[Gambas-user] Select an entry in a combo or list box by keypress - Is there a better way.

[Ian Roper]

Doriano,

Thank you for your good advice.
I like the timer clear idea especially.
I will also experiment with cursor controls and see if i can make the
code tighter.

Cheers mate,
Ian


On Sat, 2008-09-13 at 09:05 +0200, Doriano Blengino wrote:
> Ian Roper ha scritto:
> > Greetings all,
> >
> > I am looking for a better way to locate and select an entry in a combo
> > or list box by pressing a series of keys.
> >
> > I have been able to do this with the following code but there must be a
> > better way. ?
> >
> > It would be nice to have this as a standard method for these sort of
> > controls. :)
> >
> > 'Pressing Esc clears the search string.
> > 'Label_Search displays the current search string.
> >
> > PUBLIC SUB Listbox_KeyPress()
> >    DIM Count AS Integer
> >    DIM Found AS Boolean
> >    DIM SearchLen AS Integer
> >    
> >    Found = FALSE
> >    
> >    IF Key.Code = Key.Esc THEN 
> >       SearchString = "" 
> >       SearchLen = 0 
> >       Label_Search.Text = "No Search" 
> >    ELSE
> >       SearchString = SearchString & UCase(Key.Text)
> >       SearchLen = Len(SearchString)
> >       Label_Search.text = SearchString
> >    ENDIF 
> >    
> >    REPEAT 
> >       IF UCase(Left(Listbox[Count].Text, SearchLen)) = (SearchString)
> > THEN
> >          Found = TRUE
> >       END IF   
> >       INC Count
> >    UNTIL Found OR (Count = (Listbox.Count - 1)) 
> >   
> >    IF found THEN Listbox.index = Count - 1
> >   
> > END
> >
> > PUBLIC SUB Listbox_LostFocus()
> >
> >   SearchString = ""
> >
> > END
> >   
> It think this method is nice, and I think there is no other way to get 
> the same result. Perhaps I only would add that, if the user presses 
> cursor key movements, then the search string is cleared (what happens if 
> the user presses key down a few times? I think an inconsistency shows 
> up, because the search string shows something, and the combobox shows 
> something else).
> If you experience some strange behaviour, try to use "STOP EVENT" 
> somewhere before exiting the keypress handler.
> 
> I have done something similar some time ago, and I had a timer which, 
> after a few seconds (500 ms?) of no typing, cleared automatically the 
> search string - this saves the user to press Esc to clear the string, 
> but it depends a lot on what kind of application you are writing. Then, 
> Benoit said to me that this kind of comparison (if ucase(...) = ....) 
> only works with ascii strings, so more specific string comparison 
> functions should be used.
> 
> It would be nice to have this search intrinsic in combobox, listbox, 
> treeview and everywhere many strings are present, but it should be 
> excludable, because there can be two problems. First, in some 
> application it could be undesirable, or wanted a little different. For 
> example, in some application, you can press several times the same key, 
> say, "B", and get "Benoit", "Blengino", "Bozo" and so on. The second 
> problem is when the listbox has thousands items inside it - it could get 
> unresponsive, because the search code can take a few (or many) seconds. 
> I don't like long listboxes/comboboxes and I try to manage them in some 
> other way if I suspect they can grow too much, but this is my personal 
> taste.
> 
> These are just my opinions, many users think differently than me...
> 
> Best regards,
> Doriano Blengino
> 
> 
> 
> 
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