JQ - 图片在元素内拖动、缩放大小

 图片在元素内拖拽/缩放

• 先获取到起始坐标（在容器里鼠标按下时鼠标在浏览器页面中的位置）
• 鼠标移动时再计算出当前鼠标当前坐标和起始坐标的距离，再使用 position 把图片定位跟随鼠标移动
• 拖动图片时设置图片拖动边界限制
• 滚轮上下滚动时放大缩小图片

css

*{ margin:0; padding:0; } div{ width:600px; height:400px; background:#FFF; border:1px solid slateblue; position:relative; overflow:overlay; margin:20px auto; } img{ position:absolute; left:0; top:0; transform:scale(1); } img:active{ cursor:move; } ::-webkit-scrollbar { width:6px; height:6px; background-color:#F5F5F5; } ::-webkit-scrollbar-thumb { background-color:#3d4a5dd9; } ::-webkit-scrollbar-track { -webkit-box-shadow:inset 0 0 6px rgba(0, 0, 0, 0.3); box-shadow:inset 0 0 6px rgba(0, 0, 0, 0.3); background-color:#F5F5F5; }

 HTML

<div class="dragImage" ></div>

 JS

$(function(){ class DRAGIMAGE { constructor({ $dom, img, $zoomMax, $zoomMin }){ let that = this; this.$dom = $dom;    // dom
            this.$dom.html(`<img src="${img}" draggable="false" />`);    // 图片放进盒子 this.$img = $dom.find("img");         // img
            this.$start_x = 0;                    // 鼠标起始坐标x
            this.$start_y = 0;                    // 鼠标起始坐标y
            this.$move_left = 0;                // 鼠标向左移动距离
            this.$move_top = 0;                    // 鼠标向上移动距离
            this.$img_left = 0;                    // 图片当前定位 left
            this.$img_top = 0;                    // 图片当前定位 top
            this.$img_width = 0;                // 图片实际宽度
            this.$img_height = 0;                // 图片实际高度
            this.$dom_width = $dom.width();         // 父盒子宽度
            this.$dom_height = $dom.height();    // 父盒子高度
            this.$zoom = 100;                    // 缩放大小 100正常大小 
            this.$zoom_Max = ($zoomMax*100) || 200 ;    // 最大缩放
            this.$zoom_Min = ($zoomMin*100) || 0.5 ;     // 最小缩放 

            var image = new Image(); image.src = img; image.onload = function(){ // 获取到图片实际宽高
                that.$img_width = image.width; that.$img_height = image.height; // 鼠标按下执行
 that.mouseDown(); } // 滚轮事件 放大缩小图片
 that.mouseWheel(); // 鼠标抬起 清除移动事件
            that.$dom.on("mouseup", function(e){ that.stopmove() }); // 鼠标移出父盒子 清除移动事件
            that.$dom.on("mouseout", function(e){ that.stopmove() }); } /* 鼠标按下时触发 获取鼠标在图片内的坐标 */ mouseDown () { let that = this; that.$img.on("mousedown", function(e){ e = e || event; // 获取起始坐标
                that.$start_x = e.clientX; that.$start_y = e.clientY; that.stopmove(); // 清除移动事件
                that.mouseMove(); // 鼠标移动
                return false; }) } /* 鼠标移动事件 获取鼠标在图内的移动距离: 图片当前定位 - ( 起始坐标 - 当前坐标 ) */ mouseMove () { let that = this; that.$dom.on("mousemove", function(e){ e = e || event; /* 获取鼠标移动距离 */ that.$move_left = that.$img_left - ( that.$start_x - e.clientX ); that.$move_top = that.$img_top - ( that.$start_y - e.clientY ); // 随鼠标移动 更新图片定位
 that.setPosition(); return false; }) } /* 滚轮事件 放大缩小图片 */ mouseWheel () { let that = this; that.$dom.on("mousewheel", function(e){ e = e || event; e.stopPropagation(); e.preventDefault(); let width, height; //判断上下滚动 chrome & ie || firefox
                var delta = (e.originalEvent.wheelDelta && (e.originalEvent.wheelDelta > 0 ? 1 : -1)) || (e.originalEvent.detail && (e.originalEvent.detail > 0 ? -1 : 1)); // delta > 0 上滚 ，delta < 0 下滚
                if (delta > 0) { ++that.$zoom; if (that.$zoom>=that.$zoom_Max) that.$zoom = that.$zoom_Max; // 限制最大缩放
                    if (that.$zoom <= that.$zoom_Max) width = that.$img_width*((that.$zoom)/100);
                        height = that.$img_height*((that.$zoom)/100);
                } else if (delta < 0) { --that.$zoom; if (that.$zoom<=that.$zoom_Min) that.$zoom = that.$zoom_Min; // 限制最小缩放
                    if (that.$zoom >= that.$zoom_Min) width = that.$img_width*((that.$zoom)/100);
                        height = that.$img_height*((that.$zoom)/100);
 } that.scaleImg({width, height}); // 对图片进行缩放
 that.setPosition(); return false; }) } /* 通过改变 width/height 进行缩放 */ scaleImg ( { width, height } ) { this.$img.css({ 'width': width, 'height': height }); } /* 设置图片定位, 边界限制 左/上限制：图片当前宽高 大于/小于 父盒子的宽高 鼠标移动距离 = 0 右/下限制：(鼠标移动距离-父盒子最大宽高)大于当前图片宽高 || 鼠标移动距离大于 -(当前图片宽高-父盒子最大宽高) 鼠标移动距离 = -(当前图片宽高 - 父盒子宽高); */ setPosition () { let that = this; // 图片当前宽高大于父盒子的宽高 || 图片当前宽高小于父盒子的宽高
            /* 左/上 */
            if ( that.$move_left>=0 && that.$img.width()>that.$dom_width || that.$move_left<=0 && that.$img.width()<that.$dom_width ) that.$move_left = 0; if ( that.$move_top>=0 && that.$img.height()>that.$dom_height || that.$move_top<=0 && that.$img.height()<that.$dom_height ) that.$move_top = 0; /* 右/下 */ 
            if ( Math.abs(( that.$move_left-that.$dom_width ))>=that.$img.width() && that.$img.width()>that.$dom_width || that.$move_left>=(-(that.$img.width() - that.$dom_width)) && that.$img.width()<that.$dom_width ) that.$move_left = -(that.$img.width() - that.$dom_width); if ( Math.abs(( that.$move_top-that.$dom_height ))>=that.$img.height() && that.$img.height()>that.$dom_height || that.$move_top>=(-(that.$img.height() - that.$dom_height)) && that.$img.height()<that.$dom_height ) that.$move_top = -(that.$img.height() - that.$dom_height); // 定位移动的距离 = 鼠标移动的距离 
 that.$img.css({ 'left': that.$move_left, 'top': that.$move_top }); } // 停止鼠标移动
 stopmove(){ /* 清除移动事件，绑定图片当前定位 */
            this.$dom.unbind('mousemove'); this.$img_left =  this.$img.position().left; this.$img_top =  this.$img.position().top; } }
 var dragImage = new DRAGIMAGE({ $dom: $('.dragImage'),    // 图片的父元素
        img: "https://images.cnblogs.com/cnblogs_com/sanyekui/1693114/o_200409094205e56bf2254d1496cb6138b6cb271a2cf9.jpg", // 图片路径
        $zoomMax: 4,     // 缩放最大倍数，1正常大小 
        $zoomMin: 0.2    // 缩放最小倍数，1正常大小
 });
 })