/*
 * font.c:
 * Simple bitmap font rendering example.
 *
 * written by Naofumi Yasufuku  <naofumi@users.sourceforge.net>
 */

#include <stdlib.h>
#include <string.h>

#include <gtk/gtk.h>

#include <gtk/gtkgl.h>

#ifdef G_OS_WIN32
#define WIN32_LEAN_AND_MEAN 1
#include <windows.h>
#endif

#include <GL/gl.h>
#include <GL/glu.h>

static gchar font_string[] = "courier 12";
static GLuint font_list_base;
static gint font_height;

static void
realize (GtkWidget *widget,
         gpointer   data)
{
  GdkGLContext *glcontext = gtk_widget_get_gl_context (widget);
  GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable (widget);

  PangoFontDescription *font_desc;
  PangoFont *font;
  PangoFontMetrics *font_metrics;

  /*** OpenGL BEGIN ***/
  if (!gdk_gl_drawable_gl_begin (gldrawable, glcontext))
    return;

  /*
   * Generate font display lists.
   */
  font_list_base = glGenLists (128);

  font_desc = pango_font_description_from_string (font_string);

  font = gdk_gl_font_use_pango_font (font_desc, 0, 128, font_list_base);
  if (font == NULL)
    {
      g_print ("*** Can't load font '%s'\n", font_string);
      exit (1);
    }

  font_metrics = pango_font_get_metrics (font, NULL);

  font_height = pango_font_metrics_get_ascent (font_metrics) +
                pango_font_metrics_get_descent (font_metrics);
  font_height = PANGO_PIXELS (font_height);

  pango_font_description_free (font_desc);
  pango_font_metrics_unref (font_metrics);

  glClearColor (1.0, 1.0, 1.0, 1.0);
  glClearDepth (1.0);

  glViewport (0, 0,
              widget->allocation.width, widget->allocation.height);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();
  glOrtho (0.0, widget->allocation.width,
           0.0, widget->allocation.height,
           -1.0, 1.0);

  glMatrixMode (GL_MODELVIEW);
  glLoadIdentity ();

  gdk_gl_drawable_gl_end (gldrawable);
  /*** OpenGL END ***/
}

static gboolean
configure_event (GtkWidget         *widget,
                 GdkEventConfigure *event,
                 gpointer           data)
{
  GdkGLContext *glcontext = gtk_widget_get_gl_context (widget);
  GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable (widget);

  /*** OpenGL BEGIN ***/
  if (!gdk_gl_drawable_gl_begin (gldrawable, glcontext))
    return FALSE;

  glViewport (0, 0,
              widget->allocation.width, widget->allocation.height);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();
  glOrtho (0.0, widget->allocation.width,
           0.0, widget->allocation.height,
           -1.0, 1.0);

  glMatrixMode (GL_MODELVIEW);
  glLoadIdentity ();

  gdk_gl_drawable_gl_end (gldrawable);
  /*** OpenGL END ***/

  return TRUE;
}

static gboolean
expose_event (GtkWidget      *widget,
              GdkEventExpose *event,
              gpointer        data)
{
  GdkGLContext *glcontext = gtk_widget_get_gl_context (widget);
  GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable (widget);
  int i, j;

  /*** OpenGL BEGIN ***/
  if (!gdk_gl_drawable_gl_begin (gldrawable, glcontext))
    return FALSE;

  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  /*
   * Draw some text.
   */
  glColor3f (0.0, 0.0, 0.0);
  for (i = 2; i >= -2; i--)
    {
      glRasterPos2f (10.0, 0.5*widget->allocation.height + i*font_height);
      for (j = ' '; j <= 'Z'; j++)
        glCallList (font_list_base+j);
    }

  /*
   * Show font description string.
   */
  glColor3f (1.0, 0.0, 0.0);
  glRasterPos2f (10.0, 10.0);
  glListBase (font_list_base);
  glCallLists (strlen (font_string), GL_UNSIGNED_BYTE, font_string);

  if (gdk_gl_drawable_is_double_buffered (gldrawable))
    gdk_gl_drawable_swap_buffers (gldrawable);
  else
    glFlush ();

  gdk_gl_drawable_gl_end (gldrawable);
  /*** OpenGL END ***/

  return TRUE;
}

static void
print_gl_config_attrib (GdkGLConfig *glconfig,
                        const gchar *attrib_str,
                        int          attrib,
                        gboolean     is_boolean)
{
  int value;

  g_print ("%s = ", attrib_str);
  if (gdk_gl_config_get_attrib (glconfig, attrib, &value))
    {
      if (is_boolean)
        g_print ("%s\n", value == TRUE ? "TRUE" : "FALSE");
      else
        g_print ("%d\n", value);
    }
  else
    g_print ("*** Cannot get %s attribute value\n", attrib_str);
}

static void
examine_gl_config_attrib (GdkGLConfig *glconfig)
{
  g_print ("\nOpenGL visual configurations :\n\n");

  g_print ("gdk_gl_config_is_rgba (glconfig) = %s\n",
           gdk_gl_config_is_rgba (glconfig) ? "TRUE" : "FALSE");
  g_print ("gdk_gl_config_is_double_buffered (glconfig) = %s\n",
           gdk_gl_config_is_double_buffered (glconfig) ? "TRUE" : "FALSE");
  g_print ("gdk_gl_config_is_stereo (glconfig) = %s\n",
           gdk_gl_config_is_stereo (glconfig) ? "TRUE" : "FALSE");
  g_print ("gdk_gl_config_has_alpha (glconfig) = %s\n",
           gdk_gl_config_has_alpha (glconfig) ? "TRUE" : "FALSE");
  g_print ("gdk_gl_config_has_depth_buffer (glconfig) = %s\n",
           gdk_gl_config_has_depth_buffer (glconfig) ? "TRUE" : "FALSE");
  g_print ("gdk_gl_config_has_stencil_buffer (glconfig) = %s\n",
           gdk_gl_config_has_stencil_buffer (glconfig) ? "TRUE" : "FALSE");
  g_print ("gdk_gl_config_has_accum_buffer (glconfig) = %s\n",
           gdk_gl_config_has_accum_buffer (glconfig) ? "TRUE" : "FALSE");

  g_print ("\n");

  print_gl_config_attrib (glconfig, "GDK_GL_USE_GL",           GDK_GL_USE_GL,           TRUE);
  print_gl_config_attrib (glconfig, "GDK_GL_BUFFER_SIZE",      GDK_GL_BUFFER_SIZE,      FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_LEVEL",            GDK_GL_LEVEL,            FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_RGBA",             GDK_GL_RGBA,             TRUE);
  print_gl_config_attrib (glconfig, "GDK_GL_DOUBLEBUFFER",     GDK_GL_DOUBLEBUFFER,     TRUE);
  print_gl_config_attrib (glconfig, "GDK_GL_STEREO",           GDK_GL_STEREO,           TRUE);
  print_gl_config_attrib (glconfig, "GDK_GL_AUX_BUFFERS",      GDK_GL_AUX_BUFFERS,      FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_RED_SIZE",         GDK_GL_RED_SIZE,         FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_GREEN_SIZE",       GDK_GL_GREEN_SIZE,       FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_BLUE_SIZE",        GDK_GL_BLUE_SIZE,        FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_ALPHA_SIZE",       GDK_GL_ALPHA_SIZE,       FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_DEPTH_SIZE",       GDK_GL_DEPTH_SIZE,       FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_STENCIL_SIZE",     GDK_GL_STENCIL_SIZE,     FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_ACCUM_RED_SIZE",   GDK_GL_ACCUM_RED_SIZE,   FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_ACCUM_GREEN_SIZE", GDK_GL_ACCUM_GREEN_SIZE, FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_ACCUM_BLUE_SIZE",  GDK_GL_ACCUM_BLUE_SIZE,  FALSE);
  print_gl_config_attrib (glconfig, "GDK_GL_ACCUM_ALPHA_SIZE", GDK_GL_ACCUM_ALPHA_SIZE, FALSE);

  g_print ("\n");
}

int
main (int   argc,
      char *argv[])
{
  GdkGLConfig *glconfig;
  gint major, minor;

  GtkWidget *window;
  GtkWidget *vbox;
  GtkWidget *drawing_area;
  GtkWidget *button;

  /*
   * Init GTK.
   */

  gtk_init (&argc, &argv);

  /*
   * Init GtkGLExt.
   */

  gtk_gl_init (&argc, &argv);

  /*
   * Query OpenGL extension version.
   */

  gdk_gl_query_version (&major, &minor);
  g_print ("\nOpenGL extension version - %d.%d\n",
           major, minor);

  /*
   * Configure OpenGL-capable visual.
   */

  /* Try double-buffered visual */
  glconfig = gdk_gl_config_new_by_mode (GDK_GL_MODE_RGB    |
                                        GDK_GL_MODE_DOUBLE);
  if (glconfig == NULL)
    {
      g_print ("*** Cannot find the double-buffered visual.\n");
      g_print ("*** Trying single-buffered visual.\n");

      /* Try single-buffered visual */
      glconfig = gdk_gl_config_new_by_mode (GDK_GL_MODE_RGB);
      if (glconfig == NULL)
        {
          g_print ("*** No appropriate OpenGL-capable visual found.\n");
          exit (1);
        }
    }

  examine_gl_config_attrib (glconfig);

  /*
   * Top-level window.
   */

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title (GTK_WINDOW (window), "font");

  /* Get automatically redrawn if any of their children changed allocation. */
  gtk_container_set_reallocate_redraws (GTK_CONTAINER (window), TRUE);

  g_signal_connect (G_OBJECT (window), "delete_event",
                    G_CALLBACK (gtk_main_quit), NULL);

  /*
   * VBox.
   */

  vbox = gtk_vbox_new (FALSE, 0);
  gtk_container_add (GTK_CONTAINER (window), vbox);
  gtk_widget_show (vbox);

  /*
   * Drawing area for drawing OpenGL scene.
   */

  drawing_area = gtk_drawing_area_new ();
  gtk_widget_set_size_request (drawing_area, 640, 240);

  /* Set OpenGL-capability to the widget. */
  gtk_widget_set_gl_capability (drawing_area,
				glconfig,
                                NULL,
                                TRUE,
                                GDK_GL_RGBA_TYPE);

  g_signal_connect_after (G_OBJECT (drawing_area), "realize",
                          G_CALLBACK (realize), NULL);
  g_signal_connect (G_OBJECT (drawing_area), "configure_event",
		    G_CALLBACK (configure_event), NULL);
  g_signal_connect (G_OBJECT (drawing_area), "expose_event",
		    G_CALLBACK (expose_event), NULL);

  gtk_box_pack_start (GTK_BOX (vbox), drawing_area, TRUE, TRUE, 0);

  gtk_widget_show (drawing_area);

  /*
   * Simple quit button.
   */

  button = gtk_button_new_with_label ("Quit");

  g_signal_connect (G_OBJECT (button), "clicked",
                    G_CALLBACK (gtk_main_quit), NULL);

  gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);

  gtk_widget_show (button);

  /*
   * Show window.
   */

  gtk_widget_show (window);

  /*
   * Main loop.
   */

  gtk_main ();

  return 0;
}