Add --write-defaults command line switch

doc/katarakt.txt

@@ -43,6 +43,9 @@ OPTIONS
 	Quit on initialization failure.
 *-h*, *--help* ::
 	Print help and exit.
+*--write-defaults* 'FILE'::
+	Write the built-in default configuration to 'FILE' and exit. Hint: on unix
+	systems, you can use '--write-defaults /dev/stdout' to print the defaults.
 *--single-instance* 'true'|'false'::
 	Sets *single_instance_per_file* for the present katarakt instance only.
 

src/config.cpp

@@ -5,7 +5,15 @@
 CFG::CFG() :
 		settings(QSettings::IniFormat, QSettings::UserScope, "katarakt") {
 	// TODO warn about invalid user input
+	init_defaults();
+}
+
+CFG::CFG(const char* file) :
+		settings(file, QSettings::IniFormat) {
+	init_defaults();
+}
 
+void CFG::init_defaults() {
 	settings.beginGroup("Settings");
 	// canvas options
 	defaults["background_color"] = "0xDF000000";
@@ -126,6 +134,15 @@ CFG *CFG::get_instance() {
 	return &instance;
 }
 
+void CFG::write_defaults(const char *file) {
+	CFG inst(file);
+	inst.settings.clear();
+	inst.settings.setFallbacksEnabled(false);
+	inst.set_defaults();
+	inst.settings.sync();
+	get_instance();
+}
+
 QVariant CFG::get_value(const char *key) const {
 	return settings.value(QString("Settings/") + key, defaults[key]);
 }

src/config.h

@@ -12,9 +12,11 @@ class CFG {
 private:
 	CFG();
 	CFG(const CFG &other);
+	CFG(const char *file);
 	CFG &operator=(const CFG &other);
 	~CFG();
 
+	void init_defaults();
 	void set_defaults();
 
 	QSettings settings;
@@ -24,6 +26,7 @@ private:
 
 public:
 	static CFG *get_instance();
+	static void write_defaults(const char *file); // write defaults to file
 
 	QVariant get_value(const char *key) const;
 	void set_value(const char *key, QVariant value);

src/main.cpp

@@ -22,6 +22,7 @@ static void print_help(char *name) {
 	cout << "  -f, --fullscreen             Start in fullscreen mode" << endl;
 	cout << "  -q, --quit                   Quit on initialization failure" << endl;
 	cout << "  -h, --help                   Print this help and exit" << endl;
+	cout << "  --write-defaults FILE        Write the default configuration to FILE and exit" << endl;
 	cout << "  --single-instance true|false Whether to have a single instance per file" << endl;
 }
 
@@ -36,6 +37,7 @@ int main(int argc, char *argv[]) {
 		{"quit",		no_argument,		NULL,	'q'},
 		{"help",		no_argument,		NULL,	'h'},
 		{"single-instance",	required_argument,	NULL,	0},
+		{"write-defaults",	required_argument,	NULL,	0},
 		{NULL, 0, NULL, 0}
 	};
 	int option_index = 0;
@@ -52,6 +54,9 @@ int main(int argc, char *argv[]) {
 					// (according to QVariant) any string can be converted to
 					// bool, so no type check needed here
 					CFG::get_instance()->set_tmp_value("single_instance_per_file", optarg);
+				} else if (!strcmp(option_name, "write-defaults")) {
+					CFG::write_defaults(optarg);
+					return 0;
 				}
 				break;
 			}