Add a way to get an unhinted font

gsk/gskprivate.c

@@ -1,6 +1,9 @@
 #include "gskresources.h"
 #include "gskprivate.h"
 
+#include <cairo.h>
+#include <pango/pangocairo.h>
+
 static gpointer
 register_resources (gpointer data)
 {
@@ -15,3 +18,54 @@ gsk_ensure_resources (void)
 
   g_once (&register_resources_once, register_resources, NULL);
 }
+
+/*< private >
+ * gsk_get_unhinted_font:
+ * @font: (transfer full): a `PangoFont`
+ *
+ * Returns a font that is just like @font, but does not apply
+ * hinting to its glyphs or metrics.
+ *
+ * Returns: (transfer full): an unhinted `PangoFont`
+ */
+PangoFont *
+gsk_get_unhinted_font (PangoFont *font)
+{
+  PangoFont *font2 = font;
+  cairo_scaled_font_t *sc;
+  cairo_font_options_t *options;
+
+  sc = pango_cairo_font_get_scaled_font (PANGO_CAIRO_FONT (font));
+  options = cairo_font_options_create ();
+  cairo_scaled_font_get_font_options (sc, options);
+  if (cairo_font_options_get_hint_metrics (options) != CAIRO_HINT_METRICS_OFF ||
+      cairo_font_options_get_hint_style (options) != CAIRO_HINT_STYLE_NONE)
+    {
+      font2 = PANGO_FONT (g_object_get_data (G_OBJECT (font), "gsk-unhinted-font"));
+      if (!font2)
+        {
+          PangoFontMap *fontmap = pango_font_get_font_map (font);
+          PangoContext *context;
+          PangoFontDescription *desc;
+
+          cairo_font_options_set_hint_metrics (options, CAIRO_HINT_METRICS_OFF);
+          cairo_font_options_set_hint_style (options, CAIRO_HINT_STYLE_NONE);
+
+          context = pango_font_map_create_context (fontmap);
+          pango_cairo_context_set_font_options (context, options);
+
+          desc = pango_font_describe (font);
+          font2 = pango_font_map_load_font (fontmap, context, desc);
+
+          pango_font_description_free (desc);
+          g_object_unref (context);
+
+          g_object_set_data_full (G_OBJECT (font), "gsk-unhinted-font",
+                                  font2, g_object_unref);
+        }
+    }
+
+  cairo_font_options_destroy (options);
+
+  return font2;
+}

gsk/gskprivate.h

@@ -5,7 +5,9 @@
 
 G_BEGIN_DECLS
 
-void gsk_ensure_resources (void);
+void       gsk_ensure_resources  (void);
+
+PangoFont *gsk_get_unhinted_font (PangoFont *font);
 
 G_END_DECLS