Js实现截图功能

浏览数：52 / 时间：2015年06月09日

今日想试下弄个截图功能，在网上找了些资料，终于把它实现了，步骤如下：

首先要准备4个js文件：

1）prototype.js

var Class = {
create: function() {
return function() { this.initialize.apply(this, arguments); }
}
}

var Extend = function(destination, source) {
for (var property in source) {
destination[property] = source[property];
}
}

var Bind = function(object, fun) {
return function() {
return fun.apply(object, arguments);
}
}

var BindAsEventListener = function(object, fun) {
var args = Array.prototype.slice.call(arguments).slice(2);
return function(event) {
return fun.apply(object, [event || window.event].concat(args));
}
}

var CurrentStyle = function(element) {
return element.currentStyle || document.defaultView.getComputedStyle(element, null);
}

2）ImgCropper.js

//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 }
}
}

3)Drag.js

//拖放程序
var Drag = Class.create();
Drag.prototype = {
//拖放对象
initialize: function(drag, options) {
this.Drag = $(drag); //拖放对象
this._x = this._y = 0; //记录鼠标相对拖放对象的位置
this._marginLeft = this._marginTop = 0; //记录margin
//事件对象(用于绑定移除事件)
this._fM = BindAsEventListener(this, this.Move);
this._fS = Bind(this, this.Stop);

this.SetOptions(options);

this.Limit = !!this.options.Limit;
this.mxLeft = parseInt(this.options.mxLeft);
this.mxRight = parseInt(this.options.mxRight);
this.mxTop = parseInt(this.options.mxTop);
this.mxBottom = parseInt(this.options.mxBottom);

this.LockX = !!this.options.LockX;
this.LockY = !!this.options.LockY;
this.Lock = !!this.options.Lock;

this.onStart = this.options.onStart;
this.onMove = this.options.onMove;
this.onStop = this.options.onStop;

this._Handle = $(this.options.Handle) || this.Drag;
this._mxContainer = $(this.options.mxContainer) || null;

this.Drag.style.position = "absolute";
//透明
if(isIE && !!this.options.Transparent){
//填充拖放对象
with(this._Handle.appendChild(document.createElement("div")).style){
width = height = "100%"; backgroundColor = "#fff"; filter = "alpha(opacity:0)"; fontSize = 0;
}
}
//修正范围
this.Repair();
addEventHandler(this._Handle, "mousedown", BindAsEventListener(this, this.Start));
},
//设置默认属性
SetOptions: function(options) {
this.options = { //默认值
Handle: "", //设置触发对象（不设置则使用拖放对象）
Limit: false, //是否设置范围限制(为true时下面参数有用,可以是负数)
mxLeft: 0, //左边限制
mxRight: 9999, //右边限制
mxTop: 0, //上边限制
mxBottom: 9999, //下边限制
mxContainer: "", //指定限制在容器内
LockX: false, //是否锁定水平方向拖放
LockY: false, //是否锁定垂直方向拖放
Lock: false, //是否锁定
Transparent: false, //是否透明
onStart: function(){}, //开始移动时执行
onMove: function(){}, //移动时执行
onStop: function(){} //结束移动时执行
};
Extend(this.options, options || {});
},
//准备拖动
Start: function(oEvent) {
if(this.Lock){ return; }
this.Repair();
//记录鼠标相对拖放对象的位置
this._x = oEvent.clientX - this.Drag.offsetLeft;
this._y = oEvent.clientY - this.Drag.offsetTop;
//记录margin
this._marginLeft = parseInt(CurrentStyle(this.Drag).marginLeft) || 0;
this._marginTop = parseInt(CurrentStyle(this.Drag).marginTop) || 0;
//mousemove时移动 mouseup时停止
addEventHandler(document, "mousemove", this._fM);
addEventHandler(document, "mouseup", this._fS);
if(isIE){
//焦点丢失
addEventHandler(this._Handle, "losecapture", this._fS);
//设置鼠标捕获
this._Handle.setCapture();
}else{
//焦点丢失
addEventHandler(window, "blur", this._fS);
//阻止默认动作
oEvent.preventDefault();
};
//附加程序
this.onStart();
},
//修正范围
Repair: function() {
if(this.Limit){
//修正错误范围参数
this.mxRight = Math.max(this.mxRight, this.mxLeft + this.Drag.offsetWidth);
this.mxBottom = Math.max(this.mxBottom, this.mxTop + this.Drag.offsetHeight);
//如果有容器必须设置position为relative或absolute来相对或绝对定位，并在获取offset之前设置
!this._mxContainer || CurrentStyle(this._mxContainer).position == "relative" || CurrentStyle(this._mxContainer).position == "absolute" || (this._mxContainer.style.position = "relative");
}
},
//拖动
Move: function(oEvent) {
//判断是否锁定
if(this.Lock){ this.Stop(); return; };
//清除选择
window.getSelection ? window.getSelection().removeAllRanges() : document.selection.empty();
//设置移动参数
var iLeft = oEvent.clientX - this._x, iTop = oEvent.clientY - this._y;
//设置范围限制
if(this.Limit){
//设置范围参数
var mxLeft = this.mxLeft, mxRight = this.mxRight, mxTop = this.mxTop, mxBottom = this.mxBottom;
//如果设置了容器，再修正范围参数
if(!!this._mxContainer){
mxLeft = Math.max(mxLeft, 0);
mxTop = Math.max(mxTop, 0);
mxRight = Math.min(mxRight, this._mxContainer.clientWidth);
mxBottom = Math.min(mxBottom, this._mxContainer.clientHeight);
};
//修正移动参数
iLeft = Math.max(Math.min(iLeft, mxRight - this.Drag.offsetWidth), mxLeft);
iTop = Math.max(Math.min(iTop, mxBottom - this.Drag.offsetHeight), mxTop);
}
//设置位置，并修正margin
if(!this.LockX){ this.Drag.style.left = iLeft - this._marginLeft + "px"; }
if(!this.LockY){ this.Drag.style.top = iTop - this._marginTop + "px"; }
//附加程序
this.onMove();
},
//停止拖动
Stop: function() {
//移除事件
removeEventHandler(document, "mousemove", this._fM);
removeEventHandler(document, "mouseup", this._fS);
if(isIE){
removeEventHandler(this._Handle, "losecapture", this._fS);
this._Handle.releaseCapture();
}else{
removeEventHandler(window, "blur", this._fS);
};
//附加程序
this.onStop();
}
};

4)Resize.js

//缩放程序
var Resize = Class.create();
Resize.prototype = {
//缩放对象
initialize: function(obj, options) {
this._obj = $(obj); //缩放对象

this._styleWidth = this._styleHeight = this._styleLeft = this._styleTop = 0; //样式参数
this._sideRight = this._sideDown = this._sideLeft = this._sideUp = 0; //坐标参数
this._fixLeft = this._fixTop = 0; //定位参数
this._scaleLeft = this._scaleTop = 0; //定位坐标

this._mxSet = function(){}; //范围设置程序
this._mxRightWidth = this._mxDownHeight = this._mxUpHeight = this._mxLeftWidth = 0; //范围参数
this._mxScaleWidth = this._mxScaleHeight = 0; //比例范围参数

this._fun = function(){}; //缩放执行程序

//获取边框宽度
var _style = CurrentStyle(this._obj);
this._borderX = (parseInt(_style.borderLeftWidth) || 0) + (parseInt(_style.borderRightWidth) || 0);
this._borderY = (parseInt(_style.borderTopWidth) || 0) + (parseInt(_style.borderBottomWidth) || 0);
//事件对象(用于绑定移除事件)
this._fR = BindAsEventListener(this, this.Resize);
this._fS = Bind(this, this.Stop);

this.SetOptions(options);
//范围限制
this.Max = !!this.options.Max;
this._mxContainer = $(this.options.mxContainer) || null;
this.mxLeft = Math.round(this.options.mxLeft);
this.mxRight = Math.round(this.options.mxRight);
this.mxTop = Math.round(this.options.mxTop);
this.mxBottom = Math.round(this.options.mxBottom);
//宽高限制
this.Min = !!this.options.Min;
this.minWidth = Math.round(this.options.minWidth);
this.minHeight = Math.round(this.options.minHeight);
//按比例缩放
this.Scale = !!this.options.Scale;
this.Ratio = Math.max(this.options.Ratio, 0);

this.onResize = this.options.onResize;

this._obj.style.position = "absolute";
!this._mxContainer || CurrentStyle(this._mxContainer).position == "relative" || (this._mxContainer.style.position = "relative");
},
//设置默认属性
SetOptions: function(options) {
this.options = { //默认值
Max: false, //是否设置范围限制(为true时下面mx参数有用)
mxContainer:"", //指定限制在容器内
mxLeft: 0, //左边限制
mxRight: 9999, //右边限制
mxTop: 0, //上边限制
mxBottom: 9999, //下边限制
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)
onResize: function(){} //缩放时执行
};
Extend(this.options, options || {});
},
//设置触发对象
Set: function(resize, side) {
var resize = $(resize), fun;
if(!resize) return;
//根据方向设置
switch (side.toLowerCase()) {
case "up" :
fun = this.Up;
break;
case "down" :
fun = this.Down;
break;
case "left" :
fun = this.Left;
break;
case "right" :
fun = this.Right;
break;
case "left-up" :
fun = this.LeftUp;
break;
case "right-up" :
fun = this.RightUp;
break;
case "left-down" :
fun = this.LeftDown;
break;
case "right-down" :
default :
fun = this.RightDown;
};
//设置触发对象
addEventHandler(resize, "mousedown", BindAsEventListener(this, this.Start, fun));
},
//准备缩放
Start: function(e, fun, touch) {
//防止冒泡(跟拖放配合时设置)
e.stopPropagation ? e.stopPropagation() : (e.cancelBubble = true);
//设置执行程序
this._fun = fun;
//样式参数值
this._styleWidth = this._obj.clientWidth;
this._styleHeight = this._obj.clientHeight;
this._styleLeft = this._obj.offsetLeft;
this._styleTop = this._obj.offsetTop;
//四条边定位坐标
this._sideLeft = e.clientX - this._styleWidth;
this._sideRight = e.clientX + this._styleWidth;
this._sideUp = e.clientY - this._styleHeight;
this._sideDown = e.clientY + this._styleHeight;
//top和left定位参数
this._fixLeft = this._styleLeft + this._styleWidth;
this._fixTop = this._styleTop + this._styleHeight;
//缩放比例
if(this.Scale){
//设置比例
this.Ratio = Math.max(this.Ratio, 0) || this._styleWidth / this._styleHeight;
//left和top的定位坐标
this._scaleLeft = this._styleLeft + this._styleWidth / 2;
this._scaleTop = this._styleTop + this._styleHeight / 2;
};
//范围限制
if(this.Max){
//设置范围参数
var mxLeft = this.mxLeft, mxRight = this.mxRight, mxTop = this.mxTop, mxBottom = this.mxBottom;
//如果设置了容器，再修正范围参数
if(!!this._mxContainer){
mxLeft = Math.max(mxLeft, 0);
mxTop = Math.max(mxTop, 0);
mxRight = Math.min(mxRight, this._mxContainer.clientWidth);
mxBottom = Math.min(mxBottom, this._mxContainer.clientHeight);
};
//根据最小值再修正
mxRight = Math.max(mxRight, mxLeft + (this.Min ? this.minWidth : 0) + this._borderX);
mxBottom = Math.max(mxBottom, mxTop + (this.Min ? this.minHeight : 0) + this._borderY);
//由于转向时要重新设置所以写成function形式
this._mxSet = function(){
this._mxRightWidth = mxRight - this._styleLeft - this._borderX;
this._mxDownHeight = mxBottom - this._styleTop - this._borderY;
this._mxUpHeight = Math.max(this._fixTop - mxTop, this.Min ? this.minHeight : 0);
this._mxLeftWidth = Math.max(this._fixLeft - mxLeft, this.Min ? this.minWidth : 0);
};
this._mxSet();
//有缩放比例下的范围限制
if(this.Scale){
this._mxScaleWidth = Math.min(this._scaleLeft - mxLeft, mxRight - this._scaleLeft - this._borderX) * 2;
this._mxScaleHeight = Math.min(this._scaleTop - mxTop, mxBottom - this._scaleTop - this._borderY) * 2;
};
};
//mousemove时缩放 mouseup时停止
addEventHandler(document, "mousemove", this._fR);
addEventHandler(document, "mouseup", this._fS);
if(isIE){
addEventHandler(this._obj, "losecapture", this._fS);
this._obj.setCapture();
}else{
addEventHandler(window, "blur", this._fS);
e.preventDefault();
};
},
//缩放
Resize: function(e) {
//清除选择
window.getSelection ? window.getSelection().removeAllRanges() : document.selection.empty();
//执行缩放程序
this._fun(e);
//设置样式，变量必须大于等于0否则ie出错
with(this._obj.style){
width = this._styleWidth + "px"; height = this._styleHeight + "px";
top = this._styleTop + "px"; left = this._styleLeft + "px";
}
//附加程序
this.onResize();
},
//缩放程序
//上
Up: function(e) {
this.RepairY(this._sideDown - e.clientY, this._mxUpHeight);
this.RepairTop();
this.TurnDown(this.Down);
},
//下
Down: function(e) {
this.RepairY(e.clientY - this._sideUp, this._mxDownHeight);
this.TurnUp(this.Up);
},
//右
Right: function(e) {
this.RepairX(e.clientX - this._sideLeft, this._mxRightWidth);
this.TurnLeft(this.Left);
},
//左
Left: function(e) {
this.RepairX(this._sideRight - e.clientX, this._mxLeftWidth);
this.RepairLeft();
this.TurnRight(this.Right);
},
//右下
RightDown: function(e) {
this.RepairAngle(
e.clientX - this._sideLeft, this._mxRightWidth,
e.clientY - this._sideUp, this._mxDownHeight
);
this.TurnLeft(this.LeftDown) || this.Scale || this.TurnUp(this.RightUp);
},
//右上
RightUp: function(e) {
this.RepairAngle(
e.clientX - this._sideLeft, this._mxRightWidth,
this._sideDown - e.clientY, this._mxUpHeight
);
this.RepairTop();
this.TurnLeft(this.LeftUp) || this.Scale || this.TurnDown(this.RightDown);
},
//左下
LeftDown: function(e) {
this.RepairAngle(
this._sideRight - e.clientX, this._mxLeftWidth,
e.clientY - this._sideUp, this._mxDownHeight
);
this.RepairLeft();
this.TurnRight(this.RightDown) || this.Scale || this.TurnUp(this.LeftUp);
},
//左上
LeftUp: function(e) {
this.RepairAngle(
this._sideRight - e.clientX, this._mxLeftWidth,
this._sideDown - e.clientY, this._mxUpHeight
);
this.RepairTop(); this.RepairLeft();
this.TurnRight(this.RightUp) || this.Scale || this.TurnDown(this.LeftDown);
},
//修正程序
//水平方向
RepairX: function(iWidth, mxWidth) {
iWidth = this.RepairWidth(iWidth, mxWidth);
if(this.Scale){
var iHeight = this.RepairScaleHeight(iWidth);
if(this.Max && iHeight > this._mxScaleHeight){
iHeight = this._mxScaleHeight;
iWidth = this.RepairScaleWidth(iHeight);
}else if(this.Min && iHeight < this.minHeight){
var tWidth = this.RepairScaleWidth(this.minHeight);
if(tWidth < mxWidth){ iHeight = this.minHeight; iWidth = tWidth; }
}
this._styleHeight = iHeight;
this._styleTop = this._scaleTop - iHeight / 2;
}
this._styleWidth = iWidth;
},
//垂直方向
RepairY: function(iHeight, mxHeight) {
iHeight = this.RepairHeight(iHeight, mxHeight);
if(this.Scale){
var iWidth = this.RepairScaleWidth(iHeight);
if(this.Max && iWidth > this._mxScaleWidth){
iWidth = this._mxScaleWidth;
iHeight = this.RepairScaleHeight(iWidth);
}else if(this.Min && iWidth < this.minWidth){
var tHeight = this.RepairScaleHeight(this.minWidth);
if(tHeight < mxHeight){ iWidth = this.minWidth; iHeight = tHeight; }
}
this._styleWidth = iWidth;
this._styleLeft = this._scaleLeft - iWidth / 2;
}
this._styleHeight = iHeight;
},
//对角方向
RepairAngle: function(iWidth, mxWidth, iHeight, mxHeight) {
iWidth = this.RepairWidth(iWidth, mxWidth);
if(this.Scale){
iHeight = this.RepairScaleHeight(iWidth);
if(this.Max && iHeight > mxHeight){
iHeight = mxHeight;
iWidth = this.RepairScaleWidth(iHeight);
}else if(this.Min && iHeight < this.minHeight){
var tWidth = this.RepairScaleWidth(this.minHeight);
if(tWidth < mxWidth){ iHeight = this.minHeight; iWidth = tWidth; }
}
}else{
iHeight = this.RepairHeight(iHeight, mxHeight);
}
this._styleWidth = iWidth;
this._styleHeight = iHeight;
},
//top
RepairTop: function() {
this._styleTop = this._fixTop - this._styleHeight;
},
//left
RepairLeft: function() {
this._styleLeft = this._fixLeft - this._styleWidth;
},
//height
RepairHeight: function(iHeight, mxHeight) {
iHeight = Math.min(this.Max ? mxHeight : iHeight, iHeight);
iHeight = Math.max(this.Min ? this.minHeight : iHeight, iHeight, 0);
return iHeight;
},
//width
RepairWidth: function(iWidth, mxWidth) {
iWidth = Math.min(this.Max ? mxWidth : iWidth, iWidth);
iWidth = Math.max(this.Min ? this.minWidth : iWidth, iWidth, 0);
return iWidth;
},
//比例高度
RepairScaleHeight: function(iWidth) {
return Math.max(Math.round((iWidth + this._borderX) / this.Ratio - this._borderY), 0);
},
//比例宽度
RepairScaleWidth: function(iHeight) {
return Math.max(Math.round((iHeight + this._borderY) * this.Ratio - this._borderX), 0);
},
//转向程序
//转右
TurnRight: function(fun) {
if(!(this.Min || this._styleWidth)){
this._fun = fun;
this._sideLeft = this._sideRight;
this.Max && this._mxSet();
return true;
}
},
//转左
TurnLeft: function(fun) {
if(!(this.Min || this._styleWidth)){
this._fun = fun;
this._sideRight = this._sideLeft;
this._fixLeft = this._styleLeft;
this.Max && this._mxSet();
return true;
}
},
//转上
TurnUp: function(fun) {
if(!(this.Min || this._styleHeight)){
this._fun = fun;
this._sideDown = this._sideUp;
this._fixTop = this._styleTop;
this.Max && this._mxSet();
return true;
}
},
//转下
TurnDown: function(fun) {
if(!(this.Min || this._styleHeight)){
this._fun = fun;
this._sideUp = this._sideDown;
this.Max && this._mxSet();
return true;
}
},
//停止缩放
Stop: function() {
removeEventHandler(document, "mousemove", this._fR);
removeEventHandler(document, "mouseup", this._fS);
if(isIE){
removeEventHandler(this._obj, "losecapture", this._fS);
this._obj.releaseCapture();
}else{
removeEventHandler(window, "blur", this._fS);
}
}
};

然后写一个处理程序，用来画出截图：

ImageCropper.ashx

<%@ WebHandler Language="c#" Class="ImageCropper" Debug="true" %>
using System;
using System.Web;
using System.Drawing;
using System.IO;

public class ImageCropper : IHttpHandler
{

#region IHttpHandler 成员

public void ProcessRequest(HttpContext context)
{
string ImgPath = Convert.ToString(context.Request["p"]);
int PointX = Convert.ToInt32(context.Request["x"]);
int PointY = Convert.ToInt32(context.Request["y"]);
int CutWidth = Convert.ToInt32(context.Request["w"]);
int CutHeight = Convert.ToInt32(context.Request["h"]);
int PicWidth = Convert.ToInt32(context.Request["pw"]);
int PicHeight = Convert.ToInt32(context.Request["ph"]);

context.Response.ContentType = "image/jpeg";
ShowImage(HttpContext.Current.Server.MapPath(ImgPath), PointX, PointY, CutWidth, CutHeight, PicWidth, PicHeight).WriteTo(context.Response.OutputStream);
}

private MemoryStream ShowImage(string path, int PointX, int PointY, int CutWidth, int CutHeight, int PicWidth, int PicHeight)
{
Image image = Image.FromFile(path);
Bitmap bm = new Bitmap(CutWidth, CutHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
Graphics graphics = Graphics.FromImage(bm);
graphics.DrawImage(image, new Rectangle(0, 0, CutWidth, CutHeight), PointX * image.Width / PicWidth, PointY * image.Height / PicHeight, CutWidth * image.Width / PicWidth, CutHeight * image.Height / PicHeight, GraphicsUnit.Pixel);
int a = path.LastIndexOf(‘.‘);
int b = path.LastIndexOf(‘\\‘);
string _newPic = path.Substring(0, b) + "\\new_" + DateTime.Now.ToFileTimeUtc().ToString("X") + ".jpg";
bm.Save(_newPic, System.Drawing.Imaging.ImageFormat.Jpeg);
MemoryStream ms = new MemoryStream();
bm.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
image.Dispose();
graphics.Dispose();
bm.Dispose();
return ms;
}
public bool IsReusable
{
get
{
return false;
}
}

#endregion
}

最后是页面代码：

ImageCropper.htm

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>