config: add allowTearing option

include/config/rcxml.h

@@ -34,6 +34,12 @@ enum adaptive_sync_mode {
 	LAB_ADAPTIVE_SYNC_FULLSCREEN,
 };
 
+enum tearing_mode {
+	LAB_TEARING_DISABLED,
+	LAB_TEARING_ENABLED,
+	LAB_TEARING_FULLSCREEN,
+};
+
 struct usable_area_override {
 	struct border margin;
 	char *output;
@@ -53,6 +59,7 @@ struct rcxml {
 	bool xdg_shell_server_side_deco;
 	int gap;
 	enum adaptive_sync_mode adaptive_sync;
+	enum tearing_mode allow_tearing;
 	bool reuse_output_mode;
 	enum view_placement_policy placement_policy;
 

include/labwc.h

@@ -357,6 +357,7 @@ struct output {
 
 	bool leased;
 	bool gamma_lut_changed;
+	bool tearing;
 };
 
 #undef LAB_NR_LAYERS

src/config/rcxml.c

@@ -625,6 +625,26 @@ set_adaptive_sync_mode(const char *str, enum adaptive_sync_mode *variable)
 	}
 }
 
+static void
+set_tearing_mode(const char *str, enum tearing_mode *variable)
+{
+	if (!strcasecmp(str, "fullscreen")) {
+		*variable = LAB_TEARING_FULLSCREEN;
+	} else {
+		int ret = parse_bool(str, -1);
+		if (ret == 1) {
+			*variable = LAB_TEARING_ENABLED;
+		} else {
+			*variable = LAB_TEARING_DISABLED;
+		}
+	}
+	if (*variable != LAB_TEARING_DISABLED &&
+		strcmp(getenv("WLR_DRM_NO_ATOMIC"), "1")) {
+		*variable = LAB_TEARING_DISABLED;
+		wlr_log(WLR_INFO, "WLR_DRM_NO_ATOMIC is not 1, tearing disabled");
+	}
+}
+
 static void
 entry(xmlNode *node, char *nodename, char *content)
 {
@@ -727,6 +747,8 @@ entry(xmlNode *node, char *nodename, char *content)
 		rc.gap = atoi(content);
 	} else if (!strcasecmp(nodename, "adaptiveSync.core")) {
 		set_adaptive_sync_mode(content, &rc.adaptive_sync);
+	} else if (!strcasecmp(nodename, "allowTearing.core")) {
+		set_tearing_mode(content, &rc.allow_tearing);
 	} else if (!strcasecmp(nodename, "reuseOutputMode.core")) {
 		set_bool(content, &rc.reuse_output_mode);
 	} else if (!strcmp(nodename, "policy.placement")) {

src/output.c

@@ -68,7 +68,11 @@ output_frame_notify(struct wl_listener *listener, void *data)
 		return;
 	}
 
-	wlr_scene_output_commit(output->scene_output, NULL);
+	if (output->tearing) {
+		output->wlr_output->pending.tearing_page_flip = true;
+	}
+
+	lab_wlr_scene_output_commit(output->scene_output);
 
 	struct timespec now = { 0 };
 	clock_gettime(CLOCK_MONOTONIC, &now);
@@ -273,6 +277,12 @@ new_output_notify(struct wl_listener *listener, void *data)
 
 	wl_list_init(&output->regions);
 
+	if (rc.allow_tearing == LAB_TEARING_ENABLED) {
+		output->tearing = true;
+	} else {
+		output->tearing = false;
+	}
+
 	/*
 	 * Create layer-trees (background, bottom, top and overlay) and
 	 * a layer-popup-tree.

src/view.c

@@ -273,6 +273,16 @@ set_adaptive_sync_fullscreen(struct view *view)
 	wlr_output_commit(view->output->wlr_output);
 }
 
+static void
+set_tearing_fullscreen(struct view *view)
+{
+	if (rc.allow_tearing != LAB_TEARING_FULLSCREEN) {
+		return;
+	}
+	/* Enable tearing if view is fullscreen */
+	view->output->tearing = view->fullscreen;
+}
+
 void
 view_set_activated(struct view *view, bool activated)
 {
@@ -297,6 +307,7 @@ view_set_activated(struct view *view, bool activated)
 		}
 	}
 	set_adaptive_sync_fullscreen(view);
+	set_tearing_fullscreen(view);
 }
 
 void
@@ -1199,6 +1210,7 @@ view_set_fullscreen(struct view *view, bool fullscreen)
 		view_apply_special_geometry(view);
 	}
 	set_adaptive_sync_fullscreen(view);
+	set_tearing_fullscreen(view);
 }
 
 void
@@ -1869,6 +1881,9 @@ view_destroy(struct view *view)
 		if (rc.adaptive_sync == LAB_ADAPTIVE_SYNC_FULLSCREEN) {
 			wlr_output_enable_adaptive_sync(view->output->wlr_output, false);
 		}
+		if (rc.allow_tearing == LAB_TEARING_FULLSCREEN) {
+			view->output->tearing = false;
+		}
 	}
 
 	/* If we spawned a window menu, close it */