Asp.Net 上傳圖片並產生高清晰縮圖

 　　不是很複雜，大概寫一下。目的只在於實現，未仔細按照標準什麼的來寫。其中參考了網上已經存在的代碼。

　　using System.Drawing;

　　頁面，如圖：

　　點擊提交按鈕：

代碼如下

httpPostedFile hpf = UploadImage.PostedFile; //取得檔案名稱(不含路徑) string Filename = Path.GetFileName(hpf.FileName);//原文修改 if (hpf.FileName.Length < 1) { Response.Write("請選擇您要上傳的圖片檔案"); return; } if (hpf.ContentType != "image/jpeg" && hpf.ContentType != "image/gif")//原文修改 { Response.Write("只允許上傳 GIF JPG類型的檔案"); return; } else { System.Text.StringBuilder sb = new System.Text.StringBuilder(); sb.Append(DateTime.Now.Year.ToString()); sb.Append(DateTime.Now.Month.ToString()); sb.Append(DateTime.Now.Day.ToString()); sb.Append(DateTime.Now.Hour.ToString()); sb.Append(DateTime.Now.Minute.ToString()); sb.Append(DateTime.Now.Second.ToString()); if (Filename.ToLower().EndsWith("gif")) { sb.Append(".gif"); } else if (Filename.ToLower().EndsWith("jpg")) { sb.Append(".jpg"); } else if (Filename.ToLower().EndsWith("jpeg")) { sb.Append(".jpeg"); } Filename = sb.ToString(); } // 儲存圖片到伺服器上 try { hpf.SaveAs(Server.MapPath("Album") + Filename);//自己修改! } catch (Exception ee) { Response.Write("上傳圖片失敗，原因" + ee.Message); return; } // 產生縮圖 //原始圖片名稱 string originalFilename = hpf.FileName; //產生的高品質圖片名稱 string strFile = Server.MapPath("AlbumSmall_")+ Filename; //從檔案取得圖片對象 System.Drawing.Image image = System.Drawing.Image.FromStream(hpf.InputStream, true); Double Width = Double.Parse(TextBox1.Text.Trim()); Double Height = Double.Parse(TextBox2.Text.Trim()); System.Double NewWidth, NewHeight; if (image.Width > image.Height) { NewWidth = Width; NewHeight = image.Height * (NewWidth / image.Width); } else { NewHeight = Height; NewWidth = (NewHeight / image.Height) * image.Width; } if (NewWidth > Width) { NewWidth = Width; } if (NewHeight > Height) { NewHeight = Height; } System.Drawing.Size size = new Size((int)NewWidth, (int)NewHeight); // 圖片大小 System.Drawing.Image bitmap = new System.Drawing.Bitmap(size.Width, size.Height); //建立bmp圖片 System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(bitmap); //建立畫板 graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //設定高品質插值法 graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //設定高品質,低速度呈現平滑程度 graphics.Clear(Color.White); //清空畫布 //在指定位置畫圖 graphics.DrawImage(image, new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), new System.Drawing.Rectangle(0, 0, image.Width, image.Height), System.Drawing.GraphicsUnit.Pixel); //文字浮水印 System.Drawing.Graphics textGraphics = System.Drawing.Graphics.FromImage(bitmap); System.Drawing.Font font = new Font("宋體", 10); System.Drawing.Brush brush = new SolidBrush(Color.Black); textGraphics.DrawString(TextBox3.Text.Trim(), font, brush, 10, 10); textGraphics.Dispose(); ///圖片浮水印 //System.Drawing.Image copyImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath("pic/1.gif")); //Graphics a = Graphics.FromImage(bitmap); //a.DrawImage(copyImage, new Rectangle(bitmap.Width-copyImage.Width,bitmap.Height-copyImage.Height,copyImage.Width, copyImage.Height),0,0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel); //copyImage.Dispose(); //a.Dispose(); //copyImage.Dispose(); //儲存縮圖 try { bitmap.Save(strFile, System.Drawing.Imaging.ImageFormat.Jpeg); } catch (Exception ex) { Response.Write("儲存縮圖失敗:" + ex.Message); } graphics.Dispose(); image.Dispose(); bitmap.Dispose();

　　整個實現的過程如下面的圖：

　　瀏覽頁面，選擇圖片：

　　點擊提交後，圖片以及縮圖都已經產生到了目標檔案夾裡面：

　　可以看到，縮圖裡面文字浮水印已經產生：

　　至此，整個功能已實現。