Implement `focus child` command

The `focus child` command focuses the child container within the selected
container.

5 files changed, 12 insertions, 5 deletions

diff --git a/include/focus.h b/include/focus.h
index 602b6122..236d050b 100644
--- a/include/focus.h
+++ b/include/focus.h
@@ -5,7 +5,8 @@ enum movement_direction {
 	MOVE_RIGHT,
 	MOVE_UP,
 	MOVE_DOWN,
-	MOVE_PARENT
+	MOVE_PARENT,
+	MOVE_CHILD
 };
 
 #include "container.h"
diff --git a/sway/commands.c b/sway/commands.c
index ed561764..56701634 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -864,6 +864,8 @@ static struct cmd_results *cmd_focus(int argc, char **argv) {
 		move_focus(MOVE_DOWN);
 	} else if (strcasecmp(argv[0], "parent") == 0) {
 		move_focus(MOVE_PARENT);
+	} else if (strcasecmp(argv[0], "child") == 0) {
+		move_focus(MOVE_CHILD);
 	} else if (strcasecmp(argv[0], "mode_toggle") == 0) {
 		int i;
 		swayc_t *workspace = swayc_active_workspace();
@@ -903,7 +905,7 @@ static struct cmd_results *cmd_focus(int argc, char **argv) {
 		}
 	} else {
 		return cmd_results_new(CMD_INVALID, "focus",
-				"Expected 'focus <direction|parent|mode_toggle>' or 'focus output <direction|name>'");
+				"Expected 'focus <direction|parent|child|mode_toggle>' or 'focus output <direction|name>'");
 	}
 	return cmd_results_new(CMD_SUCCESS, NULL, NULL);
 }
diff --git a/sway/focus.c b/sway/focus.c
index c7737a1d..0f629e1e 100644
--- a/sway/focus.c
+++ b/sway/focus.c
@@ -72,7 +72,7 @@ bool move_focus(enum movement_direction direction) {
 		return false;
 	} else if (new_view->type == C_OUTPUT) {
 		return set_focused_container(swayc_active_workspace_for(new_view));
-	} else if (direction == MOVE_PARENT) {
+	} else if (direction == MOVE_PARENT || direction == MOVE_CHILD) {
 		return set_focused_container(new_view);
 	} else if (config->mouse_warping) {
 		swayc_t *old_op = old_view->type == C_OUTPUT ?
diff --git a/sway/layout.c b/sway/layout.c
index 1d5944f8..cd5a31bc 100644
--- a/sway/layout.c
+++ b/sway/layout.c
@@ -1009,6 +1009,10 @@ static swayc_t *get_swayc_in_output_direction(swayc_t *output, enum movement_dir
 }
 
 swayc_t *get_swayc_in_direction_under(swayc_t *container, enum movement_direction dir, swayc_t *limit) {
+	if (dir == MOVE_CHILD) {
+		return container->focused;
+	}
+
 	swayc_t *parent = container->parent;
 	if (dir == MOVE_PARENT) {
 		if (parent->type == C_OUTPUT) {
diff --git a/sway/sway.5.txt b/sway/sway.5.txt
index 18b693f8..fdf5c0c1 100644
--- a/sway/sway.5.txt
+++ b/sway/sway.5.txt
@@ -59,8 +59,8 @@ They are expected to be used with **bindsym** or at runtime through **swaymsg**(
 	Make focused view floating, non-floating, or the opposite of what it is now.
 
 **focus** <direction>::
-	Direction may be one of _up_, _down_, _left_, _right_, or _parent_. The
-	directional focus commands will move the focus in that direction. The parent
+	Direction may be one of _up_, _down_, _left_, _right_, _parent_, or _child_.
+	The directional focus commands will move the focus in that direction. The parent
 	focus command will change the focus to the parent of the currently focused
 	container, which is useful, for example, to open a sibling of the parent
 	container, or to move the entire container around.