I have barcode scanner. I need to capture string from barcode into textbox. The final word in textbox will be composed of multiple codes from barcode scanner. What event(s) should I use?
For example : Barcode sends value 123 .
I tried PreviewTextInput event and e.Text but it captured only first char 1 . How can I get all added chars to textbox when I use barcode scanner?
TextBox does not lose anything. If e.Text is "1" then it only means that your scanner sends characters to TextBox one by one. Meaning you will get one event per character added.
Your approach is really wierd tho. TextBox knows nothing about barcodes, scanners. etc. It simply displays text. Why do you ask it, if your scanner finished scanning? That makes no sense. Leave poor TextBox alone. If you want to know when the scanning procces is finished, than you should add an appropriate event to class, which actually reads barcodes. And then, after this event fires, you should access the resulting string via TextBox.Text or using other means (forexample by accessing a viewmodel property).
Edit: the thing with wpf events, is that your control needs to have "keyboard focus", if you want it to recieve keyboard events. If you show a MessageBox then your TextBox loses focus and, as a result, no longer recieves events. Again, leave the TextBox alone. You need to write a dedicated class (i.e. BarcodeReader) which will handle keyboard events for you and then fire an event when the barcode is read. You can use Keyboard class inside the BarcodeReader to handle buttons pressed.
MessageBox.Show)If you are using C# in back end then you can have a look at this question: Reading bar codes using wpf application
123), there will be 123 in textbox.. But when I try to catch it in some event (TextChanged or PreviewTextInput) it catches only 1st char (1) and remaining 2 chars disappear