GtkFileChooser filter API

[Owen Taylor <otaylor redhat com>]

One of the open issues for the GtkFileChooser API is that of filters.
There was some discussion of this earlier, though nothing was exactly
resolved.

Here's an API proposal:

==========
/* GtkFileFilter is an opaque GtkObject for for Float/Sink
 */
typedef struct _GtkFileFilter GtkFileFilter;

GtkFileFilter *gtk_file_filter_new         (void);

/* Name to display in selectable list */
void           gtk_file_filter_set_name    (GtkFileFilter *filter,
                                            const gchar   *name);
/* Shell-style glob */
void           gtk_file_filter_add_pattern (GtkFileFilter *filter,
                                            const gchar   *pattern);

/* Mime-type */
void           gtk_file_filter_add_mime_type (GtkFileFilter *filter
                                              const gchar   *mime_type);

/* Sets the current filter; can be called with an empty list
 * of user selectable filters
 */
void gtk_file_filter_set_filter (GtkFileChooser *chooser,
                                 GtkFileFilter  *filter);

/* List of user selectable filters
 */
void   gtk_file_chooser_add_filter       (GtkFileChooser *chooser,
                                          GtkFileFilter  *filter);
void   gtk_file_chooser_remove_filter    (GtkFileChooser *chooser,
                                          GtkFileFilter  *filter);
GList *gtk_file_filter_list_filters      (GtkFileChooser *choooser);
=========

One possible variation is to to make GtkFileFilter an abstract
base class:

====
GtkFileFilter *gtk_file_filter_pattern_new (const gchar *pattern);
GtkFileFilter *gtk_file_filter_mime_new    (const gchar *mime_type);
GtkFileFilter *gtk_file_filter_multi_new   (void);
void           gtk_file_filter_multi_add_filter (GtkFileFilterMulti *filter_multi,
                                                 GtkFileFilter      *filter);
====

This is a bit conceptually cleaner and you could even allow custom 
derivation from GtkFileFilter if you did that. I'm not sure it's worth 
the complexity however.

A different way to allow custom filters without the derivation
thing going on would be:

===
gboolean (*GtkFileFilterFunc) (const gchar *filename,
                               const gchar *uri,
                               const gchar *mime_type,
                               gpointer     data);

void gtk_file_filter_add_custom (GtkFileFilter    *filter,
                                 GtkFileFilterFunc func,
                                 gointer           data,
                                 GDestroyNotify    notify);
===

Any sort of custom filter system will cause difficulties for 
an out-of-process implementation of GtkFileChooser; that's not
something I'm particularly interested in, but there have been
requests to leave the possibility open for the future.

Regards,
						Owen