水印及缩略图的C#实现

老早以前写的，害怕以后忘了或找不到了，发到这里以备忘。

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

/// <summary>
/// PictureMarker 的摘要说明。
/// </summary>
public class PictureMarker
{
    /// <summary>
    /// PictureMarker的构造函数
    /// </summary>
    public PictureMarker()
    {
    }

    /// <summary>
    /// PictureMarker的构造函数
    /// </summary>
    /// <param name="width">缩略图的宽度</param>
    /// <param name="height">缩略图的高度</param>
    /// <param name="ismust">是否一定要生成缩略图，推荐为false</param>
    public PictureMarker(int width, int height, bool ismust)
    {
        this.width = width;
        this.height = height;
        this.ismust = ismust;
    }

    /// <summary>
    /// PictureMarker的构造函数
    /// </summary>
    /// <param name="width">缩略图的宽度</param>
    /// <param name="height">缩略图的高度</param>
    /// <param name="ismust">是否一定要生成缩略图，推荐为false</param>
    /// <param name="isSavePrimaryPic">是否要保存源图片</param>
    /// <param name="primaryPicPath">源图片的保存目录</param>
    public PictureMarker(int width, int height, bool ismust, bool isSavePrimaryPic, string primaryPicPath)
        : this(width, height, ismust)
    {
        this.isSavePrimaryPic = isSavePrimaryPic;
        this.primaryPicPath = primaryPicPath;
    }

    private int width;
    private int height;
    private bool ismust = false;
    private bool isSavePrimaryPic = false;
    private string primaryPicPath;

    /// <summary>
    /// 缩略图的宽度
    /// </summary>
    public int Width
    {
        get { return width; }
        set { width = value; }
    }

    /// <summary>
    /// 缩略图的高度
    /// </summary>
    public int Height
    {
        get { return height; }
        set { height = value; }
    }

    /// <summary>
    /// 是否一定要生成缩略图，推荐为false
    /// </summary>
    public bool IsMust
    {
        get { return ismust; }
        set { ismust = value; }
    }

    /// <summary>
    /// 是否要保存源图片
    /// </summary>
    public bool IsSavePrimaryPic
    {
        get { return isSavePrimaryPic; }
        set { isSavePrimaryPic = value; }
    }

    /// <summary>
    /// 源图片的保存目录
    /// </summary>
    public string PrimaryPicPath
    {
        get { return primaryPicPath; }
        set { primaryPicPath = value; }
    }

    /// <summary>
    /// 在图片上添加版权信息水印
    /// </summary>
    /// <param name="input">目标图片</param>
    /// <param name="copyright">文字版权信息</param>
    /// <param name="savepath">保存路径</param>
    /// <param name="position">水印显示位置</param>
    public void CreateMark(Stream input, string copyright, string savepath, WaterPosition position)
    {
        int xpoint, ypoint;
        System.Drawing.Image photo = System.Drawing.Image.FromStream(input);
        int pwidth = photo.Width;
        int pheight = photo.Height;
        Bitmap markpic = new Bitmap(photo);
        markpic.SetResolution(photo.HorizontalResolution, photo.VerticalResolution);

        Graphics graphics = Graphics.FromImage(markpic);

        xpoint = (pwidth - 100) / 2;
        ypoint = pheight - 40;
        graphics.DrawString(copyright, new Font("楷体", 15), new System.Drawing.SolidBrush(Color.FromArgb(255, 0, 255, 255)),
            new RectangleF(xpoint, ypoint, 400, 30));


        try
        {
            markpic.Save(savepath);
        }
        finally
        {
            input.Close();
            photo.Dispose();
            markpic.Dispose();
            graphics.Dispose();
        }
    }

    /// <summary>
    /// 在图片上添加版权信息水印
    /// </summary>
    /// <param name="input">目标图片</param>
    /// <param name="copyright">图片版权信息</param>
    /// <param name="savepath">保存路径</param>
    /// <param name="position">水印显示位置</param>
    public void CreateMark(Stream input, Stream copyright, string savepath, WaterPosition position)
    {
        int xpoint, ypoint;
        System.Drawing.Image photo = System.Drawing.Image.FromStream(input);
        System.Drawing.Image copy = System.Drawing.Image.FromStream(copyright);
        int pwidth = photo.Width;
        int pheight = photo.Height;
        int cwidth = copy.Width;
        int cheight = copy.Height;
        if (pwidth - cwidth < 20 || pheight - cheight < 20)
        {
            input.Close();
            copyright.Close();
            photo.Dispose();
            copy.Dispose();
            throw new ArgumentException("不合适的图片尺寸.目标图片比版权图片至少宽20像素,高20像素.");
        }

        if (isSavePrimaryPic)
        {
            if (primaryPicPath == null || primaryPicPath == "")
            {
                input.Close();
                copyright.Close();
                photo.Dispose();
                copy.Dispose();
                throw new ArgumentException("当要求保存源图片时,源图片的保存路径不能为空");
            }

            try
            {
                photo.Save(primaryPicPath + "\\" + Path.GetFileName(savepath) + ".jpg", ImageFormat.Jpeg);
            }
            catch (Exception ex)
            {
                input.Close();
                copyright.Close();
                photo.Dispose();
                copy.Dispose();

                throw ex;
            }
        }

        Bitmap markpic = new Bitmap(photo);
        markpic.SetResolution(photo.HorizontalResolution, photo.VerticalResolution);

        Graphics graphics = Graphics.FromImage(markpic);
        System.Drawing.Imaging.ImageAttributes att = new System.Drawing.Imaging.ImageAttributes();

        float[][] matrixelements = { 

                                           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},

                                           new float[] {0.0f,  0.0f,  0.0f,  0.0f, 1.0f}};

        System.Drawing.Imaging.ColorMatrix matrix = new System.Drawing.Imaging.ColorMatrix(matrixelements);

        att.SetColorMatrix(matrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);

        switch (position)
        {
            case WaterPosition.Left:
                xpoint = 10;
                ypoint = (pheight - cheight) / 2;
                break;
            case WaterPosition.LeftUp:
                xpoint = 10;
                ypoint = 10;
                break;
            case WaterPosition.MiddleUp:
                xpoint = (pwidth - cwidth) / 2;
                ypoint = 10;
                break;
            case WaterPosition.RightUp:
                xpoint = pwidth - cwidth - 10;
                ypoint = 10;
                break;
            case WaterPosition.Right:
                xpoint = pwidth - cwidth - 10;
                ypoint = (pheight - cheight) / 2;
                break;
            case WaterPosition.RightDown:
                xpoint = pwidth - cwidth - 10;
                ypoint = pheight - cheight - 10;
                break;
            case WaterPosition.MiddleDown:
                xpoint = (pwidth - cwidth) / 2;
                ypoint = pheight - cheight - 10;
                break;
            case WaterPosition.LeftDown:
                xpoint = 10;
                ypoint = pheight - cheight - 10;
                break;
            default:
                xpoint = (pwidth - cwidth) / 2;
                ypoint = (pheight - cheight) / 2;
                break;
        };

        graphics.DrawImage(copy, new Rectangle(xpoint, ypoint, cwidth, cheight), 0, 0, cwidth, cheight, GraphicsUnit.Pixel, att);

        if (width != 0 && height != 0)
        {
            if (ismust)
            {
                int twidth, theight;
                if (markpic.Width * height > markpic.Height * width)
                {
                    twidth = width;
                    theight = markpic.Height * width / markpic.Width;
                }
                else
                {
                    theight = height;
                    twidth = markpic.Width * height / markpic.Height;
                }

                markpic.SetResolution(twidth, theight);
                markpic = (Bitmap)markpic.GetThumbnailImage(twidth, theight, null, new IntPtr());
            }
            else
            {
                if (width < markpic.Width || height < markpic.Height)
                {
                    if (width < markpic.Width || height < markpic.Height)
                    {
                        int twidth, theight;
                        if (markpic.Width * height > markpic.Height * width)
                        {
                            twidth = width;
                            theight = markpic.Height * width / markpic.Width;
                        }
                        else
                        {
                            theight = height;
                            twidth = markpic.Width * height / markpic.Height;
                        }

                        markpic.SetResolution(twidth, theight);
                        markpic = (Bitmap)markpic.GetThumbnailImage(twidth, theight, null, new IntPtr());
                    }
                }
            }
        }

        try
        {
            markpic.Save(savepath, ImageFormat.Jpeg);
        }
        finally
        {
            graphics.Dispose();
            input.Close();
            copyright.Close();
            photo.Dispose();
            copy.Dispose();
            markpic.Dispose();
        }
    }


    /// <summary>
    /// 在图片上添加版权信息水印
    /// </summary>
    /// <param name="input">目标图片</param>
    /// <param name="copyright">版权信息,可以为图片路径或文字版权信息</param>
    /// <param name="directory">保存目录</param>
    /// <param name="filename">保存文件名</param>
    /// <param name="isDrectory">copyright是否为文件路径</param>
    /// <param name="position">水印显示位置</param>
    public void CreateMark(Stream input, string copyright, string directory, string filename, bool isDrectory, WaterPosition position)
    {
        if (isDrectory)
        {
            FileStream _copyright = new FileStream(copyright, FileMode.Open, FileAccess.Read, FileShare.Read);
            CreateMark(input, _copyright, directory, filename, position);
        }
        else
        {
            CreateMark(input, copyright, directory + "\\" + filename, position);
        }
    }

    /// <summary>
    /// 在图片上添加版权信息水印
    /// </summary>
    /// <param name="input">目标图片</param>
    /// <param name="copyright">图片版权信息</param>
    /// <param name="directory">保存目录</param>
    /// <param name="filename">保存文件名</param>
    /// <param name="position">水印显示位置</param>
    public void CreateMark(Stream input, Stream copyright, string directory, string filename, WaterPosition position)
    {
        CreateMark(input, copyright, directory + "\\" + filename, position);
    }

    /// <summary>
    /// 在图片上添加版权信息水印
    /// </summary>
    /// <param name="filepath">目标图片路径</param>
    /// <param name="copyright">版权信息,可以为图片路径或文字版权信息</param>
    /// <param name="directory">保存目录</param>
    /// <param name="filename">保存文件名</param>
    /// <param name="isDrectory">copyright是否为文件路径</param>
    /// <param name="position">水印显示位置</param>
    public void CreateMark(string filepath, string copyright, string directory, string filename, bool isDrectory, WaterPosition position)
    {
        FileStream input = new FileStream(filepath, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
        CreateMark(input, copyright, directory, filename, isDrectory, position);
    }

    /// <summary>
    /// 在图片上添加版权信息水印
    /// </summary>
    /// <param name="filepath">目标图片路径</param>
    /// <param name="copyright">版权信息,可以为图片路径或文字版权信息</param>
    /// <param name="savepath">保存路径</param>
    /// <param name="isDrectory">copyright是否为文件路径</param>
    /// <param name="position">水印显示位置</param>
    public void CreateMark(string filepath, string copyright, string savepath, bool isDrectory, WaterPosition position)
    {
        if (isDrectory)
        {
            FileStream input = new FileStream(filepath, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
            FileStream _copyright = new FileStream(copyright, FileMode.Open, FileAccess.Read, FileShare.Read);
            CreateMark(input, _copyright, savepath, position);
        }
        else
        {
            FileStream input = new FileStream(filepath, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
            CreateMark(input, copyright, savepath, position);
        }
    }

    public void CreateThumbnailImage(Stream input, string savepath)
    {
        if (width == 0 || height == 0)
        {
            input.Close();
            throw new ArgumentException("缩略图的宽度和高度不能为0.");
        }
        Image photo = Image.FromStream(input);

        if (isSavePrimaryPic)
        {
            if (primaryPicPath == null || primaryPicPath == "")
            {
                input.Close();
                photo.Dispose();
                throw new ArgumentException("当要求保存源图片时,源图片的保存路径不能为空");
            }

            try
            {
                photo.Save(Path.Combine(primaryPicPath, Path.GetFileNameWithoutExtension(savepath) + ".jpg"), ImageFormat.Jpeg);
            }
            catch (Exception ex)
            {
                input.Close();
                photo.Dispose();

                throw ex;
            }
        }

        Bitmap markpic = new Bitmap(photo);

        if (ismust)
        {
            int twidth, theight;
            if (markpic.Width * height > markpic.Height * width)
            {
                twidth = width;
                theight = markpic.Height * width / markpic.Width;
            }
            else
            {
                theight = height;
                twidth = markpic.Width * height / markpic.Height;
            }

            markpic.SetResolution(twidth, theight);
            markpic = (Bitmap)markpic.GetThumbnailImage(twidth, theight, null, new IntPtr());
        }
        else
        {
            if (width < markpic.Width || height < markpic.Height)
            {
                if (width < markpic.Width || height < markpic.Height)
                {
                    int twidth, theight;
                    if (markpic.Width * height > markpic.Height * width)
                    {
                        twidth = width;
                        theight = markpic.Height * width / markpic.Width;
                    }
                    else
                    {
                        theight = height;
                        twidth = markpic.Width * height / markpic.Height;
                    }

                    markpic.SetResolution(twidth, theight);
                    markpic = (Bitmap)markpic.GetThumbnailImage(twidth, theight, null, new IntPtr());
                }
            }
        }

        try
        {
            markpic.Save(savepath, ImageFormat.Jpeg);
        }
        finally
        {
            input.Close();
            photo.Dispose();
            markpic.Dispose();
        }
    }

    public void CreateThumbnailImage(string source, string savepath)
    {
        FileStream input = new FileStream(source, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
        CreateThumbnailImage(input, savepath);
    }

    /// <summary>
    /// 水印显示的位置
    /// </summary>
    public enum WaterPosition
    {
        /// <summary>
        /// 左上
        /// </summary>
        LeftUp,
        /// <summary>
        /// 中上
        /// </summary>
        MiddleUp,
        /// <summary>
        /// 右上
        /// </summary>
        RightUp,
        /// <summary>
        /// 右
        /// </summary>
        Right,
        /// <summary>
        /// 右下
        /// </summary>
        RightDown,
        /// <summary>
        /// 中下
        /// </summary>
        MiddleDown,
        /// <summary>
        /// 左下
        /// </summary>
        LeftDown,
        /// <summary>
        /// 左
        /// </summary>
        Left,
        /// <summary>
        /// 正中间
        /// </summary>
        Middle
    }
}

源代码