c# 添加图片水印,可以指定水印位置+生成缩略图

using System;

using System.IO;

using System.Collections;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;



namespace BLL

{

    /**//// <summary>

    /// 水印的类型

    /// </summary>

    public enum WaterMarkType

    {

        /**//// <summary>

        /// 文字水印

        /// </summary>

        TextMark,

        /**//// <summary>

        /// 图片水印

        /// </summary>

        //ImageMark // 暂时只能添加文字水印

    };



    /**//// <summary>

    /// 水印的位置

    /// </summary>

    public enum WaterMarkPosition

    {

        /**//// <summary>

        /// 左上角

        /// </summary>

        WMP_Left_Top,

        /**//// <summary>

        /// 左下角

        /// </summary>

        WMP_Left_Bottom,

        /**//// <summary>

        /// 右上角

        /// </summary>

        WMP_Right_Top,

        /**//// <summary>

        /// 右下角

        /// </summary>

        WMP_Right_Bottom

    };



    /**//// <summary>

    /// 处理图片的类(包括加水印,生成缩略图)

    /// </summary>

    public class ImageWaterMark

    {

        public ImageWaterMark()

        {

            //

            // TODO: 在此处添加构造函数逻辑

            //

        }



        给图片加水印#region 给图片加水印

        /**//// <summary>

        /// 添加水印(分图片水印与文字水印两种)

        /// </summary>

        /// <param name="oldpath">原图片绝对地址</param>

        /// <param name="newpath">新图片放置的绝对地址</param>

        /// <param name="wmtType">要添加的水印的类型</param>

        /// <param name="sWaterMarkContent">水印内容,若添加文字水印,此即为要添加的文字;

        /// 若要添加图片水印,此为图片的路径</param>

        public void addWaterMark(string oldpath, string newpath, 

            WaterMarkType wmtType, string sWaterMarkContent)

        {

            try

            {

                Image image = Image.FromFile(oldpath);



                Bitmap b = new Bitmap(image.Width, image.Height, 

                    PixelFormat.Format24bppRgb);



                Graphics g = Graphics.FromImage(b);

                g.Clear(Color.White);

                g.SmoothingMode = SmoothingMode.HighQuality;

                g.InterpolationMode = InterpolationMode.High;



                g.DrawImage(image, 0, 0, image.Width, image.Height);



                switch (wmtType)

                {

                    /**//*case WaterMarkType.ImageMark:

                        //图片水印

                        this.addWatermarkImage(g, 

                            Page.Server.MapPath(Watermarkimgpath), 

                            WatermarkPosition,image.Width,image.Height);

                        break;*/

                    case WaterMarkType.TextMark:

                        //文字水印

                        this.addWatermarkText(g, sWaterMarkContent, "WM_BOTTOM_RIGHT", 

                            image.Width, image.Height);

                        break;

                }



                b.Save(newpath);

                b.Dispose();

                image.Dispose();

            }

            catch

            {

                if(File.Exists(oldpath))

                {

                    File.Delete(oldpath);

                }

            }

            finally

            {

                if(File.Exists(oldpath))

                {

                    File.Delete(oldpath);

                }

            }  

        }



        /**//// <summary>

        ///  加水印文字

        /// </summary>

        /// <param name="picture">imge 对象</param>

        /// <param name="_watermarkText">水印文字内容</param>

        /// <param name="_watermarkPosition">水印位置</param>

        /// <param name="_width">被加水印图片的宽</param>

        /// <param name="_height">被加水印图片的高</param>

        private void addWatermarkText(Graphics picture, string _watermarkText, 

            string _watermarkPosition, int _width, int _height)

        {

            // 确定水印文字的字体大小

            int[] sizes = new int[]{32, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4};

            Font crFont = null;

            SizeF crSize = new SizeF();

            for (int i = 0;i < sizes.Length; i++)

            {

                crFont = new Font("Arial Black", sizes[i], FontStyle.Bold);

                crSize = picture.MeasureString(_watermarkText, crFont);



                if((ushort)crSize.Width < (ushort)_width)

                {

                    break;

                }

            }



            // 生成水印图片(将文字写到图片中)

            Bitmap floatBmp = new Bitmap((int)crSize.Width + 3, 

                           (int)crSize.Height + 3, PixelFormat.Format32bppArgb);

            Graphics fg=Graphics.FromImage(floatBmp);

            PointF pt=new PointF(0,0);



            // 画阴影文字

            Brush TransparentBrush0 = new SolidBrush(Color.FromArgb(255, Color.Black));

            Brush TransparentBrush1 = new SolidBrush(Color.FromArgb(255, Color.Black));

            fg.DrawString(_watermarkText,crFont,TransparentBrush0, pt.X, pt.Y + 1); 

            fg.DrawString(_watermarkText,crFont,TransparentBrush0, pt.X + 1, pt.Y); 



            fg.DrawString(_watermarkText,crFont,TransparentBrush1, pt.X + 1, pt.Y + 1); 

            fg.DrawString(_watermarkText,crFont,TransparentBrush1, pt.X, pt.Y + 2); 

            fg.DrawString(_watermarkText,crFont,TransparentBrush1, pt.X + 2, pt.Y); 



            TransparentBrush0.Dispose(); 

            TransparentBrush1.Dispose();



            // 画文字

            fg.SmoothingMode=System.Drawing.Drawing2D.SmoothingMode.HighQuality; 

            fg.DrawString(_watermarkText, 

                crFont, new SolidBrush(Color.White), 

                pt.X, pt.Y, StringFormat.GenericDefault);



            // 保存刚才的操作

            fg.Save(); 

            fg.Dispose();

            // floatBmp.Save("d:\\WebSite\\DIGITALKM\\ttt.jpg");



            // 将水印图片加到原图中

            this.addWatermarkImage(

                picture, 

                new Bitmap(floatBmp), 

                "WM_BOTTOM_RIGHT", 

                _width, 

                _height);

        }



        /**//// <summary>

        ///  加水印图片

        /// </summary>

        /// <param name="picture">imge 对象</param>

        /// <param name="iTheImage">Image对象(以此图片为水印)</param>

        /// <param name="_watermarkPosition">水印位置</param>

        /// <param name="_width">被加水印图片的宽</param>

        /// <param name="_height">被加水印图片的高</param>

        private void addWatermarkImage( Graphics picture,Image iTheImage, 

            string _watermarkPosition,int _width,int _height)

        {

            Image watermark = new Bitmap(iTheImage);

 

            ImageAttributes imageAttributes = 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};



            imageAttributes.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, 0.3f, 0.0f},

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

                                            };

 

            ColorMatrix colorMatrix = new ColorMatrix(colorMatrixElements);

 

            imageAttributes.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);



            int xpos = 0;

            int ypos = 0;

            int WatermarkWidth = 0;

            int WatermarkHeight = 0;

            double bl = 1d;



            //计算水印图片的比率

            //取背景的1/4宽度来比较

            if ((_width > watermark.Width * 4) && (_height > watermark.Height * 4))

            {

                bl = 1;

            }

            else if ((_width > watermark.Width * 4) && (_height<watermark.Height * 4))

            {

                bl = Convert.ToDouble(_height / 4) / Convert.ToDouble(watermark.Height);

            

            }

            else if ((_width < watermark.Width * 4) && (_height > watermark.Height * 4))

            {

                bl = Convert.ToDouble(_width / 4) / Convert.ToDouble(watermark.Width);

            }

            else

            {

                if ((_width * watermark.Height) > (_height * watermark.Width))

                {

                    bl = Convert.ToDouble(_height / 4) / Convert.ToDouble(watermark.Height);

                    

                }

                else

                {

                    bl = Convert.ToDouble(_width / 4) / Convert.ToDouble(watermark.Width);

                    

                }

            

            }



            WatermarkWidth = Convert.ToInt32(watermark.Width * bl);

            WatermarkHeight = Convert.ToInt32(watermark.Height * bl);



            switch (_watermarkPosition)

            {

                case "WM_TOP_LEFT":

                    xpos = 10;

                    ypos = 10;

                    break;

                case "WM_TOP_RIGHT":

                    xpos = _width - WatermarkWidth - 10;

                    ypos = 10;

                    break;

                case "WM_BOTTOM_RIGHT":

                    xpos = _width - WatermarkWidth - 10;

                    ypos = _height -WatermarkHeight - 10;

                    break;

                case "WM_BOTTOM_LEFT":

                    xpos = 10;

                    ypos = _height - WatermarkHeight - 10;

                    break;

            }



            picture.DrawImage(

                watermark, 

                new Rectangle(xpos, ypos, WatermarkWidth, WatermarkHeight), 

                0, 

                0, 

                watermark.Width, 

                watermark.Height, 

                GraphicsUnit.Pixel, 

                imageAttributes);



            watermark.Dispose();

            imageAttributes.Dispose();

        }



        /**//// <summary>

        ///  加水印图片

        /// </summary>

        /// <param name="picture">imge 对象</param>

        /// <param name="WaterMarkPicPath">水印图片的地址</param>

        /// <param name="_watermarkPosition">水印位置</param>

        /// <param name="_width">被加水印图片的宽</param>

        /// <param name="_height">被加水印图片的高</param>

        private void addWatermarkImage( Graphics picture,string WaterMarkPicPath, 

            string _watermarkPosition,int _width,int _height)

        {

            Image watermark = new Bitmap(WaterMarkPicPath);

 

            this.addWatermarkImage(picture, watermark, _watermarkPosition, _width, 

                _height);

        }

        #endregion



        生成缩略图#region 生成缩略图

        /**//// <summary>

        /// 保存图片

        /// </summary>

        /// <param name="image">Image 对象</param>

        /// <param name="savePath">保存路径</param>

        /// <param name="ici">指定格式的编解码参数</param>

        private void SaveImage(Image image, string savePath, ImageCodecInfo ici)

        {

            //设置 原图片 对象的 EncoderParameters 对象

            EncoderParameters parameters = new EncoderParameters(1);

            parameters.Param[0] = new EncoderParameter(

                System.Drawing.Imaging.Encoder.Quality, ((long) 90));

            image.Save(savePath, ici, parameters);

            parameters.Dispose();

        }



        /**//// <summary>

        /// 获取图像编码解码器的所有相关信息

        /// </summary>

        /// <param name="mimeType">包含编码解码器的多用途网际邮件扩充协议 (MIME) 类型的字符串</param>

        /// <returns>返回图像编码解码器的所有相关信息</returns>

        private ImageCodecInfo GetCodecInfo(string mimeType)

        {

            ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();

            foreach(ImageCodecInfo ici in CodecInfo)

            {

                if(ici.MimeType == mimeType)

                    return ici;

            }

            return null;

        }



        /**//// <summary>

        /// 生成缩略图

        /// </summary>

        /// <param name="sourceImagePath">原图片路径(相对路径)</param>

        /// <param name="thumbnailImagePath">生成的缩略图路径,如果为空则保存为原图片路径(相对路径)</param>

        /// <param name="thumbnailImageWidth">缩略图的宽度(高度与按源图片比例自动生成)</param>

        public void ToThumbnailImages(

            string SourceImagePath,

            string ThumbnailImagePath,

            int ThumbnailImageWidth)

        {

            Hashtable htmimes = new Hashtable();

            htmimes[".jpeg"] = "image/jpeg";

            htmimes[".jpg"] = "image/jpeg";   

            htmimes[".png"] = "image/png";   

            htmimes[".tif"] = "image/tiff";

            htmimes[".tiff"] = "image/tiff";

            htmimes[".bmp"] = "image/bmp";

            htmimes[".gif"] = "image/gif";



            // 取得原图片的后缀

            string sExt = SourceImagePath.Substring(

                SourceImagePath.LastIndexOf(".")).ToLower();



            //从 原图片 创建 Image 对象

            Image image = Image.FromFile(SourceImagePath);  

            int num = ((ThumbnailImageWidth / 4) * 3);

            int width = image.Width;

            int height = image.Height;



            //计算图片的比例

            if ((((double) width) / ((double) height)) >= 1.3333333333333333f)

            {

                num = ((height * ThumbnailImageWidth) / width);

            }

            else

            {

                ThumbnailImageWidth = ((width * num) / height);

            }

            if ((ThumbnailImageWidth < 1) || (num < 1))

            {

                return;

            }



            //用指定的大小和格式初始化 Bitmap 类的新实例

            Bitmap bitmap = new Bitmap(ThumbnailImageWidth, num, 

                PixelFormat.Format32bppArgb);



            //从指定的 Image 对象创建新 Graphics 对象

            Graphics graphics = Graphics.FromImage(bitmap);



            //清除整个绘图面并以透明背景色填充

            graphics.Clear(Color.Transparent);



            graphics.SmoothingMode = SmoothingMode.HighQuality;

            graphics.InterpolationMode = InterpolationMode.High;



            //在指定位置并且按指定大小绘制 原图片 对象

            graphics.DrawImage(image, new Rectangle(0, 0, ThumbnailImageWidth, num));

            image.Dispose(); 

   

            try

            {   

                //将此 原图片 以指定格式并用指定的编解码参数保存到指定文件 

                SaveImage(bitmap, ThumbnailImagePath, 

                    GetCodecInfo((string)htmimes[sExt]));

            }

            catch(System.Exception e)

            {

                throw e;

            }

        }

        #endregion

    }

}

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