Question

我正在使用System.Timers.Timer每N秒获得一次PrintQueueCollection所以如果发生变化，我总是保持最新状态。计时器发送一个带有PrintQueue的RefreshEvent，这样我就可以处理我的Gui中的变化。

这是刷新功能，计时器每隔n秒调用

private void Refresh()
{
    lock (_locker)
    {
        try
        {
             // _server == ServerName if isNullOrEmppty it's localhost
            PrintServer printServer = new PrintServer(_server);
            PrintQueueCollection printQueueCollection = printServer.GetPrintQueues();

            foreach (PrintQueue pq in printQueueCollection)
            {
                if (_firstRun) break;

                // List of Unique Printernames so not all printers get 'refreshed'
                if (_printersToMonitor.Contains(pq.Name))
                {
                    var currentPrinter = new Printer(pq);
                    // Event catched in Gui
                    Refreshed?.Invoke(currentPrinter);
                }
            }
        }
        catch (Exception)
        {
            //...
        }
    }
}

事件以控制方式捕获

// Printer is a Wrapper class that contains the PrintQueue and several other information I need e.g. results of SNMP walks
private void RefreshPrinter(Printer printer)
{
    if (_localPrinters.Count == 0)
        Dispatcher.Invoke(() => _localPrinters.Add(printer));
    else
    {
        // _localPrinters is a ObservableCollection<Printer> Bound to gui
        foreach (Printer p in _localPrinters.ToList())
        {
            if (p.FullName == printer.FullName)
            {
                p.NumberOfJobs = printer.NumberOfJobs;
                p.Status = printer.Status;
                return;
            }
        }
        Dispatcher.Invoke(() => _localPrinters.Add(printer));
    }
}

到目前为止，现在非常好，我不知道如何处理。 ObservableCollection<Printer>绑定到DataGrid，显示所有常规信息。现在，如果用户双击一行，我想在userControl中显示一些“更深层”的信息。但是我找不到在这里访问PrintQueue的方法，因为它是错误的线程。

private void Row_DoubleClick(object sender, MouseButtonEventArgs e)
{
    // Printer is fine, just the PrintQueue inside is full of System.InvalidOperationException
    Printer p = (sender as DataGridRow)?.DataContext as Printer;
    UcPrinterDetails.InitializeDetails(p.PrintQueue);

    UcPrinterDetails.Visibility = UcPrinterDetails.Visibility != Visibility.Visible ? Visibility.Visible : Visibility.Collapsed;
}

所以我的问题是：访问PrintQueue对象的最佳方法是什么，以及哪个Thread是对象的所有者？

Answer 1

你不应该在不同的线程中使用对象（与Windows功能相关），然后创建它。在Row_DoubleClick函数中，只需再调用一次GetPrintQueues方法并找到您感兴趣的方法。

如何在GUI事件

1 个答案: