JavaScript实现矩形块大小任意缩放

时间：2021-05-26

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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