This shows a tree of items that can be selected, expanded and collapsed. The tree can have multiple columns with custom controls like text editing, buttons and popups. It can be useful for structured displays and interactions.
Trees are built via code, using [TreeItem] objects to create the structure. They have a single root but multiple roots can be simulated if a dummy hidden root is added.
[codeblock]
func _ready():
var tree = Tree.new()
var root = tree.create_item()
tree.set_hide_root(true)
var child1 = tree.create_item(root)
var child2 = tree.create_item(root)
var subchild1 = tree.create_item(child1)
subchild1.set_text(0, "Subchild1")
[/codeblock]
To iterate over all the [TreeItem] objects in a [Tree] object, use [method TreeItem.get_next] and [method TreeItem.get_children] after getting the root through [method get_root]. You can use [method Object.free] on a [TreeItem] to remove it from the [Tree].
Creates an item in the tree and adds it as a child of [code]parent[/code], which can be either a valid [TreeItem] or [code]null[/code].
If [code]parent[/code] is [code]null[/code], the root item will be the parent, or the new item will be the root itself if the tree is empty.
The new item will be the [code]idx[/code]th child of parent, or it will be the last child if there are not enough siblings.
</description>
</method>
<methodname="edit_selected">
<returntype="bool"/>
<description>
Edits the selected tree item as if it was clicked. The item must be set editable with [method TreeItem.set_editable]. Returns [code]true[/code] if the item could be edited. Fails if no item is selected.
</description>
</method>
<methodname="ensure_cursor_is_visible">
<returntype="void"/>
<description>
Makes the currently focused cell visible.
This will scroll the tree if necessary. In [constant SELECT_ROW] mode, this will not do horizontal scrolling, as all the cells in the selected row is focused logically.
[b]Note:[/b] Despite the name of this method, the focus cursor itself is only visible in [constant SELECT_MULTI] mode.
Returns the drop section at [code]position[/code], or -100 if no item is there.
Values -1, 0, or 1 will be returned for the "above item", "on item", and "below item" drop sections, respectively. See [enum DropModeFlags] for a description of each drop section.
To get the item which the returned drop section is relative to, use [method get_item_at_position].
</description>
</method>
<methodname="get_edited"qualifiers="const">
<returntype="TreeItem"/>
<description>
Returns the currently edited item. Can be used with [signal item_edited] to get the item that was modified.
Returns the rectangle area for the specified [TreeItem]. If [code]column[/code] is specified, only get the position and size of that column, otherwise get the rectangle containing all columns.
Returns the tree's root item, or [code]null[/code] if the tree is empty.
</description>
</method>
<methodname="get_scroll"qualifiers="const">
<returntype="Vector2"/>
<description>
Returns the current scrolling position.
</description>
</method>
<methodname="get_selected"qualifiers="const">
<returntype="TreeItem"/>
<description>
Returns the currently focused item, or [code]null[/code] if no item is focused.
In [constant SELECT_ROW] and [constant SELECT_SINGLE] modes, the focused item is same as the selected item. In [constant SELECT_MULTI] mode, the focused item is the item under the focus cursor, not necessarily selected.
To get the currently selected item(s), use [method get_next_selected].
Returns the currently focused column, or -1 if no column is focused.
In [constant SELECT_SINGLE] mode, the focused column is the selected column. In [constant SELECT_ROW] mode, the focused column is always 0 if any item is selected. In [constant SELECT_MULTI] mode, the focused column is the column under the focus cursor, and there are not necessarily any column selected.
To tell whether a column of an item is selected, use [method TreeItem.is_selected].
</description>
</method>
<methodname="scroll_to_item">
<returntype="void"/>
<argumentindex="0"name="item"type="Object"/>
<description>
Causes the [Tree] to jump to the specified [TreeItem].
</description>
</method>
<methodname="set_column_expand">
<returntype="void"/>
<argumentindex="0"name="column"type="int"/>
<argumentindex="1"name="expand"type="bool"/>
<description>
If [code]true[/code], the column will have the "Expand" flag of [Control]. Columns that have the "Expand" flag will use their "min_width" in a similar fashion to [member Control.size_flags_stretch_ratio].
</description>
</method>
<methodname="set_column_min_width">
<returntype="void"/>
<argumentindex="0"name="column"type="int"/>
<argumentindex="1"name="min_width"type="int"/>
<description>
Sets the minimum width of a column. Columns that have the "Expand" flag will use their "min_width" in a similar fashion to [member Control.size_flags_stretch_ratio].
The drop mode as an OR combination of flags. See [enum DropModeFlags] constants. Once dropping is done, reverts to [constant DROP_MODE_DISABLED]. Setting this during [method Control.can_drop_data] is recommended.
This controls the drop sections, i.e. the decision and drawing of possible drop locations based on the mouse position.
Allows selection of a single cell at a time. From the perspective of items, only a single item is allowed to be selected. And there is only one column selected in the selected item.
The focus cursor is always hidden in this mode, but it is positioned at the current selection, making the currently selected item the currently focused item.
Allows selection of a single row at a time. From the perspective of items, only a single items is allowed to be selected. And all the columns are selected in the selected item.
The focus cursor is always hidden in this mode, but it is positioned at the first column of the current selection, making the currently selected item the currently focused item.
Allows selection of multiple cells at the same time. From the perspective of items, multiple items are allowed to be selected. And there can be multiple columns selected in each selected item.
The focus cursor is visible in this mode, the item or column under the cursor is not necessarily selected.
Enables "above item" and "below item" drop sections. The "above item" drop section covers the top half of the item, and the "below item" drop section covers the bottom half.
When combined with [constant DROP_MODE_ON_ITEM], these drop sections halves the height and stays on top / bottom accordingly.
