Js实现图片切割

//图片切割
var ImgCropper = Class.create();
ImgCropper.prototype = {
  //容器对象,控制层,图片地址
  initialize: function(container, handle, url, options) {
    this._Container = $(container);//容器对象
    this._layHandle = $(handle);//控制层
    this.Url = url;//图片地址
    
    this._layBase = this._Container.appendChild(document.createElement("img"));//底层
    this._layCropper = this._Container.appendChild(document.createElement("img"));//切割层
    this._layCropper.onload = Bind(this, this.SetPos);
    //用来设置大小
    this._tempImg = document.createElement("img");
    this._tempImg.onload = Bind(this, this.SetSize);
    
    this.SetOptions(options);
    
    this.Opacity = Math.round(this.options.Opacity);
    this.Color = this.options.Color;
    this.Scale = !!this.options.Scale;
    this.Ratio = Math.max(this.options.Ratio, 0);
    this.Width = Math.round(this.options.Width);
    this.Height = Math.round(this.options.Height);
    
    //设置预览对象
    var oPreview = $(this.options.Preview);//预览对象
    if(oPreview){
        oPreview.style.position = "relative";
        oPreview.style.overflow = "hidden";
        this.viewWidth = Math.round(this.options.viewWidth);
        this.viewHeight = Math.round(this.options.viewHeight);
        //预览图片对象
        this._view = oPreview.appendChild(document.createElement("img"));
        this._view.style.position = "absolute";
        this._view.onload = Bind(this, this.SetPreview);
    }
    //设置拖放
    this._drag = new Drag(this._layHandle, { Limit: true, onMove: Bind(this, this.SetPos), Transparent: true });
    //设置缩放
    this.Resize = !!this.options.Resize;
    if(this.Resize){
        var op = this.options, _resize = new Resize(this._layHandle, { Max: true, onResize: Bind(this, this.SetPos) });
        //设置缩放触发对象
        op.RightDown && (_resize.Set(op.RightDown, "right-down"));
        op.LeftDown && (_resize.Set(op.LeftDown, "left-down"));
        op.RightUp && (_resize.Set(op.RightUp, "right-up"));
        op.LeftUp && (_resize.Set(op.LeftUp, "left-up"));
        op.Right && (_resize.Set(op.Right, "right"));
        op.Left && (_resize.Set(op.Left, "left"));
        op.Down && (_resize.Set(op.Down, "down"));
        op.Up && (_resize.Set(op.Up, "up"));
        //最小范围限制
        this.Min = !!this.options.Min;
        this.minWidth = Math.round(this.options.minWidth);
        this.minHeight = Math.round(this.options.minHeight);
        //设置缩放对象
        this._resize = _resize;
    }
    //设置样式
    this._Container.style.position = "relative";
    this._Container.style.overflow = "hidden";
    this._layHandle.style.zIndex = 200;
    this._layCropper.style.zIndex = 100;
    this._layBase.style.position = this._layCropper.style.position = "absolute";
    this._layBase.style.top = this._layBase.style.left = this._layCropper.style.top = this._layCropper.style.left = 0;//对齐
    //初始化设置
    this.Init();
  },
  //设置默认属性
  SetOptions: function(options) {
    this.options = {//默认值
        Opacity:    50,//透明度(0到100)
        Color:        "",//背景色
        Width:        0,//图片高度
        Height:        0,//图片高度
        //缩放触发对象
        Resize:        false,//是否设置缩放
        Right:        "",//右边缩放对象
        Left:        "",//左边缩放对象
        Up:            "",//上边缩放对象
        Down:        "",//下边缩放对象
        RightDown:    "",//右下缩放对象
        LeftDown:    "",//左下缩放对象
        RightUp:    "",//右上缩放对象
        LeftUp:        "",//左上缩放对象
        Min:        false,//是否最小宽高限制(为true时下面min参数有用)
        minWidth:    50,//最小宽度
        minHeight:    50,//最小高度
        Scale:        false,//是否按比例缩放
        Ratio:        0,//缩放比例(宽/高)
        //预览对象设置
        Preview:    "",//预览对象
        viewWidth:    0,//预览宽度
        viewHeight:    0//预览高度
    };
    Extend(this.options, options || {});
  },
  //初始化对象
  Init: function() {
    //设置背景色
    this.Color && (this._Container.style.backgroundColor = this.Color);
    //设置图片
    this._tempImg.src = this._layBase.src = this._layCropper.src = this.Url;
    //设置透明
    if(isIE){
        this._layBase.style.filter = "alpha(opacity:" + this.Opacity + ")";
    } else {
        this._layBase.style.opacity = this.Opacity / 100;
    }
    //设置预览对象
    this._view && (this._view.src = this.Url);
    //设置缩放
    if(this.Resize){
        with(this._resize){
            Scale = this.Scale; Ratio = this.Ratio; Min = this.Min; minWidth = this.minWidth; minHeight = this.minHeight;
        }
    }
  },
  //设置切割样式
  SetPos: function() {
    //ie6渲染bug
    if(isIE6){ with(this._layHandle.style){ zoom = .9; zoom = 1; }; };
    //获取位置参数
    var p = this.GetPos();
    //按拖放对象的参数进行切割
    this._layCropper.style.clip = "rect(" + p.Top + "px " + (p.Left + p.Width) + "px " + (p.Top + p.Height) + "px " + p.Left + "px)";
    //设置预览
    this.SetPreview();
  },
  //设置预览效果
  SetPreview: function() {
    if(this._view){
        //预览显示的宽和高
        var p = this.GetPos(), s = this.GetSize(p.Width, p.Height, this.viewWidth, this.viewHeight), scale = s.Height / p.Height;
        //按比例设置参数
        var pHeight = this._layBase.height * scale, pWidth = this._layBase.width * scale, pTop = p.Top * scale, pLeft = p.Left * scale;
        //设置预览对象
        with(this._view.style){
            //设置样式
            width = pWidth + "px"; height = pHeight + "px"; top = - pTop + "px "; left = - pLeft + "px";
            //切割预览图
            clip = "rect(" + pTop + "px " + (pLeft + s.Width) + "px " + (pTop + s.Height) + "px " + pLeft + "px)";
        }
    }
  },
  //设置图片大小
  SetSize: function() {
    var s = this.GetSize(this._tempImg.width, this._tempImg.height, this.Width, this.Height);
    //设置底图和切割图
    this._layBase.style.width = this._layCropper.style.width = s.Width + "px";
    this._layBase.style.height = this._layCropper.style.height = s.Height + "px";
    //设置拖放范围
    this._drag.mxRight = s.Width; this._drag.mxBottom = s.Height;
    //设置缩放范围
    if(this.Resize){ this._resize.mxRight = s.Width; this._resize.mxBottom = s.Height; }
  },
  //获取当前样式
  GetPos: function() {
    with(this._layHandle){
        return { Top: offsetTop, Left: offsetLeft, Width: offsetWidth, Height: offsetHeight }
    }
  },
  //获取尺寸
  GetSize: function(nowWidth, nowHeight, fixWidth, fixHeight) {
    var iWidth = nowWidth, iHeight = nowHeight, scale = iWidth / iHeight;
    //按比例设置
    if(fixHeight){ iWidth = (iHeight = fixHeight) * scale; }
    if(fixWidth && (!fixHeight || iWidth > fixWidth)){ iHeight = (iWidth = fixWidth) / scale; }
    //返回尺寸对象
    return { Width: iWidth, Height: iHeight }
  }
}