Re: [gtk-list] YATU - Yet Another Tutorial Update

[Tim Janik <timj psynet net>]

On Wed, 30 Jul 1997, Ian Main wrote:

> There is also a third component called glib which contains a few
> replacements for printf, malloc etc.  These are used to increase gtk's
> portability, as some of the functions implemented here are not available on
> all unicies.   Some also contain enhancements to the libc versions (such as
> g_malloc), and others (such as g_strerror) will even pop up windows for you
> printing your error string.

hup? nope, for the moment there are no functions that will pop up a window
for you, but that could easily be implemented by consequent use of these
functions.
g_strerror and g_strsignal will only provide you with an explanatory string
for the given errno-state.


[snip]
> The last line enters the GTK main processing loop.
> 
>   gtk_main ();
> 
> gtk_main() is another call you will see in every gtk application.  When
> control reaches this point, gtk will sleep waiting for X events (such as
> button or keypresses) to occur. 
> In our simple example however, no events will be registered.

not fully correct ;)
there are a few events that will occour from the X-server, like the first
expose event after the windows creation. also there will be a few events,
that are mostly gtk-internal like SHOW, MAP, REALIZE, DRAW, SIZE_ALLOCATE...
also if you move the mouse across your empty window, you will genereate
ENTER_NOTIFY_EVENT and LEAVE_NOTIFY_EVENT. you can even click into the
window generting a BUTTON_PRESS_EVENT, there is just no function bound
to it.
[hm, taht was a little excessive... ;) ]



[snip]
>        /* and the window */
>        gtk_widget_show (window);
> 
>        /* all gtk applications must have a gtk_main().  Control ends here
>         * and waits for an event to occur (like a key press or mouse event). */
>        gtk_main ();
> 
>        return 0;
>      }

you might want to explain also, that gtk_exit(0) will be called, if the program
finishes, as well as gdk_exit(). these functions free some previously allocated
memory and do some else clean up like closing the XDisplay.

[snip]
> 
> 4) pack the widget into a container using gtk_container_add() or
> gtk_box_pack_start() (are there others ?).

yep there are a lot others, but besides GtkNotebook, the gtk_container_add()
function will always call the corresponding gtk_widget_add() function with
apropriate defaults. like gtk_container_add() for boxes will just call
gtk_box_pack_start_defaults(,) with it's arguments, which in turn calls
gtk_box_pack_start(,, TRUE, TRUE, 0).


[snip]
> 
> PACKING
> 

[snip]

> void gtk_box_pack_start (GtkBox    *box,
>                          GtkWidget *child,
>                          gint       expand,
>                          gint       fill,
>                          gint       padding);
> 

[snip]

> The fill argument to the gtk_box_pack functions control whether the extra
> space is allocated to the objects themselves (TRUE), or as extra padding
> in the box around these objects (FALSE). It only has an effect if the
> expand argument is also TRUE. 
> 
> [does the above sound right to you ?]

if the box is homogenous, all expand arguments of widgets that will be put
into it are implicitly set to TRUE. that means if you call
gtk_box_pack_start() with expand and fill set to FALSE, you might still
get a smaller allocation width for your widget if the box is homogenous.

> 
> When creating a new box, the function looks like this:
> 
> GtkWidget * gtk_hbox_new (gint homogeneous,
>                           gint spacing);
> 
> The homogeneous argument to gtk_hbox_new (and the same for gtk_vbox_new) 
> controls whether each object in the box has the same size (i.e. the same
> width in an hbox, or the same height in a vbox). If it is set, the expand
> argument to the gtk_box_pack routines is always turned on.

ups - sorry, you mentioned it here ;)


[snip]
> TIMEOUTS, IO, AND IDLE FUNCTIONS
> 
> TIMEOUTS
> 
> You may be wondering how you make gtk do useful work when in gtk_main.
> Well, you have several options.  Using the following functions you can
> create a timeout function.
> 
> gint gtk_timeout_add (guint32 interval,
>                       GtkFunction function,
> 		      gpointer data);
> 
> The first arguement is the number of milliseconds [doublecheck this] 
				       ^^^^^^^^^^^^ correct! ;)

[snip]

> This tutorial is written and maintained by Ian Main <slow@intergate.bc.ca>
> This is free software, you may use any of these examples in any of your
> code without including any disclaimer or copyright notice. 
> 
> Many thanks to the contributors
> 
> Bawer Dagdeviren <chamele0n@geocities.com>  (tutorial on menus)
> 
> And to the following from whom I stole^H^H^H^H^H borrowed some material
> 
> Raph Levien <raph@acm.org> (widget packing code and examples)
> Peter Mattis <petm@xcf.berkeley.edu>
> 
> And to all of you who commented and helped refine this document.
> 
> Thanks.

wow, that's quite a bunch of information so far - i'm impressed!

---
ciaoTJ