码云前端 2024-01-05

vue指令实现布局拉伸需求

AI 概述

实现一个简单的右拉伸1.首先我们创建两个相邻 div2.实现 resize 触发时机3.实现右拉伸功能方案一：限制最小宽度方案二：鼠标弹起后释放对应拉伸事件开始进阶实现左右拉伸功能实现 v-resize.left.right 在实际项目开发中，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。本文为...

文章目录隐藏

实现一个简单的右拉伸

1.首先我们创建两个相邻 div
2.实现 resize 触发时机
3.实现右拉伸功能

方案一：限制最小宽度
方案二：鼠标弹起后释放对应拉伸事件

开始进阶

实现左右拉伸功能

实现 v-resize.left.right

在实际项目开发中，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。本文为转载文章，来源于稀土掘金技术社区，作者是前端手术刀。

在线体验：点击这里

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

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>

效果如下：

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

会发现有两个问题：

左边宽度会>左右之和,右边宽度会 < 0
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。

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

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：

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()
  },
}

以上关于vue指令实现布局拉伸需求的文章就介绍到这了，更多相关内容请搜索码云笔记以前的文章或继续浏览下面的相关文章，希望大家以后多多支持码云笔记。

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