y：文字绘制其实位置左上角坐标y
width：文字一行的宽度，超出会自动进行换行
fontSize：文字大小，整数，单位为px
fontWeight：文字粗细bold、bolder等或者400，500，600…同css的font-weight
fontFamily：文字字体，同css
lineHeight：行高，整数，单位px
color：颜色
marginBottom：如果有多段文字，还可以指定段落之间的距离
文字绘制，同样是异步的，知道调用draw(callback)才真正进行绘制
...
<script src="../dist/li-canvas.js"></script>
...
<body>
<canvas id="test" width="1563" height="1180" style="width: 782px;height: 590px;border: 1px solid red"></canvas>
<script> var canvas=new LiCanvas('test')
canvas.addDrawTextTask("要绘制的文字",{
x:110,
y:496,
width:1340,
fontSize:54,
fontWeight:'bolder',
fontFamily:"PingFangSC-Regular,'Microsoft YaHei',SimSun,Arial,'Helvetica Neue',sans-serif",
lineHeight:70,
color:'#1a1a1a',
marginBottom:40
})
canvas.draw(()=>{
console.log("绘制完成")
}) </script>
</body>
...•绘制多段文字
方法1：反复调用addDrawTextTask(text,style)，同上
方法2：text可以传入一个数组，可以共用style
...
<script src="../dist/li-canvas.js"></script>
...
<body>
<canvas id="test" width="1563" height="1180" style="width: 782px;height: 590px;border: 1px solid red"></canvas><script> var canvas=new LiCanvas('test')
canvas.addDrawTextTask(["要绘制的文字段落1","要绘制的文字段落2"],{
x:110,
y:496,
width:1340,
fontSize:54,
fontWeight:'bolder',
fontFamily:"PingFangSC-Regular,'Microsoft YaHei',SimSun,Arial,'Helvetica Neue',sans-serif",
lineHeight:70,
color:'#1a1a1a',
marginBottom:40
})
canvas.draw(()=>{
console.log("绘制完成")
}) </script>
</body>
...
其中style也可以在对象实例化的时候传入一个默认值，避免反复设置一些共用的style
...
<script src="../dist/li-canvas.js"></script>
...
<body>
<canvas id="test" width="1563" height="1180" style="width: 782px;height: 590px;border: 1px solid red"></canvas>
<script> var canvas=new LiCanvas('test',{
fontStyle:{
fontSize:20,
fontFamily:"PingFangSC-Regular,'Microsoft YaHei',SimSun,Arial,'Helvetica Neue',sans-serif",
