记录–vue 拉伸指令

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摘要

在我们项目开发中,经常会有布局拉伸的需求,接下来 让我们一步步用 vue指令 实现这个需求


这里给大家分享我在网上总结出来的一些知识,希望对大家有所帮助

记录--vue 拉伸指令

前言

在我们项目开发中,经常会有布局拉伸的需求,接下来 让我们一步步用 vue指令 实现这个需求

动手开发

在线体验

codesandbox.io/s/dawn-cdn-…

常规使用

解决拉伸触发时机

既然我们使用了指令的方式,也就是牺牲了组件方式的绑定事件的便捷性.

那么我们如何来解决这个触发时机的问题呢?

在参考了 Element UI 的表格拉伸功能后,笔者受到了启发

记录--vue 拉伸指令

 有点抽象,这个红色区域可不是真实节点,只是笔者模拟的一个 boder-right 多说无益 直接上代码吧

const pointermove = e => {     const { right } = el.getBoundingClientRect() // 获取到节点的右边界     const { clientX } = e // 此时鼠标位置     if (right - clientX < 8) // 表明在右边界的 8px 的过渡区 可以拉伸 }

实现一个简单的右拉伸

下面让我们来实现一个简单的右拉伸功能, 既然用指令 肯定是越简单越好

笔者决定用 vue提供的 修饰符, v-resize.right

实现 v-resize.right

1.首先我们创建两个相邻 div

<template>   <div class="container">     <div       v-resize.right       class="left"     />     <div class="right" />   </div> </template> <style lang="scss" scoped> .container {   width: 400px;   height: 100px;   > div {     float: left;     height: 100%;     width: 50%;   }   .left {     background-color: lightcoral;   }   .right {     background-color: lightblue;   } } </style>

记录--vue 拉伸指令

2.实现 resize 触发时机

export const resize = {   inserted: function(el, binding) {     el.addEventListener('pointermove', (e) => {       const { right } = el.getBoundingClientRect()       if (right - e.clientX < 8) {         // 此时表明可以拉伸,时机成熟         el.style.cursor = 'col-resize'       } else {         el.style.cursor = ''       }     })   } }

3.实现右拉伸功能

el.addEventListener('pointerdown', (e) => {   const rightDom = el.nextElementSibling // 获取右节点   const startX = e.clientX // 获取当前点击坐标    const { width } = el.getBoundingClientRect() // 获取当前节点宽度   const { width: nextWidth } = rightDom.getBoundingClientRect() // 获取右节点宽度   el.setPointerCapture(e.pointerId) // HTML5 的 API 自行百度~    const onDocumentMouseMove = (e) => {     const offsetX = e.clientX - startX // 此时的 x 坐标偏差     // 更新左右节点宽度     el.style.width = width + offsetX + 'px'     rightDom.style.width = nextWidth - offsetX + 'px'   }   // 因为此时我们要在整个屏幕移动 所以我们要在 document 挂上 mousemove   document.addEventListener('mousemove',onDocumentMouseMove)

让我们看看此时的效果

记录--vue 拉伸指令

会发现有两个问题

  1. 左边宽度会>左右之和,右边宽度会 < 0
  2. 当我们鼠标弹起的时候 还能继续拉伸

让我们首先解决第一个问题

方案一:限制最小宽度
const MIN_WIDTH = 10 document.addEventListener('mousemove', (e) => {     const offsetX = e.clientX - startX // 此时的 x 坐标偏差     +if (width + offsetX < MIN_WIDTH || nextWidth - offsetX < MIN_WIDTH) return     // 更新左右节点宽度     el.style.width = width + offsetX + 'px'     rightDom.style.width = nextWidth - offsetX + 'px' })

第二个问题,其实非常简单

方案二:鼠标弹起后释放对应拉伸事件

el.addEventListener('pointerup', (e) => {     el.releasePointerCapture(e.pointerId)     document.removeEventListener('mousemove', onDocumentMouseMove) })

此时最最最基础的 v-resize 左右拉伸版本 我们已经实现了,来看下效果吧

记录--vue 拉伸指令

 看下此时的完整代码

export const resize = {   inserted: function (el, binding) {     el.addEventListener('pointermove', (e) => {       const { right } = el.getBoundingClientRect()       if (right - e.clientX < 8) {         // 此时表明可以拉伸         el.style.cursor = 'col-resize'       } else {         el.style.cursor = ''       }     })      const MIN_WIDTH = 10      el.addEventListener('pointerdown', (e) => {       const rightDom = el.nextElementSibling // 获取右节点       const startX = e.clientX // 获取当前点击坐标        const { width } = el.getBoundingClientRect() // 获取当前节点宽度       const { width: nextWidth } = rightDom.getBoundingClientRect() // 获取右节点宽度       el.setPointerCapture(e.pointerId) // HTML5 的 API 自行百度~        const onDocumentMouseMove = (e) => {         const offsetX = e.clientX - startX // 此时的 x 坐标偏差         if (width + offsetX < MIN_WIDTH || nextWidth - offsetX < MIN_WIDTH) {           return         }         // 更新左右节点宽度         el.style.width = width + offsetX + 'px'         rightDom.style.width = nextWidth - offsetX + 'px'       }       // 因为此时我们要在整个屏幕移动 所以我们要在 document 挂上 mousemove       document.addEventListener('mousemove', onDocumentMouseMove)        el.addEventListener('pointerup', (e) => {         el.releasePointerCapture(e.pointerId)         document.removeEventListener('mousemove', onDocumentMouseMove)       })     })   }, }

作为 一名 优秀的前端性能优化专家,红盾大大已经开始吐槽,这么多 EventListener 都不移除吗? 还有'top' 'left'这些硬编码,能维护吗?

是的,后续代码我们将会移除这些被绑定的事件,以及处理硬编码(此处非重点 不做赘叙)

实现完 右拉伸 想必你对 左,上,下拉伸 也已经有了自己的思路

开始进阶

接下来让我们看下这种场景

记录--vue 拉伸指令

 

我们 想实现一个 两边能同时拉伸的功能, 也就是 v-resize.left.right

实现左右拉伸功能

这种场景比较复杂,就需要我们维护一个拉伸方向上的变量 position

实现 v-resize.left.right

export const resize = {   inserted: function (el, binding) {     let position = '',       resizing = false     el.addEventListener('pointermove', (e) => {       if (resizing) return       const { left, right } = el.getBoundingClientRect()       const { clientX } = e       if (right - clientX < 8) {         position = 'right' // 此时表明右拉伸         el.style.cursor = 'col-resize'       } else if (clientX - left < 8) {         position = 'left' // 此时表明左拉伸         el.style.cursor = 'col-resize'       } else {         position = ''         el.style.cursor = ''       }     })      const MIN_WIDTH = 10      el.addEventListener('pointerdown', (e) => {       if (position === '') return       const sibling = position === 'right' ? el.nextElementSibling : el.previousElementSibling // 获取相邻节点       const startX = e.clientX // 获取当前点击坐标        const { width } = el.getBoundingClientRect() // 获取当前节点宽度       const { width: siblingWidth } = sibling.getBoundingClientRect() // 获取右节点宽度       el.setPointerCapture(e.pointerId) // HTML5 的 API 自行百度~        const onDocumentMouseMove = (e) => {         resizing = true         if (position === '') return         const offsetX = e.clientX - startX         const _elWidth = position === 'right' ? width + offsetX : width - offsetX //判断左右拉伸 所影响的当前节点宽度          const _siblingWidth = position === 'right' ? siblingWidth - offsetX : siblingWidth + offsetX //判断左右拉伸 所影响的相邻节点宽度         if (_elWidth <= MIN_WIDTH || _siblingWidth <= MIN_WIDTH) return          // 更新左右节点宽度         el.style.width = _elWidth + 'px'         sibling.style.width = _siblingWidth + 'px'       }        document.addEventListener('mousemove', onDocumentMouseMove)        el.addEventListener('pointerup', (e) => {         position = ''         resizing = false         el.releasePointerCapture(e.pointerId)         document.removeEventListener('mousemove', onDocumentMouseMove)       })     })   }, }

看下此时的效果

记录--vue 拉伸指令

非常丝滑, 当然 我们还需要考虑 传递 最小宽度 最大宽度 过渡区 等多种业务属性,但是这对于各位彦祖来说都是鸡毛蒜皮的小事. 自行改造就行了

完整代码

Js版本

const elEventsWeakMap = new WeakMap() const MIN_WIDTH = 50 const MIN_HEIGHT = 50 const TRIGGER_SIZE = 8 const TOP = 'top' const BOTTOM = 'bottom' const LEFT = 'left' const RIGHT = 'right' const COL_RESIZE = 'col-resize' const ROW_RESIZE = 'row-resize'  function getElStyleAttr(element, attr) {   const styles = window.getComputedStyle(element)   return styles[attr] }  function getSiblingByPosition(el, position) {   const siblingMap = {     left: el.previousElementSibling,     right: el.nextElementSibling,     bottom: el.nextElementSibling,     top: el.previousElementSibling   }   return siblingMap[position] }  function getSiblingsSize(el, attr) {   const siblings = el.parentNode.childNodes   return [...siblings].reduce((prev, next) => (next.getBoundingClientRect()[attr] + prev), 0) }  function updateSize({   el,   sibling,   formatter = 'px',   elSize,   siblingSize,   attr = 'width' }) {   let totalSize = elSize + siblingSize   if (formatter === 'px') {     el.style[attr] = elSize + formatter     sibling.style[attr] = siblingSize + formatter   } else if (formatter === 'flex') {     totalSize = getSiblingsSize(el, attr)     el.style.flex = elSize / totalSize * 10 // 修复 flex-grow <1     sibling.style.flex = siblingSize / totalSize * 10   } }  const initResize = ({   el,   positions,   minWidth = MIN_WIDTH,   minHeight = MIN_HEIGHT,   triggerSize = TRIGGER_SIZE,   formatter = 'px' }) => {   if (!el) return   const resizeState = {}   const defaultCursor = getElStyleAttr(el, 'cursor')   const elStyle = el.style    const canLeftResize = positions.includes(LEFT)   const canRightResize = positions.includes(RIGHT)   const canTopResize = positions.includes(TOP)   const canBottomResize = positions.includes(BOTTOM)    if (!canLeftResize && !canRightResize && !canTopResize && !canBottomResize) { return } // 未指定方向    const pointermove = (e) => {     if (resizeState.resizing) return     e.preventDefault()     const { left, right, top, bottom } = el.getBoundingClientRect()     const { clientX, clientY } = e     // 左右拉伸     if (canLeftResize || canRightResize) {       if (clientX - left < triggerSize) resizeState.position = LEFT       else if (right - clientX < triggerSize) resizeState.position = RIGHT       else resizeState.position = ''        if (resizeState.position === '') {         elStyle.cursor = defaultCursor       } else {         if (getSiblingByPosition(el, resizeState.position)) { elStyle.cursor = COL_RESIZE }         e.stopPropagation()       }     } else if (canTopResize || canBottomResize) {       // 上下拉伸       if (clientY - top < triggerSize) resizeState.position = TOP       else if (bottom - clientY < triggerSize) resizeState.position = BOTTOM       else resizeState.position = ''        if (resizeState.position === '') {         elStyle.cursor = defaultCursor       } else {         if (getSiblingByPosition(el, resizeState.position)) { elStyle.cursor = ROW_RESIZE }         e.stopPropagation()       }     }   }    const pointerleave = (e) => {     e.stopPropagation()     resizeState.position = ''     elStyle.cursor = defaultCursor     el.releasePointerCapture(e.pointerId)   }   const pointerdown = (e) => {     const { resizing, position } = resizeState     if (resizing || !position) return      if (position) e.stopPropagation() // 如果当前节点存在拉伸方向 需要阻止冒泡(用于嵌套拉伸)     el.setPointerCapture(e.pointerId)      const isFlex = getElStyleAttr(el.parentNode, 'display') === 'flex'     if (isFlex) formatter = 'flex'      resizeState.resizing = true     resizeState.startPointerX = e.clientX     resizeState.startPointerY = e.clientY      const { width, height } = el.getBoundingClientRect()      const sibling = getSiblingByPosition(el, position)     if (!sibling) {       console.error('未找到兄弟节点', position)       return     }      const rectSibling = sibling.getBoundingClientRect()      const { startPointerX, startPointerY } = resizeState     const onDocumentMouseMove = (e) => {       if (!resizeState.resizing) return       elStyle.cursor =         canLeftResize || canRightResize ? COL_RESIZE : ROW_RESIZE       const { clientX, clientY } = e        if (position === LEFT || position === RIGHT) {         const offsetX = clientX - startPointerX         const elSize = position === RIGHT ? width + offsetX : width - offsetX          const siblingSize =           position === RIGHT             ? rectSibling.width - offsetX             : rectSibling.width + offsetX         if (elSize <= minWidth || siblingSize <= minWidth) return          updateSize({ el, sibling, elSize, siblingSize, formatter })       } else if (position === TOP || position === BOTTOM) {         const offsetY = clientY - startPointerY         const elSize =           position === BOTTOM ? height + offsetY : height - offsetY          const siblingSize =           position === BOTTOM             ? rectSibling.height - offsetY             : rectSibling.height + offsetY         if (elSize <= minHeight || siblingSize <= minHeight) return          updateSize({ el, sibling, elSize, siblingSize, formatter })       }     }      const onDocumentMouseUp = (e) => {       document.removeEventListener('mousemove', onDocumentMouseMove)       document.removeEventListener('mouseup', onDocumentMouseUp)       resizeState.resizing = false       elStyle.cursor = defaultCursor     }      document.addEventListener('mousemove', onDocumentMouseMove)     document.addEventListener('mouseup', onDocumentMouseUp)   }    const bindElEvents = () => {     el.addEventListener('pointermove', pointermove)     el.addEventListener('pointerleave', pointerleave)     el.addEventListener('pointerup', pointerleave)     el.addEventListener('pointerdown', pointerdown)   }    const unBindElEvents = () => {     el.removeEventListener('pointermove', pointermove)     el.removeEventListener('pointerleave', pointerleave)     el.removeEventListener('pointerup', pointerleave)     el.removeEventListener('pointerdown', pointerdown)   }    bindElEvents()    // 设置解绑事件   elEventsWeakMap.set(el, unBindElEvents) } export const resize = {   inserted: function(el, binding) {     const { modifiers, value } = binding     const positions = Object.keys(modifiers)     initResize({ el, positions, ...value })   },   unbind: function(el) {     const unBindElEvents = elEventsWeakMap.get(el)     unBindElEvents()   } }

Ts版本

import type { DirectiveBinding } from 'vue'  const elEventsWeakMap = new WeakMap() const MIN_WIDTH = 50 const MIN_HEIGHT = 50 const TRIGGER_SIZE = 8  enum RESIZE_CURSOR {   COL_RESIZE = 'col-resize',   ROW_RESIZE = 'row-resize', }  enum POSITION {   TOP = 'top',   BOTTOM = 'bottom',   LEFT = 'left',   RIGHT = 'right', }  type Positions = [POSITION.TOP, POSITION.BOTTOM, POSITION.LEFT, POSITION.RIGHT]  interface ResizeState {   resizing: boolean   position?: POSITION   startPointerX?: number   startPointerY?: number } type WidthHeight = 'width' | 'height'  type ElAttr = WidthHeight | 'cursor' | 'display' // 后面补充  type ResizeFormatter = 'px' | 'flex'  interface ResizeInfo {   el: HTMLElement   positions: Positions   minWidth: number   minHeight: number   triggerSize: number   formatter: ResizeFormatter }  function getElStyleAttr(element: HTMLElement, attr: ElAttr) {   const styles = window.getComputedStyle(element)   return styles[attr] }  function getSiblingByPosition(el: HTMLElement, position: POSITION) {   const siblingMap = {     left: el.previousElementSibling,     right: el.nextElementSibling,     bottom: el.nextElementSibling,     top: el.previousElementSibling,   }   return siblingMap[position] }  function getSiblingsSize(el: HTMLElement, attr: WidthHeight) {   const siblings = (el.parentNode && el.parentNode.children) || []   return [...siblings].reduce(     (prev, next) => next.getBoundingClientRect()[attr] + prev,     0,   ) }  function updateSize({   el,   sibling,   formatter = 'px',   elSize,   siblingSize,   attr = 'width', }: {   el: HTMLElement   sibling: HTMLElement   formatter: ResizeFormatter   elSize: number   siblingSize: number   attr?: WidthHeight }) {   let totalSize = elSize + siblingSize   if (formatter === 'px') {     el.style[attr] = elSize + formatter     sibling.style[attr] = siblingSize + formatter   } else if (formatter === 'flex') {     totalSize = getSiblingsSize(el as HTMLElement, attr)     el.style.flex = `${(elSize / totalSize) * 10}` // 修复 flex-grow <1     sibling.style.flex = `${(siblingSize / totalSize) * 10}`   } }  const initResize = ({   el,   positions,   minWidth = MIN_WIDTH,   minHeight = MIN_HEIGHT,   triggerSize = TRIGGER_SIZE,   formatter = 'px', }: ResizeInfo) => {   if (!el || !(el instanceof HTMLElement)) return   const resizeState: ResizeState = {     resizing: false,   }   const defaultCursor = getElStyleAttr(el, 'cursor')   const elStyle = el.style    const canLeftResize = positions.includes(POSITION.LEFT)   const canRightResize = positions.includes(POSITION.RIGHT)   const canTopResize = positions.includes(POSITION.TOP)   const canBottomResize = positions.includes(POSITION.BOTTOM)    if (!canLeftResize && !canRightResize && !canTopResize && !canBottomResize) {     return   } // 未指定方向    const pointermove = (e: PointerEvent) => {     if (resizeState.resizing) return     e.preventDefault()     const { left, right, top, bottom } = el.getBoundingClientRect()     const { clientX, clientY } = e     // 左右拉伸     if (canLeftResize || canRightResize) {       if (clientX - left < triggerSize) resizeState.position = POSITION.LEFT       else if (right - clientX < triggerSize)         resizeState.position = POSITION.RIGHT       else resizeState.position = undefined        if (resizeState.position === undefined) {         elStyle.cursor = defaultCursor       } else {         if (getSiblingByPosition(el, resizeState.position)) {           elStyle.cursor = RESIZE_CURSOR.COL_RESIZE         }         e.stopPropagation()       }     } else if (canTopResize || canBottomResize) {       // 上下拉伸       if (clientY - top < triggerSize) resizeState.position = POSITION.TOP       else if (bottom - clientY < triggerSize)         resizeState.position = POSITION.BOTTOM       else resizeState.position = undefined        if (resizeState.position === undefined) {         elStyle.cursor = defaultCursor       } else {         if (getSiblingByPosition(el, resizeState.position)) {           elStyle.cursor = RESIZE_CURSOR.ROW_RESIZE         }         e.stopPropagation()       }     }   }    const pointerleave = (e: PointerEvent) => {     e.stopPropagation()     resizeState.position = undefined     elStyle.cursor = defaultCursor     el.releasePointerCapture(e.pointerId)   }   const pointerdown = (e: PointerEvent) => {     const { resizing, position } = resizeState     if (resizing || !position) return      if (position) e.stopPropagation() // 如果当前节点存在拉伸方向 需要阻止冒泡(用于嵌套拉伸)     el.setPointerCapture(e.pointerId)      if (el.parentElement) {       const isFlex = getElStyleAttr(el.parentElement, 'display') === 'flex'       if (isFlex) formatter = 'flex'     }      resizeState.resizing = true     resizeState.startPointerX = e.clientX     resizeState.startPointerY = e.clientY      const { width, height } = el.getBoundingClientRect()      const sibling: HTMLElement = getSiblingByPosition(       el,       position,     ) as HTMLElement     if (!sibling || !(sibling instanceof HTMLElement)) {       console.error('未找到兄弟节点', position)       return     }      const rectSibling = sibling.getBoundingClientRect()      const { startPointerX, startPointerY } = resizeState     const onDocumentMouseMove = (e: MouseEvent) => {       if (!resizeState.resizing) return       elStyle.cursor =         canLeftResize || canRightResize           ? RESIZE_CURSOR.COL_RESIZE           : RESIZE_CURSOR.ROW_RESIZE       const { clientX, clientY } = e        if (position === POSITION.LEFT || position === POSITION.RIGHT) {         const offsetX = clientX - startPointerX         const elSize =           position === POSITION.RIGHT ? width + offsetX : width - offsetX          const siblingSize =           position === POSITION.RIGHT             ? rectSibling.width - offsetX             : rectSibling.width + offsetX         if (elSize <= minWidth || siblingSize <= minWidth) return          updateSize({ el, sibling, elSize, siblingSize, formatter })       } else if (position === POSITION.TOP || position === POSITION.BOTTOM) {         const offsetY = clientY - startPointerY         const elSize =           position === POSITION.BOTTOM ? height + offsetY : height - offsetY          const siblingSize =           position === POSITION.BOTTOM             ? rectSibling.height - offsetY             : rectSibling.height + offsetY         if (elSize <= minHeight || siblingSize <= minHeight) return          updateSize({           el,           sibling,           elSize,           siblingSize,           formatter,           attr: 'height',         })       }     }      const onDocumentMouseUp = () => {       document.removeEventListener('mousemove', onDocumentMouseMove)       document.removeEventListener('mouseup', onDocumentMouseUp)       resizeState.resizing = false       elStyle.cursor = defaultCursor     }      document.addEventListener('mousemove', onDocumentMouseMove)     document.addEventListener('mouseup', onDocumentMouseUp)   }    const bindElEvents = () => {     el.addEventListener('pointermove', pointermove)     el.addEventListener('pointerleave', pointerleave)     el.addEventListener('pointerup', pointerleave)     el.addEventListener('pointerdown', pointerdown)   }    const unBindElEvents = () => {     el.removeEventListener('pointermove', pointermove)     el.removeEventListener('pointerleave', pointerleave)     el.removeEventListener('pointerup', pointerleave)     el.removeEventListener('pointerdown', pointerdown)   }    bindElEvents()    // 设置解绑事件   elEventsWeakMap.set(el, unBindElEvents) } export const resize = {   mounted: function (el: HTMLElement, binding: DirectiveBinding) {     const { modifiers, value } = binding     const positions = Object.keys(modifiers)     initResize({ el, positions, ...value })   },   beforeUnmount: function (el: HTMLElement) {     const unBindElEvents = elEventsWeakMap.get(el)     unBindElEvents()   }, }

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 记录--vue 拉伸指令