PathKit.StrokeJoin.BEVEL,
	cap: PathKit.StrokeCap.BUTT,
	miter_limit: 1,
	}),
	// "offset effect", that is, making a border around the shape.
	(path, counter) => {
	let orig = path.copy();
	path.stroke({
	width: 10 + (counter / 4) % 50,
	join: PathKit.StrokeJoin.ROUND,
	cap: PathKit.StrokeCap.SQUARE,
	})
	.op(orig, PathKit.PathOp.DIFFERENCE);
	orig.delete();
	},
	(path, counter) => {
	let simplified = path.simplify().copy();
	path.stroke({
	width: 2 + (counter / 2) % 100,
	join: PathKit.StrokeJoin.BEVEL,
	cap: PathKit.StrokeCap.BUTT,
	})
	.op(simplified, PathKit.PathOp.REVERSE_DIFFERENCE);
	simplified.delete();
	}
	];

	let names = ["(plain)", "Dash", "Trim", "Simplify", "Stroke", "Grow", "Shrink"];

	let counter = 0;
	function frame() {
	counter++;
	for (let i = 0; i < effects.length; i++) {
	let path = PathKit.NewPath();
	drawStar(path);

	// The transforms apply directly to the path.
	effects[i](path, counter);

	let ctx = document.getElementById(`canvas${i+5}`).getContext('2d');
	setCanvasSize(ctx, 300, 300);
	ctx.strokeStyle = '#3c597a';
	ctx.fillStyle = '#3c597a';
	if (i >=4 ) {
	ctx.fill(path.toPath2D(), path.getFillTypeString());
	} else {
	ctx.stroke(path.toPath2D());
	}

	ctx.font = '42px monospace';

	let x = 150-ctx.measureText(names[i]).width/2;
	ctx.strokeText(names[i], x, 290);

	path.delete();
	}
	window.requestAnimationFrame(frame);
	}
	window.requestAnimationFrame(frame);
	}

	function MatrixTransformExample(PathKit) {
	// Creates an animated star that twists and moves.
	let ctx = document.getElementById('canvasTransform').getContext('2d');
	setCanvasSize(ctx, 300, 300);
	ctx.strokeStyle = '#3c597a';

	let path = drawStar(PathKit.NewPath());
	// TODO(kjlubick): Perhaps expose some matrix helper functions to allow
	// clients to build their own matrices like this?
	// These matrices represent a 2 degree rotation and a 1% scale factor.
	let scaleUp = [1.0094, -0.0352, 3.1041,
	0.0352, 1.0094, -6.4885,
	0 , 0 , 1];

	let scaleDown = [ 0.9895, 0.0346, -2.8473,
	-0.0346, 0.9895, 6.5276,
	0 , 0 , 1];

	let i = 0;
	function frame(){
	i++;
	if (Math.round(i/100) % 2) {
	path.transform(scaleDown);
	} else {
	path.transform(scaleUp);
	}

	ctx.clearRect(0, 0, 300, 300);
	ctx.stroke(path.toPath2D());

	ctx.font = '42px monospace';
	let x = 150-ctx.measureText('Transform').width/2;
	ctx.strokeText('Transform', x, 290);

	window.requestAnimationFrame(frame);
	}
	window.requestAnimationFrame(frame);
	}

	function FilledSVGExample(PathKit) {
	let innerRect = PathKit.NewPath();
	innerRect.rect(80, 100, 40, 40);

	let outerRect = PathKit.NewPath();
	outerRect.rect(50, 10, 100, 100)
	.op(innerRect, PathKit.PathOp.XOR);

	let str = outerRect.toSVGString();

	let diffSVG = document.createElementNS('http://www.w3.org/2000/svg', 'path');
	diffSVG.setAttribute('stroke', 'red');
	diffSVG.setAttribute('fill', 'black');
	// force fill-rule to nonzero to demonstrate difference
	diffSVG.setAttribute('fill-rule', 'nonzero');
	diffSVG.setAttribute('d', str);
	document.getElementById('svg2').appendChild(diffSVG);

	let unionSVG = document.createElementNS('http://www.w3.org/2000/svg', 'path');
	unionSVG.setAttribute('stroke', 'red');
	unionSVG.setAttribute('fill', 'black');
	// ask what the path thinks fill-rule should be ('evenodd')
	// SVG and Canvas both use the same keys ('nonzero' and 'evenodd') and both
	// default to 'nonzero', so one call supports both.
	unionSVG.setAttribute('fill-rule', outerRect.getFillTypeString());
	unionSVG.setAttribute('d', str);
	document.getElementById('svg3').appendChild(unionSVG);

	outerRect.delete();
	innerRect.delete();
	}

	function CubicSolverExample(PathKit) {
	let ctx = document.getElementById('cubics').getContext('2d');
	setCanvasSize(ctx, 300, 300);
	// Draw lines between cp0 (0, 0) and cp1 and then cp2 and cp3 (1, 1)
	// scaled up to be on a 300x300 grid instead of unit square
	ctx.strokeStyle = 'black';
	ctx.beginPath();
	ctx.moveTo(0, 0);
	ctx.lineTo(0.1 * 300, 0.5*300);

	ctx.moveTo(0.5 * 300, 0.1*300);
	ctx.lineTo(300, 300);
	ctx.stroke();


	ctx.strokeStyle = 'green';
	ctx.beginPath();

	for (let x = 0; x < 300; x++) {
	// scale X into unit square
	let y = PathKit.cubicYFromX(0.1, 0.5, 0.5, 0.1, x/300);
	ctx.arc(x, y300, 2, 0, 2Math.PI);
	}
	ctx.stroke();
	}

	</script>