From 06af1a3cc9920780c7edeba34677fc66b18ff5eb Mon Sep 17 00:00:00 2001
From: Přemysl Eric Janouch <p@janouch.name>
Date: Thu, 18 Nov 2021 12:44:25 +0100
Subject: Add a command line option to list supported types

Make it work without a display connection.
---
 fastiv-io.c | 22 ++++++++++++++++++++++
 fastiv-io.h |  2 ++
 fastiv.c    | 25 ++++++++++++++++++-------
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/fastiv-io.c b/fastiv-io.c
index 82c3229..e1bb60a 100644
--- a/fastiv-io.c
+++ b/fastiv-io.c
@@ -78,6 +78,28 @@ const char *fastiv_io_supported_media_types[] = {
 	NULL
 };
 
+char **
+fastiv_io_all_supported_media_types(void)
+{
+	GPtrArray *types = g_ptr_array_new();
+	for (const char **p = fastiv_io_supported_media_types; *p; p++)
+		g_ptr_array_add(types, g_strdup(*p));
+
+#ifdef HAVE_GDKPIXBUF
+	GSList *formats = gdk_pixbuf_get_formats();
+	for (GSList *iter = formats; iter; iter = iter->next) {
+		gchar **subtypes = gdk_pixbuf_format_get_mime_types(iter->data);
+		for (gchar **p = subtypes; *p; p++)
+			g_ptr_array_add(types, *p);
+		g_free(subtypes);
+	}
+	g_slist_free(formats);
+#endif  // HAVE_GDKPIXBUF
+
+	g_ptr_array_add(types, NULL);
+	return (char **) g_ptr_array_free(types, FALSE);
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 #define FASTIV_IO_ERROR fastiv_io_error_quark()
diff --git a/fastiv-io.h b/fastiv-io.h
index 6275bc2..5a90e91 100644
--- a/fastiv-io.h
+++ b/fastiv-io.h
@@ -22,6 +22,8 @@
 
 extern const char *fastiv_io_supported_media_types[];
 
+char **fastiv_io_all_supported_media_types(void);
+
 cairo_surface_t *fastiv_io_open(const gchar *path, GError **error);
 cairo_surface_t *fastiv_io_open_from_data(
 	const char *data, size_t len, const gchar *path, GError **error);
diff --git a/fastiv.c b/fastiv.c
index 7162a53..70210b1 100644
--- a/fastiv.c
+++ b/fastiv.c
@@ -396,24 +396,33 @@ on_button_press_browser(G_GNUC_UNUSED GtkWidget *widget, GdkEventButton *event)
 int
 main(int argc, char *argv[])
 {
-	gboolean show_version = FALSE;
+	gboolean show_version = FALSE, show_supported_media_types = FALSE;
 	gchar **path_args = NULL;
 	const GOptionEntry options[] = {
 		{G_OPTION_REMAINING, 0, 0, G_OPTION_ARG_FILENAME_ARRAY, &path_args,
 			NULL, "[FILE | DIRECTORY]"},
+		{"list-supported-media-types", 0, G_OPTION_FLAG_IN_MAIN,
+			G_OPTION_ARG_NONE, &show_supported_media_types,
+			"Output supported media types and exit", NULL},
 		{"version", 'V', G_OPTION_FLAG_IN_MAIN, G_OPTION_ARG_NONE,
-			&show_version, "output version information and exit", NULL},
+			&show_version, "Output version information and exit", NULL},
 		{},
 	};
 
 	GError *error = NULL;
-	if (!gtk_init_with_args(
-			&argc, &argv, " - fast image viewer", options, NULL, &error))
-		exit_fatal("%s", error->message);
+	gboolean initialized = gtk_init_with_args(
+		&argc, &argv, " - fast image viewer", options, NULL, &error);
 	if (show_version) {
 		printf(PROJECT_NAME " " PROJECT_VERSION "\n");
 		return 0;
 	}
+	if (show_supported_media_types) {
+		for (char **types = fastiv_io_all_supported_media_types(); *types; )
+			g_print("%s\n", *types++);
+		return 0;
+	}
+	if (!initialized)
+		exit_fatal("%s", error->message);
 
 	// NOTE: Firefox and Eye of GNOME both interpret multiple arguments
 	// in a special way. This is problematic, because one-element lists
@@ -506,8 +515,10 @@ main(int argc, char *argv[])
 		G_CALLBACK(on_key_press), NULL);
 	gtk_container_add(GTK_CONTAINER(g.window), g.stack);
 
-	// TODO(p): Also milk gdk-pixbuf, if linked in, needs to be done in runtime.
-	g.supported_globs = extract_mime_globs(fastiv_io_supported_media_types);
+	char **types = fastiv_io_all_supported_media_types();
+	g.supported_globs = extract_mime_globs((const char **) types);
+	g_strfreev(types);
+
 	g.files = g_ptr_array_new_full(16, g_free);
 	gchar *cwd = g_get_current_dir();
 
-- 
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