<template>
<ul class="list">
<li
class="item"
v-for="item of letters"
:key="item"
:ref="item"
@touchstart.prevent="handleTouchStart"
@touchmove="handleTouchMove"
@touchend="handleTouchEnd"
@click="handleLetterClick"
>
{{item}}
</li>
</ul>
</template>
<script>
export default {
name: 'CityAlphabet',
props: {
cities: Object
},
computed: {
letters () {
const letters = []
for (let i in this.cities) {
letters.push(i)
}
return letters
}
},
data () {
return {
touchStatus: false,
startY: 0,
timer: null
}
},
updated () {
this.startY = this.$refs['A'][0].offsetTop
},
methods: {
handleLetterClick (e) {
this.$emit('change', e.target.innerText)
},
handleTouchStart () {
this.touchStatus = true
},
handleTouchMove (e) {
if (this.touchStatus) {
if (this.timer) {
clearTimeout(this.timer)
}
this.timer = setTimeout(() => {
const touchY = e.touches[0].clientY - 79
const index = Math.floor((touchY - this.startY) / 20)
if (index >= 0 && index < this.letters.length) {
this.$emit('change', this.letters[index])
}
}, 8)
}
},
handleTouchEnd () {
this.touchStatus = false
}
}
}
</script>
<style scoped>
@import '~styles/varibles.styl'
.list
display: flex
flex-direction: column
justify-content: center
position: absolute
top: 1.58rem
right: 0
bottom: 0
width: .4rem
.item
line-height: .4rem
text-align: center
color: $bgColor
</style>
