Account for remapped faces in $COLUMNS and $LINES in Eshell

* src/window.h (window_body_unit): New enum...
(window_body_width): ... use it.

* src/window.c (window_body_unit_from_symbol): New function.
(window_body_height, window_body_width): Make PIXELWISE a
'window_body_unit'.
(window-body-height, window-body-width): Accept 'remap' for PIXELWISE.
(window-lines-pixel-dimensions, window_change_record_windows)
(run_window_change_functions, resize_frame_windows, grow_mini_window)
(shrink_mini_window, scroll-left, scroll-right): Update calls to
'window_body_height' and 'window_body_width'.

* src/indent.c (compute_motion): Update calls to 'window_body_width'.

* lisp/eshell/em-ls.el (eshell-ls-find-column-widths)
(eshell-ls-find-column-lengths): Use 'window-body-width'.

* lisp/eshell/esh-var.el (eshell-variable-aliases-list): Use
'window-body-width' and 'window-body-height'.

* test/lisp/eshell/esh-var-tests.el (esh-var-test/window-height)
(esh-var-test/window-width): Rename to...
(esh-var-test/lines-var, esh-var-test/columns-var): ... and update
expected value.

* doc/lispref/windows.texi (Window Sizes): Document new behavior of
PIXELWISE argument for 'window-body-width' and 'window-body-height'.

* etc/NEWS: Announce this change (bug#55696).

3 files changed, 114 insertions, 48 deletions

diff --git a/src/indent.c b/src/indent.c
index acbb9dc9723..51f6f414de3 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -1204,7 +1204,7 @@ compute_motion (ptrdiff_t from, ptrdiff_t frombyte, EMACS_INT fromvpos,
   /* Negative width means use all available text columns.  */
   if (width < 0)
     {
-      width = window_body_width (win, 0);
+      width = window_body_width (win, WINDOW_BODY_IN_CANONICAL_CHARS);
       /* We must make room for continuation marks if we don't have fringes.  */
 #ifdef HAVE_WINDOW_SYSTEM
       if (!FRAME_WINDOW_P (XFRAME (win->frame)))
@@ -1814,7 +1814,7 @@ visible section of the buffer, and pass LINE and COL as TOPOS.  */)
                          ? window_internal_height (w)
                          : XFIXNUM (XCDR (topos))),
                         (NILP (topos)
-                         ? (window_body_width (w, 0)
+                         ? (window_body_width (w, WINDOW_BODY_IN_CANONICAL_CHARS)
                             - (
 #ifdef HAVE_WINDOW_SYSTEM
                                FRAME_WINDOW_P (XFRAME (w->frame)) ? 0 :
diff --git a/src/window.c b/src/window.c
index eba1390fed2..e5666ce38e2 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1014,11 +1014,20 @@ WINDOW must be a valid window and defaults to the selected one.  */)
   return make_fixnum (decode_valid_window (window)->top_line);
 }
 
+static enum window_body_unit
+window_body_unit_from_symbol (Lisp_Object unit)
+{
+  return
+    (unit == Qremap ? WINDOW_BODY_IN_REMAPPED_CHARS
+     : NILP (unit) ? WINDOW_BODY_IN_CANONICAL_CHARS
+     : WINDOW_BODY_IN_PIXELS);
+}
+
 /* Return the number of lines/pixels of W's body.  Don't count any mode
    or header line or horizontal divider of W.  Rounds down to nearest
    integer when not working pixelwise. */
 static int
-window_body_height (struct window *w, bool pixelwise)
+window_body_height (struct window *w, enum window_body_unit pixelwise)
 {
   int height = (w->pixel_height
                 - WINDOW_TAB_LINE_HEIGHT (w)
@@ -1029,11 +1038,27 @@ window_body_height (struct window *w, bool pixelwise)
                 - WINDOW_MODE_LINE_HEIGHT (w)
                 - WINDOW_BOTTOM_DIVIDER_WIDTH (w));
 
+  int denom = 1;
+  if (pixelwise == WINDOW_BODY_IN_REMAPPED_CHARS)
+    {
+      if (!NILP (Vface_remapping_alist))
+        {
+          struct frame *f = XFRAME (WINDOW_FRAME (w));
+          int face_id = lookup_named_face (NULL, f, Qdefault, true);
+          struct face *face = FACE_FROM_ID_OR_NULL (f, face_id);
+          if (face && face->font && face->font->height)
+            denom = face->font->height;
+        }
+      /* For performance, use canonical chars if no face remapping.  */
+      else
+        pixelwise = WINDOW_BODY_IN_CANONICAL_CHARS;
+    }
+
+  if (pixelwise == WINDOW_BODY_IN_CANONICAL_CHARS)
+    denom = FRAME_LINE_HEIGHT (WINDOW_XFRAME (w));
+
   /* Don't return a negative value.  */
-  return max (pixelwise
-              ? height
-              : height / FRAME_LINE_HEIGHT (WINDOW_XFRAME (w)),
-              0);
+  return max (height / denom, 0);
 }
 
 /* Return the number of columns/pixels of W's body.  Don't count columns
@@ -1042,7 +1067,7 @@ window_body_height (struct window *w, bool pixelwise)
    fringes either.  Round down to nearest integer when not working
    pixelwise.  */
 int
-window_body_width (struct window *w, bool pixelwise)
+window_body_width (struct window *w, enum window_body_unit pixelwise)
 {
   struct frame *f = XFRAME (WINDOW_FRAME (w));
 
@@ -1059,24 +1084,46 @@ window_body_width (struct window *w, bool pixelwise)
                    ? WINDOW_FRINGES_WIDTH (w)
                    : 0));
 
+  int denom = 1;
+  if (pixelwise == WINDOW_BODY_IN_REMAPPED_CHARS)
+    {
+      if (!NILP (Vface_remapping_alist))
+        {
+          int face_id = lookup_named_face (NULL, f, Qdefault, true);
+          struct face *face = FACE_FROM_ID_OR_NULL (f, face_id);
+          if (face && face->font)
+            {
+              if (face->font->average_width)
+                denom = face->font->average_width;
+              else if (face->font->space_width)
+                denom = face->font->space_width;
+            }
+        }
+      /* For performance, use canonical chars if no face remapping.  */
+      else
+        pixelwise = WINDOW_BODY_IN_CANONICAL_CHARS;
+    }
+
+  if (pixelwise == WINDOW_BODY_IN_CANONICAL_CHARS)
+    denom = FRAME_COLUMN_WIDTH (WINDOW_XFRAME (w));
+
   /* Don't return a negative value.  */
-  return max (pixelwise
-              ? width
-              : width / FRAME_COLUMN_WIDTH (WINDOW_XFRAME (w)),
-              0);
+  return max (width / denom, 0);
 }
 
 DEFUN ("window-body-width", Fwindow_body_width, Swindow_body_width, 0, 2, 0,
        doc: /* Return the width of WINDOW's text area.
-WINDOW must be a live window and defaults to the selected one.  Optional
-argument PIXELWISE non-nil means return the width in pixels.  The return
-value does not include any vertical dividers, fringes or marginal areas,
-or scroll bars.
+WINDOW must be a live window and defaults to the selected one.  The
+return value does not include any vertical dividers, fringes or
+marginal areas, or scroll bars.
 
-If PIXELWISE is nil, return the largest integer smaller than WINDOW's
-pixel width divided by the character width of WINDOW's frame.  This
-means that if a column at the right of the text area is only partially
-visible, that column is not counted.
+The optional argument PIXELWISE defines the units to use for the
+width.  If nil, return the largest integer smaller than WINDOW's pixel
+width in units of the character width of WINDOW's frame.  If PIXELWISE
+is `remap' and the default face is remapped (see
+`face-remapping-alist'), use the remapped face to determine the
+character width.  For any other non-nil value, return the width in
+pixels.
 
 Note that the returned value includes the column reserved for the
 continuation glyph.
@@ -1084,25 +1131,29 @@ continuation glyph.
 Also see `window-max-chars-per-line'.  */)
   (Lisp_Object window, Lisp_Object pixelwise)
 {
-  return make_fixnum (window_body_width (decode_live_window (window),
-                                         !NILP (pixelwise)));
+  return (make_fixnum
+          (window_body_width (decode_live_window (window),
+                              window_body_unit_from_symbol (pixelwise))));
 }
 
 DEFUN ("window-body-height", Fwindow_body_height, Swindow_body_height, 0, 2, 0,
        doc: /* Return the height of WINDOW's text area.
-WINDOW must be a live window and defaults to the selected one.  Optional
-argument PIXELWISE non-nil means return the height of WINDOW's text area
-in pixels.  The return value does not include the mode line or header
-line or any horizontal divider.
-
-If PIXELWISE is nil, return the largest integer smaller than WINDOW's
-pixel height divided by the character height of WINDOW's frame.  This
-means that if a line at the bottom of the text area is only partially
-visible, that line is not counted.  */)
+WINDOW must be a live window and defaults to the selected one.  The
+return value does not include the mode line or header line or any
+horizontal divider.
+
+The optional argument PIXELWISE defines the units to use for the
+height.  If nil, return the largest integer smaller than WINDOW's
+pixel height in units of the character height of WINDOW's frame.  If
+PIXELWISE is `remap' and the default face is remapped (see
+`face-remapping-alist'), use the remapped face to determine the
+character height.  For any other non-nil value, return the height in
+pixels.  */)
   (Lisp_Object window, Lisp_Object pixelwise)
 {
-  return make_fixnum (window_body_height (decode_live_window (window),
-                                          !NILP (pixelwise)));
+  return (make_fixnum
+          (window_body_height (decode_live_window (window),
+                               window_body_unit_from_symbol (pixelwise))));
 }
 
 DEFUN ("window-old-body-pixel-width",
@@ -2124,7 +2175,8 @@ though when run from an idle timer with a delay of zero seconds.  */)
   struct glyph_row *row, *end_row;
   int max_y = NILP (body) ? WINDOW_PIXEL_HEIGHT (w) : window_text_bottom_y (w);
   Lisp_Object rows = Qnil;
-  int window_width = NILP (body) ? w->pixel_width : window_body_width (w, true);
+  int window_width = NILP (body)
+    ? w->pixel_width : window_body_width (w, WINDOW_BODY_IN_PIXELS);
   int tab_line_height = WINDOW_TAB_LINE_HEIGHT (w);
   int header_line_height = WINDOW_HEADER_LINE_HEIGHT (w);
   int subtract = NILP (body) ? 0 : (tab_line_height + header_line_height);
@@ -3657,8 +3709,10 @@ window_change_record_windows (Lisp_Object window, int stamp, ptrdiff_t number)
           wset_old_buffer (w, w->contents);
           w->old_pixel_width = w->pixel_width;
           w->old_pixel_height = w->pixel_height;
-          w->old_body_pixel_width = window_body_width (w, true);
-          w->old_body_pixel_height = window_body_height (w, true);
+          w->old_body_pixel_width
+            = window_body_width (w, WINDOW_BODY_IN_PIXELS);
+          w->old_body_pixel_height
+            = window_body_height (w, WINDOW_BODY_IN_PIXELS);
         }
 
       w = NILP (w->next) ? 0 : XWINDOW (w->next);
@@ -3903,8 +3957,10 @@ run_window_change_functions (void)
              && (window_buffer_change
                  || w->pixel_width != w->old_pixel_width
                  || w->pixel_height != w->old_pixel_height
-                 || window_body_width (w, true) != w->old_body_pixel_width
-                 || window_body_height (w, true) != w->old_body_pixel_height));
+                 || (window_body_width (w, WINDOW_BODY_IN_PIXELS)
+                     != w->old_body_pixel_width)
+                 || (window_body_height (w, WINDOW_BODY_IN_PIXELS)
+                     != w->old_body_pixel_height)));
 
           /* The following two are needed when running the default
              values for this frame below.  */
@@ -4768,7 +4824,8 @@ resize_frame_windows (struct frame *f, int size, bool horflag)
   Lisp_Object mini = f->minibuffer_window;
   struct window *m = WINDOWP (mini) ? XWINDOW (mini) : NULL;
   int mini_height = ((FRAME_HAS_MINIBUF_P (f) && !FRAME_MINIBUF_ONLY_P (f))
-                     ? unit + m->pixel_height - window_body_height (m, true)
+                     ? (unit + m->pixel_height
+                        - window_body_height (m, WINDOW_BODY_IN_PIXELS))
                      : 0);
 
   new_pixel_size = max (horflag ? size : size - mini_height, unit);
@@ -5255,7 +5312,7 @@ void
 grow_mini_window (struct window *w, int delta)
 {
   struct frame *f = XFRAME (w->frame);
-  int old_height = window_body_height (w, true);
+  int old_height = window_body_height (w, WINDOW_BODY_IN_PIXELS);
   int min_height = FRAME_LINE_HEIGHT (f);
 
   eassert (MINI_WINDOW_P (w));
@@ -5289,7 +5346,8 @@ void
 shrink_mini_window (struct window *w)
 {
   struct frame *f = XFRAME (w->frame);
-  int delta = window_body_height (w, true) - FRAME_LINE_HEIGHT (f);
+  int delta = (window_body_height (w, WINDOW_BODY_IN_PIXELS)
+               - FRAME_LINE_HEIGHT (f));
 
   eassert (MINI_WINDOW_P (w));
 
@@ -6356,9 +6414,10 @@ by this function.  This happens in an interactive call.  */)
   (register Lisp_Object arg, Lisp_Object set_minimum)
 {
   struct window *w = XWINDOW (selected_window);
-  EMACS_INT requested_arg = (NILP (arg)
-                             ? window_body_width (w, 0) - 2
-                             : XFIXNUM (Fprefix_numeric_value (arg)));
+  EMACS_INT requested_arg =
+    (NILP (arg)
+     ? window_body_width (w, WINDOW_BODY_IN_CANONICAL_CHARS) - 2
+     : XFIXNUM (Fprefix_numeric_value (arg)));
   Lisp_Object result = set_window_hscroll (w, w->hscroll + requested_arg);
 
   if (!NILP (set_minimum))
@@ -6381,9 +6440,10 @@ by this function.  This happens in an interactive call.  */)
   (register Lisp_Object arg, Lisp_Object set_minimum)
 {
   struct window *w = XWINDOW (selected_window);
-  EMACS_INT requested_arg = (NILP (arg)
-                             ? window_body_width (w, 0) - 2
-                             : XFIXNUM (Fprefix_numeric_value (arg)));
+  EMACS_INT requested_arg =
+    (NILP (arg)
+     ? window_body_width (w, WINDOW_BODY_IN_CANONICAL_CHARS) - 2
+     : XFIXNUM (Fprefix_numeric_value (arg)));
   Lisp_Object result = set_window_hscroll (w, w->hscroll - requested_arg);
 
   if (!NILP (set_minimum))
diff --git a/src/window.h b/src/window.h
index 7f7de588463..298a80a5366 100644
--- a/src/window.h
+++ b/src/window.h
@@ -1186,7 +1186,13 @@ extern bool window_wants_mode_line (struct window *);
 extern bool window_wants_header_line (struct window *);
 extern bool window_wants_tab_line (struct window *);
 extern int window_internal_height (struct window *);
-extern int window_body_width (struct window *w, bool);
+enum window_body_unit
+  {
+    WINDOW_BODY_IN_CANONICAL_CHARS,
+    WINDOW_BODY_IN_PIXELS,
+    WINDOW_BODY_IN_REMAPPED_CHARS
+  };
+extern int window_body_width (struct window *w, enum window_body_unit);
 enum margin_unit { MARGIN_IN_LINES, MARGIN_IN_PIXELS };
 extern int window_scroll_margin (struct window *, enum margin_unit);
 extern void temp_output_buffer_show (Lisp_Object);