原生js 实现图片的拖拽缩放

废话不多说,直接上代码!
<!DOCTYPE html>
<html>

	<head>
		<meta charset="utf-8" />
		<title></title>
	</head>

	<body>
		<style type="text/css">
			.zoom-div {
				position: fixed;
				top: 0;
				bottom: 0;
				right: 0;
				left: 0;
				background: rgba(0, 0, 0, 0.3);
				z-index: 999;
				display: flex;
				justify-content: center;
				align-items: center;
				cursor: grab;
			}
			
			#box {
				position: absolute;
			}
			
			.zoom-div img {
				/* 200px;
  				height: 200px;
				position: absolute;*/
				/*top: 50%;
				left: 50%;
				transform: translate(-50%, -50%);*/
				z-index: 1000;
			}
		</style>
		</head>

		<body>
			<div class="zoom-div" id="father" onmousewheel="return bbimg(this)">
				<div id="box">
					<img border="0" src="https://qqadapt.qpic.cn/txdocpic/0/b2702e33487dca1d4dea09d3c52ae586/0?_type=png&w=1268&h=572">
				</div>
			</div>
		</body>
		<script language="javascript">
			var zoom = 1;

			function bbimg(o) {
				o = document.getElementById('box');
				zoom += event.wheelDelta / 40;
				if(zoom > 0) o.style.transform = 'scale(' + zoom + ')';
				return false;
			}
			var fa = document.getElementById('father');
			var box = document.getElementById('box');
			box.onmousedown = function(ev) {
				var oEvent = ev;
				// 浏览器有一些图片的默认事件,这里要阻止
				oEvent.preventDefault();
				var disX = oEvent.clientX - box.offsetLeft;
				var disY = oEvent.clientY - box.offsetTop;
				fa.onmousemove = function(ev) {
					oEvent = ev;
					oEvent.preventDefault();
					var x = oEvent.clientX - disX;
					var y = oEvent.clientY - disY;

					// 图形移动的边界判断
					//              x = x <= 0 ? 0 : x;
					//              x = x >= fa.offsetWidth-box.offsetWidth ? fa.offsetWidth-box.offsetWidth : x;
					//              y = y <= 0 ? 0 : y;
					//              y = y >= fa.offsetHeight-box.offsetHeight ? fa.offsetHeight-box.offsetHeight : y;
					box.style.left = x + 'px';
					box.style.top = y + 'px';
				}
				// 图形移出父盒子取消移动事件,防止移动过快触发鼠标移出事件,导致鼠标弹起事件失效
				fa.onmouseleave = function() {
					fa.onmousemove = null;
					fa.onmouseup = null;
				}
				// 鼠标弹起后停止移动
				fa.onmouseup = function() {
					fa.onmousemove = null;
					fa.onmouseup = null;
				}
			}
		</script>

</html>

  

原文地址:https://www.cnblogs.com/sbzf/p/13547488.html