gtk/demos/gtk-demo/textmask.c

/* Pango/Text Mask
 *
 * This demo shows how to use PangoCairo to draw text with more than
 * just a single color.
 */

#include <glib/gi18n.h>
#include <gtk/gtk.h>

static void
draw_text (GtkDrawingArea *da,
           cairo_t        *cr,
           int             width,
           int             height,
           gpointer        data)
{
  cairo_pattern_t *pattern;
  PangoLayout *layout;
  PangoFontDescription *desc;

  cairo_save (cr);

  layout = gtk_widget_create_pango_layout (GTK_WIDGET (da), "Pango power!\nPango power!\nPango power!");
  desc = pango_font_description_from_string ("sans bold 34");
  pango_layout_set_font_description (layout, desc);
  pango_font_description_free (desc);

  cairo_move_to (cr, 30, 20);
  pango_cairo_layout_path (cr, layout);
  g_object_unref (layout);

  pattern = cairo_pattern_create_linear (0.0, 0.0, width, height);
  cairo_pattern_add_color_stop_rgb (pattern, 0.0, 1.0, 0.0, 0.0);
  cairo_pattern_add_color_stop_rgb (pattern, 0.2, 1.0, 0.0, 0.0);
  cairo_pattern_add_color_stop_rgb (pattern, 0.3, 1.0, 1.0, 0.0);
  cairo_pattern_add_color_stop_rgb (pattern, 0.4, 0.0, 1.0, 0.0);
  cairo_pattern_add_color_stop_rgb (pattern, 0.6, 0.0, 1.0, 1.0);
  cairo_pattern_add_color_stop_rgb (pattern, 0.7, 0.0, 0.0, 1.0);
  cairo_pattern_add_color_stop_rgb (pattern, 0.8, 1.0, 0.0, 1.0);
  cairo_pattern_add_color_stop_rgb (pattern, 1.0, 1.0, 0.0, 1.0);

  cairo_set_source (cr, pattern);
  cairo_fill_preserve (cr);

  cairo_pattern_destroy (pattern);

  cairo_set_source_rgb (cr, 0.0, 0.0, 0.0);
  cairo_set_line_width (cr, 0.5);
  cairo_stroke (cr);

  cairo_restore (cr);
}

GtkWidget *
do_textmask (GtkWidget *do_widget)
{
  static GtkWidget *window = NULL;
  static GtkWidget *da;

  if (!window)
    {
      window = gtk_window_new ();
      gtk_window_set_resizable (GTK_WINDOW (window), TRUE);
      gtk_widget_set_size_request (window, 400, 240);
      gtk_window_set_title (GTK_WINDOW (window), "Text Mask");
      g_object_add_weak_pointer (G_OBJECT (window), (gpointer *)&window);

      da = gtk_drawing_area_new ();

      gtk_window_set_child (GTK_WINDOW (window), da);
      gtk_drawing_area_set_draw_func (GTK_DRAWING_AREA (da), draw_text, NULL, NULL);
    }

  if (!gtk_widget_get_visible (window))
    gtk_widget_set_visible (window, TRUE);
  else
    gtk_window_destroy (GTK_WINDOW (window));

  return window;
}