键盘事件无法正常运行

Question

I have created a game which works fine but I have a problem with the key commands part. When I click somewhere on the screen my KeyDown event does not work. I guessed that the control which has the event handler for KeyDown loses the focus and my application was not getting the message. I have spent one week trying to solve the problem.

I tried to set the KeyDown event for more controls. I also tried to set the focus of the control which handles the events without success.

I would appreciate if someone tell me what is the right way of handling the key press collection in my game which will work whatever happens in my application. I just want to know when the user pressed the arrow keys in order to change the contents.

Answer 1

我只是遇到了类似的问题，但是随后我在LayoutAwarePage.CoreDispatcher_AcceleratorKeyActivated中迷上了他们的工作方式，它似乎按预期工作了。

Answer 2

I am not sure about WinRT but in WPF, you can catch routed events from all child controls by adding a handler like this.

this.AddHandler(UIElement.PreviewKeyDownEvent, new RoutedEventHandler(OnKeyDown), true);

Where this is parent control. It could work for WinRT too, please try

EDIT

replace UIElement.PreviewKeyDownEvent with UIElement.KeyDownEvent if UIElement.PreviewKeyDownEvent doesn't exists in WinRT

Answer 3

I did not answered earlier because the system did not allow me to make it because I did not have 10 reputation points so I had to wait 8 hours.

This is what I typed but it seems that it needs to declare something there that I do not know how to make it.

this.AddHandler(UIElement.KeyUpEvent, new RoutedEventHandler(KeyUp), true);

The error message is

Delegate Windows.UI.Xaml.RoutedEventHandler Represents the method that will handle routed events. Error: No overload for 'KeyUp' matches delegate 'Windows.UI.Xaml.RoutedEventHandler.

The function which will work as event handler has the following format:

private void KeyUp(object sender, KeyRoutedEventArgs e)
{
}

I found a way to bypass my problem and I would like to share it with you just in case someone else needs it but if someone else knows a better way to make let me know.

I placed a button out of the visible area of the page and I used it's KeyUp event and I wrote code to make sure that it is always active. Below you can find my code.

public frmMain()
{
    this.InitializeComponent();

    btnKeboardCollector.Loaded += MyBoard_Loaded;
    btnKeboardCollector.LostFocus += btnKeboardCollector_LostFocus;
    btnKeboardCollector.KeyUp += KeyUpHandler;
}

void MyBoard_Loaded(object sender, RoutedEventArgs e)
{
    // I do other initialization here

    btnKeboardCollector.Focus(Windows.UI.Xaml.FocusState.Programmatic);
}

void btnKeboardCollector_LostFocus(object sender, RoutedEventArgs e)
{
    btnKeboardCollector.Focus(Windows.UI.Xaml.FocusState.Programmatic);
}

private void KeyUpHandler(object sender, KeyRoutedEventArgs e)
{
}

Answer 4

I've just found a very straight forward solution to this. It always works, whether an element is focused or not.

1st: the function

private void onAcceleratorKey(object sender, AcceleratorKeyEventArgs e)
{
    CoreVirtualKeyStates ctrl = Window.Current.CoreWindow.GetAsyncKeyState(VirtualKey.Control);

    if (ctrl == CoreVirtualKeyStates.Down)
    {
        switch (e.VirtualKey)
        {
            case VirtualKey.F:
                // CTRL + F pressed.
                break;
        }
    }
}

2nd: the event

Window.Current.CoreWindow.Dispatcher.AcceleratorKeyActivated += onAcceleratorKey;