解决C#打印设置控件页面边距值变化问题

protected virtual PageSettings ShowPageSetupDialog(PrintDocument printDocument)
        {
            //检查printDocument是否为空，空的话抛出异常
            ThrowPrintDocumentNullException(printDocument);

            //声明返回值的PageSettings
            PageSettings ps = new PageSettings();

            //申明并实例化PageSetupDialog
            PageSetupDialog psDlg = new PageSetupDialog();

            ps = printDocument.DefaultPageSettings;

            try
            {
                //相关文档及文档页面默认设置
                psDlg.Document = printDocument;

                Margins mg = printDocument.DefaultPageSettings.Margins;
                if (System.Globalization.RegionInfo.CurrentRegion.IsMetric)
                {
                    mg = PrinterUnitConvert.Convert(mg, PrinterUnit.Display, PrinterUnit.TenthsOfAMillimeter);
                }

                //备份打印文档的DefaultPageSettings，因为转换后会改变，而设置对话框单击取消按钮后不还原就不能正确显示原来的值
                PageSettings psPrintDocumentBack = (PageSettings)(printDocument.DefaultPageSettings.Clone());

                psDlg.PageSettings = psPrintDocumentBack;//printDocument.DefaultPageSettings; //用printDocument的时取消了对话框就要还原
                psDlg.PageSettings.Margins = mg;


                //显示对话框
                DialogResult result = psDlg.ShowDialog();
                if (result == DialogResult.OK)
                {
                    ps = psDlg.PageSettings;
                    printDocument.DefaultPageSettings = psDlg.PageSettings;
                }
                else
                {

                }


            }
            catch (System.Drawing.Printing.InvalidPrinterException e)
            {
                ShowInvalidPrinterException(e);
            }
            catch (Exception ex)
            {
                ShowPrinterException(ex);
            }
            finally
            {
                psDlg.Dispose();
                psDlg = null;
            }

            return ps;
}