commands: Learn mouse_warping.

Place mouse at center of focused view when changing to a workspace on a
different output, if option is enabled. (This replicates existing i3
option.)

This can be triggered in multiple ways:
A) via `workspace <name>` which changes output
B) via `focus <direction>` which changes output
C) via `focus output <name>` which (obviously) changes output

6 files changed, 64 insertions, 9 deletions

diff --git a/include/commands.h b/include/commands.h
index 8e53c74d..f6777930 100644
--- a/include/commands.h
+++ b/include/commands.h
@@ -2,6 +2,7 @@
 #define _SWAY_COMMANDS_H
 #include <stdbool.h>
 #include <json-c/json.h>
+#include <wlc/wlc.h>
 #include "config.h"
 
 
diff --git a/include/input_state.h b/include/input_state.h
index dd5d71a8..52759052 100644
--- a/include/input_state.h
+++ b/include/input_state.h
@@ -66,6 +66,7 @@ extern struct pointer_state {
 } pointer_state;
 
 void pointer_position_set(struct wlc_origin *new_origin, bool force_focus);
+void center_pointer_on(swayc_t *view);
 
 // on button release unset mode depending on the button.
 // on button press set mode conditionally depending on the button
diff --git a/sway.5.txt b/sway.5.txt
index dad55c5f..27735db6 100644
--- a/sway.5.txt
+++ b/sway.5.txt
@@ -102,6 +102,10 @@ Commands
 	Moves the focused container to the workspace identified by _name_.
 	_name_ may be a special workspace name. See **workspace**.
 
+**mouse_warping** <output|none>::
+	When _output_: place mouse at center of newly focused window when changing
+	output. When _none_: don't move mouse.
+
 **output** <name> <resolution|res WIDTHxHEIGHT> <position|pos X,Y>::
 	Configures the specified output. It will use the given resolution and be
 	arranged at the given position in the layout tree. You may omit either of
diff --git a/sway/commands.c b/sway/commands.c
index 441b6fd7..00a4d1b0 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -21,6 +21,7 @@
 #include "handlers.h"
 #include "sway.h"
 #include "resize.h"
+#include "input_state.h"
 
 typedef struct cmd_results *sway_cmd(int argc, char **argv);
 
@@ -45,6 +46,7 @@ static sway_cmd cmd_kill;
 static sway_cmd cmd_layout;
 static sway_cmd cmd_log_colors;
 static sway_cmd cmd_mode;
+static sway_cmd cmd_mouse_warping;
 static sway_cmd cmd_move;
 static sway_cmd cmd_output;
 static sway_cmd cmd_reload;
@@ -383,9 +385,13 @@ static struct cmd_results *cmd_focus(int argc, char **argv) {
 		} else if (!workspace_switch(swayc_active_workspace_for(output))) {
 			return cmd_results_new(CMD_FAILURE, "focus output",
 				"Switching to workspace on output '%s' was blocked", argv[1]);
-		} else {
-			return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+		} else if (config->mouse_warping) {
+			swayc_t *focused = get_focused_view(output);
+			if (focused && focused->type == C_VIEW) {
+				center_pointer_on(focused);
+			}
 		}
+		return cmd_results_new(CMD_SUCCESS, NULL, NULL);
 	} else if ((error = checkarg(argc, "focus", EXPECTED_EQUAL_TO, 1))) {
 		return error;
 	}
@@ -528,6 +534,20 @@ static struct cmd_results *cmd_mode(int argc, char **argv) {
 	return cmd_results_new(mode_make ? CMD_BLOCK_MODE : CMD_SUCCESS, NULL, NULL);
 }
 
+static struct cmd_results *cmd_mouse_warping(int argc, char **argv) {
+	struct cmd_results *error = NULL;
+	if ((error = checkarg(argc, "mouse_warping", EXPECTED_EQUAL_TO, 1))) {
+		return error;
+	} else if (strcasecmp(argv[0], "output") == 0) {
+		config->mouse_warping = true;
+	} else if (strcasecmp(argv[0], "none") == 0) {
+		config->mouse_warping = false;
+	} else {
+		return cmd_results_new(CMD_FAILURE, "mouse_warping", "Expected 'mouse_warping output|none'");
+	}
+	return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}
+
 static struct cmd_results *cmd_move(int argc, char **argv) {
 	struct cmd_results *error = NULL;
 	if (config->reading) return cmd_results_new(CMD_FAILURE, "move", "Can't be used in config file.");
@@ -1165,7 +1185,16 @@ static struct cmd_results *cmd_workspace(int argc, char **argv) {
 				ws = workspace_create(argv[0]);
 			}
 		}
+		swayc_t *old_output = swayc_active_output();
 		workspace_switch(ws);
+		swayc_t *new_output = swayc_active_output();
+
+		if (config->mouse_warping && old_output != new_output) {
+			swayc_t *focused = get_focused_view(ws);
+			if (focused && focused->type == C_VIEW) {
+				center_pointer_on(focused);
+			}
+		}
 	} else {
 		if (strcasecmp(argv[1], "output") == 0) {
 			if ((error = checkarg(argc, "workspace", EXPECTED_EQUAL_TO, 3))) {
@@ -1217,6 +1246,7 @@ static struct cmd_handler handlers[] = {
 	{ "layout", cmd_layout },
 	{ "log_colors", cmd_log_colors },
 	{ "mode", cmd_mode },
+	{ "mouse_warping", cmd_mouse_warping },
 	{ "move", cmd_move },
 	{ "output", cmd_output },
 	{ "reload", cmd_reload },
diff --git a/sway/focus.c b/sway/focus.c
index 1aa7579b..7f0b1599 100644
--- a/sway/focus.c
+++ b/sway/focus.c
@@ -4,6 +4,8 @@
 #include "log.h"
 #include "workspace.h"
 #include "layout.h"
+#include "config.h"
+#include "input_state.h"
 
 bool locked_container_focus = false;
 bool locked_view_focus = false;
@@ -49,14 +51,24 @@ static void update_focus(swayc_t *c) {
 }
 
 bool move_focus(enum movement_direction direction) {
-	swayc_t *view = get_focused_container(&root_container);
-	view = get_swayc_in_direction(view, direction);
-	if (view) {
-		if (direction == MOVE_PARENT) {
-			return set_focused_container(view);
-		} else {
-			return set_focused_container(get_focused_view(view));
+	swayc_t *old_view = get_focused_container(&root_container);
+	swayc_t *new_view = get_swayc_in_direction(old_view, direction);
+	if (!new_view) {
+		return false;
+	} else if (direction == MOVE_PARENT) {
+		return set_focused_container(new_view);
+	} else if (config->mouse_warping) {
+		swayc_t *old_op = old_view->type == C_OUTPUT ?
+			old_view : swayc_parent_by_type(old_view, C_OUTPUT);
+		swayc_t *focused = get_focused_view(new_view);
+		if (set_focused_container(focused)) {
+			if (old_op != swayc_active_output() && focused && focused->type == C_VIEW) {
+				center_pointer_on(focused);
+			}
+			return true;
 		}
+	} else {
+		return set_focused_container(get_focused_view(new_view));
 	}
 	return false;
 }
diff --git a/sway/input_state.c b/sway/input_state.c
index bd46a5ac..ee3dc7cf 100644
--- a/sway/input_state.c
+++ b/sway/input_state.c
@@ -185,6 +185,13 @@ void pointer_position_set(struct wlc_origin *new_origin, bool force_focus) {
 	wlc_pointer_set_origin(new_origin);
 }
 
+void center_pointer_on(swayc_t *view) {
+	struct wlc_origin new_origin;
+	new_origin.x = view->x + view->width/2;
+	new_origin.y = view->y + view->height/2;
+	pointer_position_set(&new_origin, true);
+}
+
 // Mode set left/right click
 
 static void pointer_mode_set_left(void) {