代码如下
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
padding: 0;
margin: 0;
}
#box {
position: relative;
width: 1000px;
height: 400px;
background-color: rosybrown;
overflow: hidden;
left: 50%;
margin-left: -500px;
top: 100px;
}
#map {
position: absolute;
}
</style>
</head>
<body>
<div id="box">
<img src="map_test.png" alt="" id="map">
</div>
</body>
<script>
var box = document.getElementById("box");
var map = document.getElementById("map");
var isRun, // 是否可移动
startX, // 鼠标落下的位置
startY,
endX, // 鼠标放开的位置
endY,
rX, // 图片最终的位置（中间量）
rY,
scaleSize = 1, // 缩放比例
bgX = 0, // left 图片的最终位置
bgY = 0; // top
var box_width = parseFloat(window.getComputedStyle(box, false)["width"].slice(0, -2));
var box_height = parseFloat(window.getComputedStyle(box, false)["height"].slice(0, -2));
var map_width = parseFloat(window.getComputedStyle(map, false)["width"].slice(0, -2));
var map_height = parseFloat(window.getComputedStyle(map, false)["height"].slice(0, -2));
function restart() {
// 初始设置显示全部地图
var map_w, map_h;
if (box_width / box_height > map_width / map_height) {
// 此时以高为基准
scaleSize = box_height / map_height;
map_h = box_height;
map_w = map_width * scaleSize;
bgX = (box_width - map_w) / 2;
bgY = 0;
} else {
// 此时以宽为基准
scaleSize = box_width / map_width;
map_h = map_height * scaleSize;
map_w = box_width;
bgX = 0;
bgY = (box_height - map_h) / 2;
}
map.style.height = map_h + "px";
map.style.width = map_w + "px";
map.style.top = bgY + "px";
map.style.left = bgX + "px";
}
restart();
box.onmousedown = function (ev) {
if (ev.which === 1) {
// 鼠标左键
isRun = true;
startX = ev.pageX;
startY = ev.pageY;
return false;
}
if (ev.which === 2) {
restart();
return false;
}
};
box.onmouseup = function (ev) {
if (ev.which === 1) {
isRun = false;
bgX = rX;
bgY = rY;
}
return false;
};
box.onmousemove = function (ev) {
if (ev.which === 1 && isRun) {
endX = ev.pageX;
endY = ev.pageY;
rX = bgX + endX - startX;
rY = bgY + endY - startY;
map.style.left = rX + "px";
map.style.top = rY + "px";
}
};
box.onwheel = function (ev) {
// 以鼠标为中心缩放
// 1.记录鼠标当前位置（相对于window）
var x = ev.pageX;
var y = ev.pageY;
// 2.阻止默认事件
ev.preventDefault();
// ev.target 滚轮滑动的目标
// 3.计算出鼠标相对于地图的位置
x = x - box.offsetLeft;
y = y - box.offsetTop;
// 4.记录滚轮的变化值 -100/+100
var change_scale = -(ev.deltaY) / 1000;
var current_scale = scaleSize;
current_scale += change_scale;
// 5.限制缩放的倍数0.1-10
current_scale = current_scale < 0.1 ? 0.1 : (current_scale > 10 ? 10 : current_scale);
// 6.计算出相对于图片的同样倍数对应的位移距离
bgX = bgX - (x - bgX) * (current_scale - scaleSize) / scaleSize;
bgY = bgY - (y - bgY) * (current_scale - scaleSize) / scaleSize;
scaleSize = current_scale;
// 7.更新属性
map.style.width = map_width * scaleSize + "px";
map.style.height = map_height * scaleSize + "px";
map.style.top = bgY + "px";
map.style.left = bgX + "px";
// 注意：要求box标签的父级标签不能出现定位属性，否则会以出现定位属性的父级为基准计算offset
}
</script>
</html>
