Trigger event for graphic handle object?

The function notify seems to be designed for user-define class. Is it possible to make it works on MATLAB graphic handle objects such as uibutton. This code

fig = uifigure;
btn = uibutton(fig);
addlistener(btn, 'PropertyAdded', @(varargin) disp('trigger'));
notify(fig, 'PropertyAdded')

returns the following error:

Returns error
Error using matlab.ui.Figure/notify
Cannot notify listeners of event 'PropertyAdded' in class 'dynamicprops'.

Answer 1

[Satwik]

Hi,

In MATLAB, the ‘notify’ function is indeed designed to work with user-defined classes that inherit from the ‘handle’ class. When you try to use notify with built-in MATLAB classes or UI components like ‘uibutton’, you're limited to the events that those classes or components explicitly define and support. Unfortunately, this means you cannot directly trigger custom events like 'PropertyAdded' on MATLAB graphics handle objects such as ‘uibutton’ without extending those classes in some way.

The error you're encountering is because the ‘uibutton’ and the ‘uifigure’ does not have an event named 'PropertyAdded' defined, and MATLAB's built-in classes do not support dynamically adding events in the same way you might add properties or methods.

While you cannot directly use notify with built-in MATLAB UI components for custom events without extending those components in some way, creating wrapper classes or custom components is a way to add custom behaviour and events to MATLAB GUI applications. Here is an example of how you could create a custom class that wraps a ‘uibutton’ and includes an event for when a custom property is added:

classdef CustomButton < handle
    properties
        Button matlab.ui.control.Button
        CustomProperties containers.Map
    end
    events
        PropertyAdded
    end
    methods
        function obj = CustomButton(parent)
            obj.Button = uibutton(parent);
            obj.CustomProperties = containers.Map;
        end
        
        function addCustomProperty(obj, propName, propValue)
            obj.CustomProperties(propName) = propValue;
            notify(obj, 'PropertyAdded');
        end
    end
end

You can now use this class in your GUI:

>> fig = uifigure;
>> btn = CustomButton(fig);
>> addlistener(btn, 'PropertyAdded', @(varargin) disp('Custom Property added'));
>> btn.addCustomProperty('propertyName', 'value');

Hope this helps!

[Bruno Luong]

Thanks.

To be honest I can't remember the context why I need notify on hraphic handle object three year earlier (2021).

.