C

A general-purpose, imperative computer programming language.

Gtk+

Gtk+ is a cross-plataform GUI toolkit created for the development of the GIMP project. Offering a complete set of widgets, Gtk+ is suitable for projects ranging from small one-off tools to complete applications suites.

For C programming with Gtk+ you need to install the development version of the important GNOME libraries. Those contain the header files and additional linker information:

sudo dnf install gtk3-devel gstreamer-devel clutter-devel webkitgtk3-devel libgda-devel gobject-introspection-devel

In addition, you will want to install the documentation packages of this libraries so you can view them in the API browser (devhelp):

sudo dnf install devhelp gtk3-devel-docs gstreamer-devel-docs clutter-doc

Getting started

To begin our introduction to Gtk+, we will start with the simplest program possible. This program will simply create a gtk+ window with the title “Hello World”.

#include <gtk/gtk.h>

int 
main(int   argc,
     char *argv[])
{
  GtkWidget *window;
    
  gtk_init (&argc, &argv);
    
  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title (GTK_WINDOW (window), "Hello World");
  gtk_widget_show  (window);
    
  gtk_main ();
    
  return 0;
}

You can compile the above program with gcc using:

gcc hello.c -o hello `pkg-config --cflags --libs gtk+-3.0`

In the program above we initially included gtk/gtk.h, which declares all the gtk+ objects used in the rest of the program:

#include <gtk/gtk.h>

After the declaration of the window object variable, we call the gtk_init method which initializes the library and its internal procedures.

gtk_init (&argc, &argv);

The next line creates a GtkWindow object with the GTK_WINDOW_TOPLEVEL type. Nearly always, that’s the type of the GtkWindow, but it could differ if you are implementing something else.

window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

Below that, we set the title of the GtkWindow to a string of our choice:

gtk_window_set_title (GTK_WINDOW (window), "Hello World");

After that, the gtk_widget_show() function lets Gtk+ know that we are done setting the attributes of this widget, and that it can display it.

gtk_window_show (window);

Finally, the last line enters the Gtk+ main processing loop.

gtk_main ();

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