TreeView

Tree view facility.

Construct a tree of Node instances, embedding your data into them.
Initialize a model.
Interact with it (conventional TEA)
- Arrow-key interactions require the call-site to use the subscriptions of the facility, otherwise only mouse-click driven interactions work, see subscriptions.
Provide manually the required CSS definitions to make your tree view look usable & nice,
- for a basic working CSS see Demo CSS.

Also, non-leaf nodes can also be collapsed / expanded programmatically, as well as selected node and visible nodes can be retrieved.

Node uid

type NodeUid comparable

= NodeUid comparable

Tree view tracks internal state (collapsed/expanded, etc) of the nodes and identifies them by their node uid, thus a node uids must be comparable.

Node uids are to be unique in the scope of the forest being displayed by a tree view.
Call-site will define how to calculate the node uid for a given node, see uidThunk in Configuration.

To make clear when a function signature is referring to a node uid and not just any other old comparable value, this product type is used.

uidOf : NodeUid comparable -> comparable

Obtains the actual node uid (comparable) value out of the product type value.

Configuration

type alias Configuration d comparable =

{ uidThunk : Node d -> NodeUid comparable

, labelThunk : Node d -> String

, cssClasses : CssClasses

}

Configuration for initializing a tree view Model, to be given to initializeModel. Its fields are:

uidThunk : Tree.Node d -> NodeUid comparable gets the uid for a node, wrapped in a NodeUid value,
labelThunk : Tree.Node d -> String gets the text representation of a node for rendering,
cssClasses : the record with the CSS class names to generate the tree view HTML element with, see CssClasses as well as defaultCssClasses.

defaultCssClasses : CssClasses

Some CSS class names you can use by default.

A tree view is constructed out of HTML elements table, tr and td, and one or more of the CSS classes will be assigned to them:

treeViewCssClass: The CSS class set on all parts of the tree view, table, tr and td, always. Default is tree-view.
selectedTreeNodeCssClass: The CSS class for the TD of a selected node. Default is tree-view-selected-node.
indentationCssClass: The CSS class for an empty TD that used for indentation purposes. Default is tree-view-indentation.
bulletExpandedCssClass: The CSS class for the TD with a bullet in expanded node state. Default is tree-view-bullet-expanded.
bulletCollapsedCssClass: The CSS class for the TD with a bullet in collapsed node state. Default is tree-view-bullet-collapsed.
bulletLeafCssClass: The CSS class for the TD with a bullet in collapsed node state. Default is tree-view-bullet-leaf.

type alias CssClasses =

{ treeViewCssClass : String

, selectedTreeNodeCssClass : String

, indentationCssClass : String

, bulletExpandedCssClass : String

, bulletCollapsedCssClass : String

, bulletLeafCssClass : String

}

Defines CSS classes to be used for a tree view. Different tree views can be made to look different by initializing them with a different set of CSS class names, see also defaultCssClasses.

The actual CSS definitions must always be provided manually, even when the default CSS class names are used. For a working default CSS declarations, see Demo CSS.

Good old TEA types and functions

type Model d comparable

Model for a tree/forest, with the ability to get the uid for a node, render a node into a string, as well as storing expanded/collapsed presentation states.

Type variables

d is the custom data,
comparable is the type of the node uid (in practice Int or String)

See initializeModel.

initializeModel : Configuration d comparable -> List (Node d) -> Model d comparable

Initializes a model for a tree view.

type Msg comparable

Message, carrying the uid of the node something happened to.

update : Msg comparable -> Model d comparable -> Model d comparable

Updates the tree view model according to the message.

view : Model d comparable -> Html (Msg comparable)

Render the tree view model into HTML.

subscriptions : Model d comparable -> Sub (Msg comparable)

Subscriptions, for enabling arrow-key based user interactions, such as:

selection navigation (up / down arrows),
collapse & expand action ( left / right arrows).

Working with tree views

getSelected : Model d comparable -> Maybe (AnnotatedNode d)

Gets the selected (annotated) node, if any. See AnnotatedNode.

getVisibleAnnotatedNodes : Model d comparable -> List (AnnotatedNode d)

Gets the currently visible nodes (annotated). See AnnotatedNode.

Collapsing a non-leaf node will make its children hidden, transitively. The remaining visible nodes are the ones navigated with the up/down arrow keys.

expandAll : Model d comparable -> Model d comparable

Expands all nodes.

collapseAll : Model d comparable -> Model d comparable

Collapses all nodes.

updateExpandedStateOf :

NodeUid comparable

-> Bool

-> Model d comparable

Updates the model by setting the epxansion state of a node, identified by its node uid. True will expand the node, False will collapse it.

dosarf/elm-tree-view/1.0.1

TreeView

Node uid

Configuration

Good old TEA types and functions

Working with tree views

Modules