vue项目使用postcss-px2rem + lib-flexible进行页面适配

前言

随着后台管理系统的不断健全，大屏页面应运而生，酷炫的效果下伴随的是页面不能根据屏幕自适应，在探索了响应式和自适应布局的优缺点后，最终结合项目实际情况，选择rem + flex 模式进行页面适配

一：引入postcss-px2rem

npm i postcss-px2rem

二：设置remUnit值

项目根目录，打开vue.config.js文件，添加如下内容

module.exports = {
    css: {
        extract: true,
        sourceMap: false,
        loaderOptions: {
          postcss: {
            plugins: [
              require('postcss-px2rem')({
                remUnit: 192 // 设计稿宽度1920 / 10
              })
            ]
          }
        }
      }
}

三：引入flexible

一般情况下，使用npm i lib-flexible –save引入，由于默认flexibled.js自适应宽度比是540，不符合实际项目需求，所以我们单独引入该js文件。
在src/utils目录下添加flexible.js（根据自己的项目调整目录）

;(function () {
  // flexible.css
  var cssText =
    '' +
    '@charset "utf-8";html{color:#000;background:#fff;overflow-y:hideen;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%;-webkit-overflow-scrolling:touch}html *{outline:0;-webkit-text-size-adjust:none;-webkit-tap-highlight-color:transparent}body,html{font-family:"Microsoft YaHei",sans-serif,Tahoma,Arial}article,aside,blockquote,body,button,code,dd,details,div,dl,dt,fieldset,figcaption,figure,footer,form,h1,h2,h3,h4,h5,h6,header,hgroup,hr,input,legend,li,menu,nav,ol,p,pre,section,td,textarea,th,ul{margin:0;padding:0;-webkit-box-sizing:border-box;-moz-box-sizing:border-box;box-sizing:border-box}article,aside,details,figcaption,figure,footer,header,hgroup,menu,nav,section{display:block}input,input[type=button],input[type=reset],input[type=submit]{resize:none;border:none;-webkit-appearance:none;border-radius:0}input,select,textarea{font-size:100%}table{border-collapse:collapse;border-spacing:0}fieldset,img{border:0}abbr,acronym{border:0;font-variant:normal}del{text-decoration:line-through}address,caption,cite,code,dfn,em,th,var{font-style:normal;}ol,ul{list-style:none}caption,th{text-align:left}h1,h2,h3,h4,h5,h6{font-size:100%;font-weight:500}q:after,q:before{content:\'\'}sub,sup{font-size:75%;line-height:0;position:relative;vertical-align:baseline}sup{top:-.5em}sub{bottom:-.25em}a:hover{text-decoration:underline}a,ins{text-decoration:none}a:active,a:hover,a:link,a:visited{background:0 0;-webkit-tap-highlight-color:transparent;-webkit-tap-highlight-color:transparent;outline:0;text-decoration:none}'
  // cssText end

  var styleEl = document.createElement('style')
  document.getElementsByTagName('head')[0].appendChild(styleEl)
  if (styleEl.styleSheet) {
    if (!styleEl.styleSheet.disabled) {
      styleEl.styleSheet.cssText = cssText
    }
  } else {
    try {
      styleEl.innerHTML = cssText
    } catch (e) {
      styleEl.innerText = cssText
    }
  }
})()
;(function (win, lib) {
  var doc = win.document
  var docEl = doc.documentElement
  var metaEl = doc.querySelector('meta[name="viewport"]')
  var flexibleEl = doc.querySelector('meta[name="flexible"]')
  var winWidth = 0
  var winHeight = 0
  //获取窗口宽度
  if (win.innerWidth) winWidth = win.innerWidth
  else if (doc.body && doc.body.clientWidth) winWidth = doc.body.clientWidth
  //获取窗口高度
  if (win.innerHeight) winHeight = win.innerHeight
  else if (doc.body && doc.body.clientHeight) winHeight = doc.body.clientHeight
  var dpr = 0
  var scale = 0
  var tid
  var flexible = lib.flexible || (lib.flexible = {})
  if (metaEl) {
    console.warn('将根据已有的meta标签来设置缩放比例')
    var match = metaEl.getAttribute('content').match(/initial\-scale=([\d\.]+)/)
    if (match) {
      scale = parseFloat(match[1])
      dpr = scale
    }
  } else if (flexibleEl) {
    var content = flexibleEl.getAttribute('content')
    if (content) {
      var initialDpr = content.match(/initial\-dpr=([\d\.]+)/)
      var maximumDpr = content.match(/maximum\-dpr=([\d\.]+)/)
      if (initialDpr) {
        dpr = parseFloat(initialDpr[1])
        scale = parseFloat((1 / dpr).toFixed(2))
      }
      if (maximumDpr) {
        dpr = parseFloat(maximumDpr[1])
        scale = parseFloat((1 / dpr).toFixed(2))
      }
    }
  }

  if (!dpr && !scale) {
    var isAndroid = win.navigator.appVersion.match(/android/gi)
    var isIPhone = win.navigator.appVersion.match(/iphone/gi)
    var devicePixelRatio = win.devicePixelRatio
    if (isIPhone) {
      // iOS下，对于2和3的屏，用2倍的方案，其余的用1倍方案
      if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {
        dpr = 3
      } else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)) {
        dpr = 2
      } else {
        dpr = 1
      }
    } else {
      dpr = 1
    }
    scale = 1
  }

  docEl.setAttribute('data-dpr', dpr)
  if (!metaEl) {
    metaEl = doc.createElement('meta')
    metaEl.setAttribute('name', 'viewport')
    metaEl.setAttribute(
      'content',
      'initial-scale=' +
        scale +
        ', maximum-scale=' +
        scale +
        ', minimum-scale=' +
        scale +
        ', user-scalable=no'
    )
    if (docEl.firstElementChild) {
      docEl.firstElementChild.appendChild(metaEl)
    } else {
      var wrap = doc.createElement('div')
      wrap.appendChild(metaEl)
      doc.write(wrap.innerHTML)
    }
  }

  function refreshRem() {
    var width = docEl.getBoundingClientRect().width
    var height = docEl.getBoundingClientRect().height
    let appStyle = doc.getElementById('app').style
    var rem = (height * 1.4 * 1.4 * 1.3) / 10
    if (width / dpr > 540) {
      width = width * dpr
    }
    // 根据实际项目情况修改
    if (width >= 1500) {
      rem = width / 10
    } else if (width < 1500 && width >= 1000) {
      rem = (width * 1.4) / 10
    } else {
      rem = (width * 1.4 * 1.5) / 10
    }
    docEl.style.fontSize = rem + 'px'
    flexible.rem = win.rem = rem
  }

  win.addEventListener(
    'resize',
    function () {
      clearTimeout(tid)
      tid = setTimeout(refreshRem, 300)
    },
    false
  )
  win.addEventListener(
    'pageshow',
    function (e) {
      if (e.persisted) {
        clearTimeout(tid)
        tid = setTimeout(refreshRem, 300)
      }
    },
    false
  )

  if (doc.readyState === 'complete') {
    doc.body.style.fontSize = 12 * dpr + 'px'
  } else {
    doc.addEventListener(
      'DOMContentLoaded',
      function (e) {
        doc.body.style.fontSize = 12 * dpr + 'px'
      },
      false
    )
  }

  refreshRem()

  flexible.dpr = win.dpr = dpr
  flexible.refreshRem = refreshRem
  flexible.rem2px = function (d) {
    var val = parseFloat(d) * this.rem
    if (typeof d === 'string' && d.match(/rem$/)) {
      val += 'px'
    }
    return val
  }
  flexible.px2rem = function (d) {
    var val = parseFloat(d) / this.rem
    if (typeof d === 'string' && d.match(/px$/)) {
      val += 'rem'
    }
    return val
  }
})(window, window['lib'] || (window['lib'] = {}))

四：在main.js文件中引入flexible文件

// 自适应,只引入一次
import Vue from 'vue'
import '@/lib/flexible'

五：禁止页面缩放

打开根目录下index.html(或public目录下)文件
设置页面缩放属性

width=device-width ：表示宽度是设备屏幕的宽度
height=device-height ：表示宽度是设备屏幕的宽度
initial-scale=1.0：表示初始的缩放比例(初始规模为1.0倍，即原始大小)
minimum-scale=0.5：表示最小的缩放比例
maximum-scale=2.0：表示最大的缩放比例
user-scalable=yes或者1：表示用户是否可以调整缩放比例(no或者0：表示不可调整缩放比例)

<meta name="viewport" content="width=device-width,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.0,user-scalable=0" />

在head中添加如下script代码

    <!--禁止页面缩放-->
    <script>
      document.addEventListener(
        'mousewheel',
        function (e) {
          e = e || window.event
          if ((e.wheelDelta && event.ctrlKey) || e.detail) {
            event.preventDefault()
          }
        },
        {
          capture: false,
          passive: false
        }
      )
      document.addEventListener(
        'keydown',
        function (event) {
          if (
            (event.ctrlKey === true || event.metaKey === true) &&
            (event.keyCode === 61 ||
              event.keyCode === 107 ||
              event.keyCode === 173 ||
              event.keyCode === 109 ||
              event.keyCode === 187 ||
              event.keyCode === 189)
          ) {
            event.preventDefault()
          }
        },
        false
      )
    </script>

至此，关于rem +flex 适配工作已经完成，重启项目运行即可