轉載：圖片拖動、縮放、旋轉 （鼠標手勢）

原文轉載自touch.js 拖動、縮放、旋轉 （鼠標手勢）該作者個人網站Somethingwhat（有一些開源demo，感覺有的用的上，記錄一下，以防丟失）

先上預覽地址：

https://www.somethingwhat.com/Project/Detail?id=f092710d3f7255b4

看下是不是你要的效果，不是就不用往下看了。

示例中我用了touch.js這個插件（百度團隊開發的，但好像已經停止更新了），再自己封裝了一下，可以實現手勢操作：拖動、縮放、旋轉。

封裝好的腳本方法是這樣的：

/*
* author: www.somethingwhat.com
*/
var cat = window.cat || {};
cat.touchjs = {
    left: 0,
    top: 0,
    scaleVal: 1,    //縮放
    rotateVal: 0,   //旋轉
    curStatus: 0,   //記錄當前手勢的狀態, 0:拖動, 1:縮放, 2:旋轉
    //初始化
    init: function ($targetObj, callback) {
        touch.on($targetObj, 'touchstart', function (ev) {
            cat.touchjs.curStatus = 0;
            ev.preventDefault();//阻止默認事件
        });
        if (!window.localStorage.cat_touchjs_data)
            callback(0, 0, 1, 0);
        else {
            var jsonObj = JSON.parse(window.localStorage.cat_touchjs_data);
            cat.touchjs.left = parseFloat(jsonObj.left), cat.touchjs.top = parseFloat(jsonObj.top), cat.touchjs.scaleVal = parseFloat(jsonObj.scale), cat.touchjs.rotateVal = parseFloat(jsonObj.rotate);
            callback(cat.touchjs.left, cat.touchjs.top, cat.touchjs.scaleVal, cat.touchjs.rotateVal);
        }
    },
    //拖動
    drag: function ($targetObj, callback) {
        touch.on($targetObj, 'drag', function (ev) {
            $targetObj.css("left", cat.touchjs.left + ev.x).css("top", cat.touchjs.top + ev.y);
        });
        touch.on($targetObj, 'dragend', function (ev) {
            cat.touchjs.left = cat.touchjs.left + ev.x;
            cat.touchjs.top = cat.touchjs.top + ev.y;
            callback(cat.touchjs.left, cat.touchjs.top);
        });
    },
    //縮放
    scale: function ($targetObj, callback) {
        var initialScale = cat.touchjs.scaleVal || 1;
        var currentScale;
        touch.on($targetObj, 'pinch', function (ev) {
            if (cat.touchjs.curStatus == 2) {
                return;
            }
            cat.touchjs.curStatus = 1;
            currentScale = ev.scale - 1;
            currentScale = initialScale + currentScale;
            cat.touchjs.scaleVal = currentScale;
            var transformStyle = 'scale(' + cat.touchjs.scaleVal + ') rotate(' + cat.touchjs.rotateVal + 'deg)';
            $targetObj.css("transform", transformStyle).css("-webkit-transform", transformStyle);
            callback(cat.touchjs.scaleVal);
        });

        touch.on($targetObj, 'pinchend', function (ev) {
            if (cat.touchjs.curStatus == 2) {
                return;
            }
            initialScale = currentScale;
            cat.touchjs.scaleVal = currentScale;
            callback(cat.touchjs.scaleVal);
        });
    },
    //旋轉
    rotate: function ($targetObj, callback) {
        var angle = cat.touchjs.rotateVal || 0;
        touch.on($targetObj, 'rotate', function (ev) {
            if (cat.touchjs.curStatus == 1) {
                return;
            }
            cat.touchjs.curStatus = 2;
            var totalAngle = angle + ev.rotation;
            if (ev.fingerStatus === 'end') {
                angle = angle + ev.rotation;
            }
            cat.touchjs.rotateVal = totalAngle;
            var transformStyle = 'scale(' + cat.touchjs.scaleVal + ') rotate(' + cat.touchjs.rotateVal + 'deg)';
            $targetObj.css("transform", transformStyle).css("-webkit-transform", transformStyle);
            $targetObj.attr('data-rotate', cat.touchjs.rotateVal);
            callback(cat.touchjs.rotateVal);
        });
    }
};

調用起來很簡單：

html：

<div style="position:relative;width: 100%;height: 250px;overflow: hidden;border: 1px dashed #ff0000;">
  <img id="targetObj" style="position:relative;transform-origin:center" src="http://demo.somethingwhat.com/images/flower1.jpg" />
</div>

js：

var $targetObj = $('#targetObj');
//初始化設置
cat.touchjs.init($targetObj, function (left, top, scale, rotate) {};
//初始化拖動手勢（不需要就註釋掉）
cat.touchjs.drag($targetObj, function (left, top) { });
//初始化縮放手勢（不需要就註釋掉）
cat.touchjs.scale($targetObj, function (scale) { });
//初始化旋轉手勢（不需要就註釋掉）
cat.touchjs.rotate($targetObj, function (rotate) { });

在線預覽、下載全在這裏：

https://www.somethingwhat.com/Project/Detail?id=f092710d3f7255b4