Asp.Net平台下的图片在线裁剪功能的实现代码(源码打包)

<link href="Styles/jquery.Jcrop.css" rel="stylesheet" type="text/css" /> 
<script src="Scripts/jquery-1.4.1.js" type="text/javascript"></script> 
<script src="Scripts/jquery.Jcrop.js" type="text/javascript"></script> 
 
页面body部分代码: 
 代码如下:

<asp:Label ID="Label1" Text="原始图片" runat="server"></asp:Label><br /> 
<asp:Image ID="target" runat="server" /> 
<br /> 
<asp:Label ID="Label2" runat="server" Text="最终显示效果"></asp:Label> 
<div id="preImg" style="width: 150px; height: 80px; overflow: hidden;"> 
<asp:Image ID="preview" alt="Preview" runat="server" /> 
</div> 
 
其中ID为preImg的Style的width和height的值是裁剪图片的尺寸,而且要定义这个DIV的overflow:hidden.能够及时看到图片的裁剪效果的关键CSS属性就是它了. 

接下来讲讲jquery.Jcrop.js的基本用法,及相关javascript的实现. 

首先定义一些临时变量,来保存相关参数 

var jcrop_api, boundx, boundy; 

然后给图片的DOM元素绑定Jcrop功能,相关的方法属性看英文就能明白其中的意思. 
 代码如下:

$('#target').Jcrop({ 
onChange: updatePreview, 
onSelect: updatePreview, 
onRelease: clearCoords, 
aspectRatio: 150 / 80, 
minSize: _minarray, 
setSelect: _array 
}, function () { 
var bounds = this.getBounds(); 
boundx = bounds[0]; 
boundy = bounds[1]; 
jcrop_api = this; 
}); 
//此方法是用来及时展现图片裁剪效果 
function updatePreview(c) { 
if (parseInt(c.w) > 0) { 
var rx = 150 / c.w; 
var ry = 80 / c.h; 
var _width; 
var _height; 
if (Math.round(rx * boundx) > $targetImg.width()) { 
_width = $targetImg.width(); 
} 
else { 
_width = Math.round(rx * boundx); 
} 
if (Math.round(ry * boundy) > $targetImg.height()) { 
_height = $targetImg.height(); 
} 
else { 
_height = Math.round(ry * boundy); 
} 
$('#preview').css({ 
width: _width + 'px', 
height: _height + 'px', 
marginLeft: '-' + Math.round(rx * c.x) + 'px', 
marginTop: '-' + Math.round(ry * c.y) + 'px' 
}); 
} 
$('#x1').val(c.x); 
$('#y1').val(c.y); 
$('#Iwidth').val(c.w); 
$('#Iheight').val(c.h); 
}; 
 
另一部分前台代码: 
 代码如下:

<form id="Form1" runat="server"> 
<asp:HiddenField ID="HdnNewImgPath" runat="server" /> 
<asp:HiddenField ID="x1" runat="server" /> 
<asp:HiddenField ID="y1" runat="server" /> 
<asp:HiddenField ID="Iwidth" runat="server" /> 
<asp:HiddenField ID="Iheight" runat="server" /> 
<br /> 
<asp:Button ID="SaveImg" runat="server" Text="裁剪并保存图片" OnClick="saveImg" OnClientClick="return CheckIMG()" /> 
</form> 
 
后台代码的实现: 
首先引用相关命名空间 
 代码如下:

using System.Drawing; 
using System.Drawing.Imaging; 
using System.Drawing.Design; 
 
保存按钮的方法,从页面取到相关参数,然后调用裁剪方法. 
 代码如下:

protected void saveImg(object sender, EventArgs e) 
{ 
if (IsPostBack) 
{ 
string tempurl = Path.Combine(ConfigAccess.UploadImagePath, _url); 
int startX = int.Parse(x1.Value); 
int startY = int.Parse(y1.Value); 
int width = int.Parse(Iwidth.Value); 
int height = int.Parse(Iheight.Value); 
ImgReduceCutOut(startX, startY, width, height, tempurl, tempurl); 
this.target.Visible = false; 
this.Label1.Visible = false; 
this.SaveImg.Enabled = false; 
} 
} 
 
接下是最重要的裁剪方法: 
 代码如下:

//通过连接创建Image对象 
System.Drawing.Image oldimage = System.Drawing.Image.FromFile(input_ImgUrl); 
oldimage.Save(Server.MapPath("temp.jpg"));//把原图Copy一份出来,然后在temp.jpg上进行裁剪,最后把裁剪后的图片覆盖原图 oldimage.Dispose();//一定要释放临时图片,要不之后的在此图上的操作会报错,原因冲突 Bitmap bm = new Bitmap(Server.MapPath("temp.jpg")); 
//处理JPG质量的函数 
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders(); 
ImageCodecInfo ici = null; 
foreach (ImageCodecInfo codec in codecs) 
{ 
if (codec.MimeType == "image/jpeg") 
{ 
ici = codec; 
break; 
} 
} 
EncoderParameters ep = new EncoderParameters(); 
ep.Param[0] = new EncoderParameter(Encoder.Quality, (long)level); 
// 裁剪图片 
Rectangle cloneRect = new Rectangle(startX, startY, int_Width, int_Height); 
PixelFormat format = bm.PixelFormat; 
Bitmap cloneBitmap = bm.Clone(cloneRect, format); 
if (int_Width > int_Standard_Width) 
{ 
//缩小图片 
System.Drawing.Image cutImg = cloneBitmap.GetThumbnailImage(int_Standard_Width, int_Standard_Height, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero); 
cutImg.Save(out_ImgUrl, ici, ep); 
cutImg.Dispose(); 
} 
else 
{ 
//保存图片 
cloneBitmap.Save(out_ImgUrl, ici, ep); 
} 
cloneBitmap.Dispose(); 
bm.Dispose(); 
} 
public bool ThumbnailCallback() 
{ 
return false; 
} 

主要页面源码:source