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/**
* 使用wxs方案实现slider
* 兼容微信,QQ,H5,Vue版的安卓和iOS
*/
/**
* 开始滑动操作
* @param {Object} e
* @param {Object} ownerInstance
*/
function onTouchMove(e, ownerInstance) {
// wxs事件对象下有一个instance属性,表示当前触发此事件的组件的实例,通过该实例,可以获取相关的dataset,设置样式等信息
// https://developers.weixin.qq.com/miniprogram/dev/framework/view/interactive-animation.html
var instance = e.instance;
// getState()为一个对象,挂载在instance上,类似组件的data一样,可以存放一些变量,供以后的触发事件中使用
var state = instance.getState()
// 滑块组件的整体尺寸信息
var mp = state.mp
if(mp.disabled) {
return
}
var distanceX = getTouchX(e) - mp.left
// 获得移动距离对整个滑块的百分比值,此为带有多位小数的值,step大于1时,不能用此更新视图
var percent = (distanceX / mp.width) * 100
updateSliderPlacement(instance, ownerInstance, percent, 'moving')
// 阻止页面滚动,可以保证在滑动过程中,不让页面可以上下滚动,造成不好的体验
e.stopPropagation && e.stopPropagation()
e.preventDefault && e.preventDefault()
}
function onClick(e, ownerInstance) {
var instance = e.instance
var state = instance.getState()
var mp = state.mp
if(mp.disabled) {
return
}
// 直接点击滑块的情况,计算方式与onTouchMove方法相同
var value = ((e.detail.x - mp.left) / mp.width) * 100
updateSliderPlacement(instance, ownerInstance, value, 'click')
}
function sizeReady(newValue, oldValue, ownerInstance, instance) {
// 页面初始化时候,也会触发此方法,传递的值为空,这里不执行往后的逻辑
if(!newValue || newValue.disabled) {
return
}
var state = instance.getState()
state.mp = newValue
updateSliderPlacement(instance, ownerInstance, newValue.value)
}
// 设置滑点的位置
function updateSliderPlacement(instance, ownerInstance, value, event) {
var state = instance.getState()
var mp = state.mp
if(mp.disabled) {
return
}
var percent = 0
if (mp.step > 1) {
// 如果step步进大于1,需要跳步,所以需要使用Math.round进行取整
percent = Math.round(Math.max(mp.min, Math.min(value, mp.max)) / mp.step) * mp.step
} else {
// 当step=1时,无需跳步,充分利用wxs性能,滑块实时跟随手势,达到丝滑的效果
percent = Math.max(mp.min, Math.min(value, mp.max))
}
// 返回组件的实例
var gapInstance = ownerInstance.selectComponent('.u-slider__gap')
// 在移动期间,不允许transition动画,否则会造成卡顿
gapInstance[event === 'click' ? 'addClass' : 'removeClass']('u-slider__gap--ani')
// 调用逻辑层的方法,修改v-model绑定的值
ownerInstance.callMethod('updateValue', Math.round(percent))
if(event) {
ownerInstance.callMethod('emitEvent', {
event: event,
value: Math.round(percent)
})
}
// 设置移动的值
gapInstance.requestAnimationFrame(function() {
gapInstance.setStyle({
width: percent / 100 * mp.width + 'px',
})
})
}
// 开始滑动
function onTouchStart(e, ownerInstance) {
ownerInstance.callMethod('emitEvent', {
event: 'start',
value: null
})
}
// 停止滑动
function onTouchEnd(e, ownerInstance) {
ownerInstance.callMethod('emitEvent', {
event: 'end',
value: null
})
}
// 获取当前手势点的X轴位移值
function getTouchX(e) {
return e.touches[0].clientX
}
module.exports = {
onTouchStart: onTouchStart,
onTouchMove: onTouchMove,
onTouchEnd: onTouchEnd,
sizeReady: sizeReady,
onClick: onClick
}