Allow underline position variables be buffer-local

* src/nsterm.m (ns_draw_text_decoration):
* src/w32term.c (x_draw_glyph_string):
* src/xterm.c (x_draw_glyph_string): Allow underline-minimum-offset,
underline-at-descent-line, and x-use-underline-position-properties
be buffer local variables.  (Bug#30553)
* src/xdisp.c (syms_of_xdisp) <underline-minimum-offset>: Add DEFSYM.

1 files changed, 30 insertions, 6 deletions

diff --git a/src/w32term.c b/src/w32term.c
index 97afb678c1d..24950dd25ec 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -2475,31 +2475,52 @@ x_draw_glyph_string (struct glyph_string *s)
               else
                 {
 		  struct font *font = font_for_underline_metrics (s);
+		  unsigned long minimum_offset;
+		  BOOL underline_at_descent_line;
+		  BOOL use_underline_position_properties;
+		  Lisp_Object val
+		    = buffer_local_value (Qunderline_minimum_offset,
+					s->w->contents);
+		  if (INTEGERP (val))
+		    minimum_offset = XFASTINT (val);
+		  else
+		    minimum_offset = 1;
+		  val = buffer_local_value (Qx_underline_at_descent_line,
+					    s->w->contents);
+		  underline_at_descent_line
+		    = !(NILP (val) || EQ (val, Qunbound));
+		  val
+		    = buffer_local_value (Qx_use_underline_position_properties,
+					  s->w->contents);
+		  use_underline_position_properties
+		    = !(NILP (val) || EQ (val, Qunbound));
 
                   /* Get the underline thickness.  Default is 1 pixel.  */
                   if (font && font->underline_thickness > 0)
                     thickness = font->underline_thickness;
                   else
                     thickness = 1;
-                  if (x_underline_at_descent_line || !font)
+                  if (underline_at_descent_line
+                      || !font)
                     position = (s->height - thickness) - (s->ybase - s->y);
                   else
                     {
-                      /* Get the underline position.  This is the recommended
-                         vertical offset in pixels from the baseline to the top of
-                         the underline.  This is a signed value according to the
+                      /* Get the underline position.  This is the
+                         recommended vertical offset in pixels from
+                         the baseline to the top of the underline.
+                         This is a signed value according to the
                          specs, and its default is
 
                          ROUND ((maximum_descent) / 2), with
                          ROUND (x) = floor (x + 0.5)  */
 
-                      if (x_use_underline_position_properties
+                      if (use_underline_position_properties
                           && font->underline_position >= 0)
                         position = font->underline_position;
                       else
                         position = (font->descent + 1) / 2;
                     }
-                  position = max (position, underline_minimum_offset);
+                  position = max (position, minimum_offset);
                 }
               /* Check the sanity of thickness and position.  We should
                  avoid drawing underline out of the current line area.  */
@@ -7385,11 +7406,14 @@ the cursor have no effect.  */);
 	       x_use_underline_position_properties,
      doc: /* SKIP: real doc in xterm.c.  */);
   x_use_underline_position_properties = 0;
+  DEFSYM (Qx_use_underline_position_properties,
+	  "x-use-underline-position-properties");
 
   DEFVAR_BOOL ("x-underline-at-descent-line",
 	       x_underline_at_descent_line,
      doc: /* SKIP: real doc in xterm.c.  */);
   x_underline_at_descent_line = 0;
+  DEFSYM (Qx_underline_at_descent_line, "x-underline-at-descent-line");
 
   DEFVAR_LISP ("x-toolkit-scroll-bars", Vx_toolkit_scroll_bars,
 	       doc: /* SKIP: real doc in xterm.c.  */);