Fix slowdown and wrong font choosed by XSETTINGS changes. bug #5157.

* font.c (font_open_entity): Enable chache and call cached_font_ok
for the driver if defined.
(QCuser_spec): New symbol.
(font_spec_from_name): Save name as user-spec.
(font_load_for_lface): Keep user-spec instead of name.
(font_open_by_name): Save name as user-spec.
(syms_of_font): Initialize QCuser_spec.

* xftfont.c (xftfont_open): Call xftfont_add_rendering_parameters.
(xftfont_add_rendering_parameters, xftfont_cached_font_ok): New.
(syms_of_xftfont): Initialize xftfont_driver.cached_font_ok.

* font.h (struct font_driver): Add cached_font_ok.

* font-setting.el (font-setting-change-default-font): Use user-spec
  instead of name.

1 files changed, 13 insertions, 10 deletions

diff --git a/src/font.c b/src/font.c
index ec4cb874b52..2141fe651c3 100644
--- a/src/font.c
+++ b/src/font.c
@@ -2991,16 +2991,6 @@ font_open_entity (f, entity, pixel_size)
   else if (CONSP (Vface_font_rescale_alist))
     scaled_pixel_size = pixel_size * font_rescale_ratio (entity);
 
-#if 0
-  /* This doesn't work if you have changed hinting or any other parameter.
-     We need to make a new object in every case to be sure. */
-  for (objlist = AREF (entity, FONT_OBJLIST_INDEX); CONSP (objlist);
-       objlist = XCDR (objlist))
-    if (! NILP (AREF (XCAR (objlist), FONT_TYPE_INDEX))
-        && XFONT_OBJECT (XCAR (objlist))->pixel_size == pixel_size)
-      return  XCAR (objlist);
-#endif
-
   val = AREF (entity, FONT_TYPE_INDEX);
   for (driver_list = f->font_driver_list;
        driver_list && ! EQ (driver_list->driver->type, val);
@@ -3008,6 +2998,19 @@ font_open_entity (f, entity, pixel_size)
   if (! driver_list)
     return Qnil;
 
+  for (objlist = AREF (entity, FONT_OBJLIST_INDEX); CONSP (objlist);
+       objlist = XCDR (objlist))
+    {
+      Lisp_Object fn = XCAR (objlist);
+      if (! NILP (AREF (fn, FONT_TYPE_INDEX))
+          && XFONT_OBJECT (fn)->pixel_size == pixel_size)
+        {
+          if (driver_list->driver->cached_font_ok == NULL
+              || driver_list->driver->cached_font_ok (f, fn, entity))
+            return fn;
+        }
+    }
+
   font_object = driver_list->driver->open (f, entity, scaled_pixel_size);
   if (!NILP (font_object))
     ASET (font_object, FONT_SIZE_INDEX, make_number (pixel_size));