本文通过json机构，HTML代码以及JS代码详细给大家分析了canvas轨迹回放功能实现的过程，以下是全部内容。
json结构
[
{
"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
}
]
}
]
html
将json作为js文件引入，并将其赋值给全局变量testPath(引入方式按照实际项目要求来)
<style>
*{margin:0; padding:0;}
#test{border:1px solid #ccc; background: #eee; margin:20px 30px;}
</style>
<p><button id="start">start</button></p>
<canvas id='test' width="600" height="200"></canvas>
<script type="text/javascript" src='js/jquery-2.1.4.min.js'></script>
<script type="text/javascript" src='js/number.js'></script>
js
$('#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();
});
以上就是本次文章的全部内容，如果大家在测试的时候还有什么疑问，可以在下方的留言区讨论。