MATLAB: App Designer terminate an execution of a function

app designerMATLAB

Hello guys,

I am working on an application with App Designer where I am running a script that's running an optimisation problem. Program starts with the button press that calls the function. Inside the function there's an optimisation algorithm that takes an anonymous function which calls multiple functions inside.

I would like to like to cancel the optimisation process by clicking on a button so I created a callback that contains command return, but it does not work, which is probably expected.

There's the command closereq but it closes the figure/app, which I don't want to.

Is it possible to pass a variable or property during the optimisation or is there some other alternative way to do it?

Best Answer

Since Matlab does not have a "kill all tasks" command, you can use a callback function to change the value of a flag that is checked repeatedly within the optimization function.

Define the flag as a public property of the app (see instructions) so the external function has access to the flag.

The app's startup function would set the flag to false: app.stopFlag = false;

The callback function would merely set the flag to true: app.stopFlag = true;

Within the external (or internal) function, you can use the condition,

if app.stopFlag   % assuming app.stopFlag=true means process should abort
    return
    % or 
    error('User stopped execution')
end

Note that if you return before the function is complete, you'll need to assign default output values and you may need to add return commands to any other invoking functions.

Then, the flag should be reset: app.stopFlag=false.

Related Solutions

MATLAB: App Designer How to “StartUp” within the App

(1) Two possibilities to reset your app to its default state:

https://www.mathworks.com/matlabcentral/answers/489003-reset-or-clear-property-values-in-app-designer#comment_763148

https://www.mathworks.com/matlabcentral/answers/489003-reset-or-clear-property-values-in-app-designer#answer_399598

I prefer the first. A simple example using a function called resetComponents:

classdef app1 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure        matlab.ui.Figure
        EditFieldLabel  matlab.ui.control.Label
        EditField       matlab.ui.control.EditField
        Button          matlab.ui.control.Button
    end
    % Component initialization
    methods (Access = private)
        % Create UIFigure and components

        function createComponents(app)
            % Create UIFigure and hide until all components are created
            app.UIFigure = uifigure('Visible', 'off');
            app.UIFigure.Position = [100 100 640 480];
            app.UIFigure.Name = 'UI Figure';
            % Create EditFieldLabel

            app.EditFieldLabel = uilabel(app.UIFigure);
            app.EditFieldLabel.HorizontalAlignment = 'right';
            app.EditFieldLabel.Position = [382 282 56 22];
            app.EditFieldLabel.Text = 'Edit Field';
            % Create EditField

            app.EditField = uieditfield(app.UIFigure, 'text');
            app.EditField.Position = [453 282 100 22];
            % Create Button

            app.Button = uibutton(app.UIFigure, 'push');
            app.Button.Position = [129 282 100 22];
            app.Button.Text = 'Reset';
            app.Button.ButtonPushedFcn = @app.resetButtonCallback;
            % Show the figure after all components are created
            app.UIFigure.Visible = 'on';
        end
        
        function resetComponents(app)
            % Create EditFieldLabel
            app.EditFieldLabel = uilabel(app.UIFigure);
            app.EditFieldLabel.HorizontalAlignment = 'right';
            app.EditFieldLabel.Position = [382 282 56 22];
            app.EditFieldLabel.Text = 'Edit Field';
            % Create EditField
            app.EditField = uieditfield(app.UIFigure, 'text');
            app.EditField.Position = [453 282 100 22];
            % Create Button
            app.Button = uibutton(app.UIFigure, 'push');
            app.Button.Position = [129 282 100 22];
            app.Button.Text = 'Reset';
            app.Button.ButtonPushedFcn = @app.resetButtonCallback;
            
            % Or, alternatively, instead of redefining each component, just figure out all
            % properties which could be changed by the user and reset them to their
            % defaults:
            %

            % app.EditField.Value = '';
            %
            % Simpler here, but takes more work for more complicated apps.
        end
        
        function resetButtonCallback(app, ~, ~)
            resetComponents(app);
        end
    end
    % App creation and deletion
    methods (Access = public)
        % Construct app
        function app = app1
            % Create UIFigure and components
            createComponents(app)
            % Register the app with App Designer
            registerApp(app, app.UIFigure)
            if nargout == 0
                clear app
            end
        end
        % Code that executes before app deletion
        function delete(app)
            % Delete UIFigure when app is deleted
            delete(app.UIFigure)
        end
    end
end

(2) You can access a callback function if you have access to an instance of the app and you are calling from a location allowed by the function's Access attribute (e.g. Public, Private, etc).

Example 1: You cannot call a callback function from within a static method, because the static method does not have access to an instance of the app.

Example 2: You cannot call a callback function externally if its Access attribute is Private.

MATLAB: App Design: stop

Actually,

In callback for the stop button, set app.stopFlag = true;

Within the plotting function check the property

% You're probably plotting with for loop or something similar,
% so include this into it
if app.stopFlag % assuming app.stopFlag=true means process should abort

    return
end

Read this as well.

Credits out to Adam's answer from my similar question

You can use a callback function to change the value of a flag that is checked repeatedly within the plotting commands.