代码实现IMapcontrol当前视图输出为图片功能

 SaveFileDialog dialog = new SaveFileDialog();
             dialog.Title = "保存输出图片";
             dialog.Filter = "JPG文件(*.jpg)|*.jpg|BMP文件(*.bmp)|*.bmp||";
             if (dialog.ShowDialog() == DialogResult.OK)
             {
                 tagRECT grect;
                 string str = System.IO.Path.GetExtension(dialog.FileName).ToLower();
                 IExport export = null;
                 if (str == ".jpg")
                 {
                     export = new ExportJPEGClass();
                 }
                 else
                 {
                     export = new ExportBMPClass();
                 }
                 export.ExportFileName = dialog.FileName;
                 int num = 0x60;
                 int num2 = ;
                 export.Resolution = num2;
                 grect.left = ;
                 grect.top = ;
                 tagRECT deviceFrame = this.m_pMapControl.ActiveView.ScreenDisplay.DisplayTransformation.get_DeviceFrame();//.DeviceFrame;
                 grect.right = (int) (((deviceFrame.right - deviceFrame.left) * num2) / ((double) num));
                 grect.bottom = (int) (((deviceFrame.bottom - deviceFrame.top) * num2) / ((double) num));
                 IEnvelope envelope = new EnvelopeClass();
                 envelope.PutCoords((double) grect.left, (double) grect.top, (double) grect.right, (double) grect.bottom);
                 export.PixelBounds = envelope;
                 int hdc = export.StartExporting();
                 double resolution = export.Resolution;
                 this.m_pMapControl.ActiveView.Output(hdc, (int) resolution, ref grect, null, null);
                 export.FinishExporting();
                 export.Cleanup();
             }