C#儲存圖檔-小畫家3

儲存圖檔之前要先知道要儲存的檔案格式(BMP JPG GIF PNG)
而儲存圖檔的方式也很簡單，只要對BitMap 物件作Save 就可以
因為之前我們的範例都是使用BitMap 當作PictureBox的 Buffer
現在只要對Buffer 做SAVE就是把PICTUER 的圖形做儲存，
得知現在儲存的圖形格式有兩種方式，第一個方式是 對話方塊的過慮器

           saveFileDialog1.Filter = "逼恩批|*.bmp|傑批居|*.jpg|批恩居|*.png"; //檔案過濾器  
          saveFileDialog1.InitialDirectory = Application.StartupPath;   //程式啟動路徑，為預設路徑
          saveFileDialog1.FileName = "";                              //清除預設檔名
          saveFileDialog1.ShowDialog();                                    //顯示對話方塊

          if (openFileDialog1.FileName.Equals(""))
          {
              MessageBox.Show("取消選取");
          }
          else
          {
              switch (saveFileDialog1.FilterIndex)
               {
                   case 1:
                       buffer.Save(saveFileDialog1.FileName , System.Drawing.Imaging.ImageFormat.Bmp);
                       break;
                   case 2:
                       buffer.Save(saveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Jpeg );
                       break;
                   case 3:
                       buffer.Save(saveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Gif );
                       break;
                   default:
                       break;
              }
          }

第二種方式，取出字串
再由字串比對

saveFileDialog1.Filter = "逼恩批|*.bmp|傑批居|*.jpg|批恩居|*.png"; //檔案過濾器  
           saveFileDialog1.InitialDirectory = Application.StartupPath;   //程式啟動路徑，為預設路徑
           saveFileDialog1.FileName = "";                              //清除預設檔名
           saveFileDialog1.ShowDialog();                                    //顯示對話方塊

           if (openFileDialog1.FileName.Equals(""))
           {
               MessageBox.Show("取消選取");
           }
           else
           {
               switch (saveFileDialog1.FileName.Substring(saveFileDialog1.FileName.Length - 3, 3).ToUpper())
               {
                   case "BMP":
                       buffer.Save(saveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Bmp);
                   break;
                   case "JPG":
                       buffer.Save(saveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Jpeg);
                   break;
                   case "GIF":
                       buffer.Save(saveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Gif );
                   break;
                   case "PNG":
                       buffer.Save(saveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Png );
                   break;
                   default:
                       MessageBox.Show ("錯誤檔名");
                   break;
               }
           }看起來是第一種寫法比較好，第二種寫法單存練習，如何取出最後三個字元，然後將其大寫