src/gesture/tap.js
import { Recognizer } from './recognizer'
var root = avalon.root
var supportPointer = !!navigator.pointerEnabled || !!navigator.msPointerEnabled
// 支持pointer的设备可用样式来取消click事件的300毫秒延迟
if (supportPointer) {
root.style.msTouchAction = root.style.touchAction = 'none'
}
var tapRecognizer = {
events: ['tap'],
touchBoundary: 10,
tapDelay: 90,
needClick: function(target) {
//判定是否使用原生的点击事件, 否则使用sendClick方法手动触发一个人工的点击事件
switch (target.nodeName.toLowerCase()) {
case 'button':
case 'select':
case 'textarea':
if (target.disabled) {
return true
}
break
case 'input':
// IOS6 pad 上选择文件，如果不是原生的click，弹出的选择界面尺寸错误
if ((Recognizer.isIOS && target.type === 'file') || target.disabled) {
return true
}
break
case 'label':
case 'iframe':
case 'video':
return true
}
return false
},
needFocus: function(target) {
switch (target.nodeName.toLowerCase()) {
case 'textarea':
case 'select': //实测android下select也需要
return true
case 'input':
switch (target.type) {
case 'button':
case 'checkbox':
case 'file':
case 'image':
case 'radio':
case 'submit':
return false
}
//如果是只读或disabled状态,就无须获得焦点了
return !target.disabled && !target.readOnly
default:
return false
}
},
focus: function(targetElement) {
var length
//在iOS7下, 对一些新表单元素(如date, datetime, time, month)调用focus方法会抛错,
//幸好的是,我们可以改用setSelectionRange获取焦点, 将光标挪到文字的最后
var type = targetElement.type
if (Recognizer.isIOS && targetElement.setSelectionRange &&
type.indexOf('date') !== 0 && type !== 'time' && type !== 'month') {
length = targetElement.value.length
targetElement.setSelectionRange(length, length)
} else {
targetElement.focus()
}
},
findControl: function(labelElement) {
// 获取label元素所对应的表单元素
// 可以能过control属性, getElementById, 或用querySelector直接找其内部第一表单元素实现
if (labelElement.control !== undefined) {
return labelElement.control
}
if (labelElement.htmlFor) {
return document.getElementById(labelElement.htmlFor)
}
return labelElement.querySelector('button, input:not([type=hidden]), keygen, meter, output, progress, select, textarea')
},
fixTarget: function(target) {
if (target.nodeType === 3) {
return target.parentNode
}
if (window.SVGElementInstance && (target instanceof SVGElementInstance)) {
return target.correspondingUseElement
}
return target
},
updateScrollParent: function(targetElement) {
//如果事件源元素位于某一个有滚动条的祖父元素中,那么保持其scrollParent与scrollTop值
var scrollParent = targetElement.tapScrollParent
if (!scrollParent || !scrollParent.contains(targetElement)) {
var parentElement = targetElement
do {
if (parentElement.scrollHeight > parentElement.offsetHeight) {
scrollParent = parentElement
targetElement.tapScrollParent = parentElement
break
}
parentElement = parentElement.parentElement
} while (parentElement)
}
if (scrollParent) {
scrollParent.lastScrollTop = scrollParent.scrollTop
}
},
touchHasMoved: function(event) {
//判定是否发生移动,其阀值是10px
var touch = event.changedTouches[0],
boundary = tapRecognizer.touchBoundary
return Math.abs(touch.pageX - tapRecognizer.pageX) > boundary ||
Math.abs(touch.pageY - tapRecognizer.pageY) > boundary
},
findType: function(targetElement) {
// 安卓chrome浏览器上，模拟的 click 事件不能让 select 打开，故使用 mousedown 事件
return Recognizer.isAndroid && targetElement.tagName.toLowerCase() === 'select' ?
'mousedown' : 'click'
},
sendClick: function(targetElement, event) {
// 在click之前触发tap事件
Recognizer.fire(targetElement, 'tap', {
touchEvent: event
})
var clickEvent, touch
//某些安卓设备必须先移除焦点，之后模拟的click事件才能让新元素获取焦点
if (document.activeElement && document.activeElement !== targetElement) {
document.activeElement.blur()
}
touch = event.changedTouches[0]
// 手动触发点击事件,此时必须使用document.createEvent('MouseEvents')来创建事件
// 及使用initMouseEvent来初始化它
clickEvent = document.createEvent('MouseEvents')
clickEvent.initMouseEvent(tapRecognizer.findType(targetElement), true, true,
window, 1, touch.screenX, touch.screenY, touch.clientX, touch.clientY,
false, false, false, false, 0, null)
clickEvent.touchEvent = event
targetElement.dispatchEvent(clickEvent)
},
touchstart: function(event) {
//忽略多点触摸
if (event.targetTouches.length !== 1) {
return true
}
//修正事件源对象
var targetElement = tapRecognizer.fixTarget(event.target)
var touch = event.targetTouches[0]
if (Recognizer.isIOS) {
// 判断是否是点击文字，进行选择等操作，如果是，不需要模拟click
var selection = window.getSelection()
if (selection.rangeCount && !selection.isCollapsed) {
return true
}
var id = touch.identifier
//当 alert 或 confirm 时，点击其他地方，会触发touch事件，identifier相同，此事件应该被忽略
if (id && isFinite(tapRecognizer.lastTouchIdentifier) && tapRecognizer.lastTouchIdentifier === id) {
event.preventDefault()
return false
}
tapRecognizer.lastTouchIdentifier = id
tapRecognizer.updateScrollParent(targetElement)
}
//收集触摸点的信息
tapRecognizer.status = "tapping"
tapRecognizer.startTime = Date.now()
tapRecognizer.element = targetElement
tapRecognizer.pageX = touch.pageX
tapRecognizer.pageY = touch.pageY
// 如果点击太快,阻止双击带来的放大收缩行为
if ((tapRecognizer.startTime - tapRecognizer.lastTime) < tapRecognizer.tapDelay) {
event.preventDefault()
}
},
touchmove: function(event) {
if (tapRecognizer.status !== "tapping") {
return true
}
// 如果事件源元素发生改变,或者发生了移动,那么就取消触发点击事件
if (tapRecognizer.element !== tapRecognizer.fixTarget(event.target) ||
tapRecognizer.touchHasMoved(event)) {
tapRecognizer.status = tapRecognizer.element = 0
}
},
touchend: function(event) {
var targetElement = tapRecognizer.element
var now = Date.now()
//如果是touchstart与touchend相隔太久,可以认为是长按,那么就直接返回
//或者是在touchstart, touchmove阶段,判定其不该触发点击事件,也直接返回
if (!targetElement || now - tapRecognizer.startTime > tapRecognizer.tapDelay) {
return true
}
tapRecognizer.lastTime = now
var startTime = tapRecognizer.startTime
tapRecognizer.status = tapRecognizer.startTime = 0
var targetTagName = targetElement.tagName.toLowerCase()
if (targetTagName === 'label') {
//尝试触发label上可能绑定的tap事件
Recognizer.fire(targetElement, 'tap', {
touchEvent: event
})
var forElement = tapRecognizer.findControl(targetElement)
if (forElement) {
tapRecognizer.focus(targetElement)
targetElement = forElement
}
} else if (tapRecognizer.needFocus(targetElement)) {
// 如果元素从touchstart到touchend经历时间过长,那么不应该触发点击事
// 或者此元素是iframe中的input元素,那么它也无法获点焦点
if ((now - startTime) > 100 || (deviceIsIOS && window.top !== window && targetTagName === 'input')) {
tapRecognizer.element = 0
return false
}
tapRecognizer.focus(targetElement)
Recognizer.isAndroid && tapRecognizer.sendClick(targetElement, event)
return false
}
if (Recognizer.isIOS) {
//如果它的父容器的滚动条发生改变,那么应该识别为划动或拖动事件,不应该触发点击事件
var scrollParent = targetElement.tapScrollParent
if (scrollParent && scrollParent.lastScrollTop !== scrollParent.scrollTop) {
return true
}
}
//如果这不是一个需要使用原生click的元素，则屏蔽原生事件，避免触发两次click
if (!tapRecognizer.needClick(targetElement)) {
event.preventDefault()
// 触发一次模拟的click
tapRecognizer.sendClick(targetElement, event)
}
},
touchcancel: function() {
tapRecognizer.startTime = tapRecognizer.element = 0
}
}
Recognizer.add('tap', tapRecognizer)