工作者线程可以在GUI中读取控件吗?

问题描述

我每隔几秒钟运行一个线程，从数据库中获取一些数据但这是基于列表框和几个复选框的选择...不使用GUI线程就可以读取这些控件的值吗?

I got a thread running every few seconds fetching some data from a dbbut this is based on the selection on a listbox and on a few checkboxes...can I read the values of these controls without using the GUI thread?

只要其中一个控件发生更改，也会读取数据，但是数据可能会在db中更改没有警告...因此线程每隔几秒钟运行一次.

The data is also read whenever one of the controls change, but the data might change in dbwithout warning...hence the thread running every few seconds.

我正在使用WPF C#

I'm working with wpf C#

推荐答案

总之，没有.控件只能由创建它们的线程访问.

In short, no. Controls can only be accessed by the thread that created them.

亲自证明:

<Window x:Class="ReadControlsBackground.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        Height="350"
        Width="525">
    <StackPanel>
        <Button x:Name="Start"
                Click="Button_Click"
                Content="Start" />
        <ListBox x:Name="List">
            <ListBoxItem>One</ListBoxItem>
            <ListBoxItem>Two</ListBoxItem>
        </ListBox>
        <CheckBox x:Name="Check" />
    </StackPanel>
</Window>



using System;
using System.Diagnostics;
using System.Threading;
using System.Windows;

namespace ReadControlsBackground {
    /// <summary>
    ///   Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window {
        public MainWindow() {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e) {
            Start.IsEnabled = false;
            var t = new Thread(Poll);
            t.Start();
        }

        private void Poll() {
            while (true) {
                Debug.WriteLine(String.Format("List: {0}", List.SelectedValue));
                Debug.WriteLine(String.Format("Check: {0}", Check.IsChecked));
                Thread.Sleep(5000);
            }
        }
    }
}

改为执行以下操作:

private void Poll() {
    while (true) {
        var selected = (String) Dispatcher.Invoke((Func<String>) (() => (List.SelectedValue ?? "?").ToString()));
        var isChecked = (Boolean?) Dispatcher.Invoke((Func<Boolean?>) (() => Check.IsChecked));
        Debug.WriteLine(String.Format("List: {0}", selected));
        Debug.WriteLine(String.Format("Check: {0}", isChecked));
        Thread.Sleep(5000);
    }
}

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