cmake/Tests/FindGTK2/pangocairo/main.c

/* Taken from
 * https://developer.gnome.org/pango/stable/pango-Cairo-Rendering.html */

#include <math.h>
#include <pango/pangocairo.h>
static void draw_text(cairo_t* cr)
{
#define RADIUS 150
#define N_WORDS 10
#define FONT "Sans Bold 27"
  PangoLayout* layout;
  PangoFontDescription* desc;
  int i;
  /* Center coordinates on the middle of the region we are drawing
   */
  cairo_translate(cr, RADIUS, RADIUS);
  /* Create a PangoLayout, set the font and text */
  layout = pango_cairo_create_layout(cr);
  pango_layout_set_text(layout, "Text", -1);
  desc = pango_font_description_from_string(FONT);
  pango_layout_set_font_description(layout, desc);
  pango_font_description_free(desc);
  /* Draw the layout N_WORDS times in a circle */
  for (i = 0; i < N_WORDS; i++) {
    int width, height;
    double angle = (360. * i) / N_WORDS;
    double red;
    cairo_save(cr);
    /* Gradient from red at angle == 60 to blue at angle == 240 */
    red = (1 + cos((angle - 60) * G_PI / 180.)) / 2;
    cairo_set_source_rgb(cr, red, 0, 1.0 - red);
    cairo_rotate(cr, angle * G_PI / 180.);
    /* Inform Pango to re-layout the text with the new transformation */
    pango_cairo_update_layout(cr, layout);
    pango_layout_get_size(layout, &width, &height);
    cairo_move_to(cr, -((double)width / PANGO_SCALE) / 2, -RADIUS);
    pango_cairo_show_layout(cr, layout);
    cairo_restore(cr);
  }
  /* free the layout object */
  g_object_unref(layout);
}
int main(int argc, char** argv)
{
  cairo_t* cr;
  char* filename;
  cairo_status_t status;
  cairo_surface_t* surface;
  if (argc != 2) {
    g_printerr("Usage: cairosimple OUTPUT_FILENAME\n");
    return 1;
  }
  filename = argv[1];
  surface =
    cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 2 * RADIUS, 2 * RADIUS);
  cr = cairo_create(surface);
  cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
  cairo_paint(cr);
  draw_text(cr);
  cairo_destroy(cr);
  status = cairo_surface_write_to_png(surface, filename);
  cairo_surface_destroy(surface);
  if (status != CAIRO_STATUS_SUCCESS) {
    g_printerr("Could not save png to '%s'\n", filename);
    return 1;
  }
  return 0;
}