+
+void
+ev_document_misc_invert_surface (cairo_surface_t *surface) {
+ cairo_t *cr;
+
+ cr = cairo_create (surface);
+
+ /* white + DIFFERENCE -> invert */
+ cairo_set_operator (cr, CAIRO_OPERATOR_DIFFERENCE);
+ cairo_set_source_rgb (cr, 1., 1., 1.);
+ cairo_paint(cr);
+ cairo_destroy (cr);
+}
+
+void
+ev_document_misc_invert_pixbuf (GdkPixbuf *pixbuf)
+{
+ guchar *data, *p;
+ guint width, height, x, y, rowstride, n_channels;
+
+ n_channels = gdk_pixbuf_get_n_channels (pixbuf);
+ g_assert (gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB);
+ g_assert (gdk_pixbuf_get_bits_per_sample (pixbuf) == 8);
+
+ /* First grab a pointer to the raw pixel data. */
+ data = gdk_pixbuf_get_pixels (pixbuf);
+
+ /* Find the number of bytes per row (could be padded). */
+ rowstride = gdk_pixbuf_get_rowstride (pixbuf);
+
+ width = gdk_pixbuf_get_width (pixbuf);
+ height = gdk_pixbuf_get_height (pixbuf);
+ for (x = 0; x < width; x++) {
+ for (y = 0; y < height; y++) {
+ /* Calculate pixel's offset into the data array. */
+ p = data + x * n_channels + y * rowstride;
+ /* Change the RGB values*/
+ p[0] = 255 - p[0];
+ p[1] = 255 - p[1];
+ p[2] = 255 - p[2];
+ }
+ }
+}
+
+gdouble
+ev_document_misc_get_screen_dpi (GdkScreen *screen)
+{
+ gdouble dp, di;
+
+ /*diagonal in pixels*/
+ dp = hypot (gdk_screen_get_width (screen), gdk_screen_get_height (screen));
+
+ /*diagonal in inches*/
+ di = hypot (gdk_screen_get_width_mm(screen), gdk_screen_get_height_mm (screen)) / 25.4;
+
+ return (dp / di);
+}
+
+/* Returns a locale specific date and time representation */
+gchar *
+ev_document_misc_format_date (GTime utime)
+{
+ time_t time = (time_t) utime;
+ char s[256];
+ const char fmt_hack[] = "%c";
+ size_t len;
+#ifdef HAVE_LOCALTIME_R
+ struct tm t;
+ if (time == 0 || !localtime_r (&time, &t)) return NULL;
+ len = strftime (s, sizeof (s), fmt_hack, &t);
+#else
+ struct tm *t;
+ if (time == 0 || !(t = localtime (&time)) ) return NULL;
+ len = strftime (s, sizeof (s), fmt_hack, t);
+#endif
+
+ if (len == 0 || s[0] == '\0') return NULL;
+
+ return g_locale_to_utf8 (s, -1, NULL, NULL, NULL);
+}