desktop-entry: separate icon and app_id icon lookup

This patch splits desktop_entry_icon_lookup() into two separate functions
- desktop_entry_load_icon(): load a icon from the configured icon theme
- desktop_entry_load_icon_from_app_id(): load a icon name from a .desktop
  file based on the given app_id and supply it to _load_icon().

The _load_icon() function will be used in a future menu icon
implementation whereas the _load_icon_from_app_id() function is used
within the SSD titlebar window icon lookup routine.

include/desktop-entry.h

@@ -7,8 +7,11 @@ struct server;
 void desktop_entry_init(struct server *server);
 void desktop_entry_finish(struct server *server);
 
-struct lab_img *desktop_entry_icon_lookup(struct server *server,
+struct lab_img *desktop_entry_load_icon_from_app_id(
-	const char *app_id, int size, float scale);
+	struct server *server, const char *app_id, int size, float scale);
+
+struct lab_img *desktop_entry_load_icon(
+	struct server *server, const char *icon_name, int size, float scale);
 
 /**
  * desktop_entry_name_lookup() - return the application name

src/desktop-entry.c

@@ -299,8 +299,47 @@ convert_img_type(enum sfdo_icon_file_format fmt)
 }
 
 struct lab_img *
-desktop_entry_icon_lookup(struct server *server, const char *app_id, int size,
+desktop_entry_load_icon(struct server *server, const char *icon_name, int size, float scale)
-		float scale)
+{
+	/* static analyzer isn't able to detect the NULL check in string_null_or_empty() */
+	if (string_null_or_empty(icon_name) || !icon_name) {
+		return NULL;
+	}
+
+	struct sfdo *sfdo = server->sfdo;
+	if (!sfdo) {
+		return NULL;
+	}
+
+	/*
+	 * libsfdo doesn't support loading icons for fractional scales,
+	 * so round down and increase the icon size to compensate.
+	 */
+	int lookup_scale = MAX((int)scale, 1);
+	int lookup_size = lroundf(size * scale / lookup_scale);
+
+	struct icon_ctx ctx = {0};
+	int ret;
+	if (icon_name[0] == '/') {
+		ret = process_abs_name(&ctx, icon_name);
+	} else {
+		ret = process_rel_name(&ctx, icon_name, sfdo, lookup_size, lookup_scale);
+	}
+	if (ret < 0) {
+		wlr_log(WLR_INFO, "failed to load icon file %s", icon_name);
+		return NULL;
+	}
+
+	wlr_log(WLR_DEBUG, "loading icon file %s", ctx.path);
+	struct lab_img *img = lab_img_load(convert_img_type(ctx.format), ctx.path, NULL);
+
+	free(ctx.path);
+	return img;
+}
+
+struct lab_img *
+desktop_entry_load_icon_from_app_id(struct server *server,
+		const char *app_id, int size, float scale)
 {
 	if (string_null_or_empty(app_id)) {
 		return NULL;
@@ -317,37 +356,11 @@ desktop_entry_icon_lookup(struct server *server, const char *app_id, int size,
 		icon_name = sfdo_desktop_entry_get_icon(entry, NULL);
 	}
 
-	/*
+	struct lab_img *img = desktop_entry_load_icon(server, icon_name, size, scale);
-	 * libsfdo doesn't support loading icons for fractional scales,
+	if (!img) {
-	 * so round down and increase the icon size to compensate.
+		/* Icon not defined in .desktop file or could not be loaded */
-	 */
+		img = desktop_entry_load_icon(server, app_id, size, scale);
-	int lookup_scale = MAX((int)scale, 1);
-	int lookup_size = lroundf(size * scale / lookup_scale);
-
-	struct icon_ctx ctx = {0};
-	int ret;
-	if (!icon_name) {
-		/* fall back to app id */
-		ret = process_rel_name(&ctx, app_id, sfdo, lookup_size, lookup_scale);
-	} else if (icon_name[0] == '/') {
-		ret = process_abs_name(&ctx, icon_name);
-	} else {
-		/* this should be the case for most icons */
-		ret = process_rel_name(&ctx, icon_name, sfdo, lookup_size, lookup_scale);
-		/* Icon defined in .desktop file could not be loaded, retry with app_id */
-		if (ret < 0) {
-			ret = process_rel_name(&ctx, app_id, sfdo, lookup_size, lookup_scale);
-		}
 	}
-	if (ret < 0) {
-		return NULL;
-	}
-
-	wlr_log(WLR_DEBUG, "loading icon file %s", ctx.path);
-	struct lab_img *img = lab_img_load(convert_img_type(ctx.format), ctx.path, NULL);
-
-	free(ctx.path);
-
 	return img;
 }
 

src/ssd/ssd-titlebar.c

@@ -609,7 +609,7 @@ ssd_update_window_icon(struct ssd *ssd)
 	 */
 	float icon_scale = output_max_scale(ssd->view->server);
 
-	struct lab_img *icon_img = desktop_entry_icon_lookup(
+	struct lab_img *icon_img = desktop_entry_load_icon_from_app_id(
 		ssd->view->server, app_id, icon_size, icon_scale);
 	if (!icon_img) {
 		wlr_log(WLR_DEBUG, "icon could not be loaded for %s", app_id);