Dynamic Theme changing

[alexanderkraemer]

Question（提问）

Is it possible to let the user choose the theme color (primary color)?

I tried it with your approach from here, but it always loads the primary color first, and then switches it after ~5 seconds.
Do you have an idea, how to load it before anything else?

I've added the functionality to the App.vue file.

  <div id="app">
    <cookie-consent />
    <router-view />
    <v-dialog />
  </div>
</template>
<script>
import EventBus from './eventbus'
import CookieConsent from './CookieConsent'
const version = require('element-ui/package.json').version // element-ui version from node_modules
const ORIGINAL_THEME = '#007996' // default color

export default {
  name: 'App',
  components: { CookieConsent },
  data: function() {
    return {
      authenticated: false,
      token_loading: false,
      theme: ''
    }
  },
  computed: {
    defaultTheme() {
      return this.$store.state.settings.theme
    }
  },
  watch: {
    defaultTheme: {
      handler: function(val, oldVal) {
        console.log('handler val')
        console.log(val)
        this.theme = val
      },
      immediate: true
    },
    theme: {
      handler: async function(val, _oldVal) {
        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()
      },
      immediate: true
    },
    async theme1(val) {

    }
  },
  mounted() {
    this.$store.dispatch('settings/loadTheme');
  },
  methods: {
    updateStyle(style, oldCluster, newCluster) {
      let newStyle = style
      oldCluster.forEach((color, index) => {
        console.log(color, index)
        console.log(newCluster)
        newStyle = newStyle.replace(new RegExp(color, 'ig'), newCluster[index])
      })
      return newStyle
    },
    getCSSString(url, variable) {
      return new Promise(resolve => {
        const xhr = new XMLHttpRequest()
        xhr.onreadystatechange = () => {
          if (xhr.readyState === 4 && xhr.status === 200) {
            this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, '')
            resolve()
          }
        }
        xhr.open('GET', url)
        xhr.send()
      })
    },
    getThemeCluster(theme) {
      const tintColor = (color, tint) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)
        if (tint === 0) { // when primary color is in its rgb space
          return [red, green, blue].join(',')
        } else {
          red += Math.round(tint * (255 - red))
          green += Math.round(tint * (255 - green))
          blue += Math.round(tint * (255 - blue))
          red = red.toString(16)
          green = green.toString(16)
          blue = blue.toString(16)
          return `#${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>

Other relevant information（格外信息）

• Your OS: macOS 11.1
• Node.js version: v14.5.0