[Urwid] ListBox loses focus

Ian Ward ian at excess.org
Mon Feb 13 10:48:04 EST 2012


Good find.

So, the reason for this is that ListBox is trying very hard to maintain the
screen column from its initial selected item (the first Columns) and the
one you switched focus to.  This is because commonly the focus changes as a
result of the user pressing up/down.

This screen column isn't set until the ListBox knows its own size (such as
when render() is called) and when it does it doesn't know that it is
clobbering a setting that you wanted to take precedence.  All this code is
in ListBox._set_focus_complete() if you want to take a look.

ListBox.set_focus() should probably set a flag that indicates not to try
and maintain the screen column when _set_focus_complete is eventually
called.

Ian

On Thu, Feb 9, 2012 at 6:55 PM, Martin Siebel <lonequestor at yahoo.de> wrote:

> Hello,
>
> I am trying to build a GridBox widget, which is similiar to the GridFlow
> widget, but can be scrolled.
>
> In doing so, I encountered a problem using urwid's ListBox when setting a
> focus explicitely.
> The following code generates a display with 3x5 checkboxes. The focus is
> explicitely set on the second entry in the third row.
> When running this code in a terminal which is large enough to hold the
> focus without scrolling the list, the focus is set to the first entry in
> the third row instead of the second.
> When the terminal is small enough not to hold the focus without scrolling,
> the focus is set properly.
>
> I could trace the problem back to the render method of the ListBox, which
> explicitely alters the focus of the contained Columns object.
> (See the second code snippet and the corresponding output).
> Is this a bug in the ListBox or am I doing something wrong when setting
> the focus?
>
> Any help would be appreciated!
> Best regards.
>
> Snippet 1:
>
> ######################################################################################
> #!
> /usr/bin/python                                                                                                                                                              &nb
> sp;
> import urwid
> import random
>
> palette = [('header', 'white', 'dark red', "", "#afd", "#f0f"),
>            ('footer', 'black', 'light blue', "", "#6f0", "#d00"),
>            ('reveal focus', 'dark green', 'yellow', "", "#fd0", "#808"),
>            ('body', 'yellow', 'dark green', 'standout', "#808", "#fd0"),
>            ('edit', 'black', 'light gray', "", "#f0f", "#afd")]
>
> buttons = [urwid.AttrMap(urwid.CheckBox(k), None, 'reveal focus')
>            for k in ["%d %s" % (i, j)
>                      for i, j in
>                      enumerate(sorted(["".join([chr(random.randint(97,
> 122))
>                                                 for x in range(
>                                                        random.randint(4,
> 16))])
>                                        for j in range(15)]))]]
> body =
> urwid.ListBox(urwid.SimpleListWalker([urwid.Columns(buttons[3*i:3*i+3])
>                                              for i in
> range(len(buttons)/3)]))
> body.set_focus(2)
> body.get_focus()[0].set_focus(1)
> loop = urwid.MainLoop(body, palette)
> loop.screen.set_terminal_properties(colors=256)
> loop.run()
>
> Snippet 2:
> ########################################################################
> #!
> /usr/bin/python                                                                                                                                                              &nb
> sp;
> import urwid
> import random
> import sys
> from math import log10
> palette = [('header', 'white', 'dark red', "", "#afd", "#f0f"),
>            ('footer', 'black', 'light blue', "", "#6f0", "#d00"),
>            ('reveal focus', 'dark green', 'yellow', "", "#fd0", "#808"),
>            ('body', 'yellow', 'dark green', 'standout', "#808", "#fd0"),
>            ('edit', 'black', 'light gray', "", "#f0f", "#afd")]
>
> def log(txt):
>     import time
>     f = open("/tmp/gridbox.log", "a")
>     f.write("%s: %s\n" % (time.strftime("%H:%M:%S"), txt))
>     f.close()
>
> class MyListBox(urwid.ListBox):
>     def __init__(self, *args, **kwargs):
>         urwid.ListBox.__init__(self, *args, **kwargs)
>     def render(self, *args, **kwargs):
>         log("BEFORE RENDER:")
>         for i in self.body:
>             l = [j.original_widget for j in i.widget_list]
>             log("row %d: [%s], focus is on %d" % (id(i),
>                                                   ", ".join([str(id(j))
> for j in l]),
>                                                   i.get_focus_column()))
>
>         retval = super(MyListBox, self).render(*args, **kwargs)
>         log("AFTER RENDER:")
>         for i in self.body:
>             l = [j.base_widget for j in i.widget_list]
>             log("row %d: [%s], focus is on %d" % (id(i),
>                                                   ", ".join([str(id(j))
> for j in l]),
>                                                   i.get_focus_column()))
>
>         return retval
>
> buttons = [urwid.AttrMap(urwid.CheckBox(k), None, 'reveal focus')
>            for k in ["%d %s" % (i, j)
>                      for i, j in
>                      enumerate(sorted(["".join([chr(random.randint(97,
> 122))
>                                                 for x in
> range(random.randint(4, 16))])
>                                        for j in range(15)]))]]
> body = MyListBox(urwid.SimpleListWalker([urwid.Columns(buttons[3*i:3*i+3])
>                                          for i in range(len(buttons)/3)]))
> body.set_focus(2)
> body.get_focus()[0].set_focus(1)
> loop = urwid.MainLoop(body, palette)
> loop.screen.set_terminal_properties(colors=256)
> loop.run()
>
> Output of snippet 2:
> 11:51:44: BEFORE RENDER:
> 11:51:44: row 35364944: [35360976, 35361296, 35361552], focus is on 0
> 11:51:44: row 35365008: [35361808, 35362064, 35362320], focus is on 0
> 11:51:44: row 35365072: [35362576, 35362832, 35363088], focus is on 1
> 11:51:44: row 35365136: [35363344, 35363600, 35363856], focus is on 0
> 11:51:44: row 35365200: [35364112, 35364368, 35364624], focus is on 0
> 11:51:44: AFTER RENDER:
> 11:51:44: row 35364944: [35360976, 35361296, 35361552], focus is on 0
> 11:51:44: row 35365008: [35361808, 35362064, 35362320], focus is on 0
> 11:51:44: row 35365072: [35362576, 35362832, 35363088], focus is on 0
> 11:51:44: row 35365136: [35363344, 35363600, 35363856], focus is on 0
> 11:51:44: row 35365200: [35364112, 35364368, 35364624], focus is on 0
>
>
>
>
> _______________________________________________
> Urwid mailing list
> Urwid at lists.excess.org
> http://lists.excess.org/mailman/listinfo/urwid
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.excess.org/pipermail/urwid/attachments/20120213/cf4c0cdb/attachment.htm 


More information about the Urwid mailing list