A custom modal dialog as an AppDesigner App

This is sample code for a custom, modal AppDesigner dialog. R2020b onwards

A sample custom modal dialog in AppDesigner.

The app is called from an ordinary function, much like uigetfile().

How it works:

1) The modal dialog app

• sets its main WindowStyle to 'modal'
• when a button is pressed
• calls its ValueChangedFcn to pass the dialog result to the caller
• closes the window

2) A .m-file function 'showModalDialog()'

• returns a variable 'result' with default value []
• has an inner function 'valueChanged' that sets 'result' per its one argument
• when running it
• creates the ModalDialogApp
• sets the app's ValueChangedFcn to 'valueChanged'
• uiwait()s on the dialog's mainFigure

Thus showModalDialog() is blocked until the dialog closes on a button press or window close. The dialog result, if any, is passed via a call to the inner function, thus minimising name pollution.

In this example the dialog result is a scalar double, but the result may be as complex as necessary.

In an app, showModalDialog() could become a private member function; this would, for example, let the app set the position of the dialog.

See MATLAB answer:

'is there a generic modal dialog for AppDesigner'