vue使用自定义指令实现拖拽

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需求背景，工作中需要实现一个自定义打印模板的需求，能够实现单个及多个dom元素的同时拖拽，也能通过外部的input元素修改dom元素的样式。在npm和GitHub上找了各种已有的vue组件，不够灵活，效果都不是自己想要的

Vue.directive('dragx', (el, binding, vnode) => {
 // 默认参数
 let defaultOpts = {
 dragDirection: 'n, e, s, w, ne, se, sw, nw, all',
 dragContainerId: '', //
 dragBarClass: '', // 类选择器
 canDrag: true,
 canResize: true,
 multiSelect: false
 }
 let isMove = false
 let isResize = false
 let constraintDom
 let constraintRect
 let constraintRectHeight
 let constraintRectWidth
 binding.value = binding.value || {}
 let cfg = Object.assign({}, defaultOpts, binding.value)
 if (cfg.dragContainerId) {
 constraintDom = document.querySelector('#' + cfg.dragContainerId)
 constraintRect = constraintDom.getBoundingClientRect()
 constraintRectHeight = constraintRect.height
 constraintRectWidth = constraintRect.width
 }

 let getStyleNumValue = (style, key) => parseInt(style.getPropertyValue(key), 10)
 // 设置约束范围
 function setConstraint (data) {
 if (cfg.dragContainerId) {
 if (data.left <= 0) data.left = 0
 if (data.top <= 0) data.top = 0
 if (data.top + data.height + data.borderTop + data.borderBottom >= constraintRectHeight) data.top = constraintRectHeight - data.height - data.borderTop - data.borderBottom
 if (data.left + data.width + data.borderLeft + data.borderRight > constraintRectWidth) data.left = constraintRectWidth - data.width - data.borderLeft - data.borderRight
 }
 }

 el.onmousemove = e => {
 if (cfg.dragBarClass.length > 0 && e.target.classList.contains(cfg.dragBarClass) && cfg.canDrag) {
 el.style.cursor = 'move'
 return
 }
 el.style.cursor = ''
 }

 el.onmouseleave = e => {
 el.style.cursor = ''
 }

 el.onmousedown = e => {
 let clickId = (e.target || e.srcElement).id
 let posData = {
 x: e.pageX, y: e.pageY
 }
 el.onmouseup = e => {
 // dom元素选中时发送active事件
 if (!cfg.active) el.dispatchEvent(new CustomEvent('bindActive', { 'detail': { ...posData } }))
 }
 isMove = false
 if (cfg.dragBarClass.length > 0 && !e.target.classList.contains('icon-icon-resize')) {
 isMove = true
 isResize = false
 document.body.style.cursor = 'move'
 } else if (e.target.classList.contains('icon-icon-resize')) {
 isMove = false
 isResize = true
 }

 let style
 let rect
 let data
 let tableStyle

 style = window.getComputedStyle(el)
 rect = el.getBoundingClientRect()
 data = {
 width: getStyleNumValue(style, 'width'),
 height: getStyleNumValue(style, 'height'),
 left: getStyleNumValue(style, 'left'),
 top: getStyleNumValue(style, 'top'),
 borderLeft: getStyleNumValue(style, 'border-left-width'),
 borderTop: getStyleNumValue(style, 'border-top-width'),
 borderRight: getStyleNumValue(style, 'border-right-width'),
 borderBottom: getStyleNumValue(style, 'border-bottom-width'),
 deltX: e.pageX - rect.left,
 deltY: e.pageY - rect.top,
 startX: rect.left,
 startY: rect.top
 }
 if (el.id.indexOf(THSIGN) > -1 || el.id.indexOf(TDSIGN) > -1) {
 let table = document.getElementById(el.id.split(SEPARATOR)[0])
 tableStyle = window.getComputedStyle(table)
 data.left = getStyleNumValue(tableStyle, 'left')
 data.top = getStyleNumValue(tableStyle, 'top')
 }

 document.onmousemove = edom => {
 if (edom.ctrlKey) return
 if (isResize) {
 data.width = Math.round(edom.pageX - data.startX + data.borderLeft + data.borderRight)
 data.height = Math.round(edom.pageY - data.startY + data.borderBottom + data.borderTop)
 }
 // 处理组件 移动
 if (isMove && cfg.canDrag && (cfg.active || cfg.multiSelect)) {
 let targetPageX = edom.pageX
 let targetPageY = edom.pageY
 let deltX = targetPageX - data.startX - data.deltX
 let deltY = targetPageY - data.startY - data.deltY
 let newLeft = Math.round(getStyleNumValue(style, 'left') || '0', 10) + deltX
 let newTop = Math.round(getStyleNumValue(style, 'top') || '0', 10) + deltY
 data.left = Math.round(newLeft)
 data.top = Math.round(newTop)
 data.startX = data.startX + deltX
 data.startY = data.startY + deltY
 setConstraint(data)
 if (el.id.indexOf(THSIGN) > -1 || el.id.indexOf(TDSIGN) > -1) {
 let newLeft = Math.round(getStyleNumValue(tableStyle, 'left') || '0', 10) + deltX
 let newTop = Math.round(getStyleNumValue(tableStyle, 'top') || '0', 10) + deltY
 data.left = Math.round(newLeft)
 data.top = Math.round(newTop)
 }
 }
 if (cfg.multiSelect) {
 let domData = {
 el: clickId,
 x: edom.pageX,
 y: edom.pageY
 }
 // 移动多个元素时发送事件 bindUpdateDoms
 el.dispatchEvent(new CustomEvent('bindUpdateDoms', { detail: domData }))
 } else {
 // 移动单个元素移动时发送事件 bindUpdate
 el.dispatchEvent(new CustomEvent('bindUpdate', { detail: data }))
 }

 document.onmouseup = edom => {
 if (cfg.multiSelect && posData.x != edom.pageX && posData.y != edom.pageY) {
 let domData = {
 x: edom.pageX,
 y: edom.pageY
 }
 // 发送下面2个事件主要是为了实现操作的撤销和恢复功能，浏览器保存一个执行栈，一个移动表示一个事件
 // 多个元素同时移动时发送事件 bindFinishMoveDoms
 el.dispatchEvent(new CustomEvent('bindFinishMoveDoms', { detail: domData }))
 } else if (posData.x != edom.pageX && posData.y != edom.pageY) {
 // 单个元素同时移动时发送事件 bindFinishMove
 el.dispatchEvent(new CustomEvent('bindFinishMove', { detail: data }))
 }
 document.body.style.cursor = ''
 document.onmousemove = null
 document.onmouseup = null
 isMove = false
 }
 }

 document.onmouseup = edom => {
 document.body.style.cursor = ''
 document.onmousemove = null
 document.onmouseup = null
 isMove = false
 }
 }
})

2.自定义事件

在vue组件使用自定义指令并添加事件监听器

如果指令需要多个值，可以传入一个 JavaScript 对象字面量。记住，指令函数能够接受所有合法的 JavaScript 表达式。

<div v-dragx="{ dragBarClass: 'drag', dragContainerId: 'page', multiSelect, active }"
 @bindUpdate="bindUpdate"
 @bindActive="activeDom"
 @bindUpdateDoms="bindUpdateDoms"
 @bindFinishMove="pushStackByDom"
 @bindFinishMoveDoms="pushStackByDoms"
 :style="style"
 :id="uId"
 class="drag-wrap">
</div>

// 添加一个适当的事件监听器
<div @bindUpdate="bindUpdate" />

// 创建并分发事件
el.dispatchEvent(new CustomEvent('bindUpdate', { detail: data }))

字段说明

<template>
 <div v-dragx="{ dragBarClass: 'drag', dragContainerId: 'page', multiSelect, active }"
 @bindUpdate="bindUpdate"
 @bindActive="activeDom"
 @bindUpdateDoms="bindUpdateDoms"
 @bindFinishMove="pushStackByDom"
 @bindFinishMoveDoms="pushStackByDoms"
 :style="style"
 :id="uId"
 class="drag-wrap">
 <slot></slot>
 <span class="iconfont icon-icon-resize"></span>
 </div>
</template>
<script>
export default {
 data () {
 return {
 prevSize: {}
 }
 },
 props: {
 item: {
 type: Object,
 default: () => ({})
 },
 isVariable: {
 type: Boolean,
 default: false
 },
 active: {
 type: Boolean,
 default: false
 },
 size: {
 type: Object,
 default: () => ({
 x: 200,
 y: 200,
 w: 200,
 h: 24
 })
 },
 multiSelect: {
 type: Boolean,
 default: false
 },
 uId: {
 type: String,
 required: true
 },
 dragContainerId: {
 type: String
 }
 },
 computed: {
 style: function () {
 return {
 top: this.size.y + 'px',
 left: this.size.x + 'px',
 width: this.size.w + 'px',
 height: this.size.h + 'px'
 }
 }
 },
 methods: {
 activeDom (e) {
 this.$emit('activated', this.uId, e.detail.x, e.detail.y)
 this.prevSize = {
 ...this.size
 }
 },
 bindUpdate (event) {
 let data = event.detail
 this.size.x = data.left
 this.size.y = data.top

 this.$store.dispatch('RESIZE_ID', { id: this.uId, ...data })
 this.$emit('resizing', { ...data })
 },
 bindUpdateDoms (e) {
 this.$emit('movingDoms', e.detail)
 },
 pushStackByDom (e) {
 this.$store.dispatch('RESIZE_ID', { prevSize: this.prevSize, id: this.uId, ...event.detail })
 },
 pushStackByDoms (e) {
 this.$emit('finishMoveDoms', e.detail)
 }
 }
}
</script>
<style scoped>
.drag {
 background-color: #ccc;
 border-top: solid 1px rgba(33, 61, 223, 0.541);
 border-bottom: solid 1px rgba(33, 61, 223, 0.541);
}
.drag-wrap {
 position: absolute;
}
.icon-icon-resize {
 position: absolute;
 right: 0;
 bottom: 0;
 line-height: 12px;
 cursor: se-resize;
 font-size: 12px;
 color: #666;
}
</style>

3.vuex实现状态管理

因为涉及到多个组件的通信，因此使用vuex，把模板信息和执行栈全部保存在vuex中

最终实现的效果如下图所示