SnapToRegion: Evacuate tiled views from destroying outputs

include/regions.h

@@ -28,6 +28,7 @@ bool regions_available(void);
 
 void regions_init(struct server *server, struct seat *seat);
 void regions_update(struct output *output);
+void regions_evacuate_output(struct output *output);
 void regions_destroy(struct wl_list *regions);
 
 struct region *regions_from_cursor(struct server *server);

include/view.h

@@ -50,7 +50,12 @@ struct view {
 	bool minimized;
 	bool maximized;
 	uint32_t tiled;  /* private, enum view_edge in src/view.c */
+
+	/* Pointer to an output owned struct region, may be NULL or already free'd */
 	struct region *tiled_region;
+	/* Set to region->name when tiled_region is free'd by a destroying output */
+	char *tiled_region_evacuate;
+
 	struct wlr_output *fullscreen;
 
 	/* geometry of the wlr_surface contained within the view */

src/output.c

@@ -41,6 +41,7 @@ static void
 output_destroy_notify(struct wl_listener *listener, void *data)
 {
 	struct output *output = wl_container_of(listener, output, destroy);
+	regions_evacuate_output(output);
 	regions_destroy(&output->regions);
 	wl_list_remove(&output->link);
 	wl_list_remove(&output->frame.link);
@@ -307,6 +308,7 @@ output_config_apply(struct server *server,
 		}
 
 		if (need_to_remove) {
+			regions_evacuate_output(output);
 			wlr_output_layout_remove(server->output_layout, o);
 			output->scene_output = NULL;
 		}

src/regions.c

@@ -156,6 +156,26 @@ regions_update(struct output *output)
 	}
 }
 
+void
+regions_evacuate_output(struct output *output)
+{
+	assert(output);
+	struct view *view;
+	struct region *region;
+
+	wl_list_for_each(view, &output->server->views, link) {
+		wl_list_for_each(region, &output->regions, link) {
+			if (view->tiled_region == region) {
+				if (!view->tiled_region_evacuate) {
+					view->tiled_region_evacuate =
+						xstrdup(region->name);
+				}
+				break;
+			}
+		}
+	}
+}
+
 void
 regions_destroy(struct wl_list *regions)
 {

src/view.c

@@ -2,6 +2,7 @@
 #include <assert.h>
 #include <stdio.h>
 #include <strings.h>
+#include "common/mem.h"
 #include "common/scene-helpers.h"
 #include "labwc.h"
 #include "menu/menu.h"
@@ -348,6 +349,29 @@ view_apply_region_geometry(struct view *view)
 	assert(view);
 	assert(view->tiled_region);
 
+	if (view->tiled_region_evacuate) {
+		/* View was evacuated from a destroying output */
+		struct output *output = view_output(view);
+		if (!output) {
+			wlr_log(WLR_INFO, "apply region geometry failed: no more ouputs");
+			return;
+		}
+
+		/* Get new output local region */
+		view->tiled_region = regions_from_name(
+			view->tiled_region_evacuate, output);
+
+		/* Get rid of the evacuate instruction */
+		zfree(view->tiled_region_evacuate);
+
+		if (!view->tiled_region) {
+			/* Existing region name doesn't exist in rc.xml anymore */
+			view_set_untiled(view);
+			view_apply_natural_geometry(view);
+			return;
+		}
+	}
+
 	/* Create a copy of the original region geometry */
 	struct wlr_box geo = view->tiled_region->geo;
 
@@ -980,6 +1004,10 @@ view_destroy(struct view *view)
 		seat_reset_pressed(&server->seat);
 	}
 
+	if (view->tiled_region_evacuate) {
+		zfree(view->tiled_region_evacuate);
+	}
+
 	osd_on_view_destroy(view);
 	undecorate(view);