Comments on Bits and pieces: Glade3 tutorial (6) - Signals

Never mind that, I just needed to omit 'static...

2011-09-30T14:28:22.192+02:00

Never mind that, I just needed to omit 'static' keyword from callback function definition.

I have been following several glade tutorials, and...

2011-09-30T14:11:16.588+02:00

I have been following several glade tutorials, and so far haven't been able to successfully connect the signals with gtk_builder_connect_signals.

At first I was using Eclipse CDT so I separated all --cflags into individual lines, deleted all instances of -I and then pasted the include paths to Project -> Properties -> C/C++ Build -> Settings -> GCC C Compiler -> Includes, and added -pthread to Miscellaneous options, just in case. This is how all options looked like:

-I/usr/include/atk-1.0 -I/usr/include/pango-1.0 -I/usr/include/gio-unix-2.0/ -I/usr/include/glib-2.0 -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/cairo -I/usr/include/gdk-pixbuf-2.0 -I/usr/lib/i386-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 -O0 -g3 -Wall -c -fmessage-length=0 -pthread

A little messy, but it compiles, after I did the same for the --libs output (only this was for linker options, of course). This is how all options look like for linker:

-pthread -Wl,--export-dynamic

It didn't list all the -L and -l switches, but since it links with all --libs output -Lxxxx and -Lxxxx added and doesn't if I delete them, I persume they are just not being displayed.

And when I compile the project, I get the dreaded Gtk-WARNING **: Could not find signal handler. The I tried manually compiling and linking.

$ gcc -c drag_drop.c -o drag_drop.o `pkg-config --cflags gtk+-2.0 gmodule-2.0`
$ gcc -o drag_drop drag_drop.o `pkg-config --libs gtk+-2.0 gmodule-2.0`

But it's the same old story:
$ ./drag_drop

(drag_drop:7238): Gtk-WARNING **: Could not find signal handler 'on_main_window_destroy'

The callback function is named in Glade as:
on_main_window_destroy

It is declared in drag_drop.h as:
static void on_main_window_destroy (GtkObject*, gpointer);

and is defined right after main() as:
static void on_main_window_destroy (GtkObject *object, gpointer userdata) { ...

It's all the same if I just define it before main() or declare it in drag_drop.c (I believe I'm using the right terms for declaration and definition, I might be wrong though) - the gmodule just can't find my function...

If anyone knows where is the problem, please let me know.
(I'm on a Ubuntu 11.04 machine).

The command used to obtain CFLAGS variables:
$ pkg-config --cflags gtk+-2.0 gmodule-2.0

The command used to obtain needed libraries:
$ pkg-config --libs gtk+-2.0 gmodule-2.0

important: if you compile Glade3 with C++, you hav...

2010-12-06T20:10:17.335+01:00

important: if you compile Glade3 with C++, you have to add ' extern "C" ' before the declaration of the callback function. Like this:

extern "C" void
on_button4_clicked (GtkButton *button, gpointer user_data)
{

This tutorial is awesome. Thanks a lot bro... Stay...

2010-11-11T16:02:35.779+01:00

This tutorial is awesome. Thanks a lot bro...
Stay healthy...

Hi if I have two glade files, both glade files als...

2010-07-27T15:27:52.846+02:00

Hi
if I have two glade files, both glade files also has the same event name "on_button_clicked", does it causes an ambiguous function call?

This tutorial is great you should do more of them,...

2010-07-08T03:45:53.873+02:00

This tutorial is great you should do more of them, especially screencasts.

I have converted the C code into Vala and put a link to to your blog here:

http://vala.posterous.com/using-gtkbuilder-to-load-a-gui-created-by-gla

If you copy the source code using the 'copy to...

2010-06-22T05:30:54.619+02:00

If you copy the source code using the 'copy to clipboard' link in the code block, the resulting Makefile will fail to compile with an error "Makefile:13: *** missing separator. Stop."

This is because there needs to be an actual tab instead of spaces at the start of the $(CC) and rm -f lines.

Once I changed these to tabs instead of spaces, this compiled correctly.

(Just a note in case anyone else was having problems.)

hi tadeboro, i have a problem 'cause i cant do...

2010-04-04T18:13:37.612+02:00

hi tadeboro, i have a problem 'cause i cant do anythig with the application after i compiled, form example when i press any button nothing hapend. coul you help me please-

thanks

So, what is this "Data User" column for?...

2010-03-09T23:41:48.941+01:00

So, what is this "Data User" column for? I only managed to get a Segmentation Fault when is set.

Hello. If you look again at second paragraph unde...

2009-11-13T18:21:38.981+01:00

Hello.

If you look again at second paragraph under Signals tab in Glade section, you'll notice this: note: if field is not empty, signal will be connected the same way as if you were to call g_signal_connect_swapped macro. And g_signal_connect_swapped does exactly what you experience: swap user data and widget parameter.

Now things should make sense;)

Tadej

Hi, nice tutorial. In your tutorial (and also in ...

2009-11-13T14:10:20.913+01:00

Hi, nice tutorial.

In your tutorial (and also in files created with glade-2, the callback functions for events have the form of:
cb_event (GtkWidget *widget, GdkEvent *event, gpointer user_data).

But when I did some testing using glade-3 I got 1st and 3rd parameters switched.
For instance, for button press event in drawing area I used this drawing area as user data, while for button release event I used the main window. In both callbacks I print out the sizes of the calling widget and the one, passed with the user data.
In both cases the size of the widget passed as user data is displayed first and of the calling widget second, which is exactly vice versa as it should be.

I was wondering if maybe you have an explanation for this strange behavior, or in other words, what am I doing wrong. And by the way, I was using gtk_builder_connect_signals(...) function.

Slatrius

Hmm, interesting! Haven't caught that one myse...

2009-11-08T05:22:00.066+01:00

Hmm, interesting! Haven't caught that one myself...

pkg-config --cflags --libs gtk+-2.0 links in gmodule-2.0 automatically, but without the linker flag??? My output is:

-D_REENTRANT -I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/directfb -I/usr/include/libpng12 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -lgtk-x11-2.0 -lgdk-x11-2.0 -latk-1.0 -lpangoft2-1.0 -lgdk_pixbuf-2.0 -lm -lpangocairo-1.0 -lgio-2.0 -lcairo -lpango-1.0 -lfreetype -lfontconfig -lgobject-2.0 -lgmodule-2.0 -lglib-2.0

Only explicitly adding gmodule-2.0 adds the -Wl,--export-dynamic linker flag.

# pkg-config --cflags --libs gmodule-2.0
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -Wl,--export-dynamic -lgmodule-2.0 -lglib-2.0

And BTW and OT: thanks for answering my other comment on Imagination about the custom cell renderer, you/it helped a lot! Now I have a thumbnail widget which is checkable, a.k.a a permanent selection :-)

Cheers!

@Todor: G_MODULE_EXPORT is indeed only needed on ...

2009-11-07T09:03:59.688+01:00

@Todor:

G_MODULE_EXPORT is indeed only needed on Windows platform, but in order to make your code portable, I would advice to use it whenever you write your code to be used with GtkBuilder (on GNU/Linux, preprocessor will strip it out, so no overhead is added to final binary).

-Wl, --export-dynamic is only needed on GNU/Linux, Windows platforms will do without it. But manually adding this is not portable, this is why I suggest to add "gmodule-2.0" to pkg-config, since it'll provide proper linker flags for your platform.

Tadej

On both Ubuntu Jaunty and Karmik G_MODULE_EXPORT -...

2009-11-07T01:38:16.926+01:00

On both Ubuntu Jaunty and Karmik G_MODULE_EXPORT - as found in the header gmodule.h - expands exactly to nothing, unless you are linking on Win32/64. I have an action, which in the glade file is connected to on_actionAbout_activate and defining it as:

G_MODULE_EXPORT void on_actionAbout_activate( GtkAction* action, gpointer data ) { ... }

gives the error:

(app:PID): Gtk-WARNING **: Could not find signal handler 'on_actionAbout_activate'

with or without G_MODULE_EXPORT in front. I needed to pass the option -Wl,--export-dynamic to the linker for it to work.

Hi you never stop for my more bigf pleasure. a won...

2009-09-28T22:17:30.292+02:00

Hi you never stop for my more bigf pleasure. a wonderfull tutorial yet. i'm only the 3 rd. Imagination is a beautifull software but could you explain in another post how do you do on this logiciel to realise two tabs and the rest like at right on the top ?

Hi. gtk_builder_connect_signals will conne...

2009-09-28T09:23:08.438+02:00

Hi.

gtk_builder_connect_signals will connect handlers to all of the signals you set with glade, so there is no need to call this function more than once on a single GtkBuilder object.

I guess you would like to send different data to different signals. This cannot be done using gtk_builder_connect_signals. You'll either have to use gtk_builder_connect_signals_full, which will give you total control over the connection process, or manually connect signals whose handlers should get special data.

Tadej

very nice, thank you. and to connect more signals,...

2009-09-28T01:52:40.760+02:00

very nice, thank you. and to connect more signals, is it correct to call gtk_builder_connect_signals() multiple successive times? like:
gtk_builder_connect_signals( builder, data );
gtk_builder_connect_signals( builder, window3 );
etc.
?