1.175.1 Instance variables

tree <- auto_layout: bool

When @on (default), the tree will recompute its layout on any change to any of its nodes or change to the tree itself. When @off the tree won't automatically recompute the layout.

Sometimes, it is desirable to allow the user to move the nodes of a tree by hand. With tree<-auto_layout: @on this is not possible as the tree will immediately move the node back to the original position.

See also tree->compute and tree->layout.

tree <- collapsed_handlers: chain

@see tree->event

tree <- direction: {horizontal,vertical,list}

Defines the layout:

horizontal

Root at the left, the sons are displayed left-to-right.

vertical

The tree is displayed top-to-bottom.

list

The tree is displayed as an indented list. The line properties of the tree<-link are used to determine the thickness, texture and colour of the lines. Each node will, if it has sons, draw a line from (x + tree<-level_gap/2, bottom side) down to halfway the last son. If to node is not the root, it will draw a line from halfway its height towards the line from its parent. See also node<->collapsed.

Note: the default tree is displayed left-to-right rather than top-to-bottom as the nodes are often much wider than high. Using left-to-right layout allows for displaying much larger hierarchies.

When a large number of items is to be displayed as an indented list, also consider class list_browser. The indentation may be realised using list_browser->tab_stops.

tree <- display_root: node*

Root of the visible part of the tree. This variable is managed using tree->zoom and tree->unzoom.

See also

- tree-root
- tree->zoom

tree <- leaf_handlers: chain

@see tree->event

tree <- level_gap: int

Distance between a node and its parents or sons.

tree <- link: link

Link used to create connections between parent- and son-nodes. Its attributes may be changed to attach arrows or modify one of the line attributes. For example,

send(Tree?link, arrows, first).

will attach an arrow pointing to the root to every relation created after this call has been made.

See also

- tree-link_gap
- tree-parent_handle
- tree-son_handle

tree <- link_gap: int

Distance between the image and the line. Used to define the X- and Y-positions of the tree<-son_handle and tree<-parent_handle.

See also

- tree-parent_handle
- tree-son_handle
- tree-link

tree <- neighbour_gap: int

Distance between two nodes that are at the same level (= distance from the root). The default (0) satisfies when the nodes are represented by text object. For other graphicals a small positive value gives better results.

See also

- tree->level_gap
- tree->neighbour_gap

tree <- node_handlers: chain

@see tree->event

tree <- parent_handle: handle

This handle object is attached to each graphical representing a node. It is the connection-point for a line linking this graphical to its parent.

This handle is automatically updated by tree->direction..

See also

- tree-link_gap
- tree-link
- tree->direction
- tree-son_handle
- class handle

tree <- root: node*

Root node of the tree. Note that the root of the visual part of the tree is represented by tree<-display_root. Class tree delegates messages not understood to its tree<-root node when present.

If the argument is *nil, all nodes are removed from the tree. If the argument is a new root object the behaviour depends on the relink argument. With relink = @off (default), the tree is first cleared using tree->root: @nil, after which the new root is attached. With relink = @on the old root is added as the only node->son of the new root.

See also tree->zoom and tree->unzoom.

See also

tree-display_root

tree <- root_handlers: chain

@see tree->event

tree <- son_handle: handle

Similar to tree<-parent_handle, but is the connection-point for the connection towards son-nodes.

See also

- tree-link_gap
- tree-link
- tree-parent_handle