Conditional prevention of the textbox change

Question

I have a TextBox, and a TextBlock within the Border. The TextBlock's Text property is bound to TextBox's value. When I type into the TextBox, the Border changes its width according to the TextBlock's new size.

There is an event handler for TextBox.TextChanged in which I test whether the size of the border exceeds a certain number. If it does, I want to prevent the TextBox from making the change that caused the handler.

If a character was always added to an end, I would be able just to substring the text, but all other sorts of changing can occur, for example pasting a large amount of text into the TextBox.

So, what would be the way of preventing the change from the handler? I remember in some WindowsForms e.Cancel property which when set would ignore the action, but haven't seen that in WPF and the TextChangedEventArgs obviously does not have one.

Thanks

[Dupe](http://stackoverflow.com/questions/335129/cancelling-a-wpf-textbox-changed-event). — Kent Boogaart, Apr 23 '09 at 07:30
if this is still an issue, please add the of your TextBox.TextChanged event handler. Else please answer your own question. — Steffen Winkler, Sep 04 '15 at 16:54

score 0 · Answer 1 · answered Apr 14 '17 at 23:10

0

You can listen to the PreviewTextInput event and set e.Handled to true to prevent the change from taking effect.

answered Apr 14 '17 at 23:10

MetaColon

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Conditional prevention of the textbox change

1 Answers1