前端动态换肤方式: vue + element-ui（一）

1、新建vue项目（由于目前公司采用的是vue2，因此采用此方式）

// 全局安装
npm install -g @vue/cli-init
// 新建项目
vue init webpack project-name

2、打开项目准备进行换肤实现

第一步：

// 安装element-ui框架
npm install --save element-ui

// 在main.js中进行引用
import ElementUI from 'element-ui'
import 'element-ui/lib/theme-chalk/index.css'

Vue.use(ElementUI)

// 如果需要进行其他设置或者只需要引用部分组件参见官网

第二步：

然后按照官网element-ui命令行主题工具部分进行操作，直到引入自定义主题部分结束

如果仅仅是定制样式而不需要换肤的话，那么到这一步就结束了；

如果仅仅是换肤的话，第二步可以忽略不进行操作。

第三步：

封装 theme-picker换肤公共组件

方式一：摘自

<template>
  <el-color-picker
    v-model="theme"
    :predefine="['#409EFF', '#1890ff', '#304156','#212121','#11a983', '#13c2c2', '#6959CD', '#f5222d', ]"
    class="theme-picker"
    popper-class="theme-picker-dropdown"
  />
</template>

<script>
const version = require('element-ui/package.json').version // element-ui version from node_modules
const ORIGINAL_THEME = '#409EFF' // default color
export default {
  name: 'themePicker',
  data () {
    return {
      chalk: '', // content of theme-chalk css
      theme: ''
    }
  },
  computed: {
    defaultTheme () {
      return this.$store.getters.theme
    }
  },
  watch: {
    defaultTheme: {
      handler: function (val, oldVal) {
        this.theme = val
      },
      immediate: true
    },
    async theme (val) {
      const oldVal = this.chalk ? this.theme : ORIGINAL_THEME
      if (typeof val !== 'string') return
      const themeCluster = this.getThemeCluster(val.replace('#', ''))
      const originalCluster = this.getThemeCluster(oldVal.replace('#', ''))
      console.log(themeCluster, originalCluster)

      const $message = this.$message({
        message: '  Compiling the theme',
        customClass: 'theme-message',
        type: 'success',
        duration: 0,
        iconClass: 'el-icon-loading'
      })

      const getHandler = (variable, id) => {
        return () => {
          const originalCluster = this.getThemeCluster(ORIGINAL_THEME.replace('#', ''))
          const newStyle = this.updateStyle(this[variable], originalCluster, themeCluster)

          let styleTag = document.getElementById(id)
          if (!styleTag) {
            styleTag = document.createElement('style')
            styleTag.setAttribute('id', id)
            document.head.appendChild(styleTag)
          }
          styleTag.innerText = newStyle
        }
      }

      if (!this.chalk) {
        const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`
        await this.getCSSString(url, 'chalk')
      }

      const chalkHandler = getHandler('chalk', 'chalk-style')

      chalkHandler()

      const styles = [].slice.call(document.querySelectorAll('style'))
        .filter(style => {
          const text = style.innerText
          return new RegExp(oldVal, 'i').test(text) && !/Chalk Variables/.test(text)
        })
      styles.forEach(style => {
        const { innerText } = style
        if (typeof innerText !== 'string') return
        style.innerText = this.updateStyle(innerText, originalCluster, themeCluster)
      })

      this.$emit('change', val)

      $message.close()
    }
  },

  methods: {
    updateStyle (style, oldCluster, newCluster) {
      let newStyle = style
      oldCluster.forEach((color, index) => {
        newStyle = newStyle.replace(new RegExp(color, 'ig'), newCluster[index])
      })
      return newStyle
    },

    getCSSString (url, variable) {
      return new Promise(resolve => {
        const xhr = new XMLHttpRequest()
        xhr.onreadystatechange = () => {
          if (xhr.readyState === 4 && xhr.status === 200) {
            this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, '')
            resolve()
          }
        }
        xhr.open('GET', url)
        xhr.send()
      })
    },

    getThemeCluster (theme) {
      const tintColor = (color, tint) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)

        if (tint === 0) { // when primary color is in its rgb space
          return [red, green, blue].join(',')
        } else {
          red += Math.round(tint * (255 - red))
          green += Math.round(tint * (255 - green))
          blue += Math.round(tint * (255 - blue))

          red = red.toString(16)
          green = green.toString(16)
          blue = blue.toString(16)

          return `#${red}${green}${blue}`
        }
      }

      const shadeColor = (color, shade) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)

        red = Math.round((1 - shade) * red)
        green = Math.round((1 - shade) * green)
        blue = Math.round((1 - shade) * blue)

        red = red.toString(16)
        green = green.toString(16)
        blue = blue.toString(16)

        return `#${red}${green}${blue}`
      }

      const clusters = [theme]
      for (let i = 0; i <= 9; i++) {
        clusters.push(tintColor(theme, Number((i / 10).toFixed(2))))
      }
      clusters.push(shadeColor(theme, 0.1))
      return clusters
    }
  }
}
</script>

<style>
  .theme-message,
  .theme-picker-dropdown {
    z-index: 99999 !important;
  }

  .theme-picker .el-color-picker__trigger {
    height: 26px !important;
    width: 26px !important;
    padding: 2px;
  }

  .theme-picker-dropdown .el-color-dropdown__link-btn {
    display: none;
  }
</style>

第四步：使用

以上样式及事件并非全部必要，按需求添加即可；

小结：

这个方案仍有不完善的地方，element-ui的部分组件比如el-header如果设置背景色，这个背景色是不会随之改变的。

待进一步研究。

此乃个人学习记录，如有问题还望指出，如有更改方案还望指教，谢谢。