C# ImageHelper

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Web;

public class ImageHelper
{
    #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>
    /// <param name="postedFile">原图HttpPostedFile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.Web.HttpPostedFile postedFile, 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(postedFile.InputStream, 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();
        }
    }

    /// <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>
    /// <param name="postedFile">原图HttpPostedFile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 正方型裁剪并缩放

    #region 固定模版裁剪并缩放

    /// <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>
    /// <param name="postedFile">原图HttpPostedFile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.Web.HttpPostedFile postedFile, 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(postedFile.InputStream, 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)Math.Floor(initImage.Width / templateRate));
                    pickedG = System.Drawing.Graphics.FromImage(pickedImage);

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

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

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

                    toR.X = 0;
                    toR.Y = 0;
                    toR.Width = (int)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 固定模版裁剪并缩放

    #region 等比缩放

    /// <summary>
    /// 图片等比缩放并添加水印
    /// </summary>
    /// <param name="postedFile">原图HttpPostedFile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>
    /// <param name="waterTextFont">文字水印字体</param>
    public static void ZoomAuto(System.IO.Stream postedFile, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage, Font waterTextFont)
    {
        //创建目录
        string dir = Path.GetDirectoryName(savePath);
        if (!Directory.Exists(dir))
            Directory.CreateDirectory(dir);

        if (waterTextFont == null)
            waterTextFont = new Font("黑体", 14, GraphicsUnit.Pixel);

        //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(postedFile);

        //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 = waterTextFont;
                    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 = waterTextFont;
                    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();
        }
    }

    /// <summary>
    /// 图片等比缩放并添加水印
    /// </summary>
    /// <param name="initImage">Image 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>
    /// <param name="waterTextFont">文字水印字体</param>
    public static void ZoomAuto(System.Drawing.Image initImage, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage, Font waterTextFont)
    {
        //创建目录
        string dir = Path.GetDirectoryName(savePath);
        if (!Directory.Exists(dir))
            Directory.CreateDirectory(dir);

        if (waterTextFont == null)
            waterTextFont = new Font("黑体", 14, GraphicsUnit.Pixel);

        //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 = waterTextFont;
                    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 = waterTextFont;
                    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();
        }
    }

    /// <summary>
    /// 图片等比缩放并添加水印
    /// </summary>
    /// <param name="postedFile">原图HttpPostedFile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>
    /// <param name="waterTextFont">文字水印字体</param>
    public static void ZoomAuto(System.Web.HttpPostedFile postedFile, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage, Font waterTextFont)
    {
        //创建目录
        string dir = Path.GetDirectoryName(savePath);
        if (!Directory.Exists(dir))
            Directory.CreateDirectory(dir);

        if (waterTextFont == null)
            waterTextFont = new Font("黑体", 14, GraphicsUnit.Pixel);

        //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(postedFile.InputStream, 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 = waterTextFont;
                    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 = waterTextFont;
                    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 等比缩放

    #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 其它

    #region 检查图片的大小

    /// <summary>
    /// 检查图片的大小
    /// </summary>
    /// <param name="postfile">HttpPostedFile</param>
    /// <param name="max">允许上图片的大小</param>
    /// <returns>true:允许上传 false:超过允许值</returns>
    public static bool CheckImageSize(HttpPostedFile postfile, int max)
    {
        int filesize = postfile.ContentLength;
        return filesize <= max;
    }

    #endregion 检查图片的大小

    #region 获取指定区域的图片

    /// <summary>
    /// 获取指定区域的图片
    /// </summary>
    /// <param name="pPath">原始图片路径</param>
    /// <param name="pSavedPath">保存路径</param>
    /// <param name="pPartStartPointX">目标图片开始绘制处的坐标X值(通常为)</param>
    /// <param name="pPartStartPointY">目标图片开始绘制处的坐标Y值(通常为)</param>
    /// <param name="pPartWidth">目标图片的宽度</param>
    /// <param name="pPartHeight">目标图片的高度</param>
    /// <param name="pOrigStartPointX">原始图片开始截取处的坐标X值</param>
    /// <param name="pOrigStartPointY">原始图片开始截取处的坐标Y值</param>
    public static void GetPartImage(string pPath, string pSavedPath, int pPartStartPointX, int pPartStartPointY, int pPartWidth, int pPartHeight, int pOrigStartPointX, int pOrigStartPointY)
    {
        string normalJpgPath = pSavedPath;

        using (System.Drawing.Image originalImg = System.Drawing.Image.FromFile(pPath))
        {
            Bitmap partImg = new Bitmap(pPartWidth, pPartHeight, PixelFormat.Format32bppArgb);

            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）

            graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;

            graphics.DrawImage(originalImg, destRect, origRect, GraphicsUnit.Pixel);

            originalImg.Dispose();

            if (File.Exists(normalJpgPath))
            {
                File.SetAttributes(normalJpgPath, FileAttributes.Normal);
                File.Delete(normalJpgPath);
            }

            using (EncoderParameters eps = new EncoderParameters(1))
            {
                eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100);
                partImg.Save(normalJpgPath, ImageFormat.Jpeg);
            }
        }
    }

    #endregion 获取指定区域的图片
}