C#+ArcEngine 自定义范围输出为栅格图像(JPG/BMP)

///   <summary>
         ///  打印输出.该功能目前测试只适用于JPEG,BMP.格式
         ///   </summary>
         ///   <param name="pExport"></param>
         ///   <param name="dResolution"> 分辨率 </param>
         ///   <param name="outputPath"> 输出路径 </param>
         ///   <param name="pVisibleBounds"> 自定义可见区域 </param>
         private   void  FunExportImage(IExport pExport,  double  dResolution,  string  outputPath,IEnvelope pVisibleBounds)
        {
            IEnvelope pPixelBounds;
            ESRI.ArcGIS.Display.tagRECT outtagRECT;
            ESRI.ArcGIS.Display.tagRECT DisplayBounds  =  m_ActiveView.ExportFrame;
             double  iScreenResolution;
             if  (pExport  ==   null )
            {
                MessageBox.Show( " 打印类型未指定 " );
                 return ;
            }

             if (pVisibleBounds != null )  // 自定义框范围
            {
                IDisplayTransformation pDisplayTransformation  =  m_ActiveView.ScreenDisplay.DisplayTransformation;
                pDisplayTransformation.TransformRect(pVisibleBounds,  ref  DisplayBounds,  8 ); // 8代表esriDisplayTransformEnum.esriTransformToDevice
            }

             if  (pExport  is  IExportImage)
            {
                IExportImage pExportImage  =  pExport  as  IExportImage;
                pExportImage.ImageType  =  esriExportImageType.esriExportImageTypeTrueColor;
            }

            iScreenResolution  =  m_ActiveView.ScreenDisplay.DisplayTransformation.Resolution;
                      
             double  l_resolution  =  Convert.ToDouble(domainResolution.Value);

             // =====================================================================
             //
             // 方法一
             //
             // 一厘米包含37.79524个像素
             // double dPixel = 37.79524;
             /// /按照设置输入分辨率计算一厘米所含的像素数
             // double tempratio = l_resolution * dPixel / iScreenResolution;
             /// /输出图形的高度
             // double tempbottom = (DisplayBounds.bottom - DisplayBounds.top) * tempratio;
             /// /输出图形的宽度
             // double tempright = (DisplayBounds.right - DisplayBounds.left) * tempratio + 0.1 * tempratio;
             // ======================================================================
             //
             // 方法二:暂时可行.
             //
             double  tempratio  =  l_resolution  /  iScreenResolution;
             double  tempbottom  =  (DisplayBounds.bottom  -  DisplayBounds.top)  *  tempratio;
             double  tempright  =  (DisplayBounds.right  -  DisplayBounds.left)  *  tempratio;
             // =====================================================================
            outtagRECT.left  =   0 ;
            outtagRECT.top  =   0 ;
            outtagRECT.bottom  =  Convert.ToInt32(Math.Truncate(tempbottom));
            outtagRECT.right  =  Convert.ToInt32(Math.Truncate(tempright));

            pPixelBounds  =   new  EnvelopeClass();
            pPixelBounds.PutCoords(outtagRECT.left, outtagRECT.top, outtagRECT.right, outtagRECT.bottom);

            pExport.Resolution  =  dResolution;
            pExport.PixelBounds  =  pPixelBounds;
            pExport.ExportFileName  =  outputPath;

             try
            {
                ITrackCancel pTrackCancel  =   new  TrackCancelClass();
                 int  hDC;
                hDC  =  pExport.StartExporting();

                 if  (m_frmProBar  ==   null )  // m_frmProBar为进度条窗体
                    FunProgressBar();
                m_frmProBar.Show();

                m_ActiveView.Output(hDC, ( int )dResolution,  ref  outtagRECT, pVisibleBounds, pTrackCancel);
                pExport.FinishExporting();

                m_frmProBar.Hide();

                 if  (DialogResult.Yes  ==  MessageBox.Show( " 出图成功! \n图片保存在 "   +  txtOutPutPath.Text + " \n是否需要打开文件所在的目录？ " ,  " 提示 " , MessageBoxButtons.YesNo, MessageBoxIcon.Information))
                {
                    System.Diagnostics.Process.Start( " explorer.exe " , txtOutPutPath.Text); 
                }
                pExport.Cleanup();
            }
             catch
            {
                MessageBox.Show( " 出图失败! " , " 警告 " ,MessageBoxButtons.OK,MessageBoxIcon.Warning);
                 // 释放变量
                m_frmProBar  =   null ;
                pExport  =   null ;
                pVisibleBounds  =   null ;
            }
             // 释放变量
            pExport  =   null ;
            pVisibleBounds  =   null ;

        }