Add new header-line-active' and header-line-inactive' faces

This is all intended to parallel the 'mode-line-active' and
'mode-line-inactive' distinction.
* doc/emacs/display.texi (Standard Faces): Document the new faces.

* lisp/faces.el (header-line-active, header-line-inactive): New
faces.

* src/dispextern.h (CURRENT_HEADER_LINE_ACTIVE_FACE_ID_3)
(CURRENT_HEADER_LINE_ACTIVE_FACE_ID): New macros based on mode
line equivalents.
(face_id): New face IDs.
* src/xdisp.c (window_box_height, pos_visible_p, init_iterator)
(window_text_pixel_size, display_mode_lines, display_mode_line)
(format-mode-line): Replace all uses of HEADER_LINE_FACE_ID with
either a new macro or the new face IDs.
* src/xfaces.c (syms_of_xfaces): New lisp symbols.
(lookup_basic_face, realize_basic_faces): Map new face IDs to
their lisp symbols.  (Bug#73862)

doc/emacs/display.texi

@@ -782,6 +782,22 @@ at the top of a window just as the mode line appears at the bottom.
 Most windows do not have a header line---only some special modes, such
 Info mode, create one.
 
+The @code{header-line-active} and @code{header-line-inactive} faces (which
+are the ones used on the header lines) inherit from this face.
+
+@item header-line-active
+@cindex faces for header lines
+Like @code{header-line}, but used for the header line of the currently
+selected window.  This face inherits from @code{header-line}, so changes
+in that face affect header lines in all windows.
+
+@item header-line-inactive
+@cindex @code{header-line-inactive} face
+Like @code{header-line}, but used for header lines of the windows other
+than the selected one (if those windows have a header line).  This face
+inherits from @code{header-line}, so changes in that face affect header
+lines in all windows.
+
 @item header-line-highlight
 @cindex @code{header-line-highlight} face
 Similar to @code{highlight} and @code{mode-line-highlight}, but used

etc/NEWS

@@ -162,6 +162,11 @@ The version bundled with Emacs is out-of-date, and is now marked as
 obsolete.  Use 'M-x list-packages' to install the 'idlwave' package from
 GNU ELPA instead.
 
++++
+** New face 'header-line-active'.
+This inherits from the 'header-line' face, but is the face actually used
+on the header lines (along with 'header-line-inactive').
+
 
 * Editing Changes in Emacs 31.1
 

lisp/faces.el

@@ -2821,6 +2821,21 @@ Use the face `mode-line-highlight' for features that can be selected."
   :version "28.1"
   :group 'basic-faces)
 
+(defface header-line-active
+  '((t :inherit header-line))
+  "Face for the selected header line.
+This inherits from the `header-line' face."
+  :version "29.5"
+  :group 'mode-line-faces
+  :group 'basic-faces)
+
+(defface header-line-inactive
+  '((t :inherit header-line))
+  "Basic header line face for non-selected windows."
+  :version "29.5"
+  :group 'mode-line-faces
+  :group 'basic-faces)
+
 (defface vertical-border
   '((((type tty)) :inherit mode-line-inactive))
   "Face used for vertical window dividers on ttys."

src/dispextern.h

@@ -1561,6 +1561,34 @@ struct glyph_string
 	 : estimate_mode_line_height					\
 	 (XFRAME ((W)->frame), CURRENT_MODE_LINE_ACTIVE_FACE_ID (W)))))
 
+/* Return the desired face id for the header line of a window, depending
+   on whether the window is selected or not, or if the window is the
+   scrolling window for the currently active minibuffer window.
+
+   Due to the way display_mode_lines manipulates with the contents of
+   selected_window, this macro needs three arguments: SELW which is
+   compared against the current value of selected_window, MBW which is
+   compared against minibuf_window (if SELW doesn't match), and SCRW
+   which is compared against minibuf_selected_window (if MBW matches).  */
+
+#define CURRENT_HEADER_LINE_ACTIVE_FACE_ID_3(SELW, MBW, SCRW)    	\
+     ((!mode_line_in_non_selected_windows			\
+       || (SELW) == XWINDOW (selected_window)			\
+       || (minibuf_level > 0					\
+           && !NILP (minibuf_selected_window)			\
+           && (MBW) == XWINDOW (minibuf_window)			\
+           && (SCRW) == XWINDOW (minibuf_selected_window)))	\
+      ? HEADER_LINE_ACTIVE_FACE_ID				\
+      : HEADER_LINE_INACTIVE_FACE_ID)
+
+
+/* Return the desired face id for the header line of window W.  */
+
+#define CURRENT_HEADER_LINE_ACTIVE_FACE_ID(W)		\
+	 CURRENT_HEADER_LINE_ACTIVE_FACE_ID_3(W, \
+					    XWINDOW (selected_window), \
+					    W)
+
 /* Return the current height of the header line of window W.  If not known
    from W->header_line_height, look at W's current glyph matrix, or return
    an estimation based on the height of the font of the face `header-line'.  */
@@ -1572,7 +1600,7 @@ struct glyph_string
       = (MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix)	\
 	 ? MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix)	\
 	 : estimate_mode_line_height				\
-	     (XFRAME ((W)->frame), HEADER_LINE_FACE_ID))))
+	 (XFRAME ((W)->frame), CURRENT_HEADER_LINE_ACTIVE_FACE_ID (W)))))
 
 /* Return the current height of the tab line of window W.  If not known
    from W->tab_line_height, look at W's current glyph matrix, or return
@@ -1893,7 +1921,8 @@ enum face_id
   MODE_LINE_INACTIVE_FACE_ID,
   TOOL_BAR_FACE_ID,
   FRINGE_FACE_ID,
-  HEADER_LINE_FACE_ID,
+  HEADER_LINE_ACTIVE_FACE_ID,
+  HEADER_LINE_INACTIVE_FACE_ID,
   SCROLL_BAR_FACE_ID,
   BORDER_FACE_ID,
   CURSOR_FACE_ID,

src/xdisp.c

@@ -1358,7 +1358,7 @@ window_box_height (struct window *w)
 	  if (hl_row && hl_row->mode_line_p)
 	    height -= hl_row->height;
 	  else
-	    height -= estimate_mode_line_height (f, HEADER_LINE_FACE_ID);
+	    height -= estimate_mode_line_height (f, CURRENT_HEADER_LINE_ACTIVE_FACE_ID (w));
 	}
     }
 
@@ -1753,7 +1753,7 @@ pos_visible_p (struct window *w, ptrdiff_t charpos, int *x, int *y,
 	= window_parameter (w, Qheader_line_format);
 
       w->header_line_height
-	= display_mode_line (w, HEADER_LINE_FACE_ID,
+	= display_mode_line (w, CURRENT_HEADER_LINE_ACTIVE_FACE_ID (w),
 			     NILP (window_header_line_format)
 			     ? BVAR (current_buffer, header_line_format)
 			     : window_header_line_format);
@@ -3197,13 +3197,14 @@ CHECK_WINDOW_END (struct window *w)
 
    BASE_FACE_ID is the id of a base face to use.  It must be one of
    DEFAULT_FACE_ID for normal text, MODE_LINE_ACTIVE_FACE_ID,
-   MODE_LINE_INACTIVE_FACE_ID, or HEADER_LINE_FACE_ID for displaying
+   MODE_LINE_INACTIVE_FACE_ID, HEADER_LINE_ACTIVE_FACE_ID, or
-   mode lines, or TOOL_BAR_FACE_ID for displaying the tool-bar.
+   HEADER_LINE_INACTIVE_FACE_ID for displaying mode lines, or
+   TOOL_BAR_FACE_ID for displaying the tool-bar.
 
    If ROW is null and BASE_FACE_ID is equal to MODE_LINE_ACTIVE_FACE_ID,
-   MODE_LINE_INACTIVE_FACE_ID, or HEADER_LINE_FACE_ID, the iterator
+   MODE_LINE_INACTIVE_FACE_ID, HEADER_LINE_ACTIVE_FACE_ID, or
-   will be initialized to use the corresponding mode line glyph row of
+   HEADER_LINE_INACTIVE_FACE_ID the iterator will be initialized to use
-   the desired matrix of W.  */
+   the corresponding mode line glyph row of the desired matrix of W.  */
 
 void
 init_iterator (struct it *it, struct window *w,
@@ -3251,7 +3252,8 @@ init_iterator (struct it *it, struct window *w,
 	row = MATRIX_MODE_LINE_ROW (w->desired_matrix);
       else if (base_face_id == TAB_LINE_FACE_ID)
 	row = MATRIX_TAB_LINE_ROW (w->desired_matrix);
-      else if (base_face_id == HEADER_LINE_FACE_ID)
+      else if (base_face_id == HEADER_LINE_ACTIVE_FACE_ID
+	       || base_face_id == HEADER_LINE_INACTIVE_FACE_ID)
 	{
 	  /* Header line row depends on whether tab line is enabled.  */
 	  w->desired_matrix->tab_line_p = window_wants_tab_line (w);
@@ -11854,7 +11856,7 @@ window_text_pixel_size (Lisp_Object window, Lisp_Object from, Lisp_Object to,
       Lisp_Object window_header_line_format
 	= window_parameter (w, Qheader_line_format);
 
-      y = y + display_mode_line (w, HEADER_LINE_FACE_ID,
+      y = y + display_mode_line (w, CURRENT_HEADER_LINE_ACTIVE_FACE_ID (w),
 				 NILP (window_header_line_format)
 				 ? BVAR (current_buffer, header_line_format)
 				 : window_header_line_format);
@@ -27453,11 +27455,11 @@ display_mode_lines (struct window *w)
   line_number_displayed = false;
   w->column_number_displayed = -1;
 
+  struct window *sel_w = XWINDOW (old_selected_window);
   if (window_wants_mode_line (w))
     {
       Lisp_Object window_mode_line_format
 	= window_parameter (w, Qmode_line_format);
-      struct window *sel_w = XWINDOW (old_selected_window);
 
       /* Select mode line face based on the real selected window.  */
       display_mode_line (w,
@@ -27485,7 +27487,7 @@ display_mode_lines (struct window *w)
       Lisp_Object window_header_line_format
 	= window_parameter (w, Qheader_line_format);
 
-      display_mode_line (w, HEADER_LINE_FACE_ID,
+      display_mode_line (w, CURRENT_HEADER_LINE_ACTIVE_FACE_ID_3 (sel_w, sel_w, w),
 			 NILP (window_header_line_format)
 			 ? BVAR (current_buffer, header_line_format)
 			 : window_header_line_format);
@@ -27500,11 +27502,12 @@ display_mode_lines (struct window *w)
 }
 
 
-/* Display mode or header/tab line of window W.  FACE_ID specifies
+/* Display mode or header/tab line of window W.  FACE_ID specifies which
-   which line to display; it is either MODE_LINE_ACTIVE_FACE_ID,
+   line to display; it is either MODE_LINE_ACTIVE_FACE_ID,
-   HEADER_LINE_FACE_ID or TAB_LINE_FACE_ID.  FORMAT is the
+   HEADER_LINE_ACTIVE_FACE_ID, HEADER_LINE_INACTIVE_FACE_ID, or
-   mode/header/tab line format to display.  Value is the pixel height
+   TAB_LINE_FACE_ID.  FORMAT is the mode/header/tab line format to
-   of the mode/header/tab line displayed.  */
+   display.  Value is the pixel height of the mode/header/tab line
+   displayed.  */
 
 static int
 display_mode_line (struct window *w, enum face_id face_id, Lisp_Object format)
@@ -27525,7 +27528,8 @@ display_mode_line (struct window *w, enum face_id face_id, Lisp_Object format)
       it.glyph_row->tab_line_p = true;
       w->desired_matrix->tab_line_p = true;
     }
-  else if (face_id == HEADER_LINE_FACE_ID)
+  else if (face_id == HEADER_LINE_ACTIVE_FACE_ID
+	   || face_id == HEADER_LINE_INACTIVE_FACE_ID)
     w->desired_matrix->header_line_p = true;
 
   /* FIXME: This should be controlled by a user option.  But
@@ -27544,7 +27548,9 @@ display_mode_line (struct window *w, enum face_id face_id, Lisp_Object format)
   record_unwind_save_match_data ();
 
   if (NILP (Vmode_line_compact)
-      || face_id == HEADER_LINE_FACE_ID || face_id == TAB_LINE_FACE_ID)
+      || face_id == HEADER_LINE_ACTIVE_FACE_ID
+      || face_id == HEADER_LINE_INACTIVE_FACE_ID
+      || face_id == TAB_LINE_FACE_ID)
     {
       mode_line_target = MODE_LINE_DISPLAY;
       display_mode_element (&it, 0, 0, 0, format, Qnil, false);
@@ -28313,7 +28319,8 @@ are the selected window and the WINDOW's buffer).  */)
 		       ? MODE_LINE_ACTIVE_FACE_ID : MODE_LINE_INACTIVE_FACE_ID)
     : EQ (face, Qmode_line_active) ? MODE_LINE_ACTIVE_FACE_ID
     : EQ (face, Qmode_line_inactive) ? MODE_LINE_INACTIVE_FACE_ID
-    : EQ (face, Qheader_line) ? HEADER_LINE_FACE_ID
+    : EQ (face, Qheader_line_active) ? HEADER_LINE_ACTIVE_FACE_ID
+    : EQ (face, Qheader_line_inactive) ? HEADER_LINE_INACTIVE_FACE_ID
     : EQ (face, Qtab_line) ? TAB_LINE_FACE_ID
     : EQ (face, Qtab_bar) ? TAB_BAR_FACE_ID
     : EQ (face, Qtool_bar) ? TOOL_BAR_FACE_ID

src/xfaces.c

@@ -5117,7 +5117,8 @@ lookup_basic_face (struct window *w, struct frame *f, int face_id)
     case DEFAULT_FACE_ID:		name = Qdefault;		break;
     case MODE_LINE_ACTIVE_FACE_ID:	name = Qmode_line_active;      	break;
     case MODE_LINE_INACTIVE_FACE_ID:	name = Qmode_line_inactive;	break;
-    case HEADER_LINE_FACE_ID:		name = Qheader_line;		break;
+    case HEADER_LINE_ACTIVE_FACE_ID:	name = Qheader_line_active;	break;
+    case HEADER_LINE_INACTIVE_FACE_ID:	name = Qheader_line_inactive;	break;
     case TAB_LINE_FACE_ID:		name = Qtab_line;		break;
     case TAB_BAR_FACE_ID:		name = Qtab_bar;		break;
     case TOOL_BAR_FACE_ID:		name = Qtool_bar;		break;
@@ -5867,7 +5868,8 @@ realize_basic_faces (struct frame *f)
       realize_named_face (f, Qmode_line_inactive, MODE_LINE_INACTIVE_FACE_ID);
       realize_named_face (f, Qtool_bar, TOOL_BAR_FACE_ID);
       realize_named_face (f, Qfringe, FRINGE_FACE_ID);
-      realize_named_face (f, Qheader_line, HEADER_LINE_FACE_ID);
+      realize_named_face (f, Qheader_line_active, HEADER_LINE_ACTIVE_FACE_ID);
+      realize_named_face (f, Qheader_line_inactive, HEADER_LINE_INACTIVE_FACE_ID);
       realize_named_face (f, Qscroll_bar, SCROLL_BAR_FACE_ID);
       realize_named_face (f, Qborder, BORDER_FACE_ID);
       realize_named_face (f, Qcursor, CURSOR_FACE_ID);
@@ -7438,6 +7440,8 @@ syms_of_xfaces (void)
   DEFSYM (Qfringe, "fringe");
   DEFSYM (Qtab_line, "tab-line");
   DEFSYM (Qheader_line, "header-line");
+  DEFSYM (Qheader_line_inactive, "header-line-inactive");
+  DEFSYM (Qheader_line_active, "header-line-active");
   DEFSYM (Qscroll_bar, "scroll-bar");
   DEFSYM (Qmenu, "menu");
   DEFSYM (Qcursor, "cursor");