Splash screen as widget

[George-60]

I am trying to make splash screen as widget.
Problems are:
1) I think command
  splash = MY_SPLASH(g_object_new(my_splash_get_type(), NULL));
should create new window (since GtkWindow is a parent) but how can I set to
this new window GTK_WINDOW_POPUP as GtkWindowType?


2) I am inheriting MySplash from GtkWindow:
struct _MySplash {
   GtkWindow window;
   GtkWidget *label, *progressBar;
};
But when I am trying to cast MySplash as GtkWindow
---
MySplash * my_splash_new(GdkPixbuf *pixbuf) {
        MySplash *splash;
        GtkWidget *vbox, *image;

        // actual object creation
        splash = MY_SPLASH(g_object_new(my_splash_get_type(), NULL));
        gtk_window_set_position (GTK_WINDOW (splash), GTK_WIN_POS_CENTER_ALWAYS);
----
I get a run-time warning:
GLib-GObject-WARNING **: invalid cast from `MySplash' to `GtkWindow'
Gtk-CRITICAL **: gtk_window_set_position: assertion `GTK_IS_WINDOW (window)'
failed

Same thing with GTK_CONTAINER(splash) or even
GTK_CONTAINER(&(splash->window))

3) Each time label or progress bar is updated on splash screen, it should be
updated on the real screen, so I define (by tutorial):
void gtk_splash_set_text(GtkWidget *widget, const gchar *text) {
        MySplash *splash;
        g_return_if_fail (widget != NULL);
        g_return_if_fail (IS_MY_SPLASH (widget));
        splash = MY_SPLASH (widget);

        gtk_label_set_text( splash->label, text);
        while(gtk_events_pending()) {
                gtk_main_iteration();
        }
}
Do I have to define first parameter here as GtkWidget or can I define it
directly as MySplash *splash?
Also I am a confused, loop while(gtk_events_pending()) gtk_main_iteration();
will run BEFORE gtk_main_loop(), Since splash screen always shown during
initialization phase of application. Will this loop work?

 


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[jcupitt]

Hi,

2008/6/9 George Brink <siberianowl@...>:
> 1) I think command
>        splash = MY_SPLASH(g_object_new(my_splash_get_type(), NULL));
> should create new window (since GtkWindow is a parent) but how can I set to
> this new window GTK_WINDOW_POPUP as GtkWindowType?

In your _init() function, do

        gtk_window_set_type_hint( GTK_WINDOW( splash ),
                GDK_WINDOW_TYPE_HINT_SPLASHSCREEN );

> 2) I am inheriting MySplash from GtkWindow:
> But when I am trying to cast MySplash as GtkWindow
> I get a run-time warning:
> GLib-GObject-WARNING **: invalid cast from `MySplash' to `GtkWindow'

Are you setting GtkWindow as the parent class in your type creator?

> 3) Each time label or progress bar is updated on splash screen, it should be
> updated on the real screen, so I define (by tutorial):
>        while(gtk_events_pending()) {
>                gtk_main_iteration();
>        }

That's from a rather old tutorial, better to use:

        while( g_main_context_iteration( NULL, FALSE ) )
                ;

> Also I am a confused, loop while(gtk_events_pending()) gtk_main_iteration();
> will run BEFORE gtk_main_loop(), Since splash screen always shown during
> initialization phase of application. Will this loop work?

Yes, should work fine.

Here's the splash class from my app, for what it's worth:

  http://vips.svn.sourceforge.net/viewvc/vips/nip2/trunk/src/boxes.c?view=markup

search for 'splash'.

John
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[George-60]

John,
Thank you for quick reply.

By the way, why splash screen is not in the default set of library widgets?
I believe it is very common thing for almost all modern applications...

>> 1) I think command
>>        splash = MY_SPLASH(g_object_new(my_splash_get_type(), NULL));
>> should create new window (since GtkWindow is a parent) but how can I set
>> to
>> this new window GTK_WINDOW_POPUP as GtkWindowType?
>
> In your _init() function, do
>
>        gtk_window_set_type_hint( GTK_WINDOW( splash ),
>                GDK_WINDOW_TYPE_HINT_SPLASHSCREEN );

Sorry, it did not do anything useful. I still get the normal window with
title and max/min/close icons. And I see splash window in task-bar (which is
the main reason I'd like to open window with GTK_WINDOW_POPUP).

>> 2) I am inheriting MySplash from GtkWindow:
>> But when I am trying to cast MySplash as GtkWindow
>> I get a run-time warning:
>> GLib-GObject-WARNING **: invalid cast from `MySplash' to `GtkWindow'
> Are you setting GtkWindow as the parent class in your type creator?
Found mistake... I thought it would be enough to use GtkWindow &
GtkWindowClass as first members of my own structures, and forget about the
first parameter to gtk_type_unique(), I did set it up to GTK_TYPE_WIDGET
(copy-paste from tutorial). As soon as I change it to GTK_TYPE_WINDOW -
everything starts to work.

That rises another question: Tutorial I read, suggests to use
g_type_register_static() with GTypeInfo structure instead of
gtk_type_unique() with GtkTypeInfo. Author of tutorial does not explain why
he prefer g_type_register_static() over gtk_type_unique(). I guess, first
function registers class on GLib level and second on GTK level? My question
is what is the difference between this two approaches? Which one better to
use and when?


>>        while(gtk_events_pending()) {
>>                gtk_main_iteration();
>>        }
>
> That's from a rather old tutorial, better to use:
>
>        while( g_main_context_iteration( NULL, FALSE ) )
>                ;
Why is that better? One is for gtk events only, other also works with glib
events?


> Here's the splash class from my app, for what it's worth:
Thank you, it gave me some ideas :)
 


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[jcupitt]

2008/6/11 George Brink <siberianowl@...>:
> By the way, why splash screen is not in the default set of library widgets?
> I believe it is very common thing for almost all modern applications...

There's one in GNOME, but it's not been pushed down into GTK. There
was a discussion about it, I seem to remember, but I forget why it was
resisted.

The HIG says that your app should start up quickly enough that it
doesn't need a splash screen, which is good advice, if not always
possible. GIMP still has a splash widget, heh.

> That rises another question: Tutorial I read, suggests to use
> g_type_register_static() with GTypeInfo structure instead of
> gtk_type_unique() with GtkTypeInfo. Author of tutorial does not explain why
> he prefer g_type_register_static() over gtk_type_unique(). I guess, first

The type system used to be in GTK, but for gtk2.0 it was moved down a
layer into glib (as the gobject library).

So the modern, recommended way is g_type_register_static() and
gtk_type_unique() is now just a compatibility stub. You still see it
sometimes in code that's been ported from gtk-1.2.

>>>       while(gtk_events_pending()) {
>>>               gtk_main_iteration();
>>>       }
>>
>> That's from a rather old tutorial, better to use:
>>
>>       while( g_main_context_iteration( NULL, FALSE ) )
>>               ;
>
> Why is that better? One is for gtk events only, other also works with glib
> events?

Same reason: the main loop used to be part of gtk, but in the 2.0
series it's been pushed down into glib and the gtk functions are just
compatibility stubs.

John
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