使用该translate()方法移动画布。HTML5画布提供了translate(x,y)方法，该方法用于将画布及其原点移动到网格中的其他点。
这里的参数x是画布向左或向右移动的量，而y是画布向上或向下移动的量
<!DOCTYPE HTML> <html> <head> <style> #test { width:100px; height:100px; margin:0px auto; } </style> <script> function drawShape(){ //使用DOM获取canvas元素 var canvas = document.getElementById('mycanvas'); //确保不支持画布时不执行 if (canvas.getContext){ //使用getContext将画布用于绘制 var ctx = canvas.getContext('2d'); ctx.fillRect(0,0,300,300); for (i = 0; i < 3; i++) { for (j = 0; j < 3; j++) { ctx.save(); ctx.strokeStyle = "#FF0066"; ctx.translate(50+j*100,50+i*100); drawSpirograph(ctx,10*(j+3)/(j+2),-2*(i+3)/(i+1),10); ctx.restore(); } } } else { alert('You need Safari or Firefox 1.5+ to see this demo.'); } } function drawSpirograph(ctx,R,r,O){ var x1 = R-O; var y1 = 0; var i = 1; ctx.beginPath(); ctx.moveTo(x1,y1); do { if (i>20000) break; var x2 = (R+r)*Math.cos(i*Math.PI/72) - (r+O)*Math.cos(((R+r)/r)*(i*Math.PI/72)); var y2 = (R+r)*Math.sin(i*Math.PI/72) - (r+O)*Math.sin(((R+r)/r)*(i*Math.PI/72)); ctx.lineTo(x2,y2); x1 = x2; y1 = y2; i++; } while (x2 != R-O && y2 != 0 ); ctx.stroke(); } </script> </head> <body id = "test" onload = "drawShape();"> <canvas id = "mycanvas" width = "400" height = "400"></canvas> </body> </html>
