Re-evaluate default_orientation auto when workspaces change outputs

Workspaces created with default_orientation auto now re-orient when
moved to a different output, evacuated on disconnect, restored on
reconnect, or when output mode/transform changes.

include/sway/tree/workspace.h

@@ -157,4 +157,6 @@ size_t workspace_num_sticky_containers(struct sway_workspace *ws);
  */
 void workspace_squash(struct sway_workspace *workspace);
 
+void workspace_reorient_auto(struct sway_workspace *ws);
+
 #endif

sway/commands/move.c

@@ -641,6 +641,7 @@ static void workspace_move_to_output(struct sway_workspace *workspace,
 	}
 
 	output_add_workspace(output, workspace);
+	workspace_reorient_auto(workspace);
 
 	// If moving the last workspace from the old output, create a new workspace
 	// on the old output

sway/config/output.c

@@ -21,6 +21,7 @@
 #include "sway/server.h"
 #include "sway/tree/arrange.h"
 #include "sway/tree/root.h"
+#include "sway/tree/workspace.h"
 #include "log.h"
 #include "util.h"
 
@@ -1086,6 +1087,10 @@ static bool apply_resolved_output_configs(struct matched_output_config *configs,
 		struct matched_output_config *cfg = &configs[idx];
 		output_update_position(cfg->output);
 		arrange_layers(cfg->output);
+		for (int i = 0; i < cfg->output->workspaces->length; i++) {
+			struct sway_workspace *ws = cfg->output->workspaces->items[i];
+			workspace_reorient_auto(ws);
+		}
 	}
 
 	arrange_root();

sway/tree/output.c

@@ -41,6 +41,7 @@ static void restore_workspaces(struct sway_output *output) {
 			if (highest == output) {
 				workspace_detach(ws);
 				output_add_workspace(output, ws);
+				workspace_reorient_auto(ws);
 				ipc_event_workspace(NULL, ws, "move");
 				j--;
 			}
@@ -59,6 +60,7 @@ static void restore_workspaces(struct sway_output *output) {
 		struct sway_workspace *ws = root->fallback_output->workspaces->items[0];
 		workspace_detach(ws);
 		output_add_workspace(output, ws);
+		workspace_reorient_auto(ws);
 
 		// If the floater was made floating while on the NOOP output, its width
 		// and height will be zero and it should be reinitialized as a floating
@@ -172,11 +174,8 @@ void output_enable(struct sway_output *output) {
 		ipc_event_workspace(NULL, ws, "init");
 	}
 
-	if (ws && config->default_orientation == L_NONE) {
-		// Since the output transformation and resolution could have changed
-		// due to applying the output config, the previously set layout for the
-		// created workspace may not be correct for `default_orientation auto`
-		ws->layout = output_get_default_layout(output);
+	if (ws) {
+		workspace_reorient_auto(ws);
 	}
 
 	wl_signal_emit_mutable(&root->events.new_node, &output->node);
@@ -241,6 +240,7 @@ static void output_evacuate(struct sway_output *output) {
 
 		workspace_output_add_priority(workspace, new_output);
 		output_add_workspace(new_output, workspace);
+		workspace_reorient_auto(workspace);
 		output_sort_workspaces(new_output);
 		ipc_event_workspace(NULL, workspace, "move");
 

sway/tree/workspace.c

@@ -979,3 +979,34 @@ void workspace_squash(struct sway_workspace *workspace) {
 		i += container_squash(child);
 	}
 }
+
+void workspace_reorient_auto(struct sway_workspace *ws) {
+	if (config->default_orientation != L_NONE) {
+		return;
+	}
+	if (!ws->output) {
+		return;
+	}
+	if (ws->tiling->length > 1) {
+		return;
+	}
+	if (ws->layout == L_TABBED || ws->layout == L_STACKED) {
+		return;
+	}
+
+	enum sway_container_layout new_layout = output_get_default_layout(ws->output);
+	if (ws->layout == new_layout) {
+		return;
+	}
+	ws->layout = new_layout;
+	workspace_update_representation(ws);
+
+	if (ws->tiling->length == 1) {
+		struct sway_container *child = ws->tiling->items[0];
+		if (!child->view &&
+				(child->pending.layout == L_HORIZ || child->pending.layout == L_VERT)) {
+			child->pending.layout = new_layout;
+			container_update_representation(child);
+		}
+	}
+}