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JavaScript實(shí)現(xiàn)放大鏡效果代碼示例

更新時間：2020年04月29日 11:16:31 作者：lanshanxiao

這篇文章主要介紹了JavaScript實(shí)現(xiàn)放大鏡效果代碼示例,文中通過示例代碼介紹的非常詳細(xì)，對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值,需要的朋友可以參考下

JavaScript實(shí)現(xiàn)放大鏡效果：

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .smallBgImg {
      width: 350px;
      height: 350px;
      border: 1px solid #ccc;
      box-sizing: border-box;
      background-clip: padding-box;
      float: left;
      position: relative;
      cursor: pointer;
    }

    .move {
      border: 1px solid #ccc;
      box-sizing: border-box;
      background: rgba(165, 201, 66, 0.5);
      position: absolute;
      left: 0;
      top: 0;
    }

    .bigBgImg {
      width: 540px;
      height: 540px;
      border: 1px solid #ccc;
      box-sizing: border-box;
      background-clip: padding-box;
      float: left;
      margin-left: 10px;
    }

    .hidden {
      display: none;
    }
  </style>
</head>

<body>
  <div class="smallBgImg">
    <div class="move hidden">

    </div>
  </div>
  <div class="bigBgImg hidden">

  </div>
  <script>
    (function () {
      //基本信息配置
      var config = {
        smallImg: "./image/smallImg.jpg", //小圖路徑
        smallDom: document.getElementsByClassName("smallBgImg")[0], //小圖 dom對象
        bigImg: "./image/bigImg.jpg", //大圖路徑
        bigDom: document.getElementsByClassName("bigBgImg")[0], //大圖 dom對象
        moveDom: document.getElementsByClassName("move")[0], //移動方塊的dom對象
        smallSize: { //小圖尺寸
          width: 350,
          height: 350
        },
        bigSize: { //大圖尺寸
          width: 800,
          height: 800
        },
        divBigSize: { //大圖框的尺寸
          width: 540,
          height: 540
        }
      };
      //根據(jù)比例尺計算移動框的寬高 移動框/小圖尺寸 = 大框尺寸/大圖尺寸
      config.moveSize = {
        width: config.divBigSize.width * config.smallSize.width / config.bigSize.width,
        height: config.divBigSize.height * config.smallSize.height / config.bigSize.height
      };
      //小圖style的計算值
      config.smallComputedStyle = window.getComputedStyle(config.smallDom);
      //大圖style的計算值
      config.bigComputedStyle = window.getComputedStyle(config.bigDom);
      //移動方塊style的計算值
      config.moveComputedStyle = window.getComputedStyle(config.moveDom);

      initSmallImg();
      initBigImg();
      initMoveDiv();

      //初始化小圖
      function initSmallImg() {
        config.smallDom.style.background = `url("${config.smallImg}") no-repeat left top/contain`; //設(shè)置背景圖片
        config.smallDom.onmousemove = function (e) { //鼠標(biāo)移入事件
          //展示移動小塊
          config.moveDom.style.display = "block";
          var move = window.getComputedStyle(config.moveDom);
          //獲取鼠標(biāo)在小圖中的坐標(biāo)
          var position = getPosition(e);
          //設(shè)置移動框的位置
          setPosition(position);

          //展示大圖框
          config.bigDom.style.display = "block";
          //大圖框中展示部分大圖
          displayBigBgImgSize();
        }

        config.smallDom.onmouseout = function () {
          //移動小塊隱藏，大圖隱藏
          config.moveDom.style.display = config.bigDom.style.display = "none";
        }
      }

      //初始化大圖
      function initBigImg() {
        config.bigDom.style.background = `url("${config.bigImg}") no-repeat`; //設(shè)置背景圖片
      }

      //初始化移動框
      function initMoveDiv() {
        config.moveDom.style.width = config.moveSize.width + "px";
        config.moveDom.style.height = config.moveSize.height + "px";
      }

      //獲取鼠標(biāo)的坐標(biāo)位置
      function getPosition(e) {
        if (e.target == config.smallDom) { //若鼠標(biāo)出現(xiàn)在小圖中,事件源是小圖
          return { //直接獲取鼠標(biāo)距離事件源的橫坐標(biāo)和縱坐標(biāo)
            x: e.offsetX,
            y: e.offsetY
          };
        } else { //鼠標(biāo)出現(xiàn)在移動框中,事件源是移動框
          return {
            x: e.offsetX + parseFloat(config.moveComputedStyle.left) +
              1, //鼠標(biāo)距離事件源的橫坐標(biāo) + 事件源在smallDom中的left值 + 邊框值
            y: e.offsetY + parseFloat(config.moveComputedStyle.top) +
//鼠標(biāo)距離事件源的縱坐標(biāo) + 事件源在smallDom中的top值 + 邊框值
          }
        }
      }

      //設(shè)置移動方塊的位置
      function setPosition(position) {
        //鼠標(biāo)要始終在移動方塊中央位置
        config.moveDom.style.left = position.x - parseFloat(config.moveComputedStyle.width) / 2 + "px";
        config.moveDom.style.top = position.y - parseFloat(config.moveComputedStyle.height) / 2 + "px";

        //要限制移動框的范圍在小圖中，否則會超出小圖
        var left = parseInt(config.moveComputedStyle.left);
        var top = parseInt(config.moveComputedStyle.top);
        if (left < 0) { //最左
          config.moveDom.style.left = "0px";
        }
        if (left > config.smallSize.width - config.moveSize.width) { //最右
          config.moveDom.style.left = config.smallSize.width - config.moveSize.width + "px";
        }
        if (top < 0) { //最上
          config.moveDom.style.top = "0px";
        }
        if (top > config.smallSize.height - config.moveSize.height) { //最下
          config.moveDom.style.top = config.smallSize.height - config.moveSize.height + "px";
        }
      }

      //展示部分大圖
      function displayBigBgImgSize() {

        //移動框的left/小圖width = 大圖框的left/大圖width
        var moveLeft = parseInt(config.moveComputedStyle.left);
        var moveTop = parseInt(config.moveComputedStyle.top);
        config.bigDom.style.backgroundPosition =
          `-${moveLeft*config.bigSize.width/config.smallSize.width}px -${moveTop*config.bigSize.height/config.smallSize.height}px`;
      }
    }());
  </script>
</body>

</html>

index.html

效果展示：