<div id="app" :style="customStyle">
  <div class="image-wrapper" :style="customStyle">
    <img :src="imageUrl" />
  </div>
  <div class="rectangle-wrapper" :style="customStyle">
    <div class="rectangle" :style="styleObject(position)"></div>
  </div>
</div>

var app = new Vue({
  el: '#app',
  data() {
    return {
      imageSize: { width: 580, height: 400 },
      imageUrl:
        'https://images.pexels.com/photos/708392/pexels-photo-708392.jpeg',
      position: { x: 8, y: 20, w: 16.6291, h: 33.0335 },
    };
  },
  computed: {
    isResultEmpty() {
      const obj = this.positionList;
      return (
        !obj.length ||
        (obj.length === 1 && this.isObjectEmpty(this.positionList[0]))
      );
    },
    customStyle() {
      return {
        maxWidth: this.imageSize.width + 'px',
        maxHeight: this.imageSize.height + 'px',
        width: this.imageSize.width + 'px',
        height: this.imageSize.height + 'px',
      };
    },
  },
  methods: {
    styleObject(obj) {
      let mig = (val) => {
        return `${val}%`;
      };
      return {
        left: mig(obj.x),
        top: mig(obj.y),
        width: mig(obj.w),
        height: mig(obj.h),
      };
    },
    isObjectEmpty(obj) {
      return !Object.values(obj).some((x) => x > 0);
    },
    setImageSize() {
      let el = document.documentElement.querySelector('body');
      let style = window.getComputedStyle
        ? getComputedStyle(el, null)
        : el.currentStyle;
      // padding은 빠진 넓이를 구함
      let paddingWidth =
        parseInt(style.paddingLeft) + parseInt(style.paddingRight);

      let pageContentWidth = el.clientWidth - paddingWidth;
      // 검출 결과 이미지 사이즈 정의
      let baseSize = pageContentWidth / 2;
      this.imageSize = {
        width: baseSize,
        height: baseSize * 0.7,
      };
    },
  },
  mounted() {
    this.$nextTick(function () {
      window.addEventListener('resize', this.setImageSize);
      // init
      this.setImageSize();
    });
  },
});

body {
  padding: 1rem;
}
#app {
  position: relative;
  background-color: #eee;
  .image-wrapper img {
    width: 100%;
    height: 100%;
  }
  .rectangle-wrapper {
    position: absolute;
    left: 0;
    top: 0;
    .rectangle {
      position: absolute;
      border: solid 2px #ff1744;
    }
  }
}