TreeNode

Tree node UI component

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Description

A tree node UI component displays an item in a tree hierarchy within an app. Use the TreeNode object to modify the appearance and behavior of a tree node after you create it.

Creation

Create a tree node in an app using the uitreenode function.

Properties

Node

Text — Node text

'Tree Node' (default) | character vector | string scalar

Node text, specified as a character vector or string scalar.

NodeData — Node data

[] (default) | array

Node data, specified as an array of any type. Specify NodeData to share node-relevant data within your app code.

Icon — Icon source or file

'' (default) | character vector | string scalar | m-by-n-by-3 truecolor image array

Icon source or file, specified as a character vector, a string scalar, or an m-by-n-by-3 truecolor image array. If you specify a file name, it can be an image file name on the MATLAB^® path or a full path to an image file. If you plan to share an app with others, put the image file on the MATLAB path to facilitate app packaging.

Supported image formats include JPEG, PNG, GIF, SVG, or m-by-n-by-3 truecolor image array. For more information about truecolor image arrays, see Working with Image Types in MATLAB.

Example: 'icon.png' specifies an icon file on the MATLAB path.

Example: 'C:\Documents\icon.png' specifies a full path to an image file.

Interactivity

ContextMenu — Context menu

empty GraphicsPlaceholder array (default) | ContextMenu object

Context menu, specified as a ContextMenu object created using the uicontextmenu function. Use this property to display a context menu when you right-click on a component.

Callbacks

CreateFcn — Creation function

'' (default) | function handle | cell array | character vector

Object creation function, specified as one of these values:

• Function handle.

• Cell array in which the first element is a function handle. Subsequent elements in the cell array are the arguments to pass to the callback function.

• Character vector containing a valid MATLAB expression (not recommended). MATLAB evaluates this expression in the base workspace.

For more information about specifying a callback as a function handle, cell array, or character vector, see Callbacks in App Designer.

This property specifies a callback function to execute when MATLAB creates the object. MATLAB initializes all property values before executing the CreateFcn callback. If you do not specify the CreateFcn property, then MATLAB executes a default creation function.

Setting the CreateFcn property on an existing component has no effect.

If you specify this property as a function handle or cell array, you can access the object that is being created using the first argument of the callback function. Otherwise, use the gcbo function to access the object.

DeleteFcn — Deletion function

'' (default) | function handle | cell array | character vector

Object deletion function, specified as one of these values:

• Function handle.

• Cell array in which the first element is a function handle. Subsequent elements in the cell array are the arguments to pass to the callback function.

• Character vector containing a valid MATLAB expression (not recommended). MATLAB evaluates this expression in the base workspace.

For more information about specifying a callback as a function handle, cell array, or character vector, see Callbacks in App Designer.

This property specifies a callback function to execute when MATLAB deletes the object. MATLAB executes the DeleteFcn callback before destroying the properties of the object. If you do not specify the DeleteFcn property, then MATLAB executes a default deletion function.

If you specify this property as a function handle or cell array, you can access the object that is being deleted using the first argument of the callback function. Otherwise, use the gcbo function to access the object.

Callback Execution Control

Interruptible — Callback interruption

'on' (default) | on/off logical value

Callback interruption, specified as 'on' or 'off', or as numeric or logical 1 (true) or 0 (false). A value of 'on' is equivalent to true, and 'off' is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

This property determines if a running callback can be interrupted. There are two callback states to consider:

• The running callback is the currently executing callback.

• The interrupting callback is a callback that tries to interrupt the running callback.

MATLAB determines callback interruption behavior whenever it executes a command that processes the callback queue. These commands include drawnow, figure, uifigure, getframe, waitfor, and pause.

If the running callback does not contain one of these commands, then no interruption occurs. MATLAB first finishes executing the running callback, and later executes the interrupting callback.

If the running callback does contain one of these commands, then the Interruptible property of the object that owns the running callback determines if the interruption occurs:

• If the value of Interruptible is 'off', then no interruption occurs. Instead, the BusyAction property of the object that owns the interrupting callback determines if the interrupting callback is discarded or added to the callback queue.

• If the value of Interruptible is 'on', then the interruption occurs. The next time MATLAB processes the callback queue, it stops the execution of the running callback and executes the interrupting callback. After the interrupting callback completes, MATLAB then resumes executing the running callback.

Note

Callback interruption and execution behave differently in these situations:

• If the interrupting callback is a DeleteFcn, CloseRequestFcn, or SizeChangedFcn callback, then the interruption occurs regardless of the Interruptible property value.

• If the running callback is currently executing the waitfor function, then the interruption occurs regardless of the Interruptible property value.

• If the interrupting callback is owned by a Timer object, then the callback executes according to schedule regardless of the Interruptible property value.

Note

When an interruption occurs, MATLAB does not save the state of properties or the display. For example, the object returned by the gca or gcf command might change when another callback executes.

BusyAction — Callback queuing

'queue' (default) | 'cancel'

Callback queuing, specified as 'queue' or 'cancel'. The BusyAction property determines how MATLAB handles the execution of interrupting callbacks. There are two callback states to consider:

• The running callback is the currently executing callback.

• The interrupting callback is a callback that tries to interrupt the running callback.

The BusyAction property determines callback queuing behavior only when both of these conditions are met:

• The running callback contains a command that processes the callback queue, such as drawnow, figure, uifigure, getframe, waitfor, or pause.

• The value of the Interruptible property of the object that owns the running callback is 'off'.

Under these conditions, the BusyAction property of the object that owns the interrupting callback determines how MATLAB handles the interrupting callback. These are possible values of the BusyAction property:

• 'queue' — Puts the interrupting callback in a queue to be processed after the running callback finishes execution.

• 'cancel' — Does not execute the interrupting callback.

BeingDeleted — Deletion status

on/off logical value

This property is read-only.

Deletion status, returned as an on/off logical value of type matlab.lang.OnOffSwitchState.

MATLAB sets the BeingDeleted property to 'on' when the DeleteFcn callback begins execution. The BeingDeleted property remains set to 'on' until the component object no longer exists.

Check the value of the BeingDeleted property to verify that the object is not about to be deleted before querying or modifying it.

Parent/Child

Parent — Parent object

Tree object | TreeNode object

Parent object, specified as a Tree or TreeNode object.

Children — Children

empty GraphicsPlaceholder array (default) | array of TreeNode objects

Children, returned as an array of TreeNode objects.

You cannot add or remove children using the Children property, but you can use the property to view the list of children. The order of the children reflects the order of the child nodes displayed on the screen. To add a child to this list, set the Parent property of the child component to be the TreeNode object.

To reorder the children, use the move function.

Objects with the HandleVisibility property set to 'off' are not listed in the Children property.

HandleVisibility — Visibility of object handle

'on' (default) | 'callback' | 'off'

Visibility of the object handle, specified as 'on', 'callback', or 'off'.

This property controls the visibility of the object in its parent's list of children. When an object is not visible in its parent's list of children, it is not returned by functions that obtain objects by searching the object hierarchy or querying properties. These functions include get, findobj, clf, and close. Objects are valid even if they are not visible. If you can access an object, you can set and get its properties, and pass it to any function that operates on objects.

HandleVisibility Value	Description
'on'	The object is always visible.
'callback'	The object is visible from within callbacks or functions invoked by callbacks, but not from within functions invoked from the command line. This option blocks access to the object at the command-line, but allows callback functions to access it.
'off'	The object is invisible at all times. This option is useful for preventing unintended changes to the UI by another function. Set the HandleVisibility to 'off' to temporarily hide the object during the execution of that function.

Identifiers

Type — Type of graphics object

'uitreenode'

This property is read-only.

Type of graphics object, returned as 'uitreenode'.

Tag — Object identifier

'' (default) | character vector | string scalar

Object identifier, specified as a character vector or string scalar. You can specify a unique Tag value to serve as an identifier for an object. When you need access to the object elsewhere in your code, you can use the findobj function to search for the object based on the Tag value.

UserData — User data

[] (default) | array

User data, specified as any MATLAB array. For example, you can specify a scalar, vector, matrix, cell array, character array, table, or structure. Use this property to store arbitrary data on an object.

If you are working in App Designer, create public or private properties in the app to share data instead of using the UserData property. For more information, see Share Data Within App Designer Apps.

Object Functions

expand	Expand tree node
collapse	Collapse tree node
move	Move tree node

Examples

Create Callback for Tree Node Selection

Create an app that displays athlete names grouped by sport. When the app user clicks on a name, MATLAB displays data about the athlete.

Create a program file called mytreeapp.m that contains the following commands to create a tree, a set of nested tree nodes, and a callback function for the tree. The SelectionChangedFcn property specifies the function to execute when the user clicks a node in the tree.

function mytreeapp
    fig = uifigure;
    t = uitree(fig,"Position",[20 20 150 150]);

    % Assign callback in response to node selection
    t.SelectionChangedFcn = @nodechange;

    % First level nodes
    category1 = uitreenode(t,"Text","Runners","NodeData",[]);
    category2 = uitreenode(t,"Text","Cyclists","NodeData",[]);

    % Second level nodes.
    % Node data is age (y), height (m), weight (kg)
    p1 = uitreenode(category1,"Text","Joe","NodeData",[40 1.67 58] );
    p2 = uitreenode(category1,"Text","Linda","NodeData",[49 1.83 90]);
    p3 = uitreenode(category2,"Text","Rajeev","NodeData",[25 1.47 53]);
    p4 = uitreenode(category2,"Text","Anne","NodeData",[88 1.92 100]);

    % Expand the tree
    expand(t);
    
    % Create the function for the SelectionChangedFcn callback
    % When the function is executed, it displays the data of the selected item
    function nodechange(src,event)
        node = event.SelectedNodes;
        display(node.NodeData);
    end
end

When the user runs mytreeapp and clicks a node in the tree, MATLAB displays the NodeData for that node.

Generate Tree Nodes Based on Table Data

Create a tree that populates nodes based on the data in a table.

Create a figure with a grid layout manager to hold the UI components. Load sample data on electric utility outages and create a table UI component to display the data. Then, create a tree to hold nodes listing the regions and causes of the outages.

fig = uifigure;
gl = uigridlayout(fig,[1 2]);
gl.ColumnWidth = {'2x','1x'};

T = readtable("outages.csv");
T = T(1:20,["Region","OutageTime","Loss","Cause"]);
tbl = uitable(gl,"Data",T);

tr = uitree(gl);

Specify the table variables to display in the tree. For each of those variables, create a top-level node whose text is the variable name. Extract the relevant data by converting the table entries for the variable to a categorical array and returning the list of categories as names. Then, loop through the categories. For each element, add a node to the tree under the appropriate parent node.

vars = ["Region","Cause"];

for k1 = 1:length(vars)
    var = vars{k1};
    varnode = uitreenode(tr,"Text",var);
    rows = T{:,var};
    names = categories(categorical(rows));
         
    for k2 = 1:length(names)
        text = names{k2};
        uitreenode(varnode,"Text",text);
    end
end

Expand the tree to see all the nodes.

expand(tr)

Share Context Menu Across Tree Nodes

Create a context menu for a tree component. Assign the context menu to all of the top-level nodes in the tree.

In a new script in your current folder, create a UI figure. Then, create a tree with four top-level nodes and a set of nested nodes.

fig = uifigure;

t = uitree(fig,"Position",[20 200 175 100]);

category1 = uitreenode(t,"Text","Runners");
r1 = uitreenode(category1,"Text","Joe");
r2 = uitreenode(category1,"Text","Linda");

category2 = uitreenode(t,"Text","Cyclists");
c1 = uitreenode(category2,"Text","Rajeev");

category3 = uitreenode(t,"Text","Hikers");
h1 = uitreenode(category3,"Text","Jack");

category4 = uitreenode(t,"Text","Swimmers");
s1 = uitreenode(category4,"Text","Logan");

Create a context menu with one menu item and two submenus that users can click to expand a single tree node or all of the tree nodes. For each submenu, specify a MenuSelectedFcn callback function to execute when a user selects the menu option. Pass the relevant app object as input to each function to access app data from within the callback function.

cm = uicontextmenu(fig);
m1 = uimenu(cm,"Text","Expand...");

sbm1 = uimenu(m1,"Text","This Node", ...
    "MenuSelectedFcn",{@expandSingle,fig});
sbm2 = uimenu(m1,"Text","All Nodes", ...
    "MenuSelectedFcn",{@expandAll,t});

Assign the context menu to the top-level tree nodes by setting the ContextMenu property of each node to the ContextMenu object.

category1.ContextMenu = cm;
category2.ContextMenu = cm;
category3.ContextMenu = cm;
category4.ContextMenu = cm;

At the bottom of the file, define the expandSingle and expandAll callback functions. Define the functions to accept the source and event data that MATLAB passes to all callback functions.

Define the expandSingle function to also accept the UI figure object containing the tree, and use the CurrentObject property of the figure to determine which tree node was clicked to bring up the context menu. Then, expand that node.

Define the expandAll function to also accept the tree object, and expand all of the nodes in the tree.

function expandSingle(src,event,f)
node = f.CurrentObject;
expand(node)
end

function expandAll(src,event,t)
expand(t)
end

Save and run the script. Right-click any of the top-level tree nodes to view the context menu.

Version History

Introduced in R2017b