Fix automatic DPI adjustment and add workarounds for some systems

* lisp/faces.el (x-create-frame-with-faces): New field
`delayed-font'.  Set the `font-parameter' property to `font' in
the given parameter list after face-set-after-frame-default is
called.
* src/fontset.c (Fset_fontset_font): Avoid changing
`font-parameter' with the call to Fmodify_frame_parameters.
* src/frame.c (gui_set_frame_parameters_1): New function.
Factor out gui_set_frame_parameters here, and add an argument
DEFAULT_PARAMETER.  If the `font' parameter is set, and
`default_parameter' is not, then set the `font-parameter' frame
parameter to the `font' parameter as well, to keep track of
which user-specified `font' frame parameter set the default
face's font on the frame.
(gui_set_frame_parameters): Call gui_set_frame_parameters_1 with
new arg set to false.
(gui_set_font): Remove broken implementation of
`font-parameter'.
(gui_default_parameter): If the default value was used, then
call gui_set_frame_parameters_1 with the new argument set to
false.  This is because no font was specified as a frame
parameter by the user, so Freconsider_frame_fonts is free to do
anything it wants.
(Freconsider_frame_fonts): If `font-parameter' is set, then use
it.
(syms_of_frame): New defsym Qfont_parameter.

* src/frame.h: Update prototypes.

* src/haikuterm.c (haiku_default_font_parameter):
* src/pgtkfns.c (pgtk_default_font_parameter):
* src/w32fns.c (w32_default_font_parameter): Stop setting
`font-parameter' here.  This code resulted in decades of
automatic font rescaling not working correctly.

* src/xfaces.c (set_font_frame_param): Clear the
`font-parameter' frame parameter.
(Finternal_merge_in_global_face):
* src/xfns.c (x_default_font_parameter): Avoid changing
`font-parameter' in response to changes to face attributes.
* src/xsettings.c (apply_xft_settings): Add workaround for
Cairo.  (bug#59371, bug#59347, bug#59283, bug#59271, bug#59285,
bug#59306.)

1 files changed, 59 insertions, 21 deletions

diff --git a/src/frame.c b/src/frame.c
index 151a4029958..b57b296be54 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -4119,10 +4119,17 @@ frame_float (struct frame *f, Lisp_Object val, enum frame_float_type what,
    If a parameter is not specially recognized, do nothing special;
    otherwise call the `gui_set_...' function for that parameter.
    Except for certain geometry properties, always call store_frame_param
-   to store the new value in the parameter alist.  */
+   to store the new value in the parameter alist.
+
+   DEFAULT_PARAMETER should be set if the alist was not specified by
+   the user, or by the face code to set the `font' parameter.  In that
+   case, the `font-parameter' frame parameter should not be changed,
+   so dynamic-setting.el can restore the user's selected font
+   correctly.  */
 
 void
-gui_set_frame_parameters (struct frame *f, Lisp_Object alist)
+gui_set_frame_parameters_1 (struct frame *f, Lisp_Object alist,
+			    bool default_parameter)
 {
   Lisp_Object tail, frame;
 
@@ -4249,7 +4256,7 @@ gui_set_frame_parameters (struct frame *f, Lisp_Object alist)
 	}
       else
 	{
-	  register Lisp_Object param_index, old_value;
+	  Lisp_Object param_index, old_value;
 
 	  old_value = get_frame_param (f, prop);
 
@@ -4260,6 +4267,12 @@ gui_set_frame_parameters (struct frame *f, Lisp_Object alist)
 	      && XFIXNAT (param_index) < ARRAYELTS (frame_parms)
 	      && FRAME_RIF (f)->frame_parm_handlers[XFIXNUM (param_index)])
 	    (*(FRAME_RIF (f)->frame_parm_handlers[XFIXNUM (param_index)])) (f, val, old_value);
+
+	  if (!default_parameter && EQ (prop, Qfont))
+	    /* The user manually specified the `font' frame parameter.
+	       Save that parameter for future use by the
+	       dynamic-setting code.  */
+	    store_frame_param (f, Qfont_parameter, val);
 	}
     }
 
@@ -4410,6 +4423,11 @@ gui_set_frame_parameters (struct frame *f, Lisp_Object alist)
   SAFE_FREE ();
 }
 
+void
+gui_set_frame_parameters (struct frame *f, Lisp_Object alist)
+{
+  gui_set_frame_parameters_1 (f, alist, false);
+}
 
 /* Insert a description of internally-recorded parameters of frame F
    into the parameter alist *ALISTPTR that is to be given to the user.
@@ -4586,9 +4604,6 @@ gui_set_font (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
 {
   Lisp_Object font_object;
   int fontset = -1;
-#ifdef HAVE_X_WINDOWS
-  Lisp_Object font_param = arg;
-#endif
 
   /* Set the frame parameter back to the old value because we may
      fail to use ARG as the new parameter value.  */
@@ -4627,16 +4642,10 @@ gui_set_font (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
 	error ("Unknown fontset: %s", SDATA (XCAR (arg)));
       font_object = XCDR (arg);
       arg = AREF (font_object, FONT_NAME_INDEX);
-#ifdef HAVE_X_WINDOWS
-      font_param = Ffont_get (font_object, QCname);
-#endif
     }
   else if (FONT_OBJECT_P (arg))
     {
       font_object = arg;
-#ifdef HAVE_X_WINDOWS
-      font_param = Ffont_get (font_object, QCname);
-#endif
       /* This is to store the XLFD font name in the frame parameter for
 	 backward compatibility.  We should store the font-object
 	 itself in the future.  */
@@ -4667,9 +4676,7 @@ gui_set_font (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
   if (FRAME_TERMINAL (f)->set_new_font_hook)
     FRAME_TERMINAL (f)->set_new_font_hook (f, font_object, fontset);
   store_frame_param (f, Qfont, arg);
-#ifdef HAVE_X_WINDOWS
-  store_frame_param (f, Qfont_parameter, font_param);
-#endif
+
   /* Recalculate tabbar height.  */
   f->n_tab_bar_rows = 0;
   /* Recalculate toolbar height.  */
@@ -5451,12 +5458,20 @@ gui_default_parameter (struct frame *f, Lisp_Object alist, Lisp_Object prop,
                        enum resource_types type)
 {
   Lisp_Object tem;
+  bool was_unbound;
 
   tem = gui_frame_get_arg (f, alist, prop, xprop, xclass, type);
+
   if (BASE_EQ (tem, Qunbound))
-    tem = deflt;
+    {
+      tem = deflt;
+      was_unbound = true;
+    }
+  else
+    was_unbound = false;
+
   AUTO_FRAME_ARG (arg, prop, tem);
-  gui_set_frame_parameters (f, arg);
+  gui_set_frame_parameters_1 (f, arg, was_unbound);
   return tem;
 }
 
@@ -5959,16 +5974,26 @@ have changed.  */)
   (Lisp_Object frame)
 {
   struct frame *f;
-  Lisp_Object params;
+  Lisp_Object params, font_parameter;
 
   f = decode_window_system_frame (frame);
 
   /* Kludge: if a `font' parameter was already specified,
-     create an alist containing just that parameter.  (bug#59371) */
+     create an alist containing just that parameter.  (bug#59371)
+
+     This sounds so simple, right?  Well, read on below: */
   params = Qnil;
 
-  if (!NILP (get_frame_param (f, Qfont)))
-    params = list1 (Fcons (Qfont, get_frame_param (f, Qfont)));
+  /* The difference between Qfont and Qfont_parameter is that the
+     latter is not set automatically by the likes of x_new_font, and
+     implicitly as the default face is realized.  It is only set when
+     the user specifically specifies a `font' frame parameter, and is
+     cleared the moment the frame's font becomes defined by a face
+     attribute, instead of through the `font' frame parameter.  */
+  font_parameter = get_frame_param (f, Qfont_parameter);
+
+  if (!NILP (font_parameter))
+    params = list1 (Fcons (Qfont, font_parameter));
 
   /* First, call this to reinitialize any font backend specific
      stuff.  */
@@ -5976,10 +6001,22 @@ have changed.  */)
   if (FRAME_RIF (f)->default_font_parameter)
     FRAME_RIF (f)->default_font_parameter (f, params);
 
+  /* For a mysterious reason, x_default_font_parameter sets Qfont to
+     nil in the alist!  */
+
+  if (!NILP (font_parameter))
+    params = list1 (Fcons (Qfont, font_parameter));
+
   /* Now call this to apply the existing value(s) of the `default'
      face.  */
   call2 (Qface_set_after_frame_default, frame, params);
 
+  /* Restore the value of the `font-parameter' parameter, as
+     `face-set-after-frame-default' will have changed it through its
+     calls to `set-face-attribute'.  */
+  if (!NILP (font_parameter))
+    store_frame_param (f, Qfont_parameter, font_parameter);
+
   return Qnil;
 }
 
@@ -6240,6 +6277,7 @@ syms_of_frame (void)
   DEFSYM (Qiconify_top_level, "iconify-top-level");
   DEFSYM (Qmake_invisible, "make-invisible");
   DEFSYM (Quse_frame_synchronization, "use-frame-synchronization");
+  DEFSYM (Qfont_parameter, "font-parameter");
 
   {
     int i;