h5 canvas 滑鼠繪畫
阿新 • • 發佈：2019-02-15
var box=document.getElementById('box');
var oc=box.getContext('2d');
box.onmousedown=function(e){
e=e||window.event;
var ox=e.clientX-box.offsetLeft;
var oy=e.clientY-box.offsetTop;
oc.moveTo(ox,oy);
document.onmousemove=function