C#实现的上传图片、保存图片、加水印、生成缩略图功能示例

本文实例讲述了c#实现的上传图片、保存图片、加水印、生成缩略图功能。分享给大家供大家参考，具体如下：

伴随移动设备地普及，处理图片、视频等需求也变得越来越基础，这里介绍的是图片的存储。

上传图片必须使用form表单提交的方式，我只知道这一种方法，如果大家知道其他方法的话请留言。

保存图片、加水印和生成缩略图这三种功能最好各自放在单独的方法中，尽量降低耦合度，提高代码复用程度，除此之外我们平常写代码是也要尽量做到方法功能的唯一性。

前台代码：

<form method="post" enctype="multipart/form-data" action="uploadimg.ashx">
  <table>
    <tr>
      <td>func：</td>
      <td><input type="text" name="func"/></td>
    </tr>
    <tr>
      <td>用户id：</td>
      <td><input type="text" name="userid"/></td>
    </tr>
    <tr>
      <td>头像：</td>
      <td><input type="file" name="icon"/></td>
    </tr>
    <tr>
      <td>水印：</td>
      <td><input type="text" name="watermark"/></td>
    </tr>
  </table>
  <input type="submit" value="提交"/>
</form>

后台代码：

private string uploadimage(httpcontext context)
{
  try
  {
    system.io.stream stream = context.request.files["icon"].inputstream;
    //返回的图片路径可以存储在数据库中
    string imageurl = saveimage(stream, "icon", "蝈蝈");
    string thumbnailimageurl = savethumbnailimage(stream, "icon");
    string thumbnailimageurlwithwatermark = savethumbnailimage(configurationmanager.appsettings["attachmentsdirectory"] + imageurl, "icon");
    return "上传成功！";
  }
  catch (exception ex)
  {
    return "上传失败！";
  }
}
private string saveimage(stream stream, string foldername, string watermark)
{
  try
  {
    string filename = guid.newguid() + ".jpg";
    string path = configurationmanager.appsettings["attachmentsdirectory"];
    path = path.combine(path, foldername + "\\" + datetime.now.year + "\\" + datetime.now.month + "\\" + datetime.now.day + "\\");
    string imageurl = "/" + foldername + "/" + datetime.now.year + "/" + datetime.now.month + "/" + datetime.now.day + "/";
    if (!string.isnullorempty(watermark))
    {
      image imgsource = image.fromstream(stream);
      addwatermarkandsave(path, filename, watermark, imgsource, imgsource.height - 300, 10, color.red,
        new font("宋体", 40));
    }
    else
    {
      byte[] buffer = new byte[stream.length];
      stream.read(buffer, 0, buffer.length);
      if (!directory.exists(path))
      {
        directory.createdirectory(path);
      }
      system.io.filestream fs = new system.io.filestream(path + filename, system.io.filemode.openorcreate,
        system.io.fileaccess.write);
      fs.write(buffer, 0, buffer.length);
      fs.flush();
      fs.close();
    }
    return imageurl + filename;
  }
  catch (exception ex)
  {
    return "";
  }
}
private string savethumbnailimage(stream stream, string foldername)
{
  try
  {
    string filename = guid.newguid() + ".jpg";
    string path = configurationmanager.appsettings["attachmentsdirectory"];
    path = path.combine(path, foldername + "\\" + datetime.now.year + "\\" + datetime.now.month + "\\" + datetime.now.day + "\\");
    string imageurl = "/" + foldername + "/" + datetime.now.year + "/" + datetime.now.month + "/" + datetime.now.day + "/";
    system.drawing.image.getthumbnailimageabort mycallback = new system.drawing.image.getthumbnailimageabort(getfalse);
    //数据源来自stream
    image image = system.drawing.bitmap.fromstream(stream);
    system.drawing.image thumbnailimage = image.getthumbnailimage(64, 64, mycallback, intptr.zero);
    thumbnailimage.save(path + filename);
    thumbnailimage.dispose();
    return imageurl + filename;
  }
  catch (exception ex)
  {
    return "";
  }
}
private string savethumbnailimage(string originalfilename, string foldername)
{
  try
  {
    string filename = guid.newguid() + ".jpg";
    string path = configurationmanager.appsettings["attachmentsdirectory"];
    path = path.combine(path, foldername + "\\" + datetime.now.year + "\\" + datetime.now.month + "\\" + datetime.now.day + "\\");
    string imageurl = "/" + foldername + "/" + datetime.now.year + "/" + datetime.now.month + "/" + datetime.now.day + "/";
    system.drawing.image.getthumbnailimageabort mycallback = new system.drawing.image.getthumbnailimageabort(getfalse);
    //数据源来自file
    image image = system.drawing.bitmap.fromfile(originalfilename);
    system.drawing.image thumbnailimage = image.getthumbnailimage(64, 64, mycallback, intptr.zero);
    thumbnailimage.save(path + filename);
    thumbnailimage.dispose();
    return imageurl + filename;
  }
  catch (exception ex)
  {
    return "";
  }
}
private bool getfalse()
{
  return false;
}
/// <summary>
/// 图片加文字水印
/// </summary>
/// <param name="filename"> </param>
/// <param name="text">水印文字，如果是多行用分号隔开</param>
/// <param name="img">图片</param>
/// <param name="paddingtop">上边距</param>
/// <param name="paddingleft">左边距</param>
/// <param name="textcolor">文字颜色</param>
/// <param name="textfont">字体</param>
/// <param name="path">保存地址</param>
/// <returns></returns>
private bool addwatermarkandsave(string path, string filename, string text, image img,
      int paddingtop, int paddingleft, color textcolor, font textfont)
{
  text = text + ";" + "当前时间：" + datetime.now.tostring("yyyy-mm-dd hh:mm");
  if (!directory.exists(path))
  {
    directory.createdirectory(path);
  }
  textfont = new font("宋体", 19);
  bitmap bm = new bitmap(img);
  system.drawing.graphics g = system.drawing.graphics.fromimage(bm);
  system.drawing.brush b = new solidbrush(textcolor);
  string[] str = text.split(';');
  for (int i = 0; i < str.length; i++)
    g.drawstring(str[i], textfont, b, paddingleft, paddingtop + 33 * i);
  g.dispose();
  bm.save(path + filename, imageformat.jpeg);
  bm.dispose();
  return true;
}

更多关于c#相关内容感兴趣的读者可查看本站专题：《c#图片操作技巧汇总》、《c#常见控件用法教程》、《winform控件用法总结》、《c#数据结构与算法教程》、《c#面向对象程序设计入门教程》及《c#程序设计之线程使用技巧总结》

希望本文所述对大家c#程序设计有所帮助。