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C#图片处理类

收集整理自网上的一个类,支持生成水印、缩略图、调整光暗等,具体出处不记得了。对其中部分方法做了调整和增加了GDI压缩方法 。

ImageClass

/// <summary>
/// 图片处理
/// </summary>
public class ImageClass
{
    private ImageClass()
    { }

    #region  生成缩略图

    #region 指定一边,得到缩略图大小
    /// <summary>
    /// 指定一边,得到缩略图大小
    /// </summary>
    /// <param name="originalSize">原大小</param>
    /// <param name="destSize">目标大小</param>
    /// <param name="mode">方式(W:宽; H:高)</param>
    /// <param name="height">实际高</param>
    /// <param name="width">实际宽</param>
    /// <returns></returns>
    private static Size GetThumbnailSize(Size originalSize, Size destSize, string mode)
    {
        int towidth = destSize.Width;
        int toheight = destSize.Height;

        int ow = originalSize.Width;
        int oh = originalSize.Height;

        switch (mode)
        {
            case "W":   //指定宽,高按比例
                toheight = Convert.ToInt32(1.0 * originalSize.Height * towidth / originalSize.Width);
                break;
            case "H":   //指定高,宽按比例
                towidth = Convert.ToInt32(1.0 * originalSize.Width * toheight / originalSize.Height);
                break;
        }
        return new Size(towidth, toheight);
    }
    #endregion

    #region 得到最大的宽
    /// <summary>
    /// 得到最大的宽
    /// </summary>
    /// <param name="destSize">目标大小</param>
    /// <param name="height"></param>
    /// <returns></returns>
    private static int GetMaxWidth(Size destSize, int height)
    {
        return Convert.ToInt32(((destSize.Width * 1.0) / destSize.Height) * height);
    }
    #endregion

    #region 得到最大的高
    /// <summary>
    /// 得到最大的高
    /// </summary>
    /// <param name="destSize">目标大小</param>
    /// <param name="height"></param>
    /// <returns></returns>
    private static int GetMaxHeight(Size destSize, int width)
    {
        return Convert.ToInt32(((destSize.Height * 1.0) / destSize.Width) * width);
    }
    #endregion

    #region 生成缩略图
    ///<summary> 
    /// 生成缩略图 
    /// </summary> 
    /// <param name="originalImagePath">源图路径(物理路径)</param> 
    /// <param name="thumbnailPath">缩略图路径(物理路径)</param> 
    /// <param name="thumbnailSize">缩略图大小</param> 
    /// <param name="mode">生成缩略图的方式</param>
    /// <param name="keepThumbnailSize">是否保持缩略图大小,此时建议保存为png格式,否则会有黑底</param>
    /// <param name="format">图片格式</param>
    public static void MakeThumbnail(string originalImagePath, string thumbnailPath, Size thumbnailSize, ThumbnailMode mode, bool keepThumbnailSize = false, ImageFormat format = null)
    {
        System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

        Size destSize = new Size(thumbnailSize.Width, thumbnailSize.Height);                      //目标图大小
        Point originalPoint = new Point(0, 0);                                                    //源图起点
        Size originalSize = new Size(originalImage.Width, originalImage.Height);                  //源图截取的大小

        #region 确定缩略图大小信息
        int tempHeight = 0, tempWidth = 0;
        Size size = new Size(0, 0);

        switch (mode)
        {
            #region 缩放模式
            case ThumbnailMode.AspectFill:
                #region AspectFill
                size = GetThumbnailSize(originalSize, destSize, "W");//定宽,高自适应
                if (size.Height >= destSize.Height)
                {
                    tempHeight = GetMaxHeight(destSize, originalSize.Width);
                    originalPoint = GetLocation(WatermarkPosition.LeftMiddle, originalSize, new Size(originalSize.Width, tempHeight), 0).ToPoint();
                    originalSize.Height = tempHeight;
                }
                else
                {
                    tempWidth = GetMaxWidth(destSize, originalSize.Height);
                    originalPoint = GetLocation(WatermarkPosition.TopCenter, originalSize, new Size(tempWidth, originalSize.Height), 0).ToPoint();
                    originalSize.Width = tempWidth;
                }
                break;
                #endregion
            case ThumbnailMode.AspectFit:
                #region AspectFit
                size = GetThumbnailSize(originalSize, destSize, "W");//定宽,高自适应
                if (size.Height <= destSize.Height)
                {
                    destSize = size;
                }
                else
                {
                    size = GetThumbnailSize(originalSize, destSize, "H");//定高,宽自适应
                    destSize = size;
                }
                break;
                #endregion
            case ThumbnailMode.ScaleToFill:
                #region ScaleToFill
                break;
                #endregion
            case ThumbnailMode.WidthFix:
                #region WidthFix
                size = GetThumbnailSize(originalSize, destSize, "W");//定宽,高自适应
                if (size.Height >= destSize.Height)
                {
                    tempHeight = GetMaxHeight(destSize, originalSize.Width);
                    originalPoint = GetLocation(WatermarkPosition.LeftMiddle, originalSize, new Size(originalSize.Width, tempHeight), 0).ToPoint();
                    originalSize.Height = tempHeight;
                }
                else
                {
                    destSize = size;
                }
                break;
                #endregion
            #endregion

            #region 裁剪模式
            case ThumbnailMode.Bottom:
            case ThumbnailMode.BottomLeft:
            case ThumbnailMode.BottomRight:
            case ThumbnailMode.Center:
            case ThumbnailMode.Left:
            case ThumbnailMode.Right:
            case ThumbnailMode.Top:
            case ThumbnailMode.TopLeft:
            case ThumbnailMode.TopRight:
                destSize.Width = Math.Min(originalSize.Width, destSize.Width);
                destSize.Height = Math.Min(originalSize.Height, destSize.Height);
                originalPoint = GetLocation((WatermarkPosition)mode, originalSize, destSize, 0).ToPoint();
                originalSize = destSize;
                break;
            #endregion
        }
        #endregion

        #region 制作缩略图
        System.Drawing.Image bitmap = keepThumbnailSize ? new System.Drawing.Bitmap(thumbnailSize.Width, thumbnailSize.Height) : new System.Drawing.Bitmap(destSize.Width, destSize.Height);

        //新建一个画板 
        Graphics g = System.Drawing.Graphics.FromImage(bitmap);
        //设置高质量插值法 
        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
        //设置高质量,低速度呈现平滑程度 
        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

        #region 绘制透明的图像
        ImageAttributes vAttr = new ImageAttributes();
        vAttr.SetColorKey(Color.Transparent, Color.Transparent);
        g.DrawImage(bitmap, new Rectangle(0, 0, bitmap.Width, bitmap.Height), 0, 0, bitmap.Width, bitmap.Height, GraphicsUnit.Pixel, vAttr);
        #endregion

        //在指定位置并且按指定大小绘制原图片的指定部分 
        if (keepThumbnailSize)
        {
            var startPoint = GetLocation(WatermarkPosition.MiddleCenter, bitmap.Size, destSize);
            g.DrawImage(originalImage, new Rectangle(startPoint.ToPoint(), destSize), new Rectangle(originalPoint, originalSize), GraphicsUnit.Pixel);
        }
        else
        {
            g.DrawImage(originalImage, new Rectangle(new Point(0, 0), destSize), new Rectangle(originalPoint, originalSize), GraphicsUnit.Pixel);
        }
        #endregion

        #region 保存图片
        try
        {
            if(format == null)
            {
                var ext = Path.GetExtension(thumbnailPath).ToLower();
                switch(ext)
                {
                    case ".png": format = System.Drawing.Imaging.ImageFormat.Png; break;
                    case ".bmp": format = System.Drawing.Imaging.ImageFormat.Bmp; break;
                    case ".emf": format = System.Drawing.Imaging.ImageFormat.Emf; break;
                    case ".exif": format = System.Drawing.Imaging.ImageFormat.Exif; break;
                    case ".gif": format = System.Drawing.Imaging.ImageFormat.Gif; break;
                    case ".ico":
                    case ".icon": format = System.Drawing.Imaging.ImageFormat.Icon; break;
                    case ".jpeg":
                    case ".jpg": format = System.Drawing.Imaging.ImageFormat.Jpeg; break;
                    case ".tiff": format = System.Drawing.Imaging.ImageFormat.Tiff; break;
                    case ".wmf": format = System.Drawing.Imaging.ImageFormat.Wmf; break;
                    default: format = System.Drawing.Imaging.ImageFormat.Png; break;
                }
            }

            bitmap.Save(thumbnailPath, format);
        }
        catch (System.Exception e)
        {
            throw e;
        }
        finally
        {
            originalImage.Dispose();
            bitmap.Dispose();
            g.Dispose();
        }
        #endregion
    }
    #endregion

    #endregion

    #region 图片水印
    /// <summary>
    /// 图片水印处理方法
    /// </summary>
    /// <param name="path">需要加载水印的图片路径(绝对路径)</param>
    /// <param name="waterpath">水印图片(绝对路径)</param>
    /// <param name="location">水印位置(传送正确的代码)</param>
    public static string ImageWatermark(string path, string waterpath, WatermarkPosition location)
    {
        string kz_name = Path.GetExtension(path);
        if (kz_name == ".jpg" || kz_name == ".bmp" || kz_name == ".jpeg")
        {
            DateTime time = DateTime.Now;
            string filename = "" + time.Year.ToString() + time.Month.ToString() + time.Day.ToString() + time.Hour.ToString() + time.Minute.ToString() + time.Second.ToString() + time.Millisecond.ToString();
            Image img = Bitmap.FromFile(path);
            Image waterimg = Image.FromFile(waterpath);
            Graphics g = Graphics.FromImage(img);
            var loca = GetLocation(location, img.Size, waterimg.Size);
            g.DrawImage(waterimg, new Rectangle(Convert.ToInt32(loca.X), Convert.ToInt32(loca.Y), waterimg.Width, waterimg.Height));
            waterimg.Dispose();
            g.Dispose();
            string newpath = Path.GetDirectoryName(path) + filename + kz_name;
            img.Save(newpath);
            img.Dispose();
            File.Copy(newpath, path, true);
            if (File.Exists(newpath))
            {
                File.Delete(newpath);
            }
        }
        return path;
    }
    #endregion

    #region 文字水印
    /// <summary>
    /// 文字水印处理方法
    /// </summary>
    /// <param name="path">图片路径(绝对路径),在这个图片上操作</param>
    /// <param name="size">字体大小</param>
    /// <param name="letter">水印文字</param>
    /// <param name="color">颜色</param>
    /// <param name="location">水印位置</param>
    public static string LetterWatermark(string path, string letter, Font font, Color color, WatermarkPosition position)
    {
        string kz_name = Path.GetExtension(path);
        if (kz_name == ".jpg" || kz_name == ".bmp" || kz_name == ".jpeg")
        {
            DateTime time = DateTime.Now;
            string filename = "" + time.Year.ToString() + time.Month.ToString() + time.Day.ToString() + time.Hour.ToString() + time.Minute.ToString() + time.Second.ToString() + time.Millisecond.ToString();
            Image img = Bitmap.FromFile(path);
            Graphics gs = Graphics.FromImage(img);

            //文字的大小
            var sizeF = gs.MeasureString(letter, font);

            var loca = GetLocation(position, img.Size, sizeF.ToSize());
            Brush br = new SolidBrush(color);
            gs.DrawString(letter, font, br, loca.X, loca.Y);
            gs.Dispose();
            string newpath = Path.GetDirectoryName(path) + filename + kz_name;
            img.Save(newpath);
            img.Dispose();
            File.Copy(newpath, path, true);
            if (File.Exists(newpath))
            {
                File.Delete(newpath);
            }
        }
        return path;
    }
    #endregion

    #region 调整光暗
    /// <summary>
    /// 调整光暗
    /// </summary>
    /// <param name="mybm">原始图片</param>
    /// <param name="width">原始图片的长度</param>
    /// <param name="height">原始图片的高度</param>
    /// <param name="val">增加或减少的光暗值</param>
    public Bitmap LDPic(Bitmap mybm, int width, int height, int val)
    {
        Bitmap bm = new Bitmap(width, height);//初始化一个记录经过处理后的图片对象
        int x, y, resultR, resultG, resultB;//x、y是循环次数,后面三个是记录红绿蓝三个值的
        Color pixel;
        for (x = 0; x < width; x++)
        {
            for (y = 0; y < height; y++)
            {
                pixel = mybm.GetPixel(x, y);//获取当前像素的值
                resultR = pixel.R + val;//检查红色值会不会超出[0, 255]
                resultG = pixel.G + val;//检查绿色值会不会超出[0, 255]
                resultB = pixel.B + val;//检查蓝色值会不会超出[0, 255]
                bm.SetPixel(x, y, Color.FromArgb(resultR, resultG, resultB));//绘图
            }
        }
        return bm;
    }
    #endregion

    #region 反色处理
    /// <summary>
    /// 反色处理
    /// </summary>
    /// <param name="mybm">原始图片</param>
    /// <param name="width">原始图片的长度</param>
    /// <param name="height">原始图片的高度</param>
    public Bitmap RePic(Bitmap mybm, int width, int height)
    {
        Bitmap bm = new Bitmap(width, height);//初始化一个记录处理后的图片的对象
        int x, y, resultR, resultG, resultB;
        Color pixel;
        for (x = 0; x < width; x++)
        {
            for (y = 0; y < height; y++)
            {
                pixel = mybm.GetPixel(x, y);//获取当前坐标的像素值
                resultR = 255 - pixel.R;//反红
                resultG = 255 - pixel.G;//反绿
                resultB = 255 - pixel.B;//反蓝
                bm.SetPixel(x, y, Color.FromArgb(resultR, resultG, resultB));//绘图
            }
        }
        return bm;
    }
    #endregion

    #region 浮雕处理
    /// <summary>
    /// 浮雕处理
    /// </summary>
    /// <param name="oldBitmap">原始图片</param>
    /// <param name="Width">原始图片的长度</param>
    /// <param name="Height">原始图片的高度</param>
    public Bitmap FD(Bitmap oldBitmap, int Width, int Height)
    {
        Bitmap newBitmap = new Bitmap(Width, Height);
        Color color1, color2;
        for (int x = 0; x < Width - 1; x++)
        {
            for (int y = 0; y < Height - 1; y++)
            {
                int r = 0, g = 0, b = 0;
                color1 = oldBitmap.GetPixel(x, y);
                color2 = oldBitmap.GetPixel(x + 1, y + 1);
                r = Math.Abs(color1.R - color2.R + 128);
                g = Math.Abs(color1.G - color2.G + 128);
                b = Math.Abs(color1.B - color2.B + 128);
                if (r > 255) r = 255;
                if (r < 0) r = 0;
                if (g > 255) g = 255;
                if (g < 0) g = 0;
                if (b > 255) b = 255;
                if (b < 0) b = 0;
                newBitmap.SetPixel(x, y, Color.FromArgb(r, g, b));
            }
        }
        return newBitmap;
    }
    #endregion

    #region 拉伸图片
    /// <summary>
    /// 拉伸图片
    /// </summary>
    /// <param name="bmp">原始图片</param>
    /// <param name="newW">新的宽度</param>
    /// <param name="newH">新的高度</param>
    public static Bitmap ResizeImage(Bitmap bmp, int newW, int newH)
    {
        try
        {
            Bitmap bap = new Bitmap(newW, newH);
            Graphics g = Graphics.FromImage(bap);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            g.DrawImage(bap, new Rectangle(0, 0, newW, newH), new Rectangle(0, 0, bap.Width, bap.Height), GraphicsUnit.Pixel);
            g.Dispose();
            return bap;
        }
        catch
        {
            return null;
        }
    }
    #endregion

    #region 滤色处理
    /// <summary>
    /// 滤色处理
    /// </summary>
    /// <param name="mybm">原始图片</param>
    /// <param name="width">原始图片的长度</param>
    /// <param name="height">原始图片的高度</param>
    public Bitmap FilPic(Bitmap mybm, int width, int height)
    {
        Bitmap bm = new Bitmap(width, height);//初始化一个记录滤色效果的图片对象
        int x, y;
        Color pixel;

        for (x = 0; x < width; x++)
        {
            for (y = 0; y < height; y++)
            {
                pixel = mybm.GetPixel(x, y);//获取当前坐标的像素值
                bm.SetPixel(x, y, Color.FromArgb(0, pixel.G, pixel.B));//绘图
            }
        }
        return bm;
    }
    #endregion

    #region 左右翻转
    /// <summary>
    /// 左右翻转
    /// </summary>
    /// <param name="mybm">原始图片</param>
    /// <param name="width">原始图片的长度</param>
    /// <param name="height">原始图片的高度</param>
    public Bitmap RevPicLR(Bitmap mybm, int width, int height)
    {
        Bitmap bm = new Bitmap(width, height);
        int x, y, z; //x,y是循环次数,z是用来记录像素点的x坐标的变化的
        Color pixel;
        for (y = height - 1; y >= 0; y--)
        {
            for (x = width - 1, z = 0; x >= 0; x--)
            {
                pixel = mybm.GetPixel(x, y);//获取当前像素的值
                bm.SetPixel(z++, y, Color.FromArgb(pixel.R, pixel.G, pixel.B));//绘图
            }
        }
        return bm;
    }
    #endregion

    #region 上下翻转
    /// <summary>
    /// 上下翻转
    /// </summary>
    /// <param name="mybm">原始图片</param>
    /// <param name="width">原始图片的长度</param>
    /// <param name="height">原始图片的高度</param>
    public Bitmap RevPicUD(Bitmap mybm, int width, int height)
    {
        Bitmap bm = new Bitmap(width, height);
        int x, y, z;
        Color pixel;
        for (x = 0; x < width; x++)
        {
            for (y = height - 1, z = 0; y >= 0; y--)
            {
                pixel = mybm.GetPixel(x, y);//获取当前像素的值
                bm.SetPixel(x, z++, Color.FromArgb(pixel.R, pixel.G, pixel.B));//绘图
            }
        }
        return bm;
    }
    #endregion

    #region 压缩图片
    /// <summary>
    /// 压缩到指定尺寸
    /// </summary>
    /// <param name="oldfile">原文件</param>
    /// <param name="newfile">新文件</param>
    public bool Compress(string oldfile, string newfile)
    {
        try
        {
            System.Drawing.Image img = System.Drawing.Image.FromFile(oldfile);
            System.Drawing.Imaging.ImageFormat thisFormat = img.RawFormat;
            Size newSize = new Size(100, 125);
            Bitmap outBmp = new Bitmap(newSize.Width, newSize.Height);
            Graphics g = Graphics.FromImage(outBmp);
            g.CompositingQuality = CompositingQuality.HighQuality;
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;
            g.DrawImage(img, new Rectangle(0, 0, newSize.Width, newSize.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel);
            g.Dispose();
            EncoderParameters encoderParams = new EncoderParameters();
            long[] quality = new long[1];
            quality[0] = 100;
            EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
            encoderParams.Param[0] = encoderParam;
            ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
            ImageCodecInfo jpegICI = null;
            for (int x = 0; x < arrayICI.Length; x++)
                if (arrayICI[x].FormatDescription.Equals("JPEG"))
                {
                    jpegICI = arrayICI[x]; //设置JPEG编码
                    break;
                }
            img.Dispose();
            if (jpegICI != null) outBmp.Save(newfile, System.Drawing.Imaging.ImageFormat.Jpeg);
            outBmp.Dispose();
            return true;
        }
        catch
        {
            return false;
        }
    }
    #endregion

    #region 图片灰度化
    public Color Gray(Color c)
    {
        int rgb = Convert.ToInt32((double)(((0.3 * c.R) + (0.59 * c.G)) + (0.11 * c.B)));
        return Color.FromArgb(rgb, rgb, rgb);
    }
    #endregion

    #region 转换为黑白图片
    /// <summary>
    /// 转换为黑白图片
    /// </summary>
    /// <param name="mybt">要进行处理的图片</param>
    /// <param name="width">图片的长度</param>
    /// <param name="height">图片的高度</param>
    public Bitmap BWPic(Bitmap mybm, int width, int height)
    {
        Bitmap bm = new Bitmap(width, height);
        int x, y, result; //x,y是循环次数,result是记录处理后的像素值
        Color pixel;
        for (x = 0; x < width; x++)
        {
            for (y = 0; y < height; y++)
            {
                pixel = mybm.GetPixel(x, y);//获取当前坐标的像素值
                result = (pixel.R + pixel.G + pixel.B) / 3;//取红绿蓝三色的平均值
                bm.SetPixel(x, y, Color.FromArgb(result, result, result));
            }
        }
        return bm;
    }
    #endregion

    #region 获取图片中的各帧
    /// <summary>
    /// 获取图片中的各帧
    /// </summary>
    /// <param name="pPath">图片路径</param>
    /// <param name="pSavePath">保存路径</param>
    public void GetFrames(string pPath, string pSavedPath)
    {
        Image gif = Image.FromFile(pPath);
        FrameDimension fd = new FrameDimension(gif.FrameDimensionsList[0]);
        int count = gif.GetFrameCount(fd); //获取帧数(gif图片可能包含多帧,其它格式图片一般仅一帧)
        for (int i = 0; i < count; i++)    //以Jpeg格式保存各帧
        {
            gif.SelectActiveFrame(fd, i);
            gif.Save(pSavedPath + "\\frame_" + i + ".jpg", ImageFormat.Jpeg);
        }
    }
    #endregion

    #region 得到区域的位置
    /// <summary>
    /// 得到区域的位置
    /// </summary>
    /// <param name="position">位置代码</param>
    /// <param name="img">图片对象</param>
    /// <param name="subSize">子区域大小</param>
    /// <param name="margin">与边框距离</param>
    /// <returns>返回左上角位置</returns>
    public static PointF GetLocation(WatermarkPosition position, Size areaSize, Size subSize, float margin = 5)
    {
        float x = 10;
        float y = 10;

        //位置:左上角为(0, 0),x向右增加,y向下增加
        var xLeft = margin;//X轴左
        var xCenter = (areaSize.Width - subSize.Width) / 2;//X轴中间
        var xRight = areaSize.Width - margin - subSize.Width;//X轴右边

        var yTop = margin;//Y轴顶部
        var yMiddle = (areaSize.Height - subSize.Height) / 2;//Y轴中间
        var yBottom = areaSize.Height - subSize.Height - margin;//Y轴底部

        switch (position)
        {
            case WatermarkPosition.TopRight:
                x = xRight;
                y = yTop;
                break;
            case WatermarkPosition.RightMiddle:
                x = xRight;
                y = yMiddle;
                break;
            case WatermarkPosition.BottomRight:
                x = xRight;
                y = yBottom;
                break;
            case WatermarkPosition.BottomCenter:
                x = xCenter;
                y = yBottom;
                break;
            case WatermarkPosition.BottomLeft:
                x = xLeft;
                y = yBottom;
                break;
            case WatermarkPosition.LeftMiddle:
                x = xLeft;
                y = yMiddle;
                break;
            case WatermarkPosition.TopLeft:
                x = xLeft;
                y = yTop;
                break;
            case WatermarkPosition.TopCenter:
                x = xCenter;
                y = yTop;
                break;
            case WatermarkPosition.MiddleCenter:
                x = xCenter;
                y = yMiddle;
                break;
            case WatermarkPosition.Random:
                var maxX = areaSize.Width - margin * 2 - subSize.Width;
                var maxY = areaSize.Height - margin * 2 - subSize.Height;
                var random = new Random();
                x = margin + Convert.ToSingle(random.NextDouble() * maxX);
                y = margin + Convert.ToSingle(random.NextDouble() * maxY);

                break;
        }

        return new PointF(x, y);

    }
    #endregion

    #region GID压缩图片
    /// <summary>
    /// GDI压缩图片
    /// </summary>
    /// <param name="bmp">传入参数Bitmap</param>
    /// <returns></returns>
    public static byte[] ImageGdi(Bitmap bmp)
    {
        Bitmap xbmp = new Bitmap(bmp);
        MemoryStream ms = new MemoryStream();
        xbmp.Save(ms, ImageFormat.Jpeg);
        byte[] buffer;
        ms.Flush();
        if (ms.Length > 95000)
        {
            //buffer = ms.GetBuffer();
            double new_width = 0;
            double new_height = 0;

            Image m_src_image = Image.FromStream(ms);
            if (m_src_image.Width >= m_src_image.Height)
            {
                new_width = 1024;
                new_height = new_width * m_src_image.Height / (double)m_src_image.Width;
            }
            else if (m_src_image.Height >= m_src_image.Width)
            {
                new_height = 768;
                new_width = new_height * m_src_image.Width / (double)m_src_image.Height;
            }

            Bitmap bbmp = new Bitmap((int)new_width, (int)new_height, m_src_image.PixelFormat);
            Graphics m_graphics = Graphics.FromImage(bbmp);
            m_graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            m_graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            m_graphics.DrawImage(m_src_image, 0, 0, bbmp.Width, bbmp.Height);

            ms = new MemoryStream();

            bbmp.Save(ms, ImageFormat.Jpeg);
            buffer = ms.GetBuffer();
            ms.Close();

            return buffer;
        }
        else
        {
            buffer = ms.GetBuffer();
            ms.Close();
            return buffer;
        }
    }
    #endregion
}

 

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