Zepto.js touch,tap增加 touch模塊深入分析

1、 touch庫實現了什么和引入背景

click事件在移動端上會有 300ms 的延遲，同時因為需要 長按 ， 雙觸擊 等富交互，所以我們通常都會引入類似 zepto 這樣的庫。zepto 中touch庫實現了 'swipe', 'swipeLeft', 'swipeRight', 'swipeUp', 'swipeDown', 'doubleTap', 'tap', 'singleTap', 'longTap' 這樣一些功能。

2、touch庫實現'swipe', 'swipeLeft', 'swipeRight', 'swipeUp', 'swipeDown', 'doubleTap', 'tap', 'singleTap', 'longTap'重要源代碼（綁定在touchend事件上）

處理Touch事件能讓你了解到用戶的每一根手指的位置，在touch事件觸發的時候產生，可以通過touch event handler的event對象取到，如果基於zepto.js開發，一般是通過event.touches[0]來獲取屬性。

重要屬性

• clientX、clientY：觸摸點相對於瀏覽器窗口viewport的位置
• pageX、pageY： 觸摸點相對於頁面的位置
• screenX,screenY：觸摸點相對於屏幕的位置
• identifier:touch：對象的unique ID

你可以綁定以下四種Touch事件來了解基本的touch事件：

• touchstart:手指觸摸屏幕上的時候觸發
• touchmove:手指在屏幕上移動的時候觸發
• touchend:手指從屏幕上拿起的時候觸發
• touchcancel:系統取消touch事件的時候觸發

Touch模塊添加以下事件，可以使用 on 和 off 來綁定。

• tap —元素tap的時候觸發。
• singleTap and doubleTap — 這一對事件可以用來檢測元素上的單擊和雙擊。(如果你不需要檢測單擊、雙擊，使用 tap 代替)。
• longTap — 當一個元素被按住超過750ms觸發。
• swipe, swipeLeft, swipeRight, swipeUp, swipeDown — 當元素被划過時觸發。(可選擇給定的方向)

這些事件也是所有Zepto對象集合上的快捷方法。

操作說明

當你觸摸屏幕並抬起手指，只觸發touchstart和touched，當如果手指觸摸屏幕並移動后抬起會觸發touchstart，多次touchmove,touchend或touchcanel，可以根據基本的touch事件來封裝成你想要實現復雜的效果，比如向左或向右滑動，向上或向下滑動，並在滑動時封裝你想實現的效果。

touch.js封裝好了滑動事件的處理，將其添加到自己的項目中，就可以直接調用向右、右、上、下滑動的事件。這樣zepto.js官網手冊中的例子就可以正常運行了。

使用示例

<style>.delete { display: none; }</style> <ul id=items> <li>List item 1 <span class=delete>DELETE</span></li> <li>List item 2 <span class=delete>DELETE</span></li> </ul> <script> // show delete buttons on swipe $('#items li').swipe(function(){ $('.delete').hide() $('.delete', this).show() }) // delete row on tapping delete button $('.delete').tap(function(){ $(this).parent('li').remove() }) </script>
官網下載下來的zepto.js在后面新增下面代碼

;
(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)

效果就實現了