Simple gtk base caro example

simple_cairo.c

#include <gtk/gtk.h>
#include <cairo.h>

static gboolean
on_draw_event( GtkWidget* widget,
  cairo_t *cr,
  gpointer user_data ) {
  
  cairo_set_source_rgb( cr, 0.3, 0.5, 0.8 );
  cairo_rectangle( cr, 100, 100, 50, 50 );
  cairo_fill( cr );
   
  return FALSE;
}

int main( int argc, char* argv[] ) {
  GtkWidget *darea;
  GtkWidget *window;
  
  gtk_init( &argc, &argv );

  window = gtk_window_new( GTK_WINDOW_TOPLEVEL );
  gtk_window_set_default_size( GTK_WINDOW(window), 400, 400 );
  gtk_window_set_title( GTK_WINDOW(window), "Simple Cairo Example" );
  
  darea = gtk_drawing_area_new();

  gtk_container_add( GTK_CONTAINER(window), darea );

  g_signal_connect( G_OBJECT(window),
    "destroy",
    G_CALLBACK( gtk_main_quit ),
    NULL );
  g_signal_connect( G_OBJECT(darea),
    "draw",
    G_CALLBACK( on_draw_event ),
    NULL );

  gtk_widget_show_all( window );

  gtk_main();

  return 0;
}