WPF: Textbox not firing onTextInput event

问题

So basically, I have a bunch of TextBoxes that the user gets to fill out. I've got a button that I want to keep disabled until all the TextBoxes have had text entered in them. Here is a sample XAML TextBox that I'm using:

<TextBox Name="DelayedRecallScore" TextInput="CheckTextBoxFilled" Width="24" />

And here is the function that I'm trying to trigger:

  //Disables the OK button until all score textboxes have content
    private void CheckTextBoxFilled(object sender, RoutedEventArgs e)
    {
        /*
        foreach (TextBox scorebox in TextBoxList)
        {
            if (string.IsNullOrEmpty(scorebox.Text))
            {
                Ok_Button.IsEnabled = false;
                return;
            }
        }
        Ok_Button.IsEnabled = true;
         */
        MessageBox.Show("THIS MAKES NO SENSE");
    }

The MessageBox is not showing up when TextInput should be getting triggered. As an experiment I tried triggering CheckTextBoxFilled() on PreviewTextInput, and it worked fine then, meaning that for whatever reason, the function just isn't getting called. I also have a validation function that is triggered by PreviewTextInput, which works as it should. At first I thought PreviewTextInput might somehow be interfering with TextInput, so I took PreviewTextInput off the TextBox, but that hasn't managed to fix anything. I'm completely befuddled by why this might happen, so any help would be appreciated.

回答1:

Your handler for the TextInput event is not fired because the TextBox is handling the event. You could try using the TextChanged event instead, since really you just want to know when characters were added or removed from the TextBox.

回答2:

InitializeComponent();
textbox.AddHandler(TextBox.TextInputEvent, 
                   new TextCompositionEventHandler(TextBox_TextInput_1), 
                   true);

回答3:

Use "PreviewTextInput" instead, it will work.

回答4:

Create a new class derived from TextBox. In the new class override the OnTextInput method. Your OnTextInput method will get called before the TextBox gets it.

来源：https://stackoverflow.com/questions/1374710/wpf-textbox-not-firing-ontextinput-event

标签

wpf

events

textbox

textinput