public  System.Drawing.Bitmap AddText(string imgPath,string saveImgPath,int baselen, string locationLeftTop, string locationRightBottom, string text, string fontName = "華文行楷")
{
    System.Drawing.Image img = System.Drawing.Image.FromFile(imgPath);
 
    int width = img.Width;
    int height = img.Height;
    System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(width, height);
    System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(bmp);
 
    // 計(jì)算文字區(qū)域
    // 左上角
    string[] location = locationLeftTop.Split(',');
    float x1 = float.Parse(location[0]);
    float y1 = float.Parse(location[1]);
    // 右下角
    location = locationRightBottom.Split(',');
    float x2 = float.Parse(location[0]);
    float y2 = float.Parse(location[1]);
    // 區(qū)域?qū)捀?
    float fontWidth = x2 - x1;
    float fontHeight = y2 - y1;
 
    float fontSize = fontHeight;  // 初次估計(jì)先用文字區(qū)域高度作為文字字體大小，后面再做調(diào)整，單位為px
 
    System.Drawing.Font font = new System.Drawing.Font(fontName,18, System.Drawing.GraphicsUnit.Pixel);
    System.Drawing.SizeF sf = graph.MeasureString(text, font);
 
 
    // 最終的得出的字體所占區(qū)域一般不會剛好等于實(shí)際區(qū)域
    // 所以根據(jù)兩個區(qū)域的相差之處再把文字開始位置(左上角定位)稍微調(diào)整一下
    string title = text;
    text = "";
    int gs = title.Length / baselen;
    if (title.Length % baselen != 0)
    {
        gs++;
    }
    string[] lines = new string[gs];
    int startpos = 0;
    
    for (int i = 0; i < gs; i++)
    {
        int len = title.Length < baselen ? title.Length : baselen;
        lines[i] = title.Substring(0, len);
        startpos += len;
        title = title.Substring(len);
        text += lines[i] + "\r\n";
    }
 
    x1 += (fontWidth - sf.Width) / 2;
    y1 += (fontHeight - sf.Height) / 2;
    x1 = (width - baselen * 18) / 2;
    y1 = (height - lines.Length * 18) / 2;
    graph.DrawImage(img, 0, 0, width, height);
 
    graph.DrawString(text, font, new System.Drawing.SolidBrush(System.Drawing.Color.White), x1, y1);
    
    graph.Dispose();
    img.Dispose();
    bmp.Save(saveImgPath,System.Drawing.Imaging.ImageFormat.Jpeg);
    return bmp;
}

            public string ImgToBase64String(string Imagefilename,bool outFullString=false)
            {
                try
                {
                    System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(Imagefilename);
 
                    MemoryStream ms = new MemoryStream();
                    //            bmp.Save(ms,ImageFormat.Jpeg)
                    System.Drawing.Imaging.ImageFormat iformat = System.Drawing.Imaging.ImageFormat.Jpeg;
                    string extension = System.IO.Path.GetExtension(Imagefilename).Replace(".", "").ToLower();
                    if (extension == "bmp")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Bmp;
                    }
                    else if (extension == "emf")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Emf;
                    }
                    else if (extension == "exif")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Exif;
                    }
                    else if (extension == "gif")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Gif;
                    }
                    else if (extension == "icon")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Icon;
                    }
                    else if (extension == "png")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Png;
                    }
                    else if (extension == "tiff")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Tiff;
                    }
                    else if (extension == "wmf")
                    {
                        iformat = System.Drawing.Imaging.ImageFormat.Wmf;
                    }
 
                    bmp.Save(ms, iformat);
                    byte[] arr = new byte[ms.Length];
                    ms.Position = 0;
                    ms.Read(arr, 0, (int)ms.Length);
                    ms.Close();
                    bmp.Dispose();
                    string rv=Convert.ToBase64String(arr);
                    if (outFullString == true)
                    {
                        rv = "data:image/" + extension + ";base64," + rv;
                    }
                    return rv;
                }
                catch (Exception ex)
                {
                    return null;
                }
            }

void Page_load(Object sender, EventArgs e){
 
    string path = "D:\\website\\test\\";
    string title="數(shù)據(jù)庫存儲過程從入門到精通";
    int baselen = title.Length;
    string x1_y1="0,0";
    string x2_y2="240,80";
 
    AddText(path + "bg.bmp", path + "bg2.jpg", baselen, x1_y1, x2_y2, title);
 
    Image1.ImageUrl = ImgToBase64String(path + "bg2.jpg", true);
 
}