input: implement cycling through keyboard layout list

1 files changed, 40 insertions, 5 deletions

diff --git a/sway/commands/input/xkb_switch_layout.c b/sway/commands/input/xkb_switch_layout.c
index 286c040d..d6548a68 100644
--- a/sway/commands/input/xkb_switch_layout.c
+++ b/sway/commands/input/xkb_switch_layout.c
@@ -1,4 +1,5 @@
 #define _POSIX_C_SOURCE 200809L
+#include <assert.h>
 #include "sway/config.h"
 #include "sway/commands.h"
 #include "sway/input/input-manager.h"
@@ -13,6 +14,26 @@ static void switch_layout(struct wlr_keyboard *kbd, xkb_layout_index_t idx) {
                 kbd->modifiers.latched, kbd->modifiers.locked, idx);
 }
 
+static xkb_layout_index_t get_current_layout_index(struct wlr_keyboard *kbd) {
+        xkb_layout_index_t num_layouts = xkb_keymap_num_layouts(kbd->keymap);
+        assert(num_layouts > 0);
+
+        xkb_layout_index_t layout_idx;
+        for (layout_idx = 0; layout_idx < num_layouts; layout_idx++) {
+                if (xkb_state_layout_index_is_active(kbd->xkb_state,
+                                layout_idx, XKB_STATE_LAYOUT_EFFECTIVE)) {
+                        break;
+                }
+        }
+        return layout_idx;
+}
+
+static void switch_layout_relative(struct wlr_keyboard *kbd, int dir) {
+        xkb_layout_index_t num_layouts = xkb_keymap_num_layouts(kbd->keymap);
+        xkb_layout_index_t idx = get_current_layout_index(kbd);
+        switch_layout(kbd, (idx + num_layouts + dir) % num_layouts);
+}
+
 struct cmd_results *input_cmd_xkb_switch_layout(int argc, char **argv) {
         struct cmd_results *error = NULL;
         if ((error = checkarg(argc, "xkb_switch_layout", EXPECTED_EQUAL_TO, 1))) {
@@ -28,11 +49,21 @@ struct cmd_results *input_cmd_xkb_switch_layout(int argc, char **argv) {
         }
 
         const char *layout_str = argv[0];
+        int relative, layout;
 
-        char *end;
-        int layout = strtol(layout_str, &end, 10);
-        if (layout_str[0] == '\0' || end[0] != '\0' || layout < 0) {
-                return cmd_results_new(CMD_FAILURE, "Invalid layout index.");
+        if (strcmp(layout_str, "next") == 0) {
+                relative = 1;
+        } else if (strcmp(layout_str, "prev") == 0) {
+                relative = -1;
+        } else {
+                char *end;
+                layout = strtol(layout_str, &end, 10);
+                if (layout_str[0] == '\0' || end[0] != '\0') {
+                        return cmd_results_new(CMD_FAILURE, "Invalid argument.");
+                } else if (layout < 0) {
+                        return cmd_results_new(CMD_FAILURE, "Invalid layout index.");
+                }
+                relative = 0;
         }
 
         struct sway_input_device *dev;
@@ -45,7 +76,11 @@ struct cmd_results *input_cmd_xkb_switch_layout(int argc, char **argv) {
                 if (dev->wlr_device->type != WLR_INPUT_DEVICE_KEYBOARD) {
                         continue;
                 }
-                switch_layout(dev->wlr_device->keyboard, layout);
+                if (relative) {
+                        switch_layout_relative(dev->wlr_device->keyboard, relative);
+                } else {
+                        switch_layout(dev->wlr_device->keyboard, layout);
+                }
         }
 
         return cmd_results_new(CMD_SUCCESS, NULL);