gtk-fortran: a GTK / Fortran binding

1. Vincent MAGNIN, 2. James TAPPIN, 3. Jens HUNGER, 4. Jerry DELISLE

1. Lille University (France), 2. RAL Space (UK), 3. Technische Universität Dresden (Germany), 4. GFortran Team (USA)

FortranCon 2020, Zurich, 2-4 July 2020

1 / 20 Why gtk-fortran? Installing, building, running Welcome to the machine To Infinity and Beyond! Plan

1 Why gtk-fortran?

2 Installing, building, running

3 Welcome to the machine

4 To Infinity and Beyond!

2 / 20 1. Vincent MAGNIN, 2. James TAPPIN,3. Jens HUNGER, 4. Jerry DELISLE gtk-fortran: a GTK / Fortran binding The scientist and the unknown pleasures of visualization. . .

Do scientists dream of electric sheep being artists? Scientific visualization is essential and is an art (left). Nothing in the Fortran standard, except ASCII art? (right)

Figure: first discovered pulsar [1]. Figure: the Mandelbrot set in 1978.

3 / 20 You can’t always get what you want

Visual Fortran (Digital, Compaq, Intel) has the Quickwin library (Windows). When migrating to Linux, I was looking for something: to make bitmap (or vectorial) drawing, and scientific plotting. To build Graphical User Interfaces (GUI). Using only standard Fortran. Multi-platform: Linux, Windows, MacOS. . . Free software (as in free beer and freedom). A perennial solution. There was/is a lot of great tools like pilib (GTK 2, but needing a C compiler), DISLIN, PLplot, gnuplot, interfacing with another language (japi), etc. But I still hadn’t found what I was looking for. . .

4 / 20 But if you try sometime you find: GTK

2nd May 2007 13:10 Tobias BURNUS posted on the comp.lang.fortran newsgroup a demo creating an empty GTK 2 window: GTK is mainly written in C language, and Fortran 2003 introduced interoperability with C.

About GTK GNU LGPL license. Multi-platform. Who’s behind? The GNOME Foundation (RedHat. . . ). 2002: GTK 2.0 2011: GTK 3.0 2020(?): GTK 4.0

5 / 20 GTK is not a library. . .

It’s a collection of libraries ! GLib: general-purpose utility library, GObject: the GLib Object System, GTK itself, GdkPixbuf: pixel drawing (even without GUI), Cairo: vectorial drawing, GIO : input/output, GDK, Pango, ATK. . .

6 / 20 A GTK / Fortran binding

gtk-fortran Project launched with J. DELISLE, J. TAPPIN and J. HUNGER. First commit: 9 January 2011. Now ≈ 10 000 functions in gtk-fortran! Not only about GUI and graphics! But also strings, regex, date and time, files, network utilities, lists, trees, hash tables, etc. Only 500 functions used in our tools and examples. . .

Figure: Commits in the GTK 3 branch.

7 / 20 Why gtk-fortran? Installing, building, running Welcome to the machine To Infinity and Beyond! Installing and building gtk-fortran

Download the zip from https://github.com/vmagnin/gtk-fortran/wiki or git clone: $ git clone [email protected]:vmagnin/gtk−fortran.git Install tools and dependencies (Debian/Ubuntu names): $ sudo apt install gfortran cmake libgtk−3−dev libplplot−dev plplot−driver−cairo Build the project and install the library: $ mkdir build&& cd build $ cmake.. $ make $ sudo make install Compile your own program: $ gfortran my_app.f90$(pkg −config −−cflags −−libs gtk−3−fortran) 8 / 20 1. Vincent MAGNIN, 2. James TAPPIN,3. Jens HUNGER, 4. Jerry DELISLE gtk-fortran: a GTK / Fortran binding And I went down to the demonstration

Figure: hl_cairo_clock.f90 (Kubuntu) Figure: hl_plplot4e.f90 (Windows 7)

Figure: mandelbrot_pixbuf.f90 (MacOS) Figure: julia_pixbuf.f90 (Fedora) 9 / 20 Some projects using gtk-fortran

"The VCU nuclear reactor simulator, Richmond Pile 3, is a classroom and research tool that emulates a large commercial pressurized water reactor (PWR)." [2] https://egr.vcu.edu/departments/mechanical/research/nuclear-simulator-lab/ Uncertradio [3]: https://www.thuenen.de/de/fi/arbeitsbereiche/meeresumwelt/ leitstelle-umweltradioaktivitaet-in-fisch/uncertradio/

10 / 20 Why gtk-fortran? Installing, building, running Welcome to the machine To Infinity and Beyond! Nobody said it was easy. . .

Event driven programming Based on a main loop, idle most of the time. If something happens a signal is emitted, received by the concerned widget, which calls its corresponding callback function.

It’s all about C pointers and C types C pointers toward functions, objects, data. . . C types: int, double, char. . . The GTK official documentation is totally C oriented: to be able to read C function prototypes is better. . .

11 / 20 1. Vincent MAGNIN, 2. James TAPPIN,3. Jens HUNGER, 4. Jerry DELISLE gtk-fortran: a GTK / Fortran binding Example: the button widget

To create my "Bye" button, I need to call that C function whose prototype is in /usr/include/gtk-3.0/gtk/gtkbutton.h:

GtkWidget ∗ gtk_button_new_with_label( const gchar ∗ l a b e l); § ¤ ¦The gtk-fortran interface for that function is in src/gtk-auto.f90: ¥ f u n c t i o n gtk_button_new_with_label(label) bind(c) § use iso_c_binding, o n l y : c_ptr, c_char ¤ type (c_ptr):: gtk_button_new_with_label c h a r a c t e r ( kind=c_char), dimension ( ∗ ):: label end function

¦In my Fortran program: ¥ use iso_c_binding § use gtk, o n l y : gtk_button_new_with_label, g_signal_connect ¤

... my_button= gtk_button_new_with_label("Bye"//c_null_char)

!I need also to connect my button toa callback function: c a l l g_signal_connect(my_button,"clicked"//c_null_char, c_funloc( my_callback_function))

¦ ¥ 12 / 20 How the Fortran interfaces are generated?

Before each gtk-fortran release The python program cfwrapper.py parses the GTK .h header files, generates the src/*-auto.f90, using especially regular expressions.

$./cfwrapper.py −g3 Pass 1: looking for enumerators, funptr and derived types... Pass 2: looking for C functions... /usr/include/atk−1.0 => atk−auto.f90 85781 bytes /usr/include/cairo => cairo−auto.f90 133740 bytes /usr/include/gdk−pixbuf−2.0 => gdk−pixbuf−auto.f90 58223 bytes /usr/include/glib−2.0 => glib−auto.f90 1299171 bytes /usr/include/gtk−3.0/gdk => gdk−auto.f90 208504 bytes /usr/include/gtk−3.0/gtk => gtk−auto.f90 1319554 bytes /usr/include/gtk−3.0/unix−print => unix−print−auto.f90 24488 bytes /usr/include/pango−1.0 => pango−auto.f90 171656 bytes 13 / 20

=== Statistics(ready to paste in the Status wiki page) ===

## GTK 3.24.12, GLib 2.62.4, Ubuntu 19.10 x86_64, Python 3.7.5 vmagnin, Tue, 30 Jun 2020 15:12:24 +0000 * nb_files scanned = 759 * nb_generated_interfaces = 10335 * nb_deprecated_functions = 1118 * nb_type_errors = 61 * nb_errors(others) = 348 * nb_lines treated = 33888 * nb_variadic functions = 136 * nb_enumerators = 376 * nb_win32_utf8= 4 * Number of types = 78 * Computing time: 12.69s * SHA1: a4542484b3a002678f983d936482f244ad5222c2 >>>>>> SHA1 HAS BEEN MODIFIED! It was1 cfa7b5cf0c2d36a8962109c8da6d3b6f758398a <<<<<<

Used types:[’c_ptr’,’c_int’,’c_char’,’c_double’,’c_funptr’ ,’c_int64_t’,’c_size_t’,’c_long’,’c_int32_t’,’c_float ’,’c_int8_t’,’?’,’c_int16_t’,’c_long_double’] Tools to ease the pain

A High Level library (J. Tappin) Offers a simplified interface for most useful GUI functions. Can be mixed with direct GTK calls.

gtkf-sketcher (J. Hunger) Complicated GUI can be graphically designed with Glade, saved in an XML file, used by gtkf-sketcher to generate a gtk-fortran program.

Other tools usemodules.pl: to generate your "USE, ONLY:" statements Some shell scripts.

14 / 20 Why gtk-fortran? Installing, building, running Welcome to the machine To Infinity and Beyond! How to contribute?

Build and test with various systems and compilers: use the gtk3 stable branch, or the gtk4 branch if you are already familiar with GTK. Report issues on GitHub. Help improve the documentation. Write tutorials. Write new examples (only 500 functions tested). ...

15 / 20 1. Vincent MAGNIN, 2. James TAPPIN,3. Jens HUNGER, 4. Jerry DELISLE gtk-fortran: a GTK / Fortran binding SWOT matrix of the project

Strengths Weaknesses Standard Fortran. Few contributors. GTK is perenial and multi-platform. No GTK programming tutorial. gtk-fortran maintained since 2011. The cfwrapper.py needs refactoring. Includes a High Level library. The binding is not 100 % complete. Many commented examples.

Opportunities Threats FortranCon 2020. Fortran is losing users. Fortran-lang Community and tools. New compilers: Flang, LFortran. . . GTK 4 soon released (Fall 2020?). Use GObject Introspection?

16 / 20 Appendices Thank you for listening!

I will be pleased to answer your questions now

or later on Slack, GitHub, Fortran-lang Discourse. . .

17 / 20 1. Vincent MAGNIN, 2. James TAPPIN,3. Jens HUNGER, 4. Jerry DELISLE gtk-fortran: a GTK / Fortran binding Acknowledgments

Tobias BURNUS who posted on the comp.lang.fortran newsgroup (2nd May 2007 13:10) an example of a program creating an empty GTK+ 2 window. Contributors and users who are not in the authors: Mehdi CHINOUNE (CMake parallelisation), Ian HARVEY. . .

18 / 20 Useful links

The gtk-fortran home [4]: https://github.com/vmagnin/gtk-fortran/wiki The GTK home: https://www.gtk.org/ Where to find its official documentation: https://developer.gnome.org/ The GTK developers blog: https://blog.gtk.org/ The GNOME Discourse: https://discourse.gnome.org/c/platform Fresh GTK News: https://gitlab.gnome.org/GNOME/gtk/-/blob/master/NEWS

19 / 20 References

Harold Dumont Craft. Radio observations of the pulse profiles and dispersion measures of twelve pulsars. Ithaca, N.Y., 1970. Ph.D. Thesis, OCLC: 741854775. D. Tincher, S. Bilbao y León, and J. Miller. Progress on real-time, interactive modeling and simulation of nuclear power plants. volume 2017-September, 2017. Günter Kanisch. Generalized evaluation of environmental radioactivity measurements with uncertradio. part i: Methods without linear unfolding. Applied Radiation and Isotopes, 110:28 – 41, 2016. V. MAGNIN, J. TAPPIN, J. HUNGER, and J. DELISLE. gtk-fortran: a GTK+ binding to build Graphical User Interfaces in Fortran. The Journal of Open Source Software, 5(34), February 2019.

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