A GtkFileFilter can be used to restrict the files being shown in a FileChooser.

Files can be filtered based on their name (with add_pattern), on their mime type (with add_mime_type), or by a custom filter function (with add_custom).

Filtering by mime types handles aliasing and subclassing of mime types; e.g. a filter for text/plain also matches a file with mime type application/rtf, since application/rtf is a subclass of text/plain. Note that FileFilter allows wildcards for the subtype of a mime type, so you can e.g. filter for image/\*.

Normally, filters are used by adding them to a FileChooser, see add_filter, but it is also possible to manually use a filter on a file with filter.

GtkFileFilter as GtkBuildable

The GtkFileFilter implementation of the GtkBuildable interface supports adding rules using the `<mime-types>`, `<patterns>` and ` <applications>` elements and listing the rules within. Specifying a `<mime-type>` or `<pattern>` has the same effect as as calling add_mime_type or add_pattern.

An example of a UI definition fragment specifying GtkFileFilter rules:

<object class="GtkFileFilter">
  <mime-types>
    <mime-type>text/plain</mime-type>
    <mime-type>image/ *</mime-type>
  </mime-types>
  <patterns>
    <pattern>*.txt</pattern>
    <pattern>*.png</pattern>
  </patterns>
</object>

Example: FileFilter:

public static int main (string[] args) {
	Gtk.init (ref args);

	Gtk.FileChooserDialog dialog = new Gtk.FileChooserDialog ("Select a File", null, Gtk.FileChooserAction.OPEN);

	Gtk.FileFilter filter = new Gtk.FileFilter ();
	filter.set_filter_name ("All Files");
	filter.add_pattern ("*");
	dialog.add_filter (filter);

	filter = new Gtk.FileFilter ();
	filter.set_filter_name ("Images");
	filter.add_pattern ("*.png");
	filter.add_pattern ("*.jpg");
	filter.add_pattern ("*.bmp");
	dialog.add_filter (filter);

	filter = new Gtk.FileFilter ();
	filter.set_filter_name ("Audio");
	filter.add_pattern ("*.ogg");
	filter.add_pattern ("*.flac");
	dialog.add_filter (filter);

	dialog.run ();
	dialog.destroy ();
	return 0;
}

valac --pkg gtk+-3.0 Gtk.FileFilter.vala