static TreeItem NextItem(Tree tree, TreeItem item) {
if (item == null) return null;
if (item.getExpanded()) {
return item.getItem(0);
} else {
TreeItem childItem = item;
TreeItem parentItem = childItem.getParentItem();
int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
int count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
while (true) {
if (index + 1 < count) {
return parentItem == null ? tree.getItem(index + 1) : parentItem.getItem(index + 1);
} else {
if (parentItem == null) {
return null;
} else {
childItem = parentItem;
parentItem = childItem.getParentItem();
index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
}
}
}
}
}
static TreeItem PreviousItem(Tree tree, TreeItem item) {
if (item == null) return null;
TreeItem childItem = item;
TreeItem parentItem = childItem.getParentItem();
int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
if (index == 0) {
return parentItem;
} else {
TreeItem nextItem =
parentItem == null ? tree.getItem(index - 1) : parentItem.getItem(index - 1);
int count = nextItem.getItemCount();
while (count > 0 && nextItem.getExpanded()) {
nextItem = nextItem.getItem(count - 1);
count = nextItem.getItemCount();
}
return nextItem;
}
}