图像裁切

public class Cutimg
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="pPath">原图地址</param>
        /// <param name="filePath">存储图片地址</param>
        /// <param name="pPartStartPointX">截取目标-x</param>
        /// <param name="pPartStartPointY">截取目标-y</param>
        /// <param name="pPartWidth">截取目标-宽度</param>
        /// <param name="pPartHeight">截取目标-高度</param>
        /// <param name="pOrigStartPointX">缩放图-x：0</param>
        /// <param name="pOrigStartPointY">缩放图-y：0</param>
        /// <param name="imageWidth">缩放图-宽度</param>
        /// <param name="imageHeight">缩放图-高度</param>
        /// <returns></returns>
        public static bool SaveCutPic(string pPath, string filePath, int pPartStartPointX, int pPartStartPointY, int pPartWidth, int pPartHeight, int pOrigStartPointX, int pOrigStartPointY, int imageWidth, int imageHeight)
        {
            using (System.Drawing.Image originalImg = System.Drawing.Image.FromFile(pPath))
            {
                try
                {
                    if (originalImg.Width == imageWidth && originalImg.Height == imageHeight)
                    {
                        return SaveCutPic(pPath, filePath, pPartStartPointX, pPartStartPointY, pPartWidth, pPartHeight,
                                pOrigStartPointX, pOrigStartPointY);

                    }
                    
                    Bitmap thumimg = MakeThumbnail(originalImg, imageWidth, imageHeight);

                    Bitmap partImg = new Bitmap(pPartWidth, pPartHeight);
                    
                    Graphics graphics = Graphics.FromImage(partImg);
                    Rectangle destRect = new Rectangle(new Point(pPartStartPointX, pPartStartPointY), new Size(pPartWidth, pPartHeight));//目标位置
                    Rectangle origRect = new Rectangle(new Point(pOrigStartPointX, pOrigStartPointY), new Size(pPartWidth, pPartHeight));//原图位置（默认从原图中截取的图片大小等于目标图片的大小）

                    ///文字水印  
                    Graphics G = Graphics.FromImage(partImg);
                    //Font f = new Font("Lucida Grande", 6);
                    //Brush b = new SolidBrush(Color.Gray);
                    G.Clear(Color.White);
                    // 指定高质量的双三次插值法。执行预筛选以确保高质量的收缩。此模式可产生质量最高的转换图像。 
                    G.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    // 指定高质量、低速度呈现。 
                    G.SmoothingMode = SmoothingMode.HighQuality;

                    graphics.DrawImage(thumimg, destRect, origRect, GraphicsUnit.Pixel);
                    //G.DrawString("Xuanye", f, b, 0, 0);
                    G.Dispose();

                    originalImg.Dispose();
                    if (File.Exists(filePath))
                    {
                        File.SetAttributes(filePath, FileAttributes.Normal);
                        File.Delete(filePath);
                    }
                    if (!Directory.Exists(Path.GetDirectoryName(filePath)))
                    {
                        Directory.CreateDirectory(Path.GetDirectoryName(filePath));
                        
                    }
                    partImg.Save(filePath, ImageFormat.Jpeg);

                    partImg.Dispose();
                    thumimg.Dispose();
                }
                catch
                {
                    return false;
                }
                return true;
            }
        }

        public static Bitmap MakeThumbnail(System.Drawing.Image fromImg, int width, int height)
        {
            Bitmap bmp = new Bitmap(width, height);
            int ow = fromImg.Width;
            int oh = fromImg.Height;

            //新建一个画板
            Graphics g = Graphics.FromImage(bmp);

            //设置高质量插值法
            g.InterpolationMode = InterpolationMode.High;
            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = SmoothingMode.Default;
            //清空画布并以透明背景色填充
            g.Clear(Color.White);

            g.DrawImage(fromImg, new Rectangle(0, 0, width, height),
                new Rectangle(0, 0, ow, oh),
                GraphicsUnit.Pixel);

            return bmp;

        }

        public static bool SaveCutPic(string pPath, string filePath, int pPartStartPointX, int pPartStartPointY, int pPartWidth, int pPartHeight, int pOrigStartPointX, int pOrigStartPointY)
        {
            using (System.Drawing.Image originalImg = System.Drawing.Image.FromFile(pPath))
            {
                try
                {
                    Bitmap partImg = new Bitmap(pPartWidth, pPartHeight);
                    Graphics graphics = Graphics.FromImage(partImg);
                    Rectangle destRect = new Rectangle(new Point(pPartStartPointX, pPartStartPointY), new Size(pPartWidth, pPartHeight));//目标位置
                    Rectangle origRect = new Rectangle(new Point(pOrigStartPointX, pOrigStartPointY), new Size(pPartWidth, pPartHeight));//原图位置（默认从原图中截取的图片大小等于目标图片的大小）

                    ///注释 文字水印  
                    Graphics G = Graphics.FromImage(partImg);
                    //Font f = new Font("Lucida Grande", 6);
                    //Brush b = new SolidBrush(Color.Gray);
                    G.Clear(Color.White);
                    // 指定高质量的双三次插值法。执行预筛选以确保高质量的收缩。此模式可产生质量最高的转换图像。 
                    G.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    // 指定高质量、低速度呈现。 
                    G.SmoothingMode = SmoothingMode.HighQuality;

                    graphics.DrawImage(originalImg, destRect, origRect, GraphicsUnit.Pixel);
                    //G.DrawString("Xuanye", f, b, 0, 0);
                    G.Dispose();

                    originalImg.Dispose();
                    if (File.Exists(filePath))
                    {
                        File.SetAttributes(filePath, FileAttributes.Normal);
                        File.Delete(filePath);
                    }
                    partImg.Save(filePath, ImageFormat.Jpeg);
                    partImg.Dispose();
                }
                catch
                {
                    return false;
                }
            }
            return true;
        }
    }