+
+/*
+ * Swaps the two containers.
+ *
+ */
+bool con_swap(Con *first, Con *second) {
+ assert(first != NULL);
+ assert(second != NULL);
+ DLOG("Swapping containers %p / %p\n", first, second);
+
+ if (first->type != CT_CON) {
+ ELOG("Only regular containers can be swapped, but found con = %p with type = %d.\n", first, first->type);
+ return false;
+ }
+
+ if (second->type != CT_CON) {
+ ELOG("Only regular containers can be swapped, but found con = %p with type = %d.\n", second, second->type);
+ return false;
+ }
+
+ if (con_is_floating(first) || con_is_floating(second)) {
+ ELOG("Floating windows cannot be swapped.\n");
+ return false;
+ }
+
+ if (first == second) {
+ DLOG("Swapping container %p with itself, nothing to do.\n", first);
+ return false;
+ }
+
+ if (con_has_parent(first, second) || con_has_parent(second, first)) {
+ ELOG("Cannot swap containers %p and %p because they are in a parent-child relationship.\n", first, second);
+ return false;
+ }
+
+ Con *old_focus = focused;
+
+ Con *first_ws = con_get_workspace(first);
+ Con *second_ws = con_get_workspace(second);
+ Con *current_ws = con_get_workspace(old_focus);
+ const bool focused_within_first = (first == old_focus || con_has_parent(old_focus, first));
+ const bool focused_within_second = (second == old_focus || con_has_parent(old_focus, second));
+ fullscreen_mode_t first_fullscreen_mode = first->fullscreen_mode;
+ fullscreen_mode_t second_fullscreen_mode = second->fullscreen_mode;
+
+ if (first_fullscreen_mode != CF_NONE) {
+ con_disable_fullscreen(first);
+ }
+ if (second_fullscreen_mode != CF_NONE) {
+ con_disable_fullscreen(second);
+ }
+
+ double first_percent = first->percent;
+ double second_percent = second->percent;
+
+ /* De- and reattaching the containers will insert them at the tail of the
+ * focus_heads. We will need to fix this. But we need to make sure first
+ * and second don't get in each other's way if they share the same parent,
+ * so we select the closest previous focus_head that isn't involved. */
+ Con *first_prev_focus_head = first;
+ while (first_prev_focus_head == first || first_prev_focus_head == second) {
+ first_prev_focus_head = TAILQ_PREV(first_prev_focus_head, focus_head, focused);
+ }
+
+ Con *second_prev_focus_head = second;
+ while (second_prev_focus_head == second || second_prev_focus_head == first) {
+ second_prev_focus_head = TAILQ_PREV(second_prev_focus_head, focus_head, focused);
+ }
+
+ /* We use a fake container to mark the spot of where the second container needs to go. */
+ Con *fake = con_new(NULL, NULL);
+ fake->layout = L_SPLITH;
+ _con_attach(fake, first->parent, first, true);
+
+ bool result = true;
+ /* Swap the containers. We set the ignore_focus flag here because after the
+ * container is attached, the focus order is not yet correct and would
+ * result in wrong windows being focused. */
+
+ /* Move first to second. */
+ result &= _con_move_to_con(first, second, false, false, false, true, false);
+ /* If swapping the containers didn't work we don't need to mess with the focus. */
+ if (!result) {
+ goto swap_end;
+ }
+
+ /* If we moved the container holding the focused window to another
+ * workspace we need to ensure the visible workspace has the focused
+ * container.
+ * We don't need to check this for the second container because we've only
+ * moved the first one at this point.*/
+ if (first_ws != second_ws && focused_within_first) {
+ con_activate(con_descend_focused(current_ws));
+ }
+
+ /* Move second to where first has been originally. */
+ result &= _con_move_to_con(second, fake, false, false, false, true, false);
+ if (!result) {
+ goto swap_end;
+ }
+
+ /* Swapping will have inserted the containers at the tail of their parents'
+ * focus head. We fix this now by putting them in the position of the focus
+ * head the container they swapped with was in. */
+ TAILQ_REMOVE(&(first->parent->focus_head), first, focused);
+ TAILQ_REMOVE(&(second->parent->focus_head), second, focused);
+
+ if (second_prev_focus_head == NULL) {
+ TAILQ_INSERT_HEAD(&(first->parent->focus_head), first, focused);
+ } else {
+ TAILQ_INSERT_AFTER(&(first->parent->focus_head), second_prev_focus_head, first, focused);
+ }
+
+ if (first_prev_focus_head == NULL) {
+ TAILQ_INSERT_HEAD(&(second->parent->focus_head), second, focused);
+ } else {
+ TAILQ_INSERT_AFTER(&(second->parent->focus_head), first_prev_focus_head, second, focused);
+ }
+
+ /* If the focus was within any of the swapped containers, do the following:
+ * - If swapping took place within a workspace, ensure the previously
+ * focused container stays focused.
+ * - Otherwise, focus the container that has been swapped in.
+ *
+ * To understand why fixing the focus_head previously wasn't enough,
+ * consider the scenario
+ * H[ V[ A X ] V[ Y B ] ]
+ * with B being focused, but X being the focus_head within its parent. If
+ * we swap A and B now, fixing the focus_head would focus X, but since B
+ * was the focused container before it should stay focused.
+ */
+ if (focused_within_first) {
+ if (first_ws == second_ws) {
+ con_activate(old_focus);
+ } else {
+ con_activate(con_descend_focused(second));
+ }
+ } else if (focused_within_second) {
+ if (first_ws == second_ws) {
+ con_activate(old_focus);
+ } else {
+ con_activate(con_descend_focused(first));
+ }
+ }
+
+ /* We need to copy each other's percentages to ensure that the geometry
+ * doesn't change during the swap. This needs to happen _before_ we close
+ * the fake container as closing the tree will recalculate percentages. */
+ first->percent = second_percent;
+ second->percent = first_percent;
+ fake->percent = 0.0;
+
+ SWAP(first_fullscreen_mode, second_fullscreen_mode, fullscreen_mode_t);
+
+swap_end:
+ /* The two windows exchange their original fullscreen status */
+ if (first_fullscreen_mode != CF_NONE) {
+ con_enable_fullscreen(first, first_fullscreen_mode);
+ }
+ if (second_fullscreen_mode != CF_NONE) {
+ con_enable_fullscreen(second, second_fullscreen_mode);
+ }
+
+ /* We don't actually need this since percentages-wise we haven't changed
+ * anything, but we'll better be safe than sorry and just make sure as we'd
+ * otherwise crash i3. */
+ con_fix_percent(first->parent);
+ con_fix_percent(second->parent);
+
+ /* We can get rid of the fake container again now. */
+ con_close(fake, DONT_KILL_WINDOW);
+
+ con_force_split_parents_redraw(first);
+ con_force_split_parents_redraw(second);
+
+ return result;
+}