@@ -538,20 +538,72 @@ impl Tree {
538538 }
539539 }
540540
541− pub fn swap_split_in_direction(&mut self, direction: Direction) {
542− if let Some(id) = self.find_split_in_direction(self.focus, direction) {
543− if let Some([focused, target]) = self.nodes.get_disjoint_mut([self.focus, id]) {
544− match (&mut focused.content, &mut target.content) {
545− (Content::View(focused), Content::View(target)) => {
546− std::mem::swap(&mut focused.doc, &mut target.doc);
547− std::mem::swap(&mut focused.id, &mut target.id);
548− self.focus = id;
549− }
550− // self.focus always points to a view which has a content of Content::View
551− // and find_split_in_direction() only returns a view which has content of
552− // Content::View.
553− _ => unreachable!(),
541+ pub fn swap_split_in_direction(&mut self, direction: Direction) -> Option<()> {
542+ let focus = self.focus;
543+ let target = self.find_split_in_direction(focus, direction)?;
544+ let focus_parent = self.nodes[focus].parent;
545+ let target_parent = self.nodes[target].parent;
546+
547+ if focus_parent == target_parent {
548+ let parent = focus_parent;
549+ let [parent, focus, target] = self.nodes.get_disjoint_mut([parent, focus, target])?;
550+ match (&mut parent.content, &mut focus.content, &mut target.content) {
551+ (
552+ Content::Container(parent),
553+ Content::View(focus_view),
554+ Content::View(target_view),
555+ ) => {
556+ let focus_pos = parent.children.iter().position(|id| focus_view.id == *id)?;
557+ let target_pos = parent
558+ .children
559+ .iter()
560+ .position(|id| target_view.id == *id)?;
561+ // swap node positions so that traversal order is kept
562+ parent.children[focus_pos] = target_view.id;
563+ parent.children[target_pos] = focus_view.id;
564+ // swap area so that views rendered at the correct location
565+ std::mem::swap(&mut focus_view.area, &mut target_view.area);
566+
567+ Some(())
554568 }
569+ _ => unreachable!(),
570+ }
571+ } else {
572+ let [focus_parent, target_parent, focus, target] =
573+ self.nodes
574+ .get_disjoint_mut([focus_parent, target_parent, focus, target])?;
575+ match (
576+ &mut focus_parent.content,
577+ &mut target_parent.content,
578+ &mut focus.content,
579+ &mut target.content,
580+ ) {
581+ (
582+ Content::Container(focus_parent),
583+ Content::Container(target_parent),
584+ Content::View(focus_view),
585+ Content::View(target_view),
586+ ) => {
587+ let focus_pos = focus_parent
588+ .children
589+ .iter()
590+ .position(|id| focus_view.id == *id)?;
591+ let target_pos = target_parent
592+ .children
593+ .iter()
594+ .position(|id| target_view.id == *id)?;
595+ // re-parent target and focus nodes
596+ std::mem::swap(
597+ &mut focus_parent.children[focus_pos],
598+ &mut target_parent.children[target_pos],
599+ );
600+ std::mem::swap(&mut focus.parent, &mut target.parent);
601+ // swap area so that views rendered at the correct location
602+ std::mem::swap(&mut focus_view.area, &mut target_view.area);
603+
604+ Some(())
605+ }
606+ _ => unreachable!(),
555607 }
556608 }
557609 }
@@ -738,7 +790,7 @@ mod test {
738790 tree.swap_split_in_direction(Direction::Down);
739791 // | l1 | l2 | |
740792 // | l0* | r0 |
741− assert_eq!(tree.focus, l1);
793+ assert_eq!(tree.focus, l0);
742794 assert_eq!(doc_id(&tree, l0), Some(doc_l1));
743795 assert_eq!(doc_id(&tree, l1), Some(doc_l0));
744796 assert_eq!(doc_id(&tree, l2), Some(doc_l2));
@@ -748,7 +800,7 @@ mod test {
748800
749801 // | l1 | l2 | |
750802 // | r0 | l0* |
751− assert_eq!(tree.focus, r0);
803+ assert_eq!(tree.focus, l0);
752804 assert_eq!(doc_id(&tree, l0), Some(doc_l1));
753805 assert_eq!(doc_id(&tree, l1), Some(doc_r0));
754806 assert_eq!(doc_id(&tree, l2), Some(doc_l2));
@@ -758,7 +810,7 @@ mod test {
758810 tree.swap_split_in_direction(Direction::Up);
759811 // | l1 | l2 | |
760812 // | r0 | l0* |
761− assert_eq!(tree.focus, r0);
813+ assert_eq!(tree.focus, l0);
762814 assert_eq!(doc_id(&tree, l0), Some(doc_l1));
763815 assert_eq!(doc_id(&tree, l1), Some(doc_r0));
764816 assert_eq!(doc_id(&tree, l2), Some(doc_l2));
@@ -768,7 +820,7 @@ mod test {
768820 tree.swap_split_in_direction(Direction::Down);
769821 // | l1 | l2 | |
770822 // | r0 | l0* |
771− assert_eq!(tree.focus, r0);
823+ assert_eq!(tree.focus, l0);
772824 assert_eq!(doc_id(&tree, l0), Some(doc_l1));
773825 assert_eq!(doc_id(&tree, l1), Some(doc_r0));
774826 assert_eq!(doc_id(&tree, l2), Some(doc_l2));
@@ -781,7 +833,7 @@ mod test {
781833 tree.swap_split_in_direction(Direction::Down);
782834 // | l1 | r0 | |
783835 // | l2* | l0 |
784− assert_eq!(tree.focus, l1);
836+ assert_eq!(tree.focus, l2);
785837 assert_eq!(doc_id(&tree, l0), Some(doc_l1));
786838 assert_eq!(doc_id(&tree, l1), Some(doc_l2));
787839 assert_eq!(doc_id(&tree, l2), Some(doc_r0));
@@ -790,7 +842,7 @@ mod test {
790842 tree.swap_split_in_direction(Direction::Up);
791843 // | l2* | r0 | |
792844 // | l1 | l0 |
793− assert_eq!(tree.focus, l0);
845+ assert_eq!(tree.focus, l2);
794846 assert_eq!(doc_id(&tree, l0), Some(doc_l2));
795847 assert_eq!(doc_id(&tree, l1), Some(doc_l1));
796848 assert_eq!(doc_id(&tree, l2), Some(doc_r0));