使用Canvas 实现手机端签名

这是继上一篇文章后的补充：

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//初始化
    function initCanvas2() {
            let offset = myCanvas.getBoundingClientRect();
            var start = (e) => {
                e.preventDefault();
                isMouseMove = true;
                drawLine(
                    e.changedTouches[0].clientX - offset.left,
                    e.changedTouches[0].clientY - offset.top,
                    false
                );
            };
            let move = (e) => {
                if (isMouseMove) {
                    drawLine(
                        e.changedTouches[0].clientX - offset.left,
                        e.changedTouches[0].clientY - offset.top,
                        true
                    );
                }
            };
            let end = (e) => {
                isMouseMove = false;
            };
            let cancel = (e) => {
                isMouseMove = false;
            };
    
            myCanvas.addEventListener('touchstart', start)
            myCanvas.addEventListener('touchmove', move)
            myCanvas.addEventListener('touchend', end)
            myCanvas.addEventListener("touchcancel", cancel)
        }