Thanks Micheal! I am going to save the "number of lines" snippet for future reference.
Best, On Wed, Feb 14, 2018 at 3:42 PM, Michael Lange <klappn...@web.de> wrote: > Hi, > > On Tue, 13 Feb 2018 17:11:47 -0700 > Bob van der Poel <b...@mellowood.ca> wrote: > > > Getting closer :) > > > > I asked the question wrongly. I need to determine the number of VISIBLE > > lines in the listbox. > > Should be (as used in my previous example) > > visible_lines = lb.nearest(lb.winfo_height()) - lb.nearest(0) > > > > > Using the .winfo_height() does return the height in pixels. Note: You do > > have to make the widget visible before doing this, otherwise you just > > get "1" returned. widget.update() works for this. > > I don't think the widget must actually be "visible"; it is only when the > widget is initially created that the widget's dimensions are reported as > 1*1 px. Calling update_idletasks() once after the widgets have been > created should be sufficient to work around this. > > > > > So, the next question is: what is the line size? > > That is definitely not needed for what you want to accomplish. > > > > > Now, to make life much simpler :) I just played a bit and discovered > > that if I make the listbox visible BEFORE the selection, it > > automatically centers. So, my code now becomes: > > > > self.lb.update() > > self.lb.select_clear(ACTIVE) # needed to un-hilite existing > > selection self.lb.see(x) > > self.lb.activate(x) > > self.lb.select_set(x) > > > > Easy. And I don't need to worry about the size of the box! > > Here see() does not necessarily center the given index. It sometimes > appears near the top or the bottom of the list. > And that's just what the manpage promises: > > " if the element is near one edge of the window then the listbox scrolls > to bring the element into view at the edge; otherwise the listbox scrolls > to center the element. " > > > > > Well, mostly. If the selection I want is already on the screen, then the > > box doesn't scroll to center. I think I can live with that. > > Good, again that's exactly what the listbox's manpage promises :) > If you want exactly predictable behavior, I think you will have to use > yview() instead. > > Best regards > > Michael > > > .-.. .. ...- . .-.. --- -. --. .- -. -.. .--. .-. --- ... .--. . .-. > > You humans have that emotional need to express gratitude. "You're > welcome," I believe, is the correct response. > -- Spock, "Bread and Circuses", stardate 4041.2 > _______________________________________________ > Tkinter-discuss mailing list > Tkinter-discuss@python.org > https://mail.python.org/mailman/listinfo/tkinter-discuss > -- **** Listen to my FREE CD at http://www.mellowood.ca/music/cedars **** Bob van der Poel ** Wynndel, British Columbia, CANADA ** EMAIL: b...@mellowood.ca WWW: http://www.mellowood.ca
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