(x_underline_at_descent_line): New variable.

(syms_of_macterm): DEFVAR_BOOL it.
(x_draw_glyph_string): Use it.
(XLoadQueryFont): Calculate min_bounds.descent and max_bounds.descent.

1 files changed, 47 insertions, 4 deletions

diff --git a/src/macterm.c b/src/macterm.c
index 7cd7bd87225..6f9e6273cb7 100644
--- a/src/macterm.c
+++ b/src/macterm.c
@@ -108,6 +108,10 @@ static Lisp_Object last_window;
    (Not yet supported.)  */
 int x_use_underline_position_properties;
 
+/* Non-zero means to draw the underline at the same place as the descent line.  */
+
+int x_underline_at_descent_line;
+
 /* This is a chain of structures for all the X displays currently in
    use.  */
 
@@ -3671,18 +3675,45 @@ x_draw_glyph_string (s)
       /* Draw underline.  */
       if (s->face->underline_p)
         {
-          unsigned long h = 1;
-          unsigned long dy = s->height - h;
+          unsigned long tem, h;
+          int y;
+
+#if 0
+          /* Get the underline thickness.  Default is 1 pixel.  */
+          if (!XGetFontProperty (s->font, XA_UNDERLINE_THICKNESS, &h))
+#endif
+            h = 1;
+
+          y = s->y + s->height - h;
+          if (!x_underline_at_descent_line)
+            {
+              /* 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 0
+              if (x_use_underline_position_properties
+                  && XGetFontProperty (s->font, XA_UNDERLINE_POSITION, &tem))
+                y = s->ybase + (long) tem;
+              else
+#endif
+              if (s->face->font)
+                y = s->ybase + (s->face->font->max_bounds.descent + 1) / 2;
+            }
 
           if (s->face->underline_defaulted_p)
-            mac_fill_rectangle (s->f, s->gc, s->x, s->y + dy,
+            mac_fill_rectangle (s->f, s->gc, s->x, y,
                                 s->background_width, h);
           else
             {
               XGCValues xgcv;
               XGetGCValues (s->display, s->gc, GCForeground, &xgcv);
               XSetForeground (s->display, s->gc, s->face->underline_color);
-              mac_fill_rectangle (s->f, s->gc, s->x, s->y + dy,
+              mac_fill_rectangle (s->f, s->gc, s->x, y,
                                   s->background_width, h);
               XSetForeground (s->display, s->gc, xgcv.foreground);
             }
@@ -8085,6 +8116,8 @@ XLoadQueryFont (Display *dpy, char *fontname)
                                              pcm->width);
             font->min_bounds.ascent   = min (font->min_bounds.ascent,
                                              pcm->ascent);
+            font->min_bounds.descent  = min (font->min_bounds.descent,
+                                             pcm->descent);
 
             font->max_bounds.lbearing = max (font->max_bounds.lbearing,
                                              pcm->lbearing);
@@ -8094,6 +8127,8 @@ XLoadQueryFont (Display *dpy, char *fontname)
                                              pcm->width);
             font->max_bounds.ascent   = max (font->max_bounds.ascent,
                                              pcm->ascent);
+            font->max_bounds.descent  = max (font->max_bounds.descent,
+                                             pcm->descent);
           }
       if (
 #if USE_ATSUI
@@ -11620,6 +11655,14 @@ to 4.1, set this to nil.
 NOTE: Not supported on Mac yet.  */);
   x_use_underline_position_properties = 0;
 
+  DEFVAR_BOOL ("x-underline-at-descent-line",
+               &x_underline_at_descent_line,
+     doc: /* *Non-nil means to draw the underline at the same place as the descent line.
+nil means to draw the underline according to the value of the variable
+`x-use-underline-position-properties', which is usually at the baseline
+level.  The default value is nil.  */);
+  x_underline_at_descent_line = 0;
+
   DEFVAR_LISP ("x-toolkit-scroll-bars", &Vx_toolkit_scroll_bars,
     doc: /* If not nil, Emacs uses toolkit scroll bars.  */);
 #ifdef USE_TOOLKIT_SCROLL_BARS