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Little HTML5 mobile web app for drawing on a canvas
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta name="viewport" content="user-scalable=no,initial-scale=1.0,maximum-scale=1.0" /> | |
| <style> | |
| body { padding:10px; margin:0px; background-color: #ccc; } | |
| #main { margin: 10px auto 0px auto; } | |
| </style> | |
| <script src="draw.js"></script> | |
| </head> | |
| <body> | |
| <button id="clear">clear</button><br> | |
| <canvas id="main" width="300" height="300"></canvas> | |
| </body> | |
| </html> |
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| window.onload = function() { | |
| document.ontouchmove = function(e){ e.preventDefault(); } | |
| var canvas = document.getElementById('main'); | |
| var canvastop = canvas.offsetTop | |
| var context = canvas.getContext("2d"); | |
| var lastx; | |
| var lasty; | |
| context.strokeStyle = "#000000"; | |
| context.lineCap = 'round'; | |
| context.lineJoin = 'round'; | |
| context.lineWidth = 5; | |
| function clear() { | |
| context.fillStyle = "#ffffff"; | |
| context.rect(0, 0, 300, 300); | |
| context.fill(); | |
| } | |
| function dot(x,y) { | |
| context.beginPath(); | |
| context.fillStyle = "#000000"; | |
| context.arc(x,y,1,0,Math.PI*2,true); | |
| context.fill(); | |
| context.stroke(); | |
| context.closePath(); | |
| } | |
| function line(fromx,fromy, tox,toy) { | |
| context.beginPath(); | |
| context.moveTo(fromx, fromy); | |
| context.lineTo(tox, toy); | |
| context.stroke(); | |
| context.closePath(); | |
| } | |
| canvas.ontouchstart = function(event){ | |
| event.preventDefault(); | |
| lastx = event.touches[0].clientX; | |
| lasty = event.touches[0].clientY - canvastop; | |
| dot(lastx,lasty); | |
| } | |
| canvas.ontouchmove = function(event){ | |
| event.preventDefault(); | |
| var newx = event.touches[0].clientX; | |
| var newy = event.touches[0].clientY - canvastop; | |
| line(lastx,lasty, newx,newy); | |
| lastx = newx; | |
| lasty = newy; | |
| } | |
| var clearButton = document.getElementById('clear') | |
| clearButton.onclick = clear | |
| clear() | |
| } |
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