js矩形块大小任意缩放 JavaScript实现矩形块大小任意缩放

时间:2021-02-03 布湫人气:0

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最近写了一个原生JavaScript实现矩形块大小任意缩放的案例，感觉里面的东西比较的绕，这里分享源码给大家，一起学习一下。

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

<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>原生JavaScript实现矩形块大小任意缩放</title>
</head>
<style>
 * {
  margin: 0;
  padding: 0;
 }

 .box {
  position: relative;
  top: 200px;
  left: 500px;
  width: 500px;
  height: 300px;
  background-color: blueviolet;
 }

 .box>div:nth-child(-n+4) {
  position: absolute;
  width: 5px;
  height: 5px;
  background-color: #cc00ff;
 }

 .box>div:nth-child(n+5) {
  position: absolute;
  background-color: #f30497;
 }

 .box>.dot1 {
  cursor: nw-resize;
  top: -5px;
  left: -5px;
 }

 .box>.dot2 {
  cursor: ne-resize;
  top: -5px;
  right: -5px;
 }

 .box>.dot3 {
  cursor: se-resize;
  bottom: -5px;
  right: -5px;
 }

 .box>.dot4 {
  cursor: sw-resize;
  bottom: -5px;
  left: -5px;
 }

 .box>.line1,
 .box>.line3 {
  width: 500px;
  height: 5px;
 }

 .box>.line1 {
  top: -5px;
  cursor: n-resize;
 }

 .box>.line3 {
  bottom: -5px;
  cursor: s-resize;
 }

 .box>.line2,
 .box>.line4 {
  width: 5px;
  height: 300px;
 }

 .box>.line2 {
  right: -5px;
  cursor: e-resize;
 }

 .box>.line4 {
  left: -5px;
  cursor: e-resize;
 }
</style>

<body>
 <div class="box">
  <div class="dot1"></div>
  <div class="dot2"></div>
  <div class="dot3"></div>
  <div class="dot4"></div>
  <div class="line1"></div>
  <div class="line2"></div>
  <div class="line3"></div>
  <div class="line4"></div>
 </div>
 <script>
  //获取相关元素节点
  let box = document.querySelector(".box");
  let dots = document.querySelectorAll(".box>div:nth-child(-n+4)");
  let lines = document.querySelectorAll(".box>div:nth-child(n+5)");
  // 类边框宽度
  let bd = 5;
  //for循环指定事件对象
  function changeBox([box, dots, lines, bd]) {
   for (let i = 0; i < 4; i++) {
    let { 0: dot1, 1: dot2, 2: dot3, 3: dot4 } = dots;  //dots对象解构
    let { 0: line1, 1: line2, 2: line3, 3: line4 } = lines;  //lines对象解构
    //矩形顶点点击拖动调整大小
    dots[i].onmousedown = function (ev) {
     //点击事件初始化相关值
     let oldY = ev.clientY;  //顶点原本的y值
     let oldX = ev.clientX;  //顶点原本的x值
     let h = box.clientHeight; //box的高度
     let w = box.clientWidth; //box的宽度
     let t = box.offsetTop;  //box距离顶部的top值
     let l = box.offsetLeft;  //box距离左边的left值
     window.onmousemove = function (e) {
      let offsetY = e.clientY - oldY;   //鼠标移动y轴偏移量
      let offsetX = e.clientX - oldX;   //鼠标移动x轴偏移量
      //if条件是判断鼠标点击的节点目标对象
      if (i == 0) {
       box.style.height = `${h - offsetY + bd}px`;  //box高度变化
       box.style.top = `${t + offsetY - bd}px`;  //box的top值变化(定位)
       box.style.width = `${w - offsetX + bd}px`;  //box的宽度变化
       box.style.left = `${l + offsetX - bd}px`;  //box的left值变化(定位)
      } else if (i == 1) {
       box.style.height = `${h - offsetY + bd}px`;
       box.style.top = `${t + offsetY - bd}px`;
       box.style.width = `${w + offsetX + bd}px`;
      } else if (i == 2) {
       box.style.height = `${h + offsetY + bd}px`;
       box.style.width = `${w + offsetX + bd}px`;
      } else if (i == 3) {
       box.style.height = `${h + offsetY + bd}px`;
       box.style.width = `${w - offsetX + bd}px`;
       box.style.left = `${l + offsetX - bd}px`;
      }
      //边框线的高度/宽度随着box的大小变化而变化
      line1.style.width = box.style.width;
      line2.style.height = box.style.height;
      line3.style.width = box.style.width;
      line4.style.height = box.style.height;
     }
    }
    //边框点击拖动调整大小
    lines[i].onmousedown = function (ev) {
     //点击事件初始化相关值
     let oldY = ev.clientY;   //顶点原本的y值   
     let oldX = ev.clientX;   //顶点原本的x值
     let h = box.clientHeight;  //box的高度
     let w = box.clientWidth;  //box的宽度
     let t = box.offsetTop;   //box距离顶部的top值
     let l = box.offsetLeft;   //box距离左边的left值
     window.onmousemove = function (e) {
      let offsetX = e.clientX - oldX;  //鼠标移动x轴偏移量
      let offsetY = e.clientY - oldY;  //鼠标移动y轴偏移量
      //if条件是判断鼠标点击的节点目标对象
      if (i == 0) {
       box.style.height = `${h - offsetY + bd}px`;
       box.style.top = `${t + offsetY - bd}px`;
      } else if (i == 1) {
       box.style.width = `${w + offsetX + bd}px`;
      } else if (i == 2) {
       box.style.height = `${h + offsetY + bd}px`;
      } else {
       box.style.width = `${w - offsetX + bd}px`;
       box.style.left = `${l + offsetX - bd}px`;
      }
      //边框线的高度/宽度随着box的大小变化而变化
      line1.style.width = box.style.width;
      line2.style.height = box.style.height;
      line3.style.width = box.style.width;
      line4.style.height = box.style.height;
     }
    }
    //鼠标抬起后清除鼠标移动事件
    window.onmouseup = function () {
     window.onmousemove = false;
    }
   }
  }
  changeBox([box, dots, lines, bd])
 </script>
</body>

</html>

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