gtk2-perl / allowing functions with callbacks to be wrapped

[Guillaume Cottenceau <gc mandrakesoft com>]

Hi,

This morning I've worked on one of the still missing things in
gtk2-perl: we haven't wrapped any function that take a callback
as a parameter - the WhateverFunc typed parameters - for example
in the following function:

void gtk_tree_selection_selected_foreach(GtkTreeSelection *selection,
                                         GtkTreeSelectionForeachFunc func,
                                         gpointer data);

I've extended `genscripts/castmacros-autogen.pl' to be able to
automatically generate a marshal function for all the function
types. One just has to call it with one parameter indicating the
desired type name:

-=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=--
[gc obiwan ~/cvs/gtk2-perl] perl genscripts/castmacros-autogen.pl GtkTreeSelectionForeachFunc
/* auto generated marshal for GtkTreeSelectionForeachFunc (using genscripts/castmacros-autogen.pl 
GtkTreeSelectionForeachFunc) */
void marshal_GtkTreeSelectionForeachFunc(GtkTreeModel *model, GtkTreePath *path, GtkTreeIter *iter, gpointer 
data)
{
    struct callback_data * cb_data = data;
    dSP;
    ENTER;
    SAVETMPS;
    PUSHMARK(SP);
    XPUSHs(sv_2mortal(gtk2_perl_new_object_from_pointer_nullok(model, "Gtk2::TreeModel")));
    XPUSHs(sv_2mortal(gtk2_perl_new_object_from_pointer_nullok(path, "Gtk2::TreePath")));
    XPUSHs(sv_2mortal(gtk2_perl_new_object_from_pointer_nullok(iter, "Gtk2::TreeIter")));
    XPUSHs(cb_data->data);
    PUTBACK;
    perl_call_sv(cb_data->pl_func, G_DISCARD);
    FREETMPS;
    LEAVE;
}
-=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=--

Then, we copy that auto-generated code to the good .c file (in
our example, Gtk2/src/TreeSelection.c), and add the following
wrapper function:

-=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=--
void gtkperl_tree_selection_selected_foreach(SV* selection, SV* func, SV* data)
{
    struct callback_data cb_data = { func, data };
    gtk_tree_selection_selected_foreach(SvGtkTreeSelection(selection), marshal_GtkTreeSelectionForeachFunc, 
&cb_data);
}
-=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=---=-=--

Pretty simple :).


There is an additional complexity for functions which install
callbacks to be called later on (cb_data needs to be allocated on
the heap, and some refcount manipulation needs to be performed),
but the story is similar (see the wrapper for
gtk_tree_selection_set_select_function if interested).


-- 
Guillaume Cottenceau - http://people.mandrakesoft.com/~gc/