swaybg: implement scaling mode "center"

swaybg/main.c

@@ -15,6 +15,7 @@ struct registry *registry;
 enum scaling_mode_t {
 	SCALING_MODE_STRETCH,
 	SCALING_MODE_FILL,
+	SCALING_MODE_CENTER,
 };
 
 void sway_terminate(void) {
@@ -64,6 +65,8 @@ int main(int argc, const char **argv) {
 		scaling_mode = SCALING_MODE_STRETCH;
 	} else if (strcmp(scaling_mode_str, "fill") == 0) {
 		scaling_mode = SCALING_MODE_FILL;
+	} else if (strcmp(scaling_mode_str, "center") == 0) {
+		scaling_mode = SCALING_MODE_CENTER;
 	} else {
 		sway_abort("Unsupported scaling mode: %s", scaling_mode_str);
 	}
@@ -99,6 +102,11 @@ int main(int argc, const char **argv) {
 						}
 					}
 					break;
+				case SCALING_MODE_CENTER:
+					cairo_set_source_surface(window->cairo, image,
+							(double) window->width/2 - width/2,
+							(double) window->height/2 - height/2);
+					break;
 				default:
 					sway_abort("Scaling mode '%s' not implemented yet!", scaling_mode_str);
 			}