在canvas中如何实现轨迹回放功能

[ { "path": [ { "x": 82, "y": 43 }, { "x": 83, "y": 43 }, { "x": 84, "y": 45 }, { "x": 86, "y": 47 }, { "x": 86, "y": 49 }, { "x": 86, "y": 54 }, { "x": 86, "y": 59 }, { "x": 86, "y": 64 }, { "x": 86, "y": 69 }, { "x": 86, "y": 74 }, { "x": 86, "y": 78 }, { "x": 86, "y": 83 }, { "x": 86, "y": 87 }, { "x": 86, "y": 89 }, { "x": 86, "y": 91 }, { "x": 86, "y": 92 }, { "x": 86, "y": 93 }, { "x": 86, "y": 94 }, { "x": 86, "y": 95 } ] }, { "path": [ { "x": 129, "y": 36 }, { "x": 129, "y": 39 }, { "x": 129, "y": 44 }, { "x": 129, "y": 49 }, { "x": 129, "y": 54 }, { "x": 129, "y": 59 }, { "x": 128, "y": 65 }, { "x": 127, "y": 73 }, { "x": 125, "y": 78 }, { "x": 125, "y": 81 }, { "x": 124, "y": 88 }, { "x": 123, "y": 91 }, { "x": 123, "y": 94 }, { "x": 123, "y": 96 }, { "x": 123, "y": 97 }, { "x": 123, "y": 98 }, { "x": 123, "y": 99 }, { "x": 122, "y": 100 } ] } ]

 
start
   

$('#start').click(function(event) { var lineIndex = 0,pointIndex = 0,line2; var obj = document.getElementById('test'); var cxt = obj.getContext('2d'); cxt.lineWidth = 1; cxt.strokeStyle = 'red'; cxt.lineCap = 'round'; cxt.clearRect(0,0,600,200); function drawBegin(){ cxt.beginPath(); pointIndex=0; var intervalHandle = window.setInterval(function () { line2 = testPath[lineIndex].path[pointIndex]; if (!line2) { window.clearInterval(intervalHandle); if (lineIndex < testPath.length - 1) { lineIndex = lineIndex + 1; drawBegin(); } }else{ if (pointIndex == 0) { cxt.moveTo(line2.x, line2.y); } pointIndex = pointIndex + 1; cxt.lineTo(line2.x, line2.y); cxt.stroke(); } },0); } drawBegin(); });