[Urwid] how to (un)hide a widget with WidgetPlaceholder ?

[Goffi]

G'day,

In documentation of WidgetPlaceholder we can read this:
? This can be useful for making an interface with a number of distinct
pages or for showing and hiding menu or status bars. ?

But I don't exactly see how to do that: we can't use None for
original_widget, and there is no ? invisible ? widget.

So far to (un)hide menus and status bar, I was adding/removing them from
my containers, so now I wonder if there is not a better method with
WidgetPlaceholder...

What is the best practice to (un)hide a widget ?

Thanks :)

Goffi

[Ian Ward]

Post by Goffi
G'day,
? This can be useful for making an interface with a number of distinct
pages or for showing and hiding menu or status bars. ?
But I don't exactly see how to do that: we can't use None for
original_widget, and there is no ? invisible ? widget.

When I wrote this I was thinking that you would switch between pages
(a blank page would could be a SolidFill widget or similar) or you
would use it to show a menu by using a Pile or Frame and then hide a
menu by replacing that with just the widget below/frame body. I wasn't
intending this as a way to make a widget hide itself from its parent.

Post by Goffi
So far to (un)hide menus and status bar, I was adding/removing them from
my containers, so now I wonder if there is not a better method with
WidgetPlaceholder...
What is the best practice to (un)hide a widget ?

I know some people have hidden widgets in Piles and ListBox widgets by
replacing them with an empty Pile (which has 0 height). This seems to
work but may not be well tested, and I'm not sure what happens if one
of these widgets gets selected somehow. I'm pretty sure there's
nothing similar for Columns to make a widget disappear.

But you're asking about menus and status bars. I would use a
WidgetPlaceholder subclass to wrap a widget that may have a menu or
status bar. Add methods that show or hide the bar by swapping
original_widget with a Pile or Overlay that includes the bar you want
to show. If your status or menu bar is for the whole application your
original_widget might be what was your topmost widget before.

Ian

[Goffi]

Thank you for your detailled answer. Actually it seems that my current
method with a Pile subclass is good enought.

If people are using Pile to simulate an empty widget, maybe and
EmptyWidget class would be usefull ? What do you think ? I mean we can
manage with WidgetPlaceholder or Pile, but this would simplify some use
cases...

Cheers
Goffi

Post by Ian Ward

Post by Goffi
G'day,
? This can be useful for making an interface with a number of distinct
pages or for showing and hiding menu or status bars. ?
But I don't exactly see how to do that: we can't use None for
original_widget, and there is no ? invisible ? widget.

When I wrote this I was thinking that you would switch between pages
(a blank page would could be a SolidFill widget or similar) or you
would use it to show a menu by using a Pile or Frame and then hide a
menu by replacing that with just the widget below/frame body. I wasn't
intending this as a way to make a widget hide itself from its parent.

Post by Goffi
So far to (un)hide menus and status bar, I was adding/removing them from
my containers, so now I wonder if there is not a better method with
WidgetPlaceholder...
What is the best practice to (un)hide a widget ?

I know some people have hidden widgets in Piles and ListBox widgets by
replacing them with an empty Pile (which has 0 height). This seems to
work but may not be well tested, and I'm not sure what happens if one
of these widgets gets selected somehow. I'm pretty sure there's
nothing similar for Columns to make a widget disappear.
But you're asking about menus and status bars. I would use a
WidgetPlaceholder subclass to wrap a widget that may have a menu or
status bar. Add methods that show or hide the bar by swapping
original_widget with a Pile or Overlay that includes the bar you want
to show. If your status or menu bar is for the whole application your
original_widget might be what was your topmost widget before.
Ian
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