DevExpress实现GridControl列头绘制Checkbox的方法

/// <summary>
/// 为列头绘制checkbox
/// </summary>
/// <param name="view">gridview</param>
/// <param name="checkitem">repositoryitemcheckedit</param>
/// <param name="fieldname">需要绘制checkbox的列名</param>
/// <param name="e">columnheadercustomdraweventargs</param>
public static void drawheadercheckbox(this gridview view, repositoryitemcheckedit checkitem, string fieldname, columnheadercustomdraweventargs e)
{
  /*说明：
   *参考：https://www.devexpress.com/support/center/question/details/q354489
   *在customdrawcolumnheader中使用
   *eg：
   * private void gvcabchdetail_customdrawcolumnheader(object sender, devexpress.xtragrid.views.grid.columnheadercustomdraweventargs e)
   * {
   * gridview _view = sender as gridview;
   * _view.drawheadercheckbox(checkitem, "check", e);
   * }
   */
  if (e.column != null && e.column.fieldname.equals(fieldname))
  {
 e.info.innerelements.clear();
 e.painter.drawobject(e.info);
 drawcheckbox(checkitem, e.graphics, e.bounds, getcheckedcount(view, fieldname) == view.datarowcount);
 e.handled = true;
  }
}
private static void drawcheckbox(repositoryitemcheckedit checkitem, graphics g, rectangle r, bool checked)
{
  checkeditviewinfo _info;
  checkeditpainter _painter;
  controlgraphicsinfoargs _args;
  _info = checkitem.createviewinfo() as checkeditviewinfo;
  _painter = checkitem.createpainter() as checkeditpainter;
  _info.editvalue = checked;

  _info.bounds = r;
  _info.paintappearance.forecolor = color.black;
  _info.calcviewinfo(g);
  _args = new controlgraphicsinfoargs(_info, new devexpress.utils.drawing.graphicscache(g), r);
  _painter.draw(_args);
  _args.cache.dispose();
}
private static int getcheckedcount(gridview view, string filedname)
{
  int count = 0;
  for (int i = 0; i < view.datarowcount; i++)
  {
 object _cellvalue = view.getrowcellvalue(i, view.columns[filedname]);
 if (_cellvalue == null) continue;
 if (string.isnullorempty(_cellvalue.tostring().trim())) continue;
 bool _checkstatus = false;
 if (bool.tryparse(_cellvalue.tostring(), out _checkstatus))
 {
   if (_checkstatus)
 count++;
 }
  }
  return count;
}

repositoryitemcheckedit checkitem = new repositoryitemcheckedit();
const string gccheckfieldname = "checked";
private void gvlampconfig_customdrawcolumnheader(object sender, columnheadercustomdraweventargs e)
{
  gridview _view = sender as gridview;
  _view.drawheadercheckbox(checkitem, gccheckfieldname, e);
}