materio-d8/web/themes/custom/materiotheme/vuejs/components/Content/Card.vue

<template>
  <div class="card">
    <header>
      <h1>{{ item.title }}</h1>
      <h4>{{ item.description }}</h4>
    </header>
    <section class="images" v-switcher>
      <figure
        v-for="(img, index) in item.images"
        :key="img.url"
      >
        <img
          class="lazy"
          v-lazy="index"
          :data-src="img.url"
          :title="img.title"
        />
        <img class="blank" :src="blanksrc">
      </figure>
    </section>
  </div>
</template>

<script>

export default {
  name: "Card",
  props: ['item'],
  data() {
    return {
      blanksrc:`${drupalSettings.path.themePath}/assets/img/blank.gif`
    }
  },
  directives: {
    lazy: {
      bind(img,binding){
        // console.log('lazy bind', img, binding);
        if(binding.value === 0){
          img.setAttribute('src', img.getAttribute('data-src'))
          img.removeAttribute('data-src')
          img.classList.remove('lazy')
        }
      }
    },
    switcher: {
      inserted(el,binding){
        // switch images on mousemove
        el.addEventListener('mousemove', function(event) {
          let figs = this.querySelectorAll('figure')
          // console.log('mousemove', this, event, figs.length);
          // let len = figs.length
          // let w = this.clientWidth;
          // let g = w / len;
          // let delta = Math.floor(event.layerX / g)
          let delta = Math.floor(event.layerX / (this.clientWidth / figs.length))
          // console.log('delta', delta);
          figs.forEach((fig, index) => {
            // console.log(index);
            if(index == delta){
              fig.style.display = "block"
            }else{
              fig.style.display = "none"
            }
          })
        })
      }
    }
  },
  mounted() {
    // lazy load images on mouseover
    this.$el.addEventListener('mouseover', function(event) {
      let imgs = this.querySelectorAll('.images figure img.lazy')
      // console.log('mouseover', this, imgs);
      imgs.forEach((img) => {
        // console.log('forEach img',img);
        img.setAttribute('src', img.getAttribute('data-src'))
        img.removeAttribute('data-src')
        img.classList.remove('lazy')
      })
    }, {once : true})
  }
}

</script>

<style lang="scss" scoped>

</style>