Tutorial 4

Using Glade3 and gtkf-sketcher (GTK 3)

This tutorial is for GTK 3 only. Concerning GTK 4, be patient, a new rapid application development (RAD) tool is under active development: the Cambalache project was released in 0.10.0 version in June 2022. Note also that our gtkf-sketcher tool was not fully ported to GTK 4.

You have three solutions to create a GUI with gtk-fortran:

1. hard-coding the GUI in Fortran, inspiring yourself with the gtk-fortran examples. In my opinion, it's better to first learn this way, in order to understand the GTK concepts.
2. Using Glade to create a .ui XML file and use the GtkBuilder API,
3. or write yourself your .ui file and use the GtkBuilder API.

This tutorial is about the solutions 2) and 3): you will discover how our gtkf-sketcher tool can help.

The GtkBuilder API

Using GtkBuilder maybe be useful if you use many widgets in your API: you can design your GUI using the UI Designer Glade3, then save it to a GktBuilder XML-file. In your gtk-fortran application, you will use the gtk_builder_new_from_file() function to build the GUI on the fly. Of course, the callback functions of your GUI will not be in the XML file: you will have to code them in Fortran, using the same names as defined in the XML-file. Our gtkf-sketcher tool (inspired by the Freebasic code sketcher GTKtobac2) can ease the pain by automatically generating sketches of those Fortran callback functions.

Playing with gtkf-sketcher

gtkf-sketcher comes with an example XML file named example.glade. You can learn to use gtkf-sketcher by playing with it:

• go into the gtk-fortran/build/sketcher/ directory and run ./gtkf-sketcher
• From its File>Open menu, load the example.glade file available in the same directory (do not choose the gtkf-sketcher.glade which is the file used to build the GUI of gtkf-sketcher itself!).
• In the Info tab, the content of the example.glade file is analyzed.
• Keep the default options available in the Options tab and go directly to the Output tab.
• Click on the Write Files button.
• In the terminal, go inside the gtk-fortran/build/sketcher/example directory where gtkf-sketcher has generated the Fortran files of the example application:

gtk-fortran/build/sketcher/example$ ls -1 *.f90
example.f90
handler_button2clicked.f90
handler_delete_event.f90
handler_destroy.f90
handler_hello.f90

• Compile and execute the example application:

$ gfortran example.f90 -o example $(pkg-config --cflags --libs gtk-3-fortran)
$ ./example

• You can see a basic application with three buttons: Button1, Button2, Exit. Of course, you will see some warnings like (example:12807): Gtk-WARNING **: 15:06:45.542: Could not find signal handler 'destroy'. Did you compile with -rdynamic? and the GUI does nothing because you now need to add code to manage each event into the specified files.

Now you can start your application starting from this example!