wayland: dark theme detection

include/Mw/LowLevel/Wayland.h

@@ -14,6 +14,7 @@
 #include <xkbcommon/xkbcommon.h>
 #include <cairo/cairo.h>
 #include <pthread.h>
+#include <dbus/dbus.h>
 
 MWDECL int MwLLWaylandCallInit(void);
 
@@ -35,8 +36,7 @@ typedef struct wayland_call_table {
 	void* lib;
 	void* xkb_lib;
 	void* cairo_lib;
-#if WAYLAND_LOAD_OPENGL
+	void* dbus_lib;
-#endif
 
 	int (*wl_display_dispatch_pending)(struct wl_display* display);
 	void (*wl_display_disconnect)(struct wl_display* display);
@@ -125,6 +125,21 @@ typedef struct wayland_call_table {
 	void (*cairo_set_antialias)(cairo_t*, cairo_antialias_t);
 	void (*cairo_set_operator)(cairo_t* cr, cairo_operator_t op);
 
+	void (*dbus_error_init)(DBusError* error);
+	DBusConnection* (*dbus_bus_get)(DBusBusType type, DBusError* error);
+	dbus_bool_t (*dbus_error_is_set)(const DBusError* error);
+	void (*dbus_error_free)(DBusError* error);
+	DBusMessage* (*dbus_message_new_method_call)(const char* bus_name, const char* path, const char* iface, const char* method);
+	void (*dbus_message_iter_init_append)(DBusMessage* message, DBusMessageIter* iter);
+	dbus_bool_t (*dbus_message_iter_append_basic)(DBusMessageIter* iter, int type, const void* value);
+	DBusMessage* (*dbus_connection_send_with_reply_and_block)(DBusConnection* connection, DBusMessage* message, int timeout_milliseconds, DBusError* error);
+	void (*dbus_message_unref)(DBusMessage* message);
+	dbus_bool_t (*dbus_message_iter_init)(DBusMessage* message, DBusMessageIter* iter);
+	int (*dbus_message_iter_get_arg_type)(DBusMessageIter* iter);
+	void (*dbus_message_iter_recurse)(DBusMessageIter* iter, DBusMessageIter* sub);
+	void (*dbus_connection_unref)(DBusConnection* connection);
+	void (*dbus_message_iter_get_basic)(DBusMessageIter* iter, void* value);
+
 } wayland_call_table_t;
 
 extern wayland_call_table_t wl_call_tbl;
@@ -225,6 +240,34 @@ MwInline int wayland_load_funcs() {
 	CAIRO_FUNC(cairo_pattern_set_filter);
 #undef CAIRO_FUNC
 
+	wl_call_tbl.dbus_lib = MwDynamicOpen("libdbus-1.so");
+	if(!wl_call_tbl.dbus_lib) {
+		fprintf(stderr, "[WARNING] Will not be able to detect dark theme: dbus library (libdbus-1.so) not found.\n");
+		return 0;
+	}
+
+#define DBUS_FUNC(x) \
+	wl_call_tbl.x = MwDynamicSymbol(wl_call_tbl.dbus_lib, #x); \
+	if(!x) { \
+		fprintf(stderr, "[WARNING] Will not be able to detect dark theme: dbus function %s (libdbus-1.so) not found.\n", #x); \
+		return 0; \
+	}
+
+	DBUS_FUNC(dbus_error_init);
+	DBUS_FUNC(dbus_bus_get);
+	DBUS_FUNC(dbus_error_is_set);
+	DBUS_FUNC(dbus_error_free);
+	DBUS_FUNC(dbus_message_new_method_call);
+	DBUS_FUNC(dbus_message_iter_init_append);
+	DBUS_FUNC(dbus_message_iter_append_basic);
+	DBUS_FUNC(dbus_connection_send_with_reply_and_block);
+	DBUS_FUNC(dbus_message_unref);
+	DBUS_FUNC(dbus_message_iter_init);
+	DBUS_FUNC(dbus_message_iter_get_arg_type);
+	DBUS_FUNC(dbus_message_iter_recurse);
+	DBUS_FUNC(dbus_connection_unref);
+	DBUS_FUNC(dbus_message_iter_get_basic);
+
 	return 0;
 }
 
@@ -436,6 +479,12 @@ struct _MwLLWayland {
 	struct zwp_locked_pointer_v1*		locked_pointer;
 	MwBool					pointer_constrained;
 
+	DBusConnection* dbus_conn;
+	DBusError	dbus_err;
+	DBusMessage*	dbus_msg;
+	DBusMessage*	dbus_reply;
+	DBusMessageIter dbus_args, dbus_variant, dbus_inner_variant;
+
 	/* clipboard related stuff.
 	 * Note that unlike most interfaces, we don't keep zwp_primary_selection stuff in a wayland_protocol_t because we use wl_data_device as a fallback and want to have it share memory space.*/
 

pl/rules.pl

@@ -49,6 +49,8 @@ if (grep(/^wayland$/, @backends)) {
     scan_wayland_protocol("unstable", "pointer-constraints", "-unstable-v1");
     scan_wayland_protocol("unstable", "relative-pointer",    "-unstable-v1");
 
+    add_cflags("-I/usr/include/dbus-1.0 -I/usr/lib/dbus-1.0/include");
+
     $gl_libs = "-lGL -lGLU";
 }
 

src/backend/wayland.c

@@ -1829,6 +1829,99 @@ static void widget_setup(MwLL r, MwLL parent, int x, int y, int width, int heigh
 		MwLLEndDraw(r);
 	}
 }
+
+static void dark_theme_detection_setup(MwLL handle) {
+
+	if(!wl_call_tbl.dbus_lib) {
+		return;
+	}
+
+	wl_call_tbl.dbus_error_init(&handle->wayland.dbus_err);
+
+	handle->wayland.dbus_conn = wl_call_tbl.dbus_bus_get(0 /* DBUS_BUS_SESSION */, &handle->wayland.dbus_err);
+	if(wl_call_tbl.dbus_error_is_set(&handle->wayland.dbus_err)) {
+		fprintf(stderr, "[WARNING] Could not detect dark theme: Connection error: %s\n", handle->wayland.dbus_err.message);
+		wl_call_tbl.dbus_error_free(&handle->wayland.dbus_err);
+		return;
+	}
+	if(!handle->wayland.dbus_conn) {
+		fprintf(stderr, "[WARNING] Could not detect dark theme: Failed to connect to session bus\n");
+		return;
+	}
+}
+
+static void detect_dark_theme(MwLL handle) {
+	const char* namespace	     = "org.freedesktop.appearance";
+	const char* key		     = "color-scheme"; /* 0=no preference, 1=dark, 2=light */
+	MwU32	    value	     = 0;
+	int	    translated_value = 0;
+
+	if(!handle->wayland.dbus_conn) {
+		return;
+	}
+
+	handle->wayland.dbus_msg = wl_call_tbl.dbus_message_new_method_call(
+	    "org.freedesktop.portal.Desktop",
+	    "/org/freedesktop/portal/desktop",
+	    "org.freedesktop.portal.Settings",
+	    "Read");
+	if(!handle->wayland.dbus_msg) {
+		fprintf(stderr, "[WARNING] Could not detect dark theme: Failed to create message\n");
+		return;
+	}
+
+	wl_call_tbl.dbus_message_iter_init_append(handle->wayland.dbus_msg, &handle->wayland.dbus_args);
+	wl_call_tbl.dbus_message_iter_append_basic(&handle->wayland.dbus_args, 's', &namespace);
+	wl_call_tbl.dbus_message_iter_append_basic(&handle->wayland.dbus_args, 's', &key);
+
+	handle->wayland.dbus_reply = wl_call_tbl.dbus_connection_send_with_reply_and_block(handle->wayland.dbus_conn, handle->wayland.dbus_msg, 100, &handle->wayland.dbus_err);
+	wl_call_tbl.dbus_message_unref(handle->wayland.dbus_msg);
+
+	if(wl_call_tbl.dbus_error_is_set(&handle->wayland.dbus_err)) {
+		fprintf(stderr, "[WARNING] Could not detect dark theme: Send error: %s\n", handle->wayland.dbus_err.message);
+		wl_call_tbl.dbus_error_free(&handle->wayland.dbus_err);
+		return;
+	}
+	if(!handle->wayland.dbus_reply) {
+		fprintf(stderr, "[WARNING] Could not detect dark theme: No reply received\n");
+		return;
+	}
+
+	if(!wl_call_tbl.dbus_message_iter_init(handle->wayland.dbus_reply, &handle->wayland.dbus_args)) {
+		fprintf(stderr, "[WARNING] Could not detect dark theme: Reply has no arguments\n");
+		wl_call_tbl.dbus_message_unref(handle->wayland.dbus_reply);
+		return;
+	}
+
+	if(wl_call_tbl.dbus_message_iter_get_arg_type(&handle->wayland.dbus_args) != 'v') {
+		fprintf(stderr, "[WARNING] Could not detect dark theme: Expected outer variant\n");
+		wl_call_tbl.dbus_message_unref(handle->wayland.dbus_reply);
+		return;
+	}
+	wl_call_tbl.dbus_message_iter_recurse(&handle->wayland.dbus_args, &handle->wayland.dbus_variant);
+
+	/* Some portals wrap the value in a second variant */
+	if(wl_call_tbl.dbus_message_iter_get_arg_type(&handle->wayland.dbus_variant) == 'v') {
+		wl_call_tbl.dbus_message_iter_recurse(&handle->wayland.dbus_variant, &handle->wayland.dbus_inner_variant);
+		wl_call_tbl.dbus_message_iter_get_basic(&handle->wayland.dbus_inner_variant, &value);
+	} else {
+		wl_call_tbl.dbus_message_iter_get_basic(&handle->wayland.dbus_variant, &value);
+	}
+
+	translated_value = (value == 1) ? 1 : 0;
+
+	MwLLDispatch(handle, dark_theme, &translated_value);
+}
+
+static void dark_theme_detection_destroy(MwLL handle) {
+	if(!wl_call_tbl.dbus_lib) {
+		return;
+	}
+
+	wl_call_tbl.dbus_message_unref(handle->wayland.dbus_reply);
+	wl_call_tbl.dbus_connection_unref(handle->wayland.dbus_conn);
+}
+
 static MwLL MwLLCreateImpl(MwLL parent, int x, int y, int width, int height) {
 	MwLL r;
 	r = malloc(sizeof(*r));
@@ -1837,6 +1930,10 @@ static MwLL MwLLCreateImpl(MwLL parent, int x, int y, int width, int height) {
 
 	widget_setup(r, parent, x, y, width, height, MWLL_WAYLAND_UNKNOWN);
 
+	if(!parent) {
+		dark_theme_detection_setup(r);
+	}
+
 	return r;
 }
 
@@ -1856,6 +1953,10 @@ static void MwLLDestroyImpl(MwLL handle) {
 
 	MwLLDestroyCommon(handle);
 
+	if(!handle->wayland.dbus_conn) {
+		dark_theme_detection_destroy(handle);
+	}
+
 	event_loop(handle);
 
 	/* sleep long enough that any active attempts to wait for the mutex will have given up and we can safely unlock/destroy it */
@@ -2144,6 +2245,10 @@ static int MwLLPendingImpl(MwLL handle) {
 	};
 	int pending = 0;
 
+	if(handle->wayland.dbus_conn) {
+		detect_dark_theme(handle);
+	}
+
 	if(!handle->wayland.did_initial_resize) {
 		recursive_dispatch_resize(handle);
 		handle->wayland.did_initial_resize = 1;