所以我目前正在尝试为Web应用程序创建笔记本样式的模块。目前它的鼠标事件工作得非常好,但在使用触摸事件时却没有。
//TOUCH LISTENER
theCanvas.addEventListener("touchstart", startT, false);
theCanvas.addEventListener("touchend", endT, false);
theCanvas.addEventListener("touchmove", moveT, false);
//MOUSE LISTENER
theCanvas.addEventListener("mousedown", start);
theCanvas.addEventListener("mouseup", end);
theCanvas.addEventListener("mousemove", move, false);
//MOUSE EVENTS
function start(event) {
if (event.button === MAIN_MOUSE_BUTTON) {
shouldDraw = true;
setLineProperties(theContext);
theContext.beginPath();
let elementRect = event.target.getBoundingClientRect();
theContext.moveTo(event.clientX - elementRect.left, event.clientY - elementRect.top);
console.log(PenType(mode));
}
}
function end(event) {
if (event.button === MAIN_MOUSE_BUTTON) {
shouldDraw = false;
}
}
function move(event) {
if (shouldDraw) {
let elementRect = event.target.getBoundingClientRect();
theContext.lineTo(event.clientX - elementRect.left, event.clientY - elementRect.top);
theContext.stroke()
}
}
//TOUCH EVENTS
function startT(event) {
event.preventDefault();
shouldDraw = true;
setLineProperties(theContext);
theContext.beginPath();
let elementRect = event.target.getBoundingClientRect();
theContext.moveTo(event.clientX - elementRect.left, event.clientY - elementRect.top);
console.log(PenType(mode));
}
function endT(event) {
if (event.touches.length == 1) {
event.preventDefault();
shouldDraw = false;
}
}
function moveT(event) {
if (shouldDraw) {
event.preventDefault();
let elementRect = event.target.getBoundingClientRect();
theContext.lineTo(event.clientX - elementRect.left, event.clientY - elementRect.top);
theContext.stroke()
}
}
虽然鼠标事件功能齐全,但允许在画布上绘图。触摸事件只能在画布的左边和上边框附近留出一个小空间,只有当你点击边框时,它才会被点亮。它应该像鼠标事件一样工作
由于触摸事件可以处理多个触摸点,因此对于鼠标,event.clientX和event.clientY不会描述手指的x和y。相反,你得到了event.touches这是一个坐标数组。所以在你的代码中,每当你想要处理触摸事件时,只需用event.clientX
替换event.touches[0].clientX
,用event.clientY
替换event.touches[0].clientY
(考虑到你当然只想处理一根手指)