Re: Question about Callback
Hi,
thanks for your answer. I think I understand my code a bit better now...
I wonder whether it is best practice to use static functions for these
callbacks - in my code it is actually a member function (because of
having many different buttons whose states form a bitfield that is
compressed to one int value. I did not find any example that does not
use such static functions.
Greetings,
Christoph Hartwig
James Scott Jr schrieb:
You can also use:
- in the routine that creates the button, save a unique value.
g_object_set_data(G_OBJECT(button), Unique-Key, some-value)
-in button callback routine, retrieve the unique value.
some-value-pointer = g_object_get_data(G_OBJECT(button), Unique-Key);
This in addition to any pre-allocated memory structure you passed in the
g_signal_connect(), or g_signal_connect_swapped(). The issue with
reuse of button callbacks is always how to determine which button! I do
two things;
1. pre-allocate a memory structure with the first value a fixed id of
some sort (or related to the button's function). example
#def EXIT_BUTTON_FLAG 1
.
.
.
typedef struct _SomeButton {
gint cb_id;
...
} SomeButton, *PSomeButton;
.
.
.
PSomeButton memButton = NULL;
.
memButton = g_new0(SomeButton, 1);
memButton-cb_id = EXIT_BUTTON_CBID;
.
g_signal_connect(G_OBJECT(button), toggled,
G_CALLBACK(fn_callback), memButton);
.
.
2. g_object_set_data() and g_object_get_data() as described earlier.
checking the cb_id of the userdata from g_signal... and also getting
this extra value helps your positively identify which button was
pressed.
Either method will work, but sometimes both come in handy.
Hope that helps. Also, here is a link to source code that may help
explain better.
http://mysite.verizon.net/ressgdw8/sitebuildercontent/sitebuilderfiles/gtkstatusicon-starter-program-0.1.0.tar.bz2
And don't forget to review 'gtk-demo', it has good examples.
James,
On Sun, 2009-01-11 at 12:42 +0100, Rudolfo Pinewood wrote:
Hi,
I have a question regarding Callback functions for Toggle buttons.
I have several togglebuttons, that are all registered to call one
specific function (ApplyFlags). In this function I actually don't know
which button was activated.
My attempt was giving each button/callback an additional parameter that
should be passed to my ApplyFlags function.
However I was not able to do so - MemberCaller1 seems to fit (regarding
the call one function with one parameter) but I did not manage to get
my parameter into that Callback in
g_signal_connect_swapped(G_OBJECT(button), toggled,
G_CALLBACK(callback.getThunk()), callback.getEnvironment()).
How could this be done?
Thanks in advance
Christoph Hartwig
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Re: Question about Callback
Hi,
thanks again for your help.
1) I did change my function to a static one
2) I updated my g_signal_connect_swapped to use G_CALLBACK(staticfunc) +
param parent (which I use to get the other buttons)
3) I noticed that the pointers were in wrong order (parent was the first
one instead of second) - changed to g_signal_connect instead and order
is right.
I now can use my function as desired. I only have to integrate some
other fields, but I think I'll get that ready with the knowledge I
received here.
Many thanks!
Christoph Hartwig
James Scott Jr schrieb:
Rudolfo,
In your case where you have multiple buttons operating on the same
logical data field, using a single callback function is very practical.
The same can be said for a callback that performs a single logical
function, all windows/object should attempt to reuse that callback if
they need that functions.
Example; being a pair of callback I wrote that is called when a window
is hidden or shown. All my dialogs/windows that need that service reuse
those single callbacks. To handle the fact that each window instance
saves its visibility value in a different variable/address, I pass into
the g_signal_connect(..., b_visible) the address of that variable when
creating each window.
void cb_main_interface_show (GtkWidget * widget, gboolean *pb_visible)
{
g_return_if_fail (pb_visible != NULL);
*pb_visible = TRUE;
}
void cb_main_interface_hide (GtkWidget * widget, gboolean *pb_visible)
{
g_return_if_fail (pb_visible != NULL);
*pb_visible = FALSE;
}
To me this helps organize the code and makes it easier to maintain. The
cost of this reuse is fairly low, and the g_object_[set|get]_data()
along with user-data cb_id flags, normally handles it well. Of course
all this reuse can be impacted by the to many global/static variables --
which limits the re-entrancy or reuse of any program.
My two.
James,
On Tue, 2009-01-13 at 20:40 +0100, Rudolfo Pinewood wrote:
Hi,
thanks for your answer. I think I understand my code a bit better now...
I wonder whether it is best practice to use static functions for these
callbacks - in my code it is actually a member function (because of
having many different buttons whose states form a bitfield that is
compressed to one int value. I did not find any example that does not
use such static functions.
Greetings,
Christoph Hartwig
James Scott Jr schrieb:
You can also use:
- in the routine that creates the button, save a unique value.
g_object_set_data(G_OBJECT(button), Unique-Key, some-value)
-in button callback routine, retrieve the unique value.
some-value-pointer = g_object_get_data(G_OBJECT(button), Unique-Key);
This in addition to any pre-allocated memory structure you passed in the
g_signal_connect(), or g_signal_connect_swapped(). The issue with
reuse of button callbacks is always how to determine which button! I do
two things;
1. pre-allocate a memory structure with the first value a fixed id of
some sort (or related to the button's function). example
#def EXIT_BUTTON_FLAG 1
.
.
.
typedef struct _SomeButton {
gint cb_id;
...
} SomeButton, *PSomeButton;
.
.
.
PSomeButton memButton = NULL;
.
memButton = g_new0(SomeButton, 1);
memButton-cb_id = EXIT_BUTTON_CBID;
.
g_signal_connect(G_OBJECT(button), toggled,
G_CALLBACK(fn_callback), memButton);
.
.
2. g_object_set_data() and g_object_get_data() as described earlier.
checking the cb_id of the userdata from g_signal... and also getting
this extra value helps your positively identify which button was
pressed.
Either method will work, but sometimes both come in handy.
Hope that helps. Also, here is a link to source code that may help
explain better.
http://mysite.verizon.net/ressgdw8/sitebuildercontent/sitebuilderfiles/gtkstatusicon-starter-program-0.1.0.tar.bz2
And don't forget to review 'gtk-demo', it has good examples.
James,
On Sun, 2009-01-11 at 12:42 +0100, Rudolfo Pinewood wrote:
Hi,
I have a question regarding Callback functions for Toggle buttons.
I have several togglebuttons, that are all registered to call one
specific function (ApplyFlags). In this function I actually don't know
which button was activated.
My attempt was giving each button/callback an additional parameter that
should be passed to my ApplyFlags function.
However I was not able to do so - MemberCaller1 seems to fit (regarding
the call one function with one parameter) but I did not manage to get
my parameter into that Callback in
g_signal_connect_swapped(G_OBJECT(button), toggled,
G_CALLBACK(callback.getThunk()), callback.getEnvironment()).
How could this be done?
Thanks in advance
Christoph Hartwig
___
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gtk-app-devel-list@gnome.org
http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
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gtk-app-devel-list mailing list
gtk-app-devel-list@gnome.org
http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Question about Callback
Rudolfo,
In your case where you have multiple buttons operating on the same
logical data field, using a single callback function is very practical.
The same can be said for a callback that performs a single logical
function, all windows/object should attempt to reuse that callback if
they need that functions.
Example; being a pair of callback I wrote that is called when a window
is hidden or shown. All my dialogs/windows that need that service reuse
those single callbacks. To handle the fact that each window instance
saves its visibility value in a different variable/address, I pass into
the g_signal_connect(..., b_visible) the address of that variable when
creating each window.
void cb_main_interface_show (GtkWidget * widget, gboolean *pb_visible)
{
g_return_if_fail (pb_visible != NULL);
*pb_visible = TRUE;
}
void cb_main_interface_hide (GtkWidget * widget, gboolean *pb_visible)
{
g_return_if_fail (pb_visible != NULL);
*pb_visible = FALSE;
}
To me this helps organize the code and makes it easier to maintain. The
cost of this reuse is fairly low, and the g_object_[set|get]_data()
along with user-data cb_id flags, normally handles it well. Of course
all this reuse can be impacted by the to many global/static variables --
which limits the re-entrancy or reuse of any program.
My two.
James,
On Tue, 2009-01-13 at 20:40 +0100, Rudolfo Pinewood wrote:
Hi,
thanks for your answer. I think I understand my code a bit better now...
I wonder whether it is best practice to use static functions for these
callbacks - in my code it is actually a member function (because of
having many different buttons whose states form a bitfield that is
compressed to one int value. I did not find any example that does not
use such static functions.
Greetings,
Christoph Hartwig
James Scott Jr schrieb:
You can also use:
- in the routine that creates the button, save a unique value.
g_object_set_data(G_OBJECT(button), Unique-Key, some-value)
-in button callback routine, retrieve the unique value.
some-value-pointer = g_object_get_data(G_OBJECT(button), Unique-Key);
This in addition to any pre-allocated memory structure you passed in the
g_signal_connect(), or g_signal_connect_swapped(). The issue with
reuse of button callbacks is always how to determine which button! I do
two things;
1. pre-allocate a memory structure with the first value a fixed id of
some sort (or related to the button's function). example
#def EXIT_BUTTON_FLAG 1
.
.
.
typedef struct _SomeButton {
gint cb_id;
...
} SomeButton, *PSomeButton;
.
.
.
PSomeButton memButton = NULL;
.
memButton = g_new0(SomeButton, 1);
memButton-cb_id = EXIT_BUTTON_CBID;
.
g_signal_connect(G_OBJECT(button), toggled,
G_CALLBACK(fn_callback), memButton);
.
.
2. g_object_set_data() and g_object_get_data() as described earlier.
checking the cb_id of the userdata from g_signal... and also getting
this extra value helps your positively identify which button was
pressed.
Either method will work, but sometimes both come in handy.
Hope that helps. Also, here is a link to source code that may help
explain better.
http://mysite.verizon.net/ressgdw8/sitebuildercontent/sitebuilderfiles/gtkstatusicon-starter-program-0.1.0.tar.bz2
And don't forget to review 'gtk-demo', it has good examples.
James,
On Sun, 2009-01-11 at 12:42 +0100, Rudolfo Pinewood wrote:
Hi,
I have a question regarding Callback functions for Toggle buttons.
I have several togglebuttons, that are all registered to call one
specific function (ApplyFlags). In this function I actually don't know
which button was activated.
My attempt was giving each button/callback an additional parameter that
should be passed to my ApplyFlags function.
However I was not able to do so - MemberCaller1 seems to fit (regarding
the call one function with one parameter) but I did not manage to get
my parameter into that Callback in
g_signal_connect_swapped(G_OBJECT(button), toggled,
G_CALLBACK(callback.getThunk()), callback.getEnvironment()).
How could this be done?
Thanks in advance
Christoph Hartwig
___
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gtk-app-devel-list@gnome.org
http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
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Question about Callback
Hi, I have a question regarding Callback functions for Toggle buttons. I have several togglebuttons, that are all registered to call one specific function (ApplyFlags). In this function I actually don't know which button was activated. My attempt was giving each button/callback an additional parameter that should be passed to my ApplyFlags function. However I was not able to do so - MemberCaller1 seems to fit (regarding the call one function with one parameter) but I did not manage to get my parameter into that Callback in g_signal_connect_swapped(G_OBJECT(button), toggled, G_CALLBACK(callback.getThunk()), callback.getEnvironment()). How could this be done? Thanks in advance Christoph Hartwig ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Question about Callback
On Sun, 11 Jan 2009 12:42:41 +0100 Rudolfo Pinewood rudolfo.pinew...@googlemail.com wrote: I have several togglebuttons, that are all registered to call one specific function (ApplyFlags). In this function I actually don't know which button was activated. My attempt was giving each button/callback an additional parameter that should be passed to my ApplyFlags function. You yet have the caller widget in ApplyFlags(). If you're using g_signal_connect_swapped(), just use the second arg: void ApplyFlags(gpointer your_data, GtkWidget *button) Ciao -- Nicola ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
