发现一个bug，就是知识单纯鼠标点击canvas内的话，并不会有痕迹出来，有没有人把这样的实现代码贴出来参考一下？
已经找到解决方法：
var isMouseMove = false;
canvas.onmouseup = function(e){
e.preventDefault();
isMouseDown = false;
var curLoc = windowToCanvas(e.clientX ,e.clientY);
console.log(curLoc.x +"," + curLoc.y +"," +lastLoc.x+"," +lastLoc.y);
if(isMouseMove != true)
{
context.beginPath()
context.arc(curLoc.x, curLoc.y, 15, 0 ,2*Math.PI);
context.fillStyle = drawColor;
context.fill();
console.log("1");
}
isMouseMove = false;
}