fxruby users - Dec 2007 - deleting children and then adding new ones

Hi all!  I''m having a small problem, which is probably really easy to
deal
with, but I''m just missing how to do it, and I haven''t had any
luck looking
in the docs or the examples.

I''m trying to delete the contents of a frame (using removeChild), and
then
add new contents to that frame.  Whenever I do this, it deletes stuff just
fine, but then the new thing doesn''t show up.  Here is a short example:

require ''fox16''

include Fox
app = FXApp.new()
main = FXMainWindow.new(app, "Window")
vf = FXVerticalFrame.new(main)
button = FXButton.new(vf, "Old Button")
button.connect(SEL_COMMAND) do
  vf.removeChild(button)
  FXButton.new(vf, "New Button")
end

app.create
main.show()
app.run

Click the button... and then there''s nothing at all.

Is there some sort of magic incantation I need to call to get the frame to
redraw itself or something?  I tried a few that looked like they did that
from the docs, but no luck

Thanks,

Ralph
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On 12/9/07, Ralph Douglass <ralph at grayskies.net> wrote:
> I''m trying to delete the contents of a frame (using removeChild),
and then
> add new contents to that frame.  Whenever I do this, it deletes stuff just
> fine, but then the new thing doesn''t show up.  Here is a short
example:
>
> require ''fox16''
>
> include Fox
> app = FXApp.new()
> main = FXMainWindow.new(app, "Window")
> vf = FXVerticalFrame.new(main)
> button = FXButton.new(vf, "Old Button")
> button.connect (SEL_COMMAND) do
>   vf.removeChild(button)
>   FXButton.new(vf, "New Button")
> end
>
> app.create
> main.show()
> app.run
>
> Click the button... and then there''s nothing at all.
>
> Is there some sort of magic incantation I need to call to get the frame to
> redraw itself or something?
Yes, you need to call create() on the button and then recalc() on the
button''s parent:

	buttton.connect(SEL_COMMAND) do
		vf.removeChild(button)
		btn = FXButton.new(vf, "New Button")
		btn.create
		btn.recalc
	end

Note that I''m not sure it''s a good idea to destroy an object
while
you''re executing a message handler for it (as in this example). What
is it that you''re trying to accomplish by removing the old button and
creating a new one? If you''re just wanting to change the
button''s
label (for example), you can just do:

	button.connect(SEL_COMMAND) do
		button.text = "New Button Text"
	end

Hope this helps,

Lyle

I''m working on the ui for a little video game.  On the left in a map of
the
game''s galaxy, and on the right in a panel.  When a planet on the left
in
clicked on, I want the panel on the right to change to display information
and options for that planet.  When a user clicks on a fleet of ships, I want
it to change to display information and options for the fleet.

Is there perhaps a better way to do this than destroying the contents of the
frame on the right every time?

Thanks,

Ralph

On 12/10/07, Lyle Johnson <lyle at lylejohnson.name>
wrote:
>
> On 12/9/07, Ralph Douglass <ralph at grayskies.net> wrote:
>
> > I''m trying to delete the contents of a frame (using
removeChild), and
> then
> > add new contents to that frame.  Whenever I do this, it deletes stuff
> just
> > fine, but then the new thing doesn''t show up.  Here is a
short example:
> >
> > require ''fox16''
> >
> > include Fox
> > app = FXApp.new()
> > main = FXMainWindow.new(app, "Window")
> > vf = FXVerticalFrame.new(main)
> > button = FXButton.new(vf, "Old Button")
> > button.connect (SEL_COMMAND) do
> >   vf.removeChild(button)
> >   FXButton.new(vf, "New Button")
> > end
> >
> > app.create
> > main.show()
> > app.run
> >
> > Click the button... and then there''s nothing at all.
> >
> > Is there some sort of magic incantation I need to call to get the
frame
> to
> > redraw itself or something?
>
> Yes, you need to call create() on the button and then recalc() on the
> button''s parent:
>
>         buttton.connect(SEL_COMMAND) do
>                 vf.removeChild(button)
>                 btn = FXButton.new(vf, "New Button")
>                 btn.create
>                 btn.recalc
>         end
>
> Note that I''m not sure it''s a good idea to destroy an
object while
> you''re executing a message handler for it (as in this example).
What
> is it that you''re trying to accomplish by removing the old button
and
> creating a new one? If you''re just wanting to change the
button''s
> label (for example), you can just do:
>
>         button.connect(SEL_COMMAND) do
>                 button.text = "New Button Text"
>         end
>
> Hope this helps,
>
> Lyle
> _______________________________________________
> fxruby-users mailing list
> fxruby-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/fxruby-users
>


-- 
Ralph
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On 12/10/07, Ralph Douglass <ralph at grayskies.net> wrote:
> I''m working on the ui for a little video game.  On the left in a
map of the
> game''s galaxy, and on the right in a panel.  When a planet on the
left in
> clicked on, I want the panel on the right to change to display information
> and options for that planet.  When a user clicks on a fleet of ships, I
want
> it to change to display information and options for the fleet.
>
> Is there perhaps a better way to do this than destroying the contents of
the
> frame on the right every time?
Is the information associated with a planet always the same set of
widgets, just with different values? If so, I''d just update the
widgets'' values whenever the user clicks on a new planet, e.g.

    planet_button.connect(SEL_COMMAND) do
        planet_name_label.text = planet.name
        planet_size_label.text = planet.size
    end

Now, I''m assuming that you''re displaying completely different
kinds of
information when the user clicks on a fleet of ships, so you''d need to
do something different in that case. One option would be to implement
the right-hand side information panel as a switcher (FXSwitcher), with
one page for "planet information", another page for "fleet
information", etc. See the shutter.rb example for an idea of how you
might do that.

Hope this helps,

Lyle

Thanks, the recalc and create worked really well.  I saw the example of the
FXSwitcher widget on the website, but thought it wasn''t really what I
wanted
at the time.  I''ll give it a second look now.

On 12/10/07, Lyle Johnson <lyle at lylejohnson.name>
wrote:
>
> On 12/10/07, Ralph Douglass <ralph at grayskies.net> wrote:
>
> > I''m working on the ui for a little video game.  On the left
in a map of
> the
> > game''s galaxy, and on the right in a panel.  When a planet on
the left
> in
> > clicked on, I want the panel on the right to change to display
> information
> > and options for that planet.  When a user clicks on a fleet of ships,
I
> want
> > it to change to display information and options for the fleet.
> >
> > Is there perhaps a better way to do this than destroying the contents
of
> the
> > frame on the right every time?
>
> Is the information associated with a planet always the same set of
> widgets, just with different values? If so, I''d just update the
> widgets'' values whenever the user clicks on a new planet, e.g.
>
>     planet_button.connect(SEL_COMMAND) do
>         planet_name_label.text = planet.name
>         planet_size_label.text = planet.size
>     end
>
> Now, I''m assuming that you''re displaying completely
different kinds of
> information when the user clicks on a fleet of ships, so you''d
need to
> do something different in that case. One option would be to implement
> the right-hand side information panel as a switcher (FXSwitcher), with
> one page for "planet information", another page for "fleet
> information", etc. See the shutter.rb example for an idea of how you
> might do that.
>
> Hope this helps,
>
> Lyle
> _______________________________________________
> fxruby-users mailing list
> fxruby-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/fxruby-users
>


-- 
Ralph
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On Monday 10 December 2007, Ralph Douglass wrote:
> Thanks, the recalc and create worked really well.  I saw the example of the
> FXSwitcher widget on the website, but thought it wasn''t really
what I wanted
> at the time.  I''ll give it a second look now.
FXSwitcher is probably recommended for something like this; however, it is
not forbidden to destroy windows in response to SEL_COMMAND callback from
FXButton.

But please note, many callback messages are generated in the middle of a 
user-transaction, and not at the end of one.  In such cases, the widget
is expected to exist upon return from the callback.

We take great pains to ensure that for the SEL_COMMAND callback, no further
references to the originating widgets are made.  So its true that for *most*
widgets, you are allowed to do anything in the SEL_COMMAND, including deleteing
the originating widget.  

But I do suggest not to make a habit of it.  



		- Jeroen




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| Copyright (C) 22:40 12/ 3/2007 Jeroen van der Zijp.   All Rights Reserved. |
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