These are my notes when I first started on generating source code in Glade.
They are a bit out-of-date now.


Writing Source Code
===================

My original notes:
	- C first, other languages later hopefully (any volunteers??).
	- Write create_<window_name>() functions for all windows in one file
	  and write prototypes of signal handlers in another file which the
	  user can edit. Could alternatively put each window in a separate
	  file.
	- Hopefully it would be possible to edit the interface again after
	  code has been added by the user. If the user doesn't change the
	  window creation code that would be possible. New signal handler
	  prototypes could be added on to the end of the handlers file.
	- Need to allow the creation of multiple windows of the same type,
	  so need to be careful about global variable naming. My current
	  idea is to use the object hash of each window to store pointers
	  to all the widgets in the window, using the name as the key. That
	  would make it easy for the programmer to access any widget.
	- Also need to be careful about the order of some Gtk commands.
	  Some of them need the widget to be realized first etc.
	  e.g. gtk_widget_grab_default() must be after setting CAN_DEFAULT.
	  + need to realize a widget to create pixmaps.
	  + need to realize a text widget before setting the text?
	- Output resource '.rc' files?
	- See the section on Custom widgets.
	- Ouput Makefile, or better a Makefile.am and configure.in?
	- Should pixmaps be included in the source, or loaded from a file
	  when the program is run? Project option? Also, should make pixmap
	  filenames relative, so code tree is portable.


I think you need to make several passes through the widget tree, so for
external programs using Glade's output, you'll have to read in a component
at a time. (Actually I did the C code in one pass, adding code to several
buffers which are then output in the correct order.)

I'm thinking of C output here. For other languages this may be different.

There are 4 output files - two pairs of .c & .h files.
The first pair contains code to create the components, and declarations.
The second pair contains empty signal handler functions, and declarations.


Strings
=======

NOTE: be careful with strings in the resulting code. I added a function
source_make_string() which converts all non-printable characters to escape
codes so that the output can be compiled OK.

e.g. if you have a label with the text:

"first \line
second line"

It is converted to

"first \\line\nsecond line"

when output.


Stages:
=======

1. Write start of all 4 files -
      For main source file:
	#include <gtk/gtk.h>
	#include "<main source file>.h"
	#include "<signal handler declarations>.h"

      For signal handler source file:
	#include <gtk/gtk.h>
	#include "<main source file>.h"
	#include "<signal handler declarations>.h"


	(Any globals needed?)
	possibly some utility functions like create/load_pixmap()
	also convenience function to get a widget from the widget hash,
	could be called with any widget in a component - calls get_toplevel()
	to get the component, then get_data to get the named widget.

	create all styles in an init() function? or just named styles?
	- create widget's own styles in widget code?


2. Iterate over components:

2.1 Write function prototype to source file -
      Add to main source file:
	GtkWidget* create_<component name>() {

      Add to main header file:
	GtkWidget* create_<component name>();

2.2 Write variable declarations. For this we need to scan the component
    hierarchy to collect the types and names needed, e.g.
	GtkWidget *window1, *hbox1, *table1, *entry1, *label1, *label2; ...
	GtkTooltips *tooltips;

2.3 Create tooltips if needed by the component. (May need to walk the tree to
    find out if tooltips are needed.)
	tooltips = gtk_tooltips_new();

2.4 Walk the hierarchy, creating and adding widgets as we go. We also have to
    set up any signals and accelerators.

      Add to main source file:
	entry1 = gtk_entry_new();
	gtk_box_pack_start(GTK_BOX(hbox1), entry, TRUE, TRUE, 2);
	gtk_entry_set_editable(GTK_ENTRY(entry1), FALSE);
	gtk_entry_set_visible(GTK_ENTRY(entry1), FALSE);
	gtk_signal_connect(GTK_OBJECT(entry1), "key_press_event",
			   GTK_SIGNAL_FUNC(on_entry1_key_press_event), NULL);

      Add widget to hash of component? - So programmers can find easily.
      The other alternative is to create a struct for each component which
      contains all the widgets in it.

      Add to handlers header file (Note: we have to figure out the prototype):
	gint on_entry1_key_press_event(GtkWidget *widget, GdkEventKey *event,
				       gpointer data);

      Add to handlers source file:
	gint on_entry1_key_press_event(GtkWidget *widget, GdkEventKey *event,
				       gpointer data) {

	  return FALSE;
	}

    Note: for events which correspond to X events add 'return FALSE' as above,
    so that code will run OK without changes.
    Note: if we try to use Args wherever possible, then the output may be
    more portable to other languages?


2.5 Write function end. For C that's just '}'.



Damon, 24 June 1998