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Created
June 23, 2018 07:06
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <meta name="viewport" content="initial-scale=1.0, maximum-scale=1.0" /> | |
| <title>touch me</title> | |
| </head> | |
| <body> | |
| <div style="position:absolute;top:0;left:0;right:0;bottom:0"> | |
| <canvas width="100%" height="100%" id="canvas"></canvas> | |
| </div> | |
| <script> | |
| var canvas = document.getElementById("canvas"); | |
| canvas.width = window.innerWidth; | |
| canvas.height = window.innerHeight; | |
| var context = canvas.getContext("2d"); | |
| var update = function(e) { | |
| console.log(e); | |
| context.clearRect(0, 0, canvas.width, canvas.height); | |
| var len = e.touches.length; | |
| for (var i = 0; i < len; i++) { | |
| var p = e.touches.item(i); | |
| for (var j = i + 1; j < len; j++) { | |
| var q = e.touches.item(j); | |
| context.beginPath(); | |
| context.moveTo(p.clientX, p.clientY); | |
| context.lineTo(q.clientX, q.clientY); | |
| context.stroke(); | |
| } | |
| } | |
| }; | |
| canvas.addEventListener("touchstart", update); | |
| canvas.addEventListener("touchmove", update); | |
| canvas.addEventListener("touchend", update); | |
| console.log(canvas.width, canvas.height); | |
| </script> | |
| </body> | |
| </html> |
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