C#裁剪,缩放,清晰度,水印处理操作示例

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

namespace WuJian.Common
{
 /// <summary>
 /// 图片处理
 /// http://www.cnblogs.com/wu-jian/
 /// 
 /// 吴剑 2011-02-20 创建
 /// 吴剑 2012-08-08 修改
 /// </summary>
 public class Image
 {
  #region 正方型裁剪并缩放

  /// <summary>
  /// 正方型裁剪
  /// 以图片中心为轴心，截取正方型，然后等比缩放
  /// 用于头像处理
  /// </summary>
  /// <remarks>吴剑 2012-08-08</remarks>
  /// <param name="fromFile">原图Stream对象</param>
  /// <param name="fileSaveUrl">缩略图存放地址</param>
  /// <param name="side">指定的边长（正方型）</param>
  /// <param name="quality">质量（范围0-100）</param>
  public static void CutForSquare(System.IO.Stream fromFile, string fileSaveUrl, int side, int quality)
  {
   //创建目录
   string dir = Path.GetDirectoryName(fileSaveUrl);
   if (!Directory.Exists(dir))
    Directory.CreateDirectory(dir);

   //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);

   //原图宽高均小于模版，不作处理，直接保存
   if (initImage.Width <= side && initImage.Height <= side)
   {
    initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
   }
   else
   {
    //原始图片的宽、高
    int initWidth = initImage.Width;
    int initHeight = initImage.Height;

    //非正方型先裁剪为正方型
    if (initWidth != initHeight)
    {
     //截图对象
     System.Drawing.Image pickedImage = null;
     System.Drawing.Graphics pickedG = null;

     //宽大于高的横图
     if (initWidth > initHeight)
     {
      //对象实例化
      pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);
      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
      Rectangle fromR = new Rectangle((initWidth - initHeight) / 2, 0, initHeight, initHeight);
      Rectangle toR = new Rectangle(0, 0, initHeight, initHeight);
      //画图
      pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
      //重置宽
      initWidth = initHeight;
     }
     //高大于宽的竖图
     else
     {
      //对象实例化
      pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);
      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
      Rectangle fromR = new Rectangle(0, (initHeight - initWidth) / 2, initWidth, initWidth);
      Rectangle toR = new Rectangle(0, 0, initWidth, initWidth);
      //画图
      pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
      //重置高
      initHeight = initWidth;
     }

     //将截图对象赋给原图
     initImage = (System.Drawing.Image)pickedImage.Clone();
     //释放截图资源
     pickedG.Dispose();
     pickedImage.Dispose();
    }

    //缩略图对象
    System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side);
    System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage);
    //设置质量
    resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    //用指定背景色清空画布
    resultG.Clear(Color.White);
    //绘制缩略图
    resultG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, side, side), new System.Drawing.Rectangle(0, 0, initWidth, initHeight), 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
    ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();
    ImageCodecInfo ici = null;
    foreach (ImageCodecInfo i in icis)
    {
     if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif")
     {
      ici = i;
     }
    }
    EncoderParameters ep = new EncoderParameters(1);
    ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality);

    //保存缩略图
    resultImage.Save(fileSaveUrl, ici, ep);

    //释放关键质量控制所用资源
    ep.Dispose();

    //释放缩略图资源
    resultG.Dispose();
    resultImage.Dispose();

    //释放原始图片资源
    initImage.Dispose();
   }
  }

  #endregion

  #region 自定义裁剪并缩放

  /// <summary>
  /// 指定长宽裁剪
  /// 按模版比例最大范围的裁剪图片并缩放至模版尺寸
  /// </summary>
  /// <remarks>吴剑 2012-08-08</remarks>
  /// <param name="fromFile">原图Stream对象</param>
  /// <param name="fileSaveUrl">保存路径</param>
  /// <param name="maxWidth">最大宽(单位:px)</param>
  /// <param name="maxHeight">最大高(单位:px)</param>
  /// <param name="quality">质量（范围0-100）</param>
  public static void CutForCustom(System.IO.Stream fromFile, string fileSaveUrl, int maxWidth, int maxHeight, int quality)
  {
   //从文件获取原始图片，并使用流中嵌入的颜色管理信息
   System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);

   //原图宽高均小于模版，不作处理，直接保存
   if (initImage.Width <= maxWidth && initImage.Height <= maxHeight)
   {
    initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
   }
   else
   {
    //模版的宽高比例
    double templateRate = (double)maxWidth / maxHeight;
    //原图片的宽高比例
    double initRate = (double)initImage.Width / initImage.Height;

    //原图与模版比例相等，直接缩放
    if (templateRate == initRate)
    {
     //按模版大小生成最终图片
     System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
     System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
     templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
     templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
     templateG.Clear(Color.White);
     templateG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, maxWidth, maxHeight), new System.Drawing.Rectangle(0, 0, initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel);
     templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
    }
    //原图与模版比例不等，裁剪后缩放
    else
    {
     //裁剪对象
     System.Drawing.Image pickedImage = null;
     System.Drawing.Graphics pickedG = null;

     //定位
     Rectangle fromR = new Rectangle(0, 0, 0, 0);//原图裁剪定位
     Rectangle toR = new Rectangle(0, 0, 0, 0);//目标定位

     //宽为标准进行裁剪
     if (templateRate > initRate)
     {
      //裁剪对象实例化
      pickedImage = new System.Drawing.Bitmap(initImage.Width, (int)System.Math.Floor(initImage.Width / templateRate));
      pickedG = System.Drawing.Graphics.FromImage(pickedImage);

      //裁剪源定位
      fromR.X = 0;
      fromR.Y = (int)System.Math.Floor((initImage.Height - initImage.Width / templateRate) / 2);
      fromR.Width = initImage.Width;
      fromR.Height = (int)System.Math.Floor(initImage.Width / templateRate);

      //裁剪目标定位
      toR.X = 0;
      toR.Y = 0;
      toR.Width = initImage.Width;
      toR.Height = (int)System.Math.Floor(initImage.Width / templateRate);
     }
     //高为标准进行裁剪
     else
     {
      pickedImage = new System.Drawing.Bitmap((int)System.Math.Floor(initImage.Height * templateRate), initImage.Height);
      pickedG = System.Drawing.Graphics.FromImage(pickedImage);

      fromR.X = (int)System.Math.Floor((initImage.Width - initImage.Height * templateRate) / 2);
      fromR.Y = 0;
      fromR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
      fromR.Height = initImage.Height;

      toR.X = 0;
      toR.Y = 0;
      toR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
      toR.Height = initImage.Height;
     }

     //设置质量
     pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
     pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

     //裁剪
     pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);

     //按模版大小生成最终图片
     System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
     System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
     templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
     templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
     templateG.Clear(Color.White);
     templateG.DrawImage(pickedImage, new System.Drawing.Rectangle(0, 0, maxWidth, maxHeight), new System.Drawing.Rectangle(0, 0, pickedImage.Width, pickedImage.Height), 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
     ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();
     ImageCodecInfo ici = null;
     foreach (ImageCodecInfo i in icis)
     {
      if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif")
      {
       ici = i;
      }
     }
     EncoderParameters ep = new EncoderParameters(1);
     ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality);

     //保存缩略图
     templateImage.Save(fileSaveUrl, ici, ep);
     //templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);

     //释放资源
     templateG.Dispose();
     templateImage.Dispose();

     pickedG.Dispose();
     pickedImage.Dispose();
    }
   }

   //释放资源
   initImage.Dispose();
  }
  #endregion

  #region 等比缩放

  /// <summary>
  /// 图片等比缩放
  /// </summary>
  /// <remarks>吴剑 2012-08-08</remarks>
  /// <param name="fromFile">原图Stream对象</param>
  /// <param name="savePath">缩略图存放地址</param>
  /// <param name="targetWidth">指定的最大宽度</param>
  /// <param name="targetHeight">指定的最大高度</param>
  /// <param name="watermarkText">水印文字(为""表示不使用水印)</param>
  /// <param name="watermarkImage">水印图片路径(为""表示不使用水印)</param>
  public static void ZoomAuto(System.IO.Stream fromFile, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage)
  {
   //创建目录
   string dir = Path.GetDirectoryName(savePath);
   if (!Directory.Exists(dir))
    Directory.CreateDirectory(dir);

   //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);

   //原图宽高均小于模版，不作处理，直接保存
   if (initImage.Width <= targetWidth && initImage.Height <= targetHeight)
   {
    //文字水印
    if (watermarkText != "")
    {
     using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(initImage))
     {
      System.Drawing.Font fontWater = new Font("黑体", 10);
      System.Drawing.Brush brushWater = new SolidBrush(Color.White);
      gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10);
      gWater.Dispose();
     }
    }

    //透明图片水印
    if (watermarkImage != "")
    {
     if (File.Exists(watermarkImage))
     {
      //获取水印图片
      using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage))
      {
       //水印绘制条件：原始图片宽高均大于或等于水印图片
       if (initImage.Width >= wrImage.Width && initImage.Height >= wrImage.Height)
       {
        Graphics gWater = Graphics.FromImage(initImage);

        //透明属性
        ImageAttributes imgAttributes = new ImageAttributes();
        ColorMap colorMap = new ColorMap();
        colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);
        colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
        ColorMap[] remapTable = { colorMap };
        imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);

        float[][] colorMatrixElements = { 
         new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//透明度:0.5
         new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
        };

        ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);
        imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
        gWater.DrawImage(wrImage, new Rectangle(initImage.Width - wrImage.Width, initImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);

        gWater.Dispose();
       }
       wrImage.Dispose();
      }
     }
    }

    //保存
    initImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg);
   }
   else
   {
    //缩略图宽、高计算
    double newWidth = initImage.Width;
    double newHeight = initImage.Height;

    //宽大于高或宽等于高（横图或正方）
    if (initImage.Width > initImage.Height || initImage.Width == initImage.Height)
    {
     //如果宽大于模版
     if (initImage.Width > targetWidth)
     {
      //宽按模版，高按比例缩放
      newWidth = targetWidth;
      newHeight = initImage.Height * (targetWidth / initImage.Width);
     }
    }
    //高大于宽（竖图）
    else
    {
     //如果高大于模版
     if (initImage.Height > targetHeight)
     {
      //高按模版，宽按比例缩放
      newHeight = targetHeight;
      newWidth = initImage.Width * (targetHeight / initImage.Height);
     }
    }

    //生成新图
    //新建一个bmp图片
    System.Drawing.Image newImage = new System.Drawing.Bitmap((int)newWidth, (int)newHeight);
    //新建一个画板
    System.Drawing.Graphics newG = System.Drawing.Graphics.FromImage(newImage);

    //设置质量
    newG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    newG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

    //置背景色
    newG.Clear(Color.White);
    //画图
    newG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, newImage.Width, newImage.Height), new System.Drawing.Rectangle(0, 0, initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel);

    //文字水印
    if (watermarkText != "")
    {
     using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(newImage))
     {
      System.Drawing.Font fontWater = new Font("宋体", 10);
      System.Drawing.Brush brushWater = new SolidBrush(Color.White);
      gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10);
      gWater.Dispose();
     }
    }

    //透明图片水印
    if (watermarkImage != "")
    {
     if (File.Exists(watermarkImage))
     {
      //获取水印图片
      using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage))
      {
       //水印绘制条件：原始图片宽高均大于或等于水印图片
       if (newImage.Width >= wrImage.Width && newImage.Height >= wrImage.Height)
       {
        Graphics gWater = Graphics.FromImage(newImage);

        //透明属性
        ImageAttributes imgAttributes = new ImageAttributes();
        ColorMap colorMap = new ColorMap();
        colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);
        colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
        ColorMap[] remapTable = { colorMap };
        imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);

        float[][] colorMatrixElements = { 
         new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//透明度:0.5
         new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
        };

        ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);
        imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
        gWater.DrawImage(wrImage, new Rectangle(newImage.Width - wrImage.Width, newImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);
        gWater.Dispose();
       }
       wrImage.Dispose();
      }
     }
    }

    //保存缩略图
    newImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg);

    //释放资源
    newG.Dispose();
    newImage.Dispose();
    initImage.Dispose();
   }
  }

  #endregion

  #region 其它

  /// <summary>
  /// 判断文件类型是否为WEB格式图片
  /// (注：JPG,GIF,BMP,PNG)
  /// </summary>
  /// <param name="contentType">HttpPostedFile.ContentType</param>
  /// <returns></returns>
  public static bool IsWebImage(string contentType)
  {
   if (contentType == "image/pjpeg" || contentType == "image/jpeg" || contentType == "image/gif" || contentType == "image/bmp" || contentType == "image/png")
   {
    return true;
   }
   else
   {
    return false;
   }
  }

  #endregion

 }//end class
}