commands: accept 'next'/'prev' output names

`move container to output`, `move workspace to output` and `focus
output` now accept 'next' and 'prev', which cycle through the enabled
outputs with wrap-around. This matches i3's behaviour of expanding
'next' into the full output list so the following output relative to
the current one is picked.

The name/direction/current resolution used by the move commands was
also duplicated inline in `focus_output`; both call sites now share a
new `output_by_direction_or_name` helper in `sway/desktop/output.c`.

Closes: #8799

i3 implementation in https://github.com/i3/i3/pull/4338
Note:
- i3 accepts multiple output arguments and `next` works as a wildcard. I
  considered that out of scope for this PR.
- i3 does not have `prev`. Accepting it in sway is natural and
  practically free complexity-wise so I added it.

include/sway/output.h

@@ -110,6 +110,9 @@ struct sway_output *output_by_name_or_id(const char *name_or_id);
 // this includes all the outputs, including disabled ones
 struct sway_output *all_output_by_name_or_id(const char *name_or_id);
 
+struct sway_output *output_by_direction_or_name(const char *spec,
+		const struct sway_output *reference, double ref_lx, double ref_ly);
+
 void output_sort_workspaces(struct sway_output *output);
 
 void output_enable(struct sway_output *output);

sway/commands/focus.c

@@ -1,6 +1,5 @@
 #include <float.h>
 #include <strings.h>
-#include <wlr/types/wlr_output_layout.h>
 #include "log.h"
 #include "sway/commands.h"
 #include "sway/input/input-manager.h"
@@ -12,7 +11,6 @@
 #include "sway/tree/view.h"
 #include "sway/tree/workspace.h"
 #include "stringop.h"
-#include "util.h"
 
 static bool get_direction_from_next_prev(struct sway_container *container,
 		struct sway_seat *seat, const char *name, enum wlr_direction *out) {
@@ -295,43 +293,31 @@ static struct cmd_results *focus_output(struct sway_seat *seat,
 		int argc, char **argv) {
 	if (!argc) {
 		return cmd_results_new(CMD_INVALID,
-			"Expected 'focus output <direction|name>'.");
+			"Expected 'focus output <direction|name|next|prev|current>'.");
 	}
 	char *identifier = join_args(argv, argc);
-	struct sway_output *output = output_by_name_or_id(identifier);
+
+	struct sway_workspace *ws = seat_get_focused_workspace(seat);
+	struct sway_output *reference = ws ? ws->output : NULL;
+	double ref_lx = 0, ref_ly = 0;
+	if (reference) {
+		ref_lx = reference->lx + reference->width / 2;
+		ref_ly = reference->ly + reference->height / 2;
+	}
+
+	struct sway_output *output = output_by_direction_or_name(identifier,
+			reference, ref_lx, ref_ly);
 
 	if (!output) {
-		enum wlr_direction direction;
+		struct cmd_results *err = cmd_results_new(CMD_INVALID,
-		if (!parse_direction(identifier, &direction)) {
+			"No output matches '%s'.", identifier);
-			free(identifier);
+		free(identifier);
-			return cmd_results_new(CMD_INVALID,
+		return err;
-				"There is no output with that name.");
-		}
-		struct sway_workspace *ws = seat_get_focused_workspace(seat);
-		if (!ws) {
-			free(identifier);
-			return cmd_results_new(CMD_FAILURE,
-				"No focused workspace to base directions off of.");
-		}
-		output = output_get_in_direction(ws->output, direction);
-
-		if (!output) {
-			int center_lx = ws->output->lx + ws->output->width / 2;
-			int center_ly = ws->output->ly + ws->output->height / 2;
-			struct wlr_output *target = wlr_output_layout_farthest_output(
-					root->output_layout, opposite_direction(direction),
-					ws->output->wlr_output, center_lx, center_ly);
-			if (target) {
-				output = output_from_wlr_output(target);
-			}
-		}
 	}
-
 	free(identifier);
-	if (output) {
+
-		seat_set_focus(seat, seat_get_focus_inactive(seat, &output->node));
+	seat_set_focus(seat, seat_get_focus_inactive(seat, &output->node));
-		seat_consider_warp_to_focus(seat);
+	seat_consider_warp_to_focus(seat);
-	}
 
 	return cmd_results_new(CMD_SUCCESS, NULL);
 }
@@ -426,7 +412,7 @@ struct cmd_results *cmd_focus(int argc, char **argv) {
 		if (!get_direction_from_next_prev(container, seat, argv[0], &direction)) {
 			return cmd_results_new(CMD_INVALID,
 				"Expected 'focus <direction|next|prev|parent|child|mode_toggle|floating|tiling>' "
-				"or 'focus output <direction|name>'");
+				"or 'focus output <direction|name|next|prev|current>'");
 		} else if (argc == 2 && strcasecmp(argv[1], "sibling") == 0) {
 			descend = false;
 		}

sway/commands/move.c

@@ -24,58 +24,9 @@
 static const char expected_syntax[] =
 	"Expected 'move <left|right|up|down> <[px] px>' or "
 	"'move [--no-auto-back-and-forth] <container|window> [to] workspace <name>' or "
-	"'move <container|window|workspace> [to] output <name|direction>' or "
+	"'move <container|window|workspace> [to] output <name|direction|next|prev|current>' or "
 	"'move <container|window> [to] mark <mark>'";
 
-static struct sway_output *output_in_direction(const char *direction_string,
-		struct sway_output *reference, int ref_lx, int ref_ly) {
-	if (strcasecmp(direction_string, "current") == 0) {
-		struct sway_workspace *active_ws =
-			seat_get_focused_workspace(config->handler_context.seat);
-		if (!active_ws) {
-			return NULL;
-		}
-		return active_ws->output;
-	}
-
-	struct {
-		char *name;
-		enum wlr_direction direction;
-	} names[] = {
-		{ "up", WLR_DIRECTION_UP },
-		{ "down", WLR_DIRECTION_DOWN },
-		{ "left", WLR_DIRECTION_LEFT },
-		{ "right", WLR_DIRECTION_RIGHT },
-	};
-
-	enum wlr_direction direction = 0;
-
-	for (size_t i = 0; i < sizeof(names) / sizeof(names[0]); ++i) {
-		if (strcasecmp(names[i].name, direction_string) == 0) {
-			direction = names[i].direction;
-			break;
-		}
-	}
-
-	if (reference && direction) {
-		struct wlr_output *target = wlr_output_layout_adjacent_output(
-				root->output_layout, direction, reference->wlr_output,
-				ref_lx, ref_ly);
-
-		if (!target) {
-			target = wlr_output_layout_farthest_output(
-					root->output_layout, opposite_direction(direction),
-					reference->wlr_output, ref_lx, ref_ly);
-		}
-
-		if (target) {
-			return target->data;
-		}
-	}
-
-	return output_by_name_or_id(direction_string);
-}
-
 static bool is_parallel(enum sway_container_layout layout,
 		enum wlr_direction dir) {
 	switch (layout) {
@@ -516,7 +467,7 @@ static struct cmd_results *cmd_move_container(bool no_auto_back_and_forth,
 		struct sway_container *dst = seat_get_focus_inactive_tiling(seat, ws);
 		destination = dst ? &dst->node : &ws->node;
 	} else if (strcasecmp(argv[0], "output") == 0) {
-		struct sway_output *new_output = output_in_direction(argv[1],
+		struct sway_output *new_output = output_by_direction_or_name(argv[1],
 				old_output, container->pending.x, container->pending.y);
 		if (!new_output) {
 			return cmd_results_new(CMD_FAILURE,
@@ -650,7 +601,7 @@ static struct cmd_results *cmd_move_workspace(int argc, char **argv) {
 	struct sway_output *old_output = workspace->output;
 	int center_x = workspace->width / 2 + workspace->x,
 		center_y = workspace->height / 2 + workspace->y;
-	struct sway_output *new_output = output_in_direction(argv[0],
+	struct sway_output *new_output = output_by_direction_or_name(argv[0],
 			old_output, center_x, center_y);
 	if (!new_output) {
 		return cmd_results_new(CMD_FAILURE,

sway/desktop/output.c

@@ -7,29 +7,22 @@
 #include <wlr/backend/headless.h>
 #include <wlr/render/swapchain.h>
 #include <wlr/render/wlr_renderer.h>
-#include <wlr/types/wlr_buffer.h>
 #include <wlr/types/wlr_alpha_modifier_v1.h>
-#include <wlr/types/wlr_gamma_control_v1.h>
 #include <wlr/types/wlr_output_layout.h>
 #include <wlr/types/wlr_output_management_v1.h>
 #include <wlr/types/wlr_output_power_management_v1.h>
 #include <wlr/types/wlr_output.h>
 #include <wlr/types/wlr_presentation_time.h>
 #include <wlr/types/wlr_compositor.h>
-#include <wlr/util/region.h>
-#include <wlr/util/transform.h>
-#include "config.h"
 #include "log.h"
 #include "sway/config.h"
 #include "sway/desktop/transaction.h"
 #include "sway/input/input-manager.h"
 #include "sway/input/seat.h"
 #include "sway/ipc-server.h"
-#include "sway/layers.h"
 #include "sway/output.h"
 #include "sway/scene_descriptor.h"
 #include "sway/server.h"
-#include "sway/tree/arrange.h"
 #include "sway/tree/container.h"
 #include "sway/tree/root.h"
 #include "sway/tree/view.h"
@@ -72,6 +65,75 @@ struct sway_output *all_output_by_name_or_id(const char *name_or_id) {
 	return NULL;
 }
 
+static struct sway_output *output_cycle(const struct sway_output *reference,
+		bool forward) {
+	if (root->outputs->length == 0) {
+		return NULL;
+	}
+	int ref_idx = -1;
+	if (reference) {
+		for (int i = 0; i < root->outputs->length; ++i) {
+			if (root->outputs->items[i] == reference) {
+				ref_idx = i;
+				break;
+			}
+		}
+	}
+	int next_idx;
+	if (ref_idx < 0) {
+		next_idx = forward ? 0 : root->outputs->length - 1;
+	} else {
+		next_idx = forward
+			? (ref_idx + 1) % root->outputs->length
+			: (ref_idx - 1 + root->outputs->length) % root->outputs->length;
+	}
+	return root->outputs->items[next_idx];
+}
+
+struct sway_output *output_by_direction_or_name(const char *spec,
+		const struct sway_output *reference, double ref_lx, double ref_ly) {
+	if (strcasecmp(spec, "current") == 0) {
+		const struct sway_workspace *active_ws =
+			seat_get_focused_workspace(config->handler_context.seat);
+		return active_ws ? active_ws->output : NULL;
+	}
+
+	if (strcasecmp(spec, "next") == 0) {
+		return output_cycle(reference, true);
+	}
+	if (strcasecmp(spec, "prev") == 0) {
+		return output_cycle(reference, false);
+	}
+
+	enum wlr_direction direction = 0;
+	if (strcasecmp(spec, "up") == 0) {
+		direction = WLR_DIRECTION_UP;
+	} else if (strcasecmp(spec, "down") == 0) {
+		direction = WLR_DIRECTION_DOWN;
+	} else if (strcasecmp(spec, "left") == 0) {
+		direction = WLR_DIRECTION_LEFT;
+	} else if (strcasecmp(spec, "right") == 0) {
+		direction = WLR_DIRECTION_RIGHT;
+	}
+
+	if (reference && direction) {
+		struct wlr_output *target = wlr_output_layout_adjacent_output(
+				root->output_layout, direction, reference->wlr_output,
+				ref_lx, ref_ly);
+
+		if (!target) {
+			target = wlr_output_layout_farthest_output(
+					root->output_layout, opposite_direction(direction),
+					reference->wlr_output, ref_lx, ref_ly);
+		}
+
+		if (target) {
+			return target->data;
+		}
+	}
+
+	return output_by_name_or_id(spec);
+}
 
 struct sway_workspace *output_get_active_workspace(struct sway_output *output) {
 	struct sway_seat *seat = input_manager_current_seat();

sway/sway.5.scd

@@ -139,6 +139,13 @@ They are expected to be used with *bindsym* or at runtime through *swaymsg*(1).
 *focus* output up|right|down|left
 	Moves focus to the next output in the specified direction.
 
+*focus* output next|prev
+	Moves focus to the next or previous output, wrapping around.
+
+*focus* output current
+	Moves focus to the output containing the focused workspace. Mainly useful
+	with criteria to refocus the seat's current output.
+
 *focus* output <name>
 	Moves focus to the named output.
 
@@ -275,6 +282,10 @@ set|plus|minus|toggle <amount>
 	Moves the focused container to next output in the specified
 	direction.
 
+*move* [container|window] [to] output next|prev
+	Moves the focused container to the next or previous output,
+	wrapping around.
+
 *move* [container|window] [to] scratchpad
 	Moves the focused container to the scratchpad.
 
@@ -290,6 +301,14 @@ set|plus|minus|toggle <amount>
 *move* workspace to [output] up|right|down|left
 	Moves the focused workspace to next output in the specified direction.
 
+*move* workspace [to] output next|prev
+	Moves the focused workspace to the next or previous output,
+	wrapping around.
+
+*move* workspace to [output] next|prev
+	Moves the focused workspace to the next or previous output,
+	wrapping around.
+
 *nop* <comment>
 	A no operation command that can be used to override default behaviour. The
 	optional comment argument is ignored, but logged for debugging purposes.