XAML Binding with Delay and KeyBinding-CodePudding

I have this XAML code that works like a charm:

<TextBox Text="{Binding MyTextProperty, UpdateSourceTrigger=PropertyChanged}">
    <TextBox.InputBindings>
        <KeyBinding Command="{Binding MyOwnCommand}" CommandParameter="{Binding MyTextProperty}" Key="Enter" />
    </TextBox.InputBindings>
</TextBox>

There I have MyTextProperty that is passed as parameter to MyOwnCommand when I press enter key.

I do not want MyTextProperty updates every time I type a letter (because it has some logic asociated), but I do want it executes once I finish typing (without pressing enter key or losing the focus). The ideal solution would be this:

<TextBox Text="{Binding MyTextProperty, UpdateSourceTrigger=PropertyChanged, Delay=400}">
    <TextBox.InputBindings>
        <KeyBinding Command="{Binding MyOwnCommand}" CommandParameter="{Binding MyTextProperty}" Key="Enter" />
    </TextBox.InputBindings>
</TextBox>

The point here is the "Delay=400" parameter. It waits until I finish typing and then updates MyTextProperty.

But the problem I found at this point is that if I type something and immediately press enter, MyOwnCommand is called but MyTextProperty is not updated yet (it will be updated 400ms later).

I have tried to add the same delay in CommandParameter="{Binding MyTextProperty, Delay=400}", but it does not work.

What is the right approach to pass the CommandParameter once MyTextProperty has been updated?

CodePudding user response：

TextBox.Text changes immediately after user types symbol from keyboard, even if there is a delay to send value to bound property. So you can bind CommandParameter to TextBox.Text directly:

<TextBox Name="MyTextBox" 
         Text="{Binding MyTextProperty, UpdateSourceTrigger=PropertyChanged, Delay=400}">
    <TextBox.InputBindings>
        <KeyBinding Command="{Binding MyOwnCommand}" 
                    CommandParameter="{Binding Text, ElementName=MyTextBox}" 
                    Key="Enter" />
    </TextBox.InputBindings>
</TextBox>

CodePudding user response：

but I do want it executes once I finish typing

I would split out this property into different properties. Then only have the enter Command extract the final value, set in the final property and excecute the final step.


// bound to the active textbox, which receives character by character changes
public string MyTextProperty { get { ... } 
                               set { ...do individual key press logic here... }

public string MyTextProperty_Final  { }

public void EnterCommand()
{
  MyTextProperty_Final = MyTextProperty;
  FinalOperationCommand(MyTextProperty_Final); // Or FinalOperationCommand.Invoke(MyTextProperty_Final);
}

public void FinalOperationCommand(string text)
{
   ... delay if needed ...
   ... Do stuff with MyTextProperty_Final
}