给图片添加透明文字水印的方法

给图片添加透明文字水印的方法(可以定义文字水印的位置、水印的透明度)

using System;
using System.Collections.Generic;
using System.Text;

using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace DocMIS.AppConfig
{
    /**//// <summary>
    /// 水印位置
    /// </summary>
    public enum ImagePosition
    {
        /**//// <summary>
        /// 左上
        /// </summary>
        LeftTop,
        /**//// <summary>
        /// 左下
        /// </summary>
        LeftBottom,
        /**//// <summary>
        /// 右上
        /// </summary>
        RightTop,
        /**//// <summary>
        /// 右下
        /// </summary>
        RigthBottom,
        /**//// <summary>
        /// 顶部居中
        /// </summary>
        TopMiddle,
        /**//// <summary>
        /// 底部居中
        /// </summary>
        BottomMiddle,
        /**//// <summary>
        /// 中心
        /// </summary>
        Center 
    }

    /**//// <summary>
    /// 图像操作类(主要用于给图片加上透明文字水印)
    /// </summary>
    class ImageWater_Word
    {
        private string _ErrMsg;
        出错信息#region 出错信息
        /**//// <summary>
        /// 出错信息
        /// </summary>
        public string ErrMsg
        {
            get { return _ErrMsg; }
            set { _ErrMsg = value; }
        }
        #endregion


        将文件转换成流#region 将文件转换成流
        //public byte[] SetImageToByteArray(string fileName, ref string fileSize)
        /**//// <summary>
        /// 将文件转换成流
        /// </summary>
        /// <param name="fileName">文件全路径</param>
        /// <returns></returns>
        private byte[] SetImageToByteArray(string fileName)
        {
            byte[] image = null;
            try
            {
                FileStream fs = new FileStream(fileName, FileMode.Open);
                FileInfo fileInfo = new FileInfo(fileName);
                //fileSize = Convert.ToDecimal(fileInfo.Length / 1024).ToString("f2") + " K";
                int streamLength = (int)fs.Length;
                image = new byte[streamLength];
                fs.Read(image, 0, streamLength);
                fs.Close();
                return image;
            }
            catch
            {
                return image;
            }
        }
        #endregion

        将byte转换成MemoryStream类型#region 将byte转换成MemoryStream类型
        /**//// <summary>
        /// 将byte转换成MemoryStream类型
        /// </summary>
        /// <param name="mybyte">byte[]变量</param>
        /// <returns></returns>
        private MemoryStream ByteToStream(byte[] mybyte)
        {
            MemoryStream mymemorystream = new MemoryStream(mybyte, 0, mybyte.Length);
            return mymemorystream;
        }
        #endregion

        将byte转换成Image文件#region 将byte转换成Image文件
        /**//// <summary>
        /// 将byte转换成Image文件
        /// </summary>
        /// <param name="mybyte">byte[]变量</param>
        /// <returns></returns>
        private System.Drawing.Image SetByteToImage(byte[] mybyte)
        {
            System.Drawing.Image image;
            MemoryStream mymemorystream = new MemoryStream(mybyte, 0, mybyte.Length);
            image = System.Drawing.Image.FromStream(mymemorystream);
            return image;
        }
        #endregion


        批量在图片上添加透明水印文字#region 批量在图片上添加透明水印文字
        /**//// <summary>
        /// 批量在图片上添加透明水印文字
        /// </summary>
        /// <param name="arrsourcePicture">原来图片地址(路径+文件名)</param>
        /// <param name="waterWords">需要添加到图片上的文字</param>
        /// <param name="alpha">透明度(0.1~1.0之间)</param>
        /// <param name="position">文字显示的位置</param>
        /// <param name="fRewrite">是否覆盖原图片(如果不覆盖，那么将在同目录下生成一个文件名带0607的文件)</param>
        /// <returns></returns>
        public bool DrawWords(string[] arrsourcePicture, string waterWords, float alpha, ImagePosition position, bool fRewrite)
        {
            foreach (string imgPath in arrsourcePicture)
            {
                if (!DrawWords(imgPath, waterWords, alpha, position, fRewrite))
                {
                    _ErrMsg += "——处理文件：" + imgPath + " 时出错。";
                    return false;
                }
            }
            return true;
        }
        #endregion

        在图片上添加透明水印文字#region 在图片上添加透明水印文字
        /**//// <summary>
        /// 在图片上添加透明水印文字
        /// </summary>
        /// <param name="sourcePicture">原来图片地址(路径+文件名)</param>
        /// <param name="waterWords">需要添加到图片上的文字</param>
        /// <param name="alpha">透明度(0.1~1.0之间)</param>
        /// <param name="position">文字显示的位置</param>
        /// <param name="fRewrite">是否覆盖原图片(如果不覆盖，那么将在同目录下生成一个文件名带0607的文件)</param>
        /// <returns></returns>
        public bool DrawWords(string sourcePicture, string waterWords, float alpha, ImagePosition position, bool fRewrite)
        {
            if (!System.IO.File.Exists(sourcePicture))
            {
                _ErrMsg = "文件不存在！";
                return false;
            }
            string fileExtension = System.IO.Path.GetExtension(sourcePicture).ToLower();
            if (fileExtension != ".gif" && fileExtension != ".jpg" && fileExtension != ".png" && fileExtension != ".bmp")
            {
                _ErrMsg = "不是图片文件！";
                return false;
            }

            Image imgPhoto = null;
            Bitmap bmPhoto = null;
            Graphics grPhoto = null;
            try
            {
                //创建一个图片对象用来装载要被添加水印的图片
                imgPhoto = Image.FromStream(ByteToStream(SetImageToByteArray(sourcePicture)));

                //获取图片的宽和高
                int phWidth = imgPhoto.Width;
                int phHeight = imgPhoto.Height;

                //建立一个bitmap，和我们需要加水印的图片一样大小
                bmPhoto = new Bitmap(phWidth, phHeight, PixelFormat.Format24bppRgb);

                //SetResolution：设置此 Bitmap 的分辨率
                //这里直接将我们需要添加水印的图片的分辨率赋给了bitmap
                bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);

                //Graphics：封装一个 GDI+ 绘图图面。
                grPhoto = Graphics.FromImage(bmPhoto);

                //设置图形的品质
                grPhoto.SmoothingMode = SmoothingMode.AntiAlias;

                //将我们要添加水印的图片按照原始大小描绘（复制）到图形中
                grPhoto.DrawImage(
                 imgPhoto,                                           //   要添加水印的图片
                 new Rectangle(0, 0, phWidth, phHeight), //  根据要添加的水印图片的宽和高
                 0,                                                     //  X方向从0点开始描绘
                 0,                                                     // Y方向 
                 phWidth,                                            //  X方向描绘长度
                 phHeight,                                           //  Y方向描绘长度
                 GraphicsUnit.Pixel);                              // 描绘的单位，这里用的是像素

                //根据图片的大小我们来确定添加上去的文字的大小
                //在这里我们定义一个数组来确定
                int[] sizes = new int[] { 48, 36, 28, 24, 16, 14, 12, 10 };

                //字体
                Font crFont = null;
                //矩形的宽度和高度，SizeF有三个属性，分别为Height高，width宽，IsEmpty是否为空
                SizeF crSize = new SizeF();

                //利用一个循环语句来选择我们要添加文字的型号
                //直到它的长度比图片的宽度小
                for (int i = 0; i < sizes.Length; i++)
                {
                    crFont = new Font("arial", sizes[i], FontStyle.Bold);

                    //测量用指定的 Font 对象绘制并用指定的 StringFormat 对象格式化的指定字符串。
                    crSize = grPhoto.MeasureString(waterWords, crFont);

                    // ushort 关键字表示一种整数数据类型
                    if ((ushort)crSize.Width < (ushort)phWidth)
                        break;
                }

                //截边5%的距离，定义文字显示(由于不同的图片显示的高和宽不同，所以按百分比截取)
                int yPixlesFromBottom = (int)(phHeight * .05);

                //定义在图片上文字的位置
                float wmHeight = crSize.Height;
                float wmWidth = crSize.Width;

                float xPosOfWm;
                float yPosOfWm;

                //设置水印的位置
                switch (position)
                {
                    case ImagePosition.BottomMiddle:
                        xPosOfWm = phWidth / 2;
                        yPosOfWm = phHeight - wmHeight - 10;
                        break;
                    case ImagePosition.Center:
                        xPosOfWm = phWidth / 2;
                        yPosOfWm = phHeight / 2;
                        break;
                    case ImagePosition.LeftBottom:
                        xPosOfWm = wmWidth;
                        yPosOfWm = phHeight - wmHeight - 10;
                        break;
                    case ImagePosition.LeftTop:
                        xPosOfWm = wmWidth / 2;
                        yPosOfWm = wmHeight / 2;
                        break;
                    case ImagePosition.RightTop:
                        xPosOfWm = phWidth - wmWidth - 10;
                        yPosOfWm = wmHeight;
                        break;
                    case ImagePosition.RigthBottom:
                        xPosOfWm = phWidth - wmWidth - 10;
                        yPosOfWm = phHeight - wmHeight - 10;
                        break;
                    case ImagePosition.TopMiddle:
                        xPosOfWm = phWidth / 2;
                        yPosOfWm = wmWidth;
                        break;
                    default:
                        xPosOfWm = wmWidth;
                        yPosOfWm = phHeight - wmHeight - 10;
                        break;
                }
                //封装文本布局信息（如对齐、文字方向和 Tab 停靠位），显示操作（如省略号插入和国家标准 (National) 数字替换）和 OpenType 功能。
                StringFormat StrFormat = new StringFormat();

                //定义需要印的文字居中对齐
                StrFormat.Alignment = StringAlignment.Center;

                //SolidBrush:定义单色画笔。画笔用于填充图形形状，如矩形、椭圆、扇形、多边形和封闭路径。
                //这个画笔为描绘阴影的画笔，呈灰色
                int m_alpha = Convert.ToInt32(256 * alpha);
                SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(m_alpha, 0, 0, 0));

                //描绘文字信息，这个图层向右和向下偏移一个像素，表示阴影效果
                //DrawString 在指定矩形并且用指定的 Brush 和 Font 对象绘制指定的文本字符串。
                grPhoto.DrawString(waterWords,                                    //string of text
                                           crFont,                                         //font
                                           semiTransBrush2,                            //Brush
                                           new PointF(xPosOfWm + 1, yPosOfWm + 1),  //Position
                                           StrFormat);

                //从四个 ARGB 分量（alpha、红色、绿色和蓝色）值创建 Color 结构，这里设置透明度为153
                //这个画笔为描绘正式文字的笔刷，呈白色
                SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255));

                //第二次绘制这个图形，建立在第一次描绘的基础上
                grPhoto.DrawString(waterWords,                 //string of text
                                           crFont,                                   //font
                                           semiTransBrush,                           //Brush
                                           new PointF(xPosOfWm, yPosOfWm),  //Position
                                           StrFormat);

                //imgPhoto是我们建立的用来装载最终图形的Image对象
                //bmPhoto是我们用来制作图形的容器，为Bitmap对象
                imgPhoto = bmPhoto;
                //释放资源，将定义的Graphics实例grPhoto释放，grPhoto功德圆满
                //grPhoto.Dispose();

                //将grPhoto保存
                if (fRewrite)
                {
                    imgPhoto.Save(sourcePicture);
                }
                else
                {
                    // 目标图片名称及全路径
                    string targetImage = sourcePicture.Replace(System.IO.Path.GetExtension(sourcePicture), "") + "_0607" + fileExtension;
                    imgPhoto.Save(targetImage);
                }
                //imgPhoto.Dispose();
                return true;
            }
            catch (Exception ex)
            {
                _ErrMsg = ex.Message;
                return false;
            }
            finally
            {
                if (imgPhoto != null)
                    imgPhoto.Dispose();
                if (bmPhoto != null)
                    bmPhoto.Dispose();
                if (grPhoto != null)
                    grPhoto.Dispose();
            }


        }
        #endregion

    }
}