如何指定范围保存jpg?

• 回答：

         private void WriteJpg()
          {
            
  
              SaveFileDialog sfd = new SaveFileDialog();
              sfd.Filter = "jpg 文件(*.jpg)|*.jpg";
  
              if (sfd.ShowDialog() != DialogResult.OK)
              {
                  return;
              }
  
              MxDrawUiPrPoint getpoint = new MxDrawUiPrPoint();
              getpoint.message = "选择范围第一个点";
              if (getpoint.go() != MCAD_McUiPrStatus.mcOk)
              {
                  return;
              }
  
              MxDrawResbuf param = new MxDrawResbuf();
             
              param.AddDouble(getpoint.value().x);
              param.AddDouble(getpoint.value().y);
  
              MxDrawResbuf retParam = (MxDrawResbuf)axMxDrawX1.CallEx("Mx_GetCorner", param);
  
              if (retParam.AtString(0) != "Ok")
              {
                  
                  return;
                  
              }
  
              MxDrawResbuf savejpgParam = new MxDrawResbuf();
              savejpgParam.AddString(sfd.FileName);
              savejpgParam.AddDouble(getpoint.value().x);
              savejpgParam.AddDouble(getpoint.value().y);
  
              savejpgParam.AddDouble(retParam.AtDouble(1));
              savejpgParam.AddDouble(retParam.AtDouble(2));
  
              // jpg文件的宽高.
              savejpgParam.AddLong(500);
              savejpgParam.AddLong(500);
  
              MxDrawResbuf ret = (MxDrawResbuf)axMxDrawX1.CallEx("Mx_DrawToJpg", savejpgParam);
  
              if(ret != null && ret.AtString(0)== "Ok")
              {
                  MessageBox.Show("输出jpg文件成功");
              }
  
          }