目的：记录 Zepto.js touch模块 源码阅读
源码：
// Zepto.js
// (c) 2010-2015 Thomas Fuchs
// Zepto.js may be freely distributed under the MIT license. ;
(function($) {
var touch = {},
touchTimeout, tapTimeout, swipeTimeout, longTapTimeout,
longTapDelay = 750,
gesture function swipeDirection(x1, x2, y1, y2) {
return Math.abs(x1 - x2) >=
Math.abs(y1 - y2) ? (x1 - x2 > 0 ? 'Left' : 'Right') : (y1 - y2 > 0 ? 'Up' : 'Down')
} function longTap() {
longTapTimeout = null
if (touch.last) {
touch.el.trigger('longTap')
touch = {}
}
} function cancelLongTap() {
if (longTapTimeout) clearTimeout(longTapTimeout)
longTapTimeout = null
} function cancelAll() {
if (touchTimeout) clearTimeout(touchTimeout)
if (tapTimeout) clearTimeout(tapTimeout)
if (swipeTimeout) clearTimeout(swipeTimeout)
if (longTapTimeout) clearTimeout(longTapTimeout)
touchTimeout = tapTimeout = swipeTimeout = longTapTimeout = null
touch = {}
} function isPrimaryTouch(event) {
return (event.pointerType == 'touch' ||
event.pointerType == event.MSPOINTER_TYPE_TOUCH) && event.isPrimary
} function isPointerEventType(e, type) {
return (e.type == 'pointer' + type ||
e.type.toLowerCase() == 'mspointer' + type)
} $(document).ready(function() {
var now, delta, deltaX = 0,
deltaY = 0,
firstTouch, _isPointerType if ('MSGesture' in window) {
gesture = new MSGesture()
gesture.target = document.body
} $(document)
.bind('MSGestureEnd', function(e) {
var swipeDirectionFromVelocity =
e.velocityX > 1 ? 'Right' : e.velocityX < -1 ? 'Left' : e.velocityY > 1 ? 'Down' : e.velocityY < -1 ? 'Up' : null;
if (swipeDirectionFromVelocity) {
touch.el.trigger('swipe')
touch.el.trigger('swipe' + swipeDirectionFromVelocity)
}
})
.on('touchstart MSPointerDown pointerdown', function(e) {
if ((_isPointerType = isPointerEventType(e, 'down')) && !isPrimaryTouch(e)) return
firstTouch = _isPointerType ? e : e.touches[0]
if (e.touches && e.touches.length === 1 && touch.x2) {
// Clear out touch movement data if we have it sticking around
// This can occur if touchcancel doesn't fire due to preventDefault, etc.
touch.x2 = undefined
touch.y2 = undefined
}
now = Date.now()
delta = now - (touch.last || now)
touch.el = $('tagName' in firstTouch.target ? firstTouch.target : firstTouch.target.parentNode)
touchTimeout && clearTimeout(touchTimeout)
touch.x1 = firstTouch.pageX
touch.y1 = firstTouch.pageY
if (delta > 0 && delta <= 250) touch.isDoubleTap = true
touch.last = now
longTapTimeout = setTimeout(longTap, longTapDelay)
// adds the current touch contact for IE gesture recognition
if (gesture && _isPointerType) gesture.addPointer(e.pointerId);
})
.on('touchmove MSPointerMove pointermove', function(e) {
if ((_isPointerType = isPointerEventType(e, 'move')) && !isPrimaryTouch(e)) return
firstTouch = _isPointerType ? e : e.touches[0]
cancelLongTap()
touch.x2 = firstTouch.pageX
touch.y2 = firstTouch.pageY deltaX += Math.abs(touch.x1 - touch.x2)
deltaY += Math.abs(touch.y1 - touch.y2)
})
.on('touchend MSPointerUp pointerup', function(e) {
if ((_isPointerType = isPointerEventType(e, 'up')) && !isPrimaryTouch(e)) return
cancelLongTap() // swipe
if ((touch.x2 && Math.abs(touch.x1 - touch.x2) > 30) ||
(touch.y2 && Math.abs(touch.y1 - touch.y2) > 30)) swipeTimeout = setTimeout(function() {
touch.el.trigger('swipe')
touch.el.trigger('swipe' + (swipeDirection(touch.x1, touch.x2, touch.y1, touch.y2)))
touch = {}
}, 0) // normal tap
else if ('last' in touch)
// don't fire tap when delta position changed by more than 30 pixels,
// for instance when moving to a point and back to origin
if (deltaX < 30 && deltaY < 30) {
// delay by one tick so we can cancel the 'tap' event if 'scroll' fires
// ('tap' fires before 'scroll')
tapTimeout = setTimeout(function() { // trigger universal 'tap' with the option to cancelTouch()
// (cancelTouch cancels processing of single vs double taps for faster 'tap' response)
var event = $.Event('tap')
event.cancelTouch = cancelAll
touch.el.trigger(event) // trigger double tap immediately
if (touch.isDoubleTap) {
if (touch.el) touch.el.trigger('doubleTap')
touch = {}
} // trigger single tap after 250ms of inactivity
else {
touchTimeout = setTimeout(function() {
touchTimeout = null
if (touch.el) touch.el.trigger('singleTap')
touch = {}
}, 250)
}
}, 0)
} else {
touch = {}
}
deltaX = deltaY = 0 })
// when the browser window loses focus,
// for example when a modal dialog is shown,
// cancel all ongoing events
.on('touchcancel MSPointerCancel pointercancel', cancelAll) // scrolling the window indicates intention of the user
// to scroll, not tap or swipe, so cancel all ongoing events
$(window).on('scroll', cancelAll)
}) ;
['swipe', 'swipeLeft', 'swipeRight', 'swipeUp', 'swipeDown',
'doubleTap', 'tap', 'singleTap', 'longTap'
].forEach(function(eventName) {
$.fn[eventName] = function(callback) {
return this.on(eventName, callback)
}
})
})(Zepto)
分析：
var now, delta, touch = {};
$(document)
.on('touchstart', startListener)
.on('touchmove', moveListener)
.on('touchend', endListener);1、是单击还是双击
function startListener(e){
now = Date.now();
delta = now - (touch.last || now);
// 手指连续轻触两次，时间间隔大于0，小于等于.25s，则为双击，反之单击
if ( delta > 0 && delta <= 250 ) {
touch.isDoubleTap = true;
}
touch.last = now;
}2、处理手指长按
var longTapTimeout, longTapDelay = 750;
function longTap() {
longTapTimeout = null
if (touch.last) {
touch.el.trigger('longTap')
touch = {}
}
}
function cancelLongTap() {
if (longTapTimeout) clearTimeout(longTapTimeout)
longTapTimeout = null
} function startListener(e){
// 默认就是长按，如果手指未移动和离开，超过.75s就触发longTap
longTapTimeout = setTimeout(longTap, longTapDelay)
}
function moveListener(e){
// 如果手指轻触屏幕后未超过.75s，则取消手指长按监听
longTapTimeout = setTimeout(longTap, longTapDelay)
}
function endListener(e){
// 如果手指轻触屏幕后未超过.75s，则取消手指长按监听
longTapTimeout = setTimeout(longTap, longTapDelay)
}
3、是滑动(swipe)还是轻触(tap)
// 如果手指移动屏幕超过30像素，则触发相应的滑动事件，swipeLeft, swipeRight, swipeUp, swipeDown
function endListener(e){
// swipe
if ((touch.x2 && Math.abs(touch.x1 - touch.x2) > 30) ||
(touch.y2 && Math.abs(touch.y1 - touch.y2) > 30)) { swipeTimeout = setTimeout(function() {
touch.el.trigger('swipe')
touch.el.trigger('swipe' + (swipeDirection(touch.x1, touch.x2, touch.y1, touch.y2)))
touch = {}
}, 0);
}
else {
// handle tap
// 关于处理tap事件，请看第四点
}
}
4、轻触 tap, singleTap, doubleTap
4.1、何时触发 tap ？
条件1：手指移动不超过30像素
if ((touch.x2 && Math.abs(touch.x1 - touch.x2) > 30) ||
(touch.y2 && Math.abs(touch.y1 - touch.y2) > 30)) {
// swipe
}
else {
// tap
}
条件2：依据条件1，基本上可以触发tap了，但是还考虑了另一种情况，手指滑动屏幕后又滑动到起始点，那么：
!Math.abs(touch.x1 - touch.x2) > 30) === !Math.abs(touch.y1 - touch.y2) > 30) === true;
为了不触发tap事件，这里又加了条件限制，理解这点很重要
if (deltaX < 30 && deltaY < 30) {
// handle tap
}注意：
deltaX !== Math.abs(touch.x1 - touch.x2);
deltaY !== Math.abs(touch.y1 - touch.y2);
请看 moveListener 中的代码：
function moveListener(e){
// ...
touch.x2 = firstTouch.pageX
touch.y2 = firstTouch.pageY
deltaX += Math.abs(touch.x1 - touch.x2)
deltaY += Math.abs(touch.y1 - touch.y2)
}例: deltaX的计算，你懂得...
if ( Math.abs(touch.x1 - touch.x2) === 10 ) {
deltaX = 10 + 9 + 8 + ... + 0;
}4.2、处理tap,doubleTap,singleTap三者之间的关系
function cancelAll() {
if (touchTimeout) clearTimeout(touchTimeout)
if (tapTimeout) clearTimeout(tapTimeout)
if (swipeTimeout) clearTimeout(swipeTimeout)
if (longTapTimeout) clearTimeout(longTapTimeout)
touchTimeout = tapTimeout = swipeTimeout = longTapTimeout = null
// 这句很重要，将影响所有需要对touch对象属性判断的语句
touch = {}
}
function endListener(e){
tapTimeout = setTimeout(function() {
var event = $.Event('tap')
// tap事件对象event可以取消后续绑定的doubleTap, singleTap处理器
event.cancelTouch = cancelAll
touch.el.trigger(event)
// 立即触发双击事件
if (touch.isDoubleTap) {
if (touch.el) touch.el.trigger('doubleTap')
touch = {}
}
// 定时.25s后再触发单击事件
else {
touchTimeout = setTimeout(function() {
touchTimeout = null
if (touch.el) touch.el.trigger('singleTap')
touch = {}
}, 250)
}
}, 0)
}例如：如何在tap事件处理器中取消 doubleTap或singleTap事件监听器
$('body')
.on('tap', function(e){
console.log('tap');
// 执行下面语句将影响是否触发绑定的 doubleTap或singleTap 处理器
e.cancelTouch();
})
.on('doubleTap', function(e){
console.log('doubleTap');
})
.on('singleTap', function(e){
console.log('singleTap');
});
// 'tap'5、兼容指针事件系统
// 判断是否是指针事件类型
function isPointerEventType(e, type) {
return (e.type == 'pointer' + type ||
e.type.toLowerCase() == 'mspointer' + type)
} // 判断是否是第一个touch或pointer事件对象
function isPrimaryTouch(event) {
return (event.pointerType == 'touch' ||
event.pointerType == event.MSPOINTER_TYPE_TOUCH) && event.isPrimary
}
// 如果是指针类型是 pointerdown 或 pointermove 或 pointerup 且 不是第一个touch 或 pointer 事件对象，返回空，
// 直接屏蔽了第二个、第三...的触摸处理
if ((_isPointerType = isPointerEventType(e, 'down')) && !isPrimaryTouch(e)) return
if ((_isPointerType = isPointerEventType(e, 'move')) && !isPrimaryTouch(e)) return
if ((_isPointerType = isPointerEventType(e, 'up')) && !isPrimaryTouch(e)) return
6、快捷注册事件
['swipe', 'swipeLeft', 'swipeRight', 'swipeUp', 'swipeDown',
'doubleTap', 'tap', 'singleTap', 'longTap'
].forEach(function(eventName) {
$.fn[eventName] = function(callback) {
return this.on(eventName, callback)
}
});
你可以用 on 方法注册事件，也可以快捷注册，下面两种方式都是一样的，类似jQuery用法
$('body').on('tap', function(){ console.log('body trigger tap event'); });
$('body').tap(function(){ console.log('body trigger tap event'); });篇尾总结：
源码中大部分代码都已经解析完毕，如有不合理的地方，还请赐教，touch模块的中所有的事件都支持冒泡，但是不会对原生的touch事件产生影响，另外所有元素绑定的事件都是在文档document元素的touchend处理中触发，
如果页面中有一元素在原生touch事件中阻止了冒泡，那么页面中所有元素注册的 zepto touch事件都不会被触发，慎重慎重...，至此完毕，感谢阅读！！