TreeNode Properties

Control appearance and behavior of tree node

Tree nodes are the items listed in a tree hierarchy. The uitreenode function creates a tree node and sets any required properties before displaying it. By changing tree node property values, you can modify certain aspects of its appearance and behavior. Use dot notation to refer to a specific object and property.

uf = uifigure;
tree = uitree(uf);
node = uitreenode(tree);
node.Text = 'Item 1';

Node

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

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

Icon image file, specified as a character vector or string scalar. Specify a file name that is on the MATLAB® path when the user runs the app. Alternatively, specify a full path to the image file.

Callbacks

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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 Write 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.

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 Write 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

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Callback interruption, specified as 'on' or 'off'. The Interruptible 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.

Whenever MATLAB invokes a callback, that callback attempts to interrupt the running callback (if one exists). The Interruptible property of the object owning the running callback determines if interruption is allowed. The Interruptible property has two possible values:

  • 'on' — Allows other callbacks to interrupt the object's callbacks. The interruption occurs at the next point where MATLAB processes the queue, such as when there is a drawnow, figure, uifigure, getframe, waitfor, or pause command.

    • If the running callback contains one of those commands, then MATLAB stops the execution of the callback at that point and executes the interrupting callback. MATLAB resumes executing the running callback when the interrupting callback completes.

    • If the running callback does not contain one of those commands, then MATLAB finishes executing the callback without interruption.

  • 'off' — Blocks all interruption attempts. The BusyAction property of the object owning the interrupting callback determines if the interrupting callback is discarded or put into a queue.

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.

  • Timer objects execute according to schedule regardless of the Interruptible property value.

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.

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.

Whenever MATLAB invokes a callback, that callback attempts to interrupt a running callback. The Interruptible property of the object owning the running callback determines if interruption is permitted. If interruption is not permitted, then the BusyAction property of the object owning the interrupting callback determines if it is discarded or put in the queue. 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.

This property is read-only.

Deletion status, returned as 'off' or 'on'. 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

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Parent object, specified as a Tree or TreeNode object.

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' do not list in the Children property.

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 ValueDescription
'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

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This property is read-only.

Type of graphics object, returned as 'uitreenode'.

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.

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.

Introduced in R2017b