实现在arcengine中导出图片的功能

1. private void outPictureToolStripMenuItem_Click(object sender, EventArgs e)
           {
               saveFileDialog1.Title = "导出地图成JPEG图片";
               saveFileDialog1.Filter = "图片文件(*.bmp)|*.bmp|图片文件(*.jpeg)|*.jpeg|图片文件(*.gif)|*.gif";
   
               if (saveFileDialog1.ShowDialog() == DialogResult.OK)
               {
                   IExport pExport = null;
                   switch (saveFileDialog1.FilterIndex)
                   {
                       case 1:
                           pExport=new ExportBMPClass();
                           break;
                       case 2:
                           pExport=new ExportJPEGClass();
                           break;
                       case 3:
                           pExport=new ExportTIFFClass();
                           break;
                       default:
                           break;
                   }
   
                   pExport.ExportFileName= saveFileDialog1.FileName;
                 //default resolution
                   int reslution = 96;
                   pExport.Resolution = reslution;
                   //get export's extend
                   tagRECT exportRect = axMapControl1.ActiveView.ExportFrame;
                   IEnvelope Env = new EnvelopeClass();
                   Env.PutCoords(exportRect.left, exportRect.top, exportRect.right, exportRect.bottom);
                   pExport.PixelBounds = Env;
                   //begin to export,get DC
                   int hDC = pExport.StartExporting();
   
   
                   axMapControl1.ActiveView.Output(hDC, reslution, ref exportRect, null, null);
                   pExport.FinishExporting();
                   pExport.Cleanup();
               }