头像裁剪是一个经常用到的功能，实现原理也较为简单，就是在本地选择好所需裁剪图片的坐标，将坐标发送到服务器，由服务器执行图片裁剪操作。
jQuery插件Jcrop提供了强大的图片裁剪坐标选择插件。一下来介绍它的用法。本处采用了AJAX本地上传一张图片的方法让用户裁剪。很多验证没有做，因为作为一个关于Jcrop的例子，很多验证不如与本文研究的范畴。服务器端采用MVC3实现。
直接贴代码，详解注释里面有了。
一、前台页面代码。
<link href="http://www.cnblogs.com/Content/jquery.Jcrop.css" rel="stylesheet" type="text/css" />
<script src="http://www.cnblogs.com/Content/jquery-1.7.1.js" type="text/javascript"></script>
<script src="http://www.cnblogs.com/Content/ajaxfileupload.js" type="text/javascript"></script>
<script src="http://www.cnblogs.com/Content/jquery.Jcrop.js" type="text/javascript"></script>
<script type="text/javascript">
$(function () {
$(":button").click(function () {
//当点击上传按钮时，AJAX上传图片到服务器
ajaxFileUpload();
})
}) //当裁剪框变动时，将左上角相对图片的X坐标与Y坐标，宽度以及高度放到<input type="hidden">中(上传到服务器上裁剪会用到)
function showCoords(c) {
$("#p1").text(c.x + " " + c.y + " " + c.w + " " + c.h );
$("#x1").val(c.x);
$("#y1").val(c.y);
$("#cw").val(c.w);
$("#ch").val(c.h); } //当AJAX上传图片操作
function ajaxFileUpload() {
$.ajaxFileUpload
(
{
url: '/uploadandcut/upload?action=up', //用于文件上传的服务器端请求地址up参数标记此次是上传操作还是裁剪操作
secureuri: false, //一般设置为false，是否安全上传
fileElementId: 'file1', //文件上传控件的id属性 <input type="file" id="file" name="file" />
dataType: 'json', //返回值类型 一般设置为json 期望服务器传回的数据类型
success: function (data, status) //服务器成功响应处理函数
{
//上传成功后在将服务器上刚刚上传的图片显示在img1上
$("#img1").attr("src", data.imgurl);
if (typeof (data.error) != 'undefined') {
if (data.error != '') {
alert(data.error);
} else {
alert(data.msg);
}
} //同时启动裁剪操作，触发裁剪框显示，让用户选择图片区域
$("#img1").Jcrop({
bgColor: 'black',
bgOpacity: .4,
setSelect: [100, 100, 150,150], //设定4个角的初始位置
aspectRatio: 1 / 1,
onChange: showCoords, //当裁剪框变动时执行的函数
onSelect: showCoords, //当选择完成时执行的函数
}); },
error: function (data, status, e)//服务器响应失败处理函数
{
alert(e);
}
}
)
return false;
}
</script> <div>
<p><input type="file" id="file1" name="file" /></p>
<input type="button" value="上传" />
<p><img id="img1" alt="上传成功啦!" src="" /></p>
<p id="p1"></p> <form id="FaceUpload" name="FaceUpload" method="post" enctype="multipart/form-data" action="/uploadandcut/Upload?action=cut">
<input type="hidden" id="x1" name="x1" value="0" />
<input type="hidden" id="y1" name="y1" value="0" />
<input type="hidden" id="cw" name="cw" value="0" />
<input type="hidden" id="ch" name="ch" value="0" />
<input type="submit" value="裁剪上传" />
</form> </div>
二、后台代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
using System.Drawing; namespace UploadAndCut.Controllers
{
public class UploadAndCutController : Controller
{
/// <summary>
/// 打开页面
/// </summary>
/// <returns></returns>
public ActionResult Index()
{
return View();
} /// <summary>
/// 上传操作，包括提交表单与AJAX上传图片
/// </summary>
/// <returns></returns>
public ActionResult Upload()
{
string action = HttpContext.Request.QueryString["action"];
//判断用户的操作类型
switch (action.ToLower())
{
#region 当为上传图片操作时
case "up":
foreach (string upload in Request.Files)
{
if (!Request.Files[upload].HasFile())
{
continue;
}
string ExtensionName = Path.GetExtension(Request.Files[upload].FileName).ToLower();
if (ExtensionName != ".jpg" && ExtensionName != ".png" && ExtensionName != ".gif" && ExtensionName != ".bmp")
{
return Redirect("/Tips/tip?error=您上传的图片不符合格式!");
}
string ImgPath = Server.MapPath("/uploads/" + "img" + ExtensionName);
Request.Files[upload].SaveAs(ImgPath);
}
string error = "";
string msg = "上传成功";
string imgurl = "/uploads/img.jpg";
string res = "{ error:'" + error + "', msg:'" + msg + "',imgurl:'" + imgurl + "'}";
return Content(res);
break;
#endregion #region 当为裁剪图片操作时
case "cut":
string strx1 = HttpContext.Request.Form["x1"];
string stry1 = HttpContext.Request.Form["y1"];
string strcw = HttpContext.Request.Form["cw"];
string strch = HttpContext.Request.Form["ch"];
int intx1 = Convert.ToInt32(strx1);
int inty1 = Convert.ToInt32(stry1);
int intcw = Convert.ToInt32(strcw);
int intch = Convert.ToInt32(strch); Stream imgStream = GetLocalStream(Server.MapPath("/uploads/" + "img.jpg"));
//System.Drawing.Image initImage = System.Drawing.Image.FromStream(imgStream);
Cut(imgStream, Server.MapPath("/uploads/img.jpg"), intx1, inty1, intcw, intch, 100);
return Redirect("/uploadandcut/index");
break;
#endregion default:
return null;
break;
}
} /// <summary>
/// 将一个文件读成字符流
/// </summary>
/// <param name="InFilePath"></param>
/// <returns></returns>
public static Stream GetLocalStream(string InFilePath)
{
return new MemoryStream(ReadFileReturnBytes(InFilePath));
} /// <summary>从文件中读取二进制数据</summary>
/// <param name="filePath">文件路径</param>
/// <returns> byte[]二进制数据</returns>
public static byte[] ReadFileReturnBytes(string filePath)
{
FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
BinaryReader br = new BinaryReader(fs);
byte[] buff = br.ReadBytes((int)fs.Length);
br.Close();
fs.Close();
return buff;
} #region 裁剪操作
public static void Cut(System.IO.Stream fromFile, string fileSaveUrl, int xPosition, int yPosition, int width, int height, int quality)
{
//创建目录
//原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）
System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);
//原始图片的宽、高
int initWidth = initImage.Width;
int initHeight = initImage.Height;
if (xPosition + width > initWidth)
width = initWidth - xPosition;
if (yPosition + height > initHeight)
height = initHeight - yPosition;
//与原图相等直接保存
if ((width >= initWidth && height >= initHeight) || (width < 1 && height < 1))
{
initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
}
else
{
System.Drawing.Image pickedImage = null;
System.Drawing.Graphics pickedG = null;
//对象实例化
pickedImage = new System.Drawing.Bitmap(width, height);
pickedG = System.Drawing.Graphics.FromImage(pickedImage);
//设置质量
pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//定位
System.Drawing.Rectangle fromR = new System.Drawing.Rectangle(xPosition, yPosition, width, height);
System.Drawing.Rectangle toR = new System.Drawing.Rectangle(0, 0, width, height);
//画图
pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
//关键质量控制
//获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff
System.Drawing.Imaging.ImageCodecInfo[] icis = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders();
System.Drawing.Imaging.ImageCodecInfo ici = null;
foreach (System.Drawing.Imaging.ImageCodecInfo i in icis)
{
if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif")
{
ici = i;
}
}
System.Drawing.Imaging.EncoderParameters ep = new System.Drawing.Imaging.EncoderParameters(1);
ep.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality);
//保存缩略图
pickedImage.Save(fileSaveUrl, ici, ep);
//释放关键质量控制所用资源
ep.Dispose();
//释放截图资源
pickedG.Dispose();
pickedImage.Dispose();
//释放原始图片资源
initImage.Dispose();
}
}
#endregion
}
}
还有一个扩展方法，在DEMO里面会有，不粘贴了。DEMO下载地址