diff --git a/src/move.c b/src/move.c index 97ca6d40..72cf9d61 100644 --- a/src/move.c +++ b/src/move.c @@ -12,6 +12,54 @@ typedef enum { BEFORE, AFTER } position_t; +/* + * Returns the lowest container in the tree that has both a and b as descendants. + * + */ +static Con *lowest_common_ancestor(Con *a, Con *b) { + Con *parent_a = a; + while (parent_a) { + Con *parent_b = b; + while (parent_b) { + if (parent_a == parent_b) { + return parent_a; + } + parent_b = parent_b->parent; + } + parent_a = parent_a->parent; + } + assert(false); +} + +/* + * Returns the direct child of ancestor that contains con. + * + */ +static Con *child_containing_con_recursively(Con *ancestor, Con *con) { + Con *child = con; + while (child && child->parent != ancestor) { + child = child->parent; + assert(child->parent); + } + return child; +} + +/* + * Returns true if the given container is the focused descendant of ancestor, recursively. + * + */ +static bool is_focused_descendant(Con *con, Con *ancestor) { + Con *current = con; + while (current != ancestor) { + if (TAILQ_FIRST(&(current->parent->focus_head)) != current) { + return false; + } + current = current->parent; + assert(current->parent); + } + return true; +} + /* * This function detaches 'con' from its parent and inserts it either before or * after 'target'. @@ -24,6 +72,52 @@ static void insert_con_into(Con *con, Con *target, position_t position) { * afterwards which might then close the con if it is empty. */ Con *old_parent = con->parent; + /* We compare the focus order of the children of the lowest common ancestor. If con or + * its ancestor is before target's ancestor then con should be placed before the target + * in the focus stack. */ + Con *lca = lowest_common_ancestor(con, parent); + if (lca == con) { + ELOG("Container is being inserted into one of its descendants.\n"); + return; + } + + Con *con_ancestor = child_containing_con_recursively(lca, con); + Con *target_ancestor = child_containing_con_recursively(lca, target); + bool moves_focus_from_ancestor = is_focused_descendant(con, con_ancestor); + bool focus_before; + + /* Determine if con is going to be placed before or after target in the parent's focus stack. */ + if (con_ancestor == target_ancestor) { + /* Happens when the target is con's old parent. Eg with layout V [ A H [ B C ] ], + * if we move C up. Target will be H. */ + focus_before = moves_focus_from_ancestor; + } else { + /* Look at the focus stack order of the children of the lowest common ancestor. */ + Con *current; + TAILQ_FOREACH(current, &(lca->focus_head), focused) { + if (current == con_ancestor || current == target_ancestor) { + break; + } + } + focus_before = (current == con_ancestor); + } + + /* If con is the focused container in our old ancestor we place the new ancestor + * before the old ancestor in the focus stack. Example: + * Consider the layout [ H [ V1 [ A* B ] V2 [ C ] ] ] where A is focused. We move to + * a second workspace and from there we move A to the right and switch back to the + * original workspace. Without the change focus would move to B instead of staying + * with A. */ + if (moves_focus_from_ancestor && focus_before) { + Con *place = TAILQ_PREV(con_ancestor, focus_head, focused); + TAILQ_REMOVE(&(lca->focus_head), target_ancestor, focused); + if (place) { + TAILQ_INSERT_AFTER(&(lca->focus_head), place, target_ancestor, focused); + } else { + TAILQ_INSERT_HEAD(&(lca->focus_head), target_ancestor, focused); + } + } + con_detach(con); con_fix_percent(con->parent); @@ -46,12 +140,28 @@ static void insert_con_into(Con *con, Con *target, position_t position) { con->parent = parent; + if (parent == lca) { + if (focus_before) { + /* Example layout: H [ A B* ], we move A up/down. 'target' will be H. */ + TAILQ_INSERT_BEFORE(target, con, focused); + } else { + /* Example layout: H [ A B* ], we move A up/down. 'target' will be H. */ + TAILQ_INSERT_AFTER(&(parent->focus_head), target, con, focused); + } + } else { + if (focus_before) { + /* Example layout: V [ H [ A B ] C* ], we move C up. 'target' will be A. */ + TAILQ_INSERT_HEAD(&(parent->focus_head), con, focused); + } else { + /* Example layout: V [ H [ A* B ] C ], we move C up. 'target' will be A. */ + TAILQ_INSERT_TAIL(&(parent->focus_head), con, focused); + } + } + if (position == BEFORE) { TAILQ_INSERT_BEFORE(target, con, nodes); - TAILQ_INSERT_HEAD(&(parent->focus_head), con, focused); } else if (position == AFTER) { TAILQ_INSERT_AFTER(&(parent->nodes_head), target, con, nodes); - TAILQ_INSERT_HEAD(&(parent->focus_head), con, focused); } /* Pretend the con was just opened with regards to size percent values.