ContextMenu Properties

Control appearance and behavior of context menu

The properties listed here are valid for ContextMenu objects in GUIDE or in apps created with the figure function.

A context menu is a menu that appears when the user right-clicks on a graphics object or UI component. The uicontextmenu function creates a context menu and sets any required properties. By changing property values, you can modify the appearance and behavior of a context menu. Use dot notation to refer to a specific object and property.

c = uicontextmenu;
c.Position = [20 20];

Interactivity

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Context menu visibility, specified as 'on' or 'off'. You can use the Visible property in one of two ways:

  • Query the value to find out if the context menu is currently posted. The context menu is posted while the Visible property value is set to 'on'.

  • Set the Visible property to 'on' to make the context menu to appear. Set this property to 'off' to make the context menu to disappear.

Position

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Content menu location, specified as the vector, [left bottom]. This table describes each element in the vector.

ElementDescription
leftDistance from the inner left edge of the figure to the left edge of the context menu
bottomDistance from the inner bottom edge of the figure to the top edge of the context menu

The Position property defines the location of a context menu when its Visible property is set to 'on'.

Callbacks

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Context menu callback function, specified as one of these values:

  • A function handle.

  • A 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.

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

For more information about specifying a callback property value as a function handle, cell array, or character vector, see How to Specify Callback Property Values.

Data Types: function_handle | cell | char

Component creation function, specified as one of these values:

  • A function handle.

  • A 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.

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

For more information about specifying a callback property value as a function handle, cell array, or character vector, see How to Specify Callback Property Values.

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

Use the gcbo function in your CreateFcn code to get the component object that is being created.

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

Component deletion function, specified as one of these values:

  • A function handle.

  • A 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.

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

For more information about specifying a callback property value as a function handle, cell array, or character vector, see How to Specify Callback Property Values.

The DeleteFcn property specifies a callback function to execute when MATLAB deletes the component (for example, when the user closes the window). MATLAB executes the DeleteFcn callback before destroying the properties of the component object. If you do not specify the DeleteFcn property, then MATLAB executes a default deletion function.

Use the gcbo function in your DeleteFcn code to get the component object that is being deleted.

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:

  • A value of '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, getframe, waitfor, or pause.

    • If the running callback contains one of these commands, then MATLAB stops the execution of the callback at this 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 these commands, then MATLAB finishes executing the callback without interruption.

  • A value of '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.

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

See Interrupt Callback Execution for an example that shows how the Interruptible and BusyAction properties affect the behavior of a program.

Callback queuing specified as 'queue' (default) 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 of the source of the interrupting callback determines how MATLAB handles its execution. The BusyAction property has these values:

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

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

Whenever MATLAB invokes a callback, that callback always attempts to interrupt an executing callback. The Interruptible property of the object whose callback is running determines if interruption is allowed. If Interruptible is set to:

  • on — Interruption occurs at the next point where MATLAB processes the queue. This is the default.

  • off — The BusyAction property (of the object owning the interrupting callback) determines if MATLAB enqueues or ignores the interrupting callback.

See Interrupt Callback Execution for an example that shows how the BusyAction and Interruptible properties affect the behavior of a program.

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 figure. You can move a ContextMenu to a different figure by setting this property to the target Figure object.

Menu children, returned as an empty GraphicsPlaceholder or a 1-D array of Menu objects. The children of menus are other menus that function as submenus.

You cannot add or remove children using the Children property. Use this property to view the list of children or to reorder the child menu items. The order of the children in this array reflects the order of the displayed menu items.

To add a child to this list, set the Parent property of the child component to be the ContextMenu object.

Objects with the HandleVisibility property set to 'off' do not list in the Children property.

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

This property controls the visibility of the object handle in its parent's list of children. When a handle is not visible in its parent's list of children, it is not returned by functions that obtain handles by searching the object hierarchy or querying handle properties. These functions include get, findobj, gca, gcf, gco, newplot, cla, clf, and close. The HandleVisibility property also controls the visibility of the object’s handle in the parent figure's CurrentObject property. Handles are still 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 handle is always visible.
'callback'The object handle 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 handle 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 handle during the execution of that function.

Set the graphics root ShowHiddenHandles property to 'on' to make all handles visible, regardless of their HandleVisibility value. This setting has no effect on their HandleVisibility values.

Identifiers

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This property is read-only.

Type of graphics object, returned as 'uicontextmenu'.

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 array. Specifying UserData can be useful for sharing data within apps. See Share Data Among Callbacks for more information.

Introduced before R2006a