Dynamic combo-field% behavior - filtering choices by typed text

Questions & Answers
1

Looking for a way to implement an 'auto-complete' for combo-field%.

As the user types text into the combo-field%, the callback filters non-matching text options from the list and add faded 'tab-complete' text after the caret position. If the text-field% is cleared, restore list to original, unfiltered options.

For example:

(require racket/gui)
(define search-fields '("AB" "AA" "AC" "BC" "DZ"))

(define toplevel (new frame% [label "search"] [min-width 400] [min-height 400]))

(define combo (new combo-field%
                  [label ""]
                  [choices search-fields]
                  [parent toplevel]
                 ))
(send toplevel show #t)

Typing 'A' into the text box should reduce the dropdown options to 3 : AA AB and AC.

Have looked over the documentation for combo-field% but can't find anything that would allow behavior as described. The documentation doesn't offer a way to do this but allows (send a-combo-field append l) which adds a item to the list. I want to do the opposite, restricting options as text is typed. Even the underlying popup-menu% doesn't appear to allow this.

Is there any way to do this? I have thought about deleting the popup-menu% and recreating it with new options but there doesn't seem to a way to assign it to the combo-field% afterwards.

Thanks in advance for any suggestions!

2

The trick is to remove all items from the popup-menu%, and then you can add new items, either directly or via append in combo-field%. Removing all items from a menu m will be something like

(for ([i (in-list (send m get-items))])
   (send i delete))