你可以从另一个线程访问UI元素？ （得到未设置） [英] Can you access UI elements from another thread? (get not set)

问题描述

我看到了很多关于谷歌的线程/这里从另一个线程更新UI元素。

I see a lot of threads on google/here on UPDATING a UI element from another thread.

如果我只想得到一个复选框的值是什么？

What if I want to just get the value of a checkbox?

我是能够做到这一点，而不必做什么特别？

Am I able to do this without having to do anything special?

推荐答案

修改：看来我要收回我之前写的。试过如下：

Edit: It seems I have to take back what I wrote before. Tried the following:

增加了一个名为文本框 myTextBox 并试图检索文本属性的值：

Added a textbox called myTextBox and tried to retrieve the value of the Text property:

Thread t = new Thread(
    o =>
    {
        Thread.Sleep(2000);                    
        string value = myTextBox.Text;
        Thread.Sleep(2000);
    });
t.Start();

和似乎在应用程序（WPF）2秒钟后崩溃。使用调度工作：

And it seems that the app (WPF) crashes after 2 seconds. Using the dispatcher works:

Thread t = new Thread(
    o =>
    {
        Thread.Sleep(2000);
        myTextBox.Dispatcher.BeginInvoke(
            (Action)(() => { string value = myTextBox.Text; }));
        Thread.Sleep(2000);
    });
t.Start();

因此，你仍然需要从GUI组件，至少在WPF读值时，要经过调度线程。

二修改：这变得更好。显然，重复经典的WinForms实验表明，它的作品读文本属性，而不使用调用/的BeginInvoke 。有趣的是，似乎还设置属性工作正常（无调用），虽然我敢打赌它不是线程安全和应用程序不抱怨的某些原因。

Second edit: This gets better. Apparently repeating the experiment for classic WinForms reveals that it works to read the Text property without using Invoke/BeginInvoke. Interestingly enough, it seems that also setting the property works fine (without invoke), although I'll wager it's not thread safe and the app doesn't complain for some reason.

底线：这是在任何情况下与其他线程的GUI组件进行交互时使用的调度是一个好主意，因为它确保了读/写操作序列化到一个单独的线程，所以你有没有线程安全问题。

Bottom line: It's a good idea in any case to use the dispatcher when interacting with GUI components from other threads, as it ensures the reads/writes are serialized to a single thread and so you have no thread-safety issues.

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