Re: [Java-gnome-developer] Thanks and some questions

[Mikael H. <mi...@im...>]

s=C3=B6n 2003-06-29 klockan 19.49 skrev Mark Wielaard:
> Hi,

Hi!

Haven't tried out the bindings myself (had some problems building the
.jar-files and didn't have time to look into it), will soon though. I've
been a GNOME developers for several years though.

> The org.gnu.gnome.About class doesn't seem to work correctly.=20

Why is org.gnu.gnome namespace used anyway? org.gnome.* looks more
correct.

> In general the library doesn't behave very nicely when calls are made
> in the wrong order or are given the wrong arguments. Often it wasn't
> that hard to see what went wrong or when I object should no longer be
> used but crashing the whole application instead of throwing
> IllegalStateExceptions makes debugging a bit harder then necessary.
> An example is using a widget from a window which close box has just
> been pressed.

This might be the underlying GTK+ that makes this hard. Since C/GTK+
doesn't have ref counts as in Java I'm not sure if the fact that you
keep a java ref on an object makes you have a gtk-ref on the C-object.

My guess is that you have to be careful how you use the widgets and that
you will have to explicitly call g_object_ref (not sure if that is
wrapped or not) to keep a reference to a widget in a closed window after
destroying the window but I'm not sure.

> When using the UIInfo class to get some standard widget like
> UIInfo.quitItem() when you try to call quitMenuItem.getWidget() before
> the window that it is attched to is shown it crashes. Is this know
> behaviour?

Might be that the item/widget isn't created yet?

> I couldn't find documentation about how to work with java-gnome from
> multiple threads. To be save I just created a Fireable and a Timer
> that sets off a couple times a second and then update the Widgets in
> the fire() method that checks progress flags set in other threads.
> What is the recommended way to handle multiple thread that want to
> update the GUI. When is it save to call a widget or other glib, gtk or
> gnome object from a thread that isn't the main gtk thread?

When working with GTK+ you need to make sure that only one thread at a
time work on a widget. Therefor you will have to create locks around
calls that updates the widgets to prevent several simultanious accesses
to a widget.

> For the window layout I tried following the Gnome HIG. Is there
> example code to do some of the things described there? Currently I use
> alot of VBoxes inside HBoxes with different borders and spacing values
> tied together with SizeGroups which seems to make it look like the HIG
> describes. But since every Gnome application implements these kinds of
> things I wondered if there isn't an example library that just does the
> right thing.

You probably want to work with Glade/Libglade (not sure if it is wrapped
in java-gnome yet) for doing that. Most GNOME applications today use
Glade to create the GUI in a GUI-editor which outputs an XML-file
describing the UI. This saves lots of code and makes your application
more maintainable since you can change the UI without touching the code.

Hope it helps even though I don't know the current status of java-gnome.

Regards,
  Mikael Hallendal
--=20
Mikael Hallendal                mi...@im...
Imendio                         http://www.imendio.com
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