1、由于网络安全性，所以不能再网络图片上写字，首先进行图片下载，然后在本地进行写字
具体调用代码如下：
Dictionary<string, string> dic_User = new Dictionary<string, string>(); dic_User.Add("input", "" + ds.Tables[0].Rows[0]["surname"] + ds.Tables[0].Rows[0]["userName"] + "");//当前接收发证人的姓名 dic_User.Add("x", "600"); dic_User.Add("y", "700"); dic_User.Add("middle", "true");//是否居中显示 true 居中 false 不居中 Dictionary<string, string> dic_CourseName = new Dictionary<string, string>(); dic_CourseName.Add("input", "" + ds.Tables[0].Rows[0]["courseName"] + "");//课程名称 dic_CourseName.Add("x", "600"); dic_CourseName.Add("y", "900"); dic_CourseName.Add("middle", "true");//是否居中显示 true 居中 false 不居中 Dictionary<string, string> dic_Time = new Dictionary<string, string>(); dic_Time.Add("input", "" + Convert.ToDateTime(ds.Tables[0].Rows[0]["StartTime"]).ToString("yyyy.MM.dd") + "-" + Convert.ToDateTime(ds.Tables[0].Rows[0]["EndTime"]).ToString("yyyy.MM.dd") + "");//证书有效期 dic_Time.Add("x", "600"); dic_Time.Add("y", "1200"); dic_Time.Add("middle", "true");//是否居中显示 true 居中 false 不居中 Dictionary<string, string> dic_teacher = new Dictionary<string, string>(); //学员讲师 dic_teacher.Add("input", "" + ds.Tables[0].Rows[0]["teacher"] + ""); dic_teacher.Add("x", "400"); dic_teacher.Add("y", "1500"); dic_teacher.Add("middle", "flase");//是否居中显示 true 居中 false 不居中 List<Dictionary<string, string>> listdict = new List<Dictionary<string, string>>(); listdict.Add(dic_User); listdict.Add(dic_CourseName); listdict.Add(dic_Time); listdict.Add(dic_teacher); BuildImage.CreateImgage(listdict, Color.Black, ConfigurationManager.AppSettings["examfile"].ToString() + ds.Tables[0].Rows[0]["Url"], tid); ImagePrint.ImageUrl = "tempPic/" + tid + ".jpg";
具体实现代码：
using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Drawing; using System.Drawing.Imaging; using System.IO; using System.Drawing.Drawing2D; using System.Net; namespace ELearning.ELearning.Common { /// <summary> /// 图片提供程序 /// create by gaoxing /// 2013-06-09 /// </summary> public static class ImageProvider { private static BuildImage buildImage = null; /// <summary> /// 生成图片 /// create by gaoxing /// 2013-06-09 /// </summary> public static BuildImage Provider { get { if (buildImage == null) { buildImage = new BuildImage(); } return buildImage; } } } public class BuildImage { private static Matrix m = new Matrix(); // 定义字体 private static Font[] fonts = { new Font(new FontFamily("Times New Roman"), 18, FontStyle.Bold), new Font(new FontFamily("Georgia"), 18 , FontStyle.Bold), new Font(new FontFamily("Helvetica"), 18, FontStyle.Bold), new Font(new FontFamily("Arial"), 18 , FontStyle.Bold) }; /// <summary> /// 生成图片 /// create by gaoxing 2013-06-09 /// </summary> /// <param name="str">传入字符串</param> /// <param name="bgImg">当前图片对象</param> /// <param name="x">X坐标</param> /// <param name="y">Y坐标</param> /// <param name="color">当前字体颜色</param> /// <param name="middle">是否居中显示 true 居中显示 false 不居中显示</param> /// <returns></returns> private ImageInfo GenerateImage(string str, System.Drawing.Image bgImg, float x, float y, Color color, object middle) { ImageInfo imageInfo = new ImageInfo(); imageInfo.ImageFormat = ImageFormat.Jpeg; imageInfo.ContentType = "image/pjpeg"; Bitmap bitmap = new Bitmap(bgImg, bgImg.Width, bgImg.Height); Graphics g = Graphics.FromImage(bitmap); //是否居中显示 if (middle != null) { if (middle.ToString() == "true") { //设置X坐标 x = SetX(str, x, bitmap, g); } } // 定义前景色 字体颜色 SolidBrush drawBrush = new SolidBrush(color); // 写字 g.DrawString(str, fonts[3], drawBrush, new PointF(x, y)); GetStringLength(str, g); g.ResetTransform(); drawBrush.Dispose(); g.Dispose(); g.Dispose(); imageInfo.Image = bitmap; return imageInfo; } /// <summary> /// 设置X坐标（居中显示） /// create by gaoxing /// </summary> /// <param name="str">当前要显示的字符串</param> /// <param name="x">X坐标</param> /// <param name="bitmap">当前的图片对象</param> /// <param name="g">当前的图形对象</param> /// <returns>更新后的X</returns> private static float SetX(string str, float x, Bitmap bitmap, Graphics g) { /////////////////////计算字符串的长度///////////////////////// Graphics tmpG = g; SizeF size = tmpG.MeasureString(str, fonts[3]); float length = size.Width; ////////////////////////////////////////////// //计算当前字符串的长度 //计算当前字符串的起始像素 float piclength = bitmap.Width; x = (piclength / 2) - (length / 2)-25; return x; } /// <summary> /// 获取当前字符串的像素长度 /// create by gaoxing /// </summary> /// <param name="str">输入字符串</param> /// <param name="g"></param> private static float GetStringLength(string str, Graphics g) { /////////////////////计算字符串的长度///////////////////////// Graphics tmpG = g; SizeF size = tmpG.MeasureString(str, fonts[3]); float StringWidth = size.Width; return StringWidth; ////////////////////////////////////////////// } /// <summary> /// 下载文件 /// create by 高兴 /// 2013-06-09 /// </summary> /// <param name="uriString">网络路径地址</param> /// <param name="id">当前Id</param> /// <returns></returns> private static string DownLoadFile(string uriString, string id) { Uri address = new Uri(uriString); string fileName = HttpContext.Current.Server.MapPath("TempPic") + @"\" + id + "Model.jpg"; using (WebClient wc = new WebClient()) { try { wc.DownloadFile(address, fileName); } catch { } return fileName; } } /// <summary> /// 生成图片，主方法调用 /// 传入数据集合 /// 每个字典为一组输入数据 /// key=input:要打印的字符 /// key=x X坐标 /// key=y X坐标 /// Create by gaoxing /// 2013-06-09 /// </summary> /// <param name="listdict">集合数据</param> /// <param name="color">当前字体颜色</param> /// <param name="ImgUrl">图片网络路径</param> /// <param name="imgId">图片Id</param> /// <returns></returns> public static void CreateImgage(List<Dictionary<string, string>> listdict, Color color, string ImgUrl, string imgId) { ////更改Http头 //HttpContext.Current.Response.ClearContent(); //HttpContext.Current.Response.ContentType = "image/pjpeg"; //HttpContext.Current.Response.BinaryWrite(BuildImage.GetImage(listdict, color, BuildImage.DownLoadFile(ImgUrl, imgId)).ToArray()); //HttpContext.Current.Response.End(); string fileName = HttpContext.Current.Server.MapPath("TempPic") + "/" + imgId + ".jpg"; using (MemoryStream ms = new MemoryStream(BuildImage.GetImage(listdict, color, BuildImage.DownLoadFile(ImgUrl, imgId)).ToArray())) { Image image = new Bitmap(ms, true); if (File.Exists(fileName)) { File.Delete(fileName); } image.Save(fileName); } } /// <summary> /// 传入数据集合 /// 每个字典为一组输入数据 /// key=input:要打印的字符 /// key=x X坐标 /// key=y X坐标 /// Create by gaoxing /// 2013-06-09 /// </summary> /// <param name="listdict">集合数据</param> /// <param name="color">当前字体颜色</param> /// <param name="imgPath">图片路径</param> /// <returns></returns> private static MemoryStream GetImage(List<Dictionary<string, string>> listdict, Color color, string imgPath) { BuildImage buildImage = ImageProvider.Provider; ImageInfo imageInfo = new ImageInfo(); using (MemoryStream ms = new MemoryStream()) { int i = 0; foreach (Dictionary<string, string> dic in listdict) { if (i < 1) { imageInfo = buildImage.GenerateImage(dic["input"].ToString(), System.Drawing.Image.FromFile(imgPath), float.Parse(dic["x"].ToString()), float.Parse(dic["y"].ToString()), color, dic["middle"].ToString()); } else { imageInfo = buildImage.GenerateImage(dic["input"].ToString(), imageInfo.Image, float.Parse(dic["x"].ToString()), float.Parse(dic["y"].ToString()), color, dic["middle"].ToString()); } i++; } long with = System.Drawing.Image.FromFile(imgPath).Width; imageInfo.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); return ms; } } } /// <summary> /// 图片信息 /// create by gaoxing /// 2013-06-09 /// </summary> public class ImageInfo { private Bitmap image; private string contentType = "image/pjpeg"; private ImageFormat imageFormat = ImageFormat.Jpeg; /// <summary> /// 生成的图片 /// </summary> public Bitmap Image { get { return image; } set { image = value; } } /// <summary> /// 图片类型，如 image/pjpeg /// </summary> public string ContentType { get { return contentType; } set { contentType = value; } } /// <summary> /// 图片格式 /// </summary> public ImageFormat ImageFormat { get { return imageFormat; } set { imageFormat = value; } } } }
