Port double-line underlines to GUI systems

* src/xterm.c (x_get_scale_factor): Replace display in first
argument with a pointer to dpyinfo.
(x_draw_underwave): Adjust to match.
(x_draw_glyph_string): Implement double-line underlines.

* src/androidterm.c (android_get_scale_factor)
(android_draw_glyph_string):

* src/haikuterm.c (haiku_draw_text_decoration):

* src/nsterm.m (ns_draw_text_decoration):

* src/pgtkterm.c (pgtk_draw_glyph_string):

* src/w32term.c (w32_draw_glyph_string): Synchronize with X.

* src/xfaces.c (realize_gui_face): Enable `double-line' on
window systems.

1 files changed, 22 insertions, 8 deletions

diff --git a/src/pgtkterm.c b/src/pgtkterm.c
index e08e4b2b230..8441189ab8d 100644
--- a/src/pgtkterm.c
+++ b/src/pgtkterm.c
@@ -2553,13 +2553,17 @@ pgtk_draw_glyph_string (struct glyph_string *s)
               else
                 pgtk_draw_underwave (s, s->face->underline_color);
             }
-          else if (s->face->underline == FACE_UNDERLINE_SINGLE)
+          else if (s->face->underline == FACE_UNDERLINE_SINGLE
+                   || s->face->underline == FACE_UNDERLINE_DOUBLE_LINE)
             {
               unsigned long thickness, position;
               int y;
+              unsigned long foreground;
 
               if (s->prev
-                  && s->prev->face->underline == FACE_UNDERLINE_SINGLE
+                  && ((s->prev->face->underline == FACE_UNDERLINE_SINGLE)
+                      || (s->prev->face->underline
+                          == FACE_UNDERLINE_DOUBLE_LINE))
                   && (s->prev->face->underline_at_descent_line_p
                       == s->face->underline_at_descent_line_p)
                   && (s->prev->face->underline_pixels_above_descent_line
@@ -2616,15 +2620,25 @@ pgtk_draw_glyph_string (struct glyph_string *s)
               s->underline_thickness = thickness;
               s->underline_position = position;
               y = s->ybase + position;
+
               if (s->face->underline_defaulted_p)
-                pgtk_fill_rectangle (s->f, s->xgcv.foreground,
-                                     s->x, y, s->width, thickness,
-                                     false);
+                foreground = s->xgcv.foreground;
               else
+                foreground = s->face->underline_color;
+
+              pgtk_fill_rectangle (s->f, foreground, s->x, y, s->width,
+                                   thickness, false);
+
+              /* Place a second underline above the first if this was
+                 requested in the face specification.  */
+
+              if (s->face->underline == FACE_UNDERLINE_DOUBLE_LINE)
                 {
-                  pgtk_fill_rectangle (s->f, s->face->underline_color,
-                                       s->x, y, s->width, thickness,
-                                       false);
+                  /* Compute the position of the second underline.  */
+                  position = position - thickness - 1;
+                  y        = s->ybase + position;
+                  pgtk_fill_rectangle (s->f, foreground, s->x, y, s->width,
+                                       thickness, false);
                 }
             }
         }