react移动端svg等图片拖拽缩放

谁借莪１个温暖的怀抱￠ 2021-09-08 15:24 593阅读 0赞

![react移动端图片缩放拖拽][react]

使用es6类的方法实现
    
    
    
    /**
     *定义svg，png，jpeg图片移动端缩放功能
     * 
     * 可拖拽，看缩放
        let zoomEl = document.getElementById('zoomEl');
        let zoom = new Zoom({
            el:zoomEl,
            options:{'top': zoomEl.offsetTop+50, 'left': zoomEl.offsetLeft+50, 'width': 400, 'height': 400 }
        });
        zoom.setScale(1)
     * @class Zoom
     */
    class Zoom{
        
        /**
         *Creates an instance of Zoom.
         * @param {el,options:{top,left,width,height}} ops 参数配置
         * @memberof Zoom
         */
        constructor(ops){
            //参数配置
            this.ops = Object.assign({
                minScale:1,
                maxScale:3,
                top:50,
                left:50,
            },ops.options)
            //展示的存放容器
            this.el = ops.el;
    
            this.lastSapce = 0;
            this.touchState = 0;
            this.lastPoint = null;
            this.targetPoint = null;
            //放大缩小的倍数 当前缩放倍数
            this.minScale = this.ops.minScale || 1;
            this.maxScale = this.ops.maxScale || 10;
    
            // dom 的尺寸参数
            this.width = this.ops.width;
            this.height = this.ops.height;
            this.top = this.ops.top;
            this.left = this.ops.left;
            this.scale = 1;
    
            // 初始位置以及初始宽高
            this.originTop = this.ops.top;
            this.originLeft = this.ops.left;
            this.originW = this.width;
            this.originH = this.height;
            
            // 图片中心点
            this.centerX = this.left + this.originW/2;
            this.centerY = this.top  + this.originH/2;
            this.el.style.position = "absolute";
            this.init();
        }
    
        /**
         *初始化数据
         *
         * @memberof Zoom
         */
        init(){
            this.el.addEventListener('touchmove',this.touchmoveHandler);
            this.el.addEventListener('touchstart',this.touchmoveHandler);
            this.el.addEventListener('touchend',this.touchEndHandler);
            this.el.addEventListener('touchcancel',this.touchEndHandler);
            this.el.addEventListener('touchstart',this.dbclickHandler);
            this.el.zoom = this;
        }
    
        getTouches(event){
            let touches = event.touches;
            if(!touches){
                touches = event.originalEvent.touches;
            }
            return touches;
        }
    
        getTouchsDistance(t1,t2){
            let dx = parseInt(t1.pageX - t2.pageX);
            let dy = parseInt(t1.pageY - t2.pageY);
    
            let d = Math.pow((dx*dx+dy+dy),0.8);
            return d.toFixed(5); 
        }
    
        restView(){
            this.el.style.width = this.width +"px";
            this.el.style.height = this.height +"px";
            this.el.style.top = this.top +"px";
            this.el.style.left = this.left +"px";
        }
    
        dbclickHandler(event){
            event.stopPropagation();
            event.preventDefault();
    
            let el = event.currentTarget;
            let zoom = el.zoom;
            let time = new Date(event.timeStamp).getTime();
            let touchs = zoom.getTouches(event);
            if (touchs.length == 1) {
                if (!el.lastClickTime) {
                    el.lastClickTime = time;
                }else{
                    if (time - el.lastClickTime < 300) {
                        el.lastClickTime = 0;
                        if (zoom.scale != 1) {
                            zoom.setScale(1);
                        }else if(zoom.scale == 1){
                            zoom.setScale(2);
                        }
                    }else{
                        el.lastClickTime = time;
                    }
                }
            }
            zoom.touchStartTime = new Date().getTime();
            return false;
        }
    
        drage(touch){
            if (this.lastPoint == null) {
                this.lastPoint = {
                    x:touch.pageX,
                    y:touch.pageY,
                }
            }else{
                let dx = parseInt(touch.pageX - this.lastPoint.x);
                let dy = parseInt(touch.pageY - this.lastPoint.y);
    
    
                this.lastPoint.x = touch.pageX;
                this.lastPoint.y = touch.pageY;
    
                this.left += dx;
                this.top += dy;
    
                this.setTransform(false);
            } 
        }
    
        zoom(touchs){
            this.lastPoint = null;
            let t1 = touchs[0];
            let t2 = touchs[1];
    
            let x1 = t1.pageX;
            let x2 = t2.pageX;
            let y1 = t1.pageY;
            let y2 = t2.pageY;
    
            let d = this.getTouchsDistance(t1,t2);
    
            if (this.touchState == 0) {
                this.lastSapce = d;
                this.touchState = 1;
    
                this.pointX = (x2 + (x1 - x2) / 2 - this.left)/this.scale;
                this.pointY = (y2 + (y1 - y2) / 2 - this.top)/this.scale;
            }else if(this.touchState == 1){
    
                let scaleChange = ((d / this.lastSapce) - 1) * 2;
    
                let scale = this.scale + scaleChange / 2;
    
                this.setScale(scale,this.pointX,this.pointY);
    
                this.lastSapce = d;
            }
        }
    
        touchmoveHandler(event){
            event.stopPropagation();
            event.preventDefault();
            let el = event.currentTarget;
            let zoom = el.zoom;
            let touchs = zoom.getTouches(event);
            if (touchs.length == 1) {
                zoom.drage(touchs[0]);//拖动处理
            }else if (touchs.length >= 2) {
                zoom.lastPoint = null;//终止拖动事件
                zoom.zoom(touchs);//缩放处理
    
            }
            return false;
        }
    
        touchEndHandler(event){
            let zoom = event.currentTarget.zoom;
    
            zoom.touchState = 0;
            zoom.lastPoint = null;
            zoom.lastSapce = 0;
    
            let minSpace = 20;
            let parentWidth = zoom.el.parentElement.offsetWidth;
            let parentHight =zoom.el.parentElement.offsetHeight;
            let scale = zoom.scale;
    
            if(scale < zoom.minScale){
                scale = zoom.minScale;
            }
            if(scale > zoom.maxScale){
                scale = zoom.maxScale;
            }
    
            if(scale != zoom.scale){
                zoom.preSetScale(scale,zoom.lastPointX,zoom.lastPointY);
            }
    
            if((zoom.left + zoom.width) < minSpace){
                    zoom.left = - zoom.width + minSpace;
            }
            if(zoom.left >= (parentWidth - minSpace)){
                    zoom.left = parentWidth - minSpace;
            }
    
            if((zoom.top + zoom.height) < minSpace){
                zoom.top = - zoom.height + minSpace;
            }
            if(zoom.top >= (parentHight - minSpace)){
                zoom.top = parentHight - minSpace;
            }
            zoom.setTransform(true);
            return;  
        }
    
        setTransform(needAnimation,originX,originY){
            let distanceX = this.left - this.originLeft;
            let distanceY = this.top - this.originTop;
            let scale = this.scale;
            originX = originX == undefined ? (this.originTop + 'px') : originX;
            originY = originY == undefined ? (this.originLeft + 'px') : originY;
            this.el.style.transformOrigin = 'left top';
            this.el.style.transform = 'matrix('+scale+',0,0,'+scale+','+distanceX+','+distanceY+')';
            if(needAnimation == true){
                this.el.style.transition = 'all .3s ease-in-out 0s'
            }else{
                this.el.style.transition = ''
            }
        }
    
        destroy(){
            this.el.removeEventListener('touchmove',this.touchmoveHandler);
            this.el.removeEventListener('touchstart',this.touchmoveHandler);
            this.el.removeEventListener('touchend',this.touchEndHandler);
            this.el.removeEventListener('touchcancel',this.touchEndHandler);
    
            this.el.zoom = null;
        }
    
        setScale(scale,pointX,pointY){
            this.preSetScale(scale,pointX,pointY);
            this.setTransform(false);
        }
    
        preSetScale(scale,pointX,pointY){
            if (scale < 0.5) {
                scale = 0.5;
            }
    
            if (pointX ==undefined) {
                this.left = this.centerX - this.originW / 2 - this.originW/2*(scale - 1);
                this.top = this.centerY - this.originH / 2 - this.originH/2*(scale - 1);
                this.width = scale * this.originW;
                this.height = scale * this.originH;
                this.scale = scale;
            }else{
                this.width = scale * this.originW;
                this.height = scale * this.originH;
                this.left = this.left - pointX * (scale - this.scale);
                this.top = this.top - pointY * (scale - this.scale);
                this.lastPointX = pointX;
                this.lastPointY = pointY;
                this.scale = scale;
            }
        }
    }
    export default Zoom;

[react]: /images/20210908/1ffd7e9fb1e446a48084d4014c3f3744.png