区分由用户输入Vs触发的事件。 UWP背后的代码

Question

I have a CheckBox in a UWP app that is manipulated by both the user and code behind. When the user checks it, I do want the Checked event to fire. However, when the code behind checks it (like below), I don't want it to fire.

checkBoxExample.isChecked = true; //The Checked event should not fire.

I figured I would get this information from either the sender (object) or e (RoutedEventArgs) but it isn't there.

Answer 1

You could just add a flag that you then set to avoid processing the event:

private bool _checkedFromCode = false;

private void CheckboxChecked(object sender, RoutedEventArgs e)
{
    if ( !_checkedFromCode )
    {
        //your logic
    }
}

Now when setting the IsChecked from code:

_checkedFromCode = true;
checkBoxExample.IsChecked = true;
_checkedFromCode = false;

The event will still fire, but you can limit the processing to only when it actually is from the user interaction.

Alternatively, you could create a custom derived version of CheckBox that would have a custom event only for this scenario.

RE: Tapped event : The suggested solution with Tapped event would not work as you should not presume the user is using touch, mouse or pen, as Windows 10 works with any kind of input, so the only reliable event is the Checked event. It should not matter which input type you use. This is especially true to make your app accessible and inclusive. Keyboard, for example, does not cause Tapped event.