移动端Canvas手写签名

效果图

基于vue,可以保存上传

项目地址 vue-signature

实现

1.canvas画图,参考 jrainlau

<script>
var draw;
var preHandler = function(e){e.preventDefault();}
class Draw {
constructor(el) {
this.el = el
this.canvas = document.getElementById(this.el)
this.cxt = this.canvas.getContext('2d')
this.stage_info = canvas.getBoundingClientRect()
this.path = {
beginX: 0,
beginY: 0,
endX: 0,
endY: 0
}
}
init(btn) {
var that = this;

this.canvas.addEventListener('touchstart', function(event) {
document.addEventListener('touchstart', preHandler, false);
that.drawBegin(event)
})
this.canvas.addEventListener('touchend', function(event) {
document.addEventListener('touchend', preHandler, false);
that.drawEnd()

})
this.clear(btn)
}
drawBegin(e) {
var that = this;
window.getSelection() ? window.getSelection().removeAllRanges() : document.selection.empty()
this.cxt.strokeStyle = "#000"
this.cxt.beginPath()
this.cxt.moveTo(
e.changedTouches[0].clientX - this.stage_info.left,
e.changedTouch
4000
es[0].clientY - this.stage_info.top
)
this.path.beginX = e.changedTouches[0].clientX - this.stage_info.left
this.path.beginY = e.changedTouches[0].clientY - this.stage_info.top
canvas.addEventListener("touchmove",function(){
that.drawing(event)
})
}
drawing(e) {
this.cxt.lineTo(
e.changedTouches[0].clientX - this.stage_info.left,
e.changedTouches[0].clientY - this.stage_info.top
)
this.path.endX = e.changedTouches[0].clientX - this.stage_info.left
this.path.endY = e.changedTouches[0].clientY - this.stage_info.top
this.cxt.stroke()
}
drawEnd() {
document.removeEventListener('touchstart', preHandler, false);
document.removeEventListener('touchend', preHandler, false);
document.removeEventListener('touchmove', preHandler, false);
//canvas.ontouchmove = canvas.ontouchend = null
}
clear(btn) {
this.cxt.clearRect(0, 0, 300, 600)
}
save(){
return canvas.toDataURL("image/png")
}
}

export default {
data () {
return {
msg: 'Welcome to Your Vue.js App',
val:true,
url:""
}
},
mounted() {
draw=new Draw('canvas');
draw.init();
},
methods:{
clear:function(){
draw.clear();
},
save:function(){
var data=draw.save();
this.url = data;
console.log(data)
}
}
}
</script>

2.移动端事件监听,参考 [BlandonTsai(http://www.caihaibo.cn/author/blandon)

var preHandler = function(e){e.preventDefault();}
document.addEventListener('touchmove', preHandler, false);
document.removeEventListener('touchmove', preHandler, false);

遇到的问题

移动端的事件监听

作者：Shayne_Wang
链接：https://www.jianshu.com/p/9536d4f4fe6a
來源：简书
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

感谢分享   https://www.jianshu.com/p/9536d4f4fe6a[/code]