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JavaScript source to create quadratic curves between successive points drawn with the mouse
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <script src="//code.jquery.com/jquery-2.1.0.min.js"></script> | |
| <script class="jsbin" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script> | |
| <meta charset=utf-8 /> | |
| <title>quadraticCurveTo given three points</title> | |
| <style> | |
| body { background:#000; margin:0px; padding:0px; overflow:hidden; } | |
| </style> | |
| </head> | |
| <body> | |
| Used <a href="http://stackoverflow.com/a/3789278">this answer</a> from | |
| <a href="http://stackoverflow.com/questions/3783419/smooth-user-drawn-lines-in-canvas">Smooth user drawn lines in canvas</a> | |
| on SO as a starting point. | |
| <canvas id="canvas"></canvas> | |
| </body> | |
| </html> |
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| $(function() { | |
| var canvas = $('canvas'); | |
| var ctx = canvas[0].getContext('2d'); | |
| var width = window.innerWidth; | |
| var height = window.innerHeight; | |
| canvas.height = height; | |
| canvas.width = width; | |
| canvas.css('border', '1px solid white;'); | |
| var pts = []; | |
| function drawPoint(evt) { | |
| var pt = { | |
| x: parseInt(evt.pageX - canvas.offset().left), | |
| y: parseInt(evt.pageY - canvas.offset().top) | |
| }; | |
| circle(pt.x, pt.y, 2); | |
| pts.push(pt); | |
| if (pts.length == 3) { | |
| ctx.beginPath(); | |
| ctx.moveTo(pts[0].x, pts[0].y); | |
| ctx.quadraticCurveTo(pts[1].x, pts[1].y, pts[2].x, pts[2].y); | |
| ctx.strokeStyle = '#ccc'; | |
| ctx.stroke(); | |
| pts.shift(); pts.shift(); | |
| } | |
| } // drawPoint(evt) | |
| function circle(cx, cy, r) { | |
| ctx.beginPath(); | |
| ctx.arc(cx, cy, r, 0, 2*Math.PI, false); | |
| ctx.strokeStyle = '#ffffff'; | |
| ctx.fillStyle = 'white'; | |
| ctx.fill(); | |
| ctx.stroke(); | |
| } | |
| function rgb() { | |
| color = 'rgb('; | |
| for(var i = 0; i< 3; i++) { | |
| color += Math.floor(Math.random() * 255)+','; | |
| } | |
| return color.replace(/\,$/,')'); | |
| } | |
| $('canvas').mousedown(drawPoint); | |
| }); |
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