当用户开始输入时自动激活文本框

问题描述：

我想在用户开始在我的 Windows 8.1 Store 应用中输入时激活一个文本框.

I want to activate a textbox when users starts typing in my Windows 8.1 Store app.

我尝试处理 Page 的 KeyDown 事件，类似于以下代码:

I tried handling KeyDown event of Page, something like this code:

    private void pageRoot_KeyDown(object sender, KeyRoutedEventArgs e)
    {
        if (SearchBox.FocusState == Windows.UI.Xaml.FocusState.Unfocused)
        {
            string pressedKey = e.Key.ToString();
            SearchBox.Text = pressedKey;
            SearchBox.Focus(Windows.UI.Xaml.FocusState.Keyboard);
        }
    }

但问题是 e.Key.ToString() 总是返回按下键的大写英文字符，而用户可能正在用另一种语言输入.例如，Key D 在波斯语键盘中输入 ی，用户可能想输入波斯语，但 e.Key.ToString()仍将返回 D 而不是 ی.

But the problem is e.Key.ToString() always returns capital english character of the pressed key, while user might be typing in another language. For example, the Key D types ی in Persian keyboard, and user might want to type in Persian, but e.Key.ToString() will still return D instead of ی.

我还尝试使该文本框始终处于焦点(我的页面包含一些网格视图等，以及一个文本框)，虽然此解决方案适用于 PC，但它使屏幕键盘始终显示在平板电脑上.

Also I tried making that textbox always focused (my page contains some gridviews and so on, and a textbox) and while this solution works on PCs, it makes the on-screen keyboard to always appear on tablets.

那我该怎么办?有没有办法在 KeyDown 事件中获得准确的输入字符?

So, what should I do? Is there any way to get the exact typed character in KeyDown event?

答

正如 Mark Hall 所建议的那样，CoreWindow.CharacterReceived 事件可以帮助解决这个问题.

As Mark Hall suggested, It seemed that CoreWindow.CharacterReceived event can help solving this issue.

所以，我在这里找到了最终答案.

So, I found the final answer here.

这是来自该链接的代码:

This is the code from that link:

public Foo()
{
    this.InitializeComponent();
    Window.Current.CoreWindow.CharacterReceived += KeyPress;
}

void KeyPress(CoreWindow sender, CharacterReceivedEventArgs args)
{
    args.Handled = true;
    Debug.WriteLine("KeyPress " + Convert.ToChar(args.KeyCode));
    return;
}

但是此事件将在与当前活动页面无关的任何地方触发.因此，当用户导航到另一个页面时，我必须删除该事件，并在用户返回时再次添加它.

But this event will fire anywhere independent of current active page. So I must remove that event when user navigates to another page, and add it again when user comes back.

更新:我还必须将文本框的光标移动到文本的末尾，以便用户可以自然地书写.这是我的最终代码:

Update: I also had to move the cursor of the textbox to the end of the text, so user can write naturally. Here's my final code:

private void KeyPress(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.CharacterReceivedEventArgs args)
{
    if (SearchBox.FocusState == Windows.UI.Xaml.FocusState.Unfocused)
    {
        SearchBox.Text = Convert.ToChar(args.KeyCode).ToString();
        SearchBox.SelectionStart = SearchBox.Text.Length;
        SearchBox.SelectionLength = 0;
        SearchBox.Focus(FocusState.Programmatic);

    }
}

private void pageRoot_GotFocus(object sender, RoutedEventArgs e)
{
    Window.Current.CoreWindow.CharacterReceived += KeyPress;
}

private void pageRoot_LostFocus(object sender, RoutedEventArgs e)
{
    Window.Current.CoreWindow.CharacterReceived -= KeyPress;
}

当用户开始输入时自动激活文本框

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