Cache current header and mode line height for each window.

* window.h (struct window): New fields mode_line_height
and header_line_height.
* window.c (make_window): Initialize them.
* dispextern.h (CURRENT_MODE_LINE_HEIGHT)
(CURRENT_HEADER_LINE_HEIGHT): Use them.  Adjust comment.
(current_mode_line_height, current_header_line_height):
Remove declaration.
* xdisp.c (current_mode_line_height, current_header_line_height):
Remove.
(pos_visible_p, init_xdisp): Adjust user.
(redisplay_window): Invalidate mode_line_height and
header_line_height if current and desired matrices do not agree.

1 files changed, 23 insertions, 24 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index 947e50fa4dd..ebb07c1d37f 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1428,31 +1428,31 @@ struct glyph_string
 #define CURRENT_MODE_LINE_FACE_ID(W)            \
         (CURRENT_MODE_LINE_FACE_ID_3((W), XWINDOW (selected_window), (W)))
 
-/* Return the current height of the mode line of window W.  If not
-   known from current_mode_line_height, look at W's current glyph
-   matrix, or return a default based on the height of the font of the
-   face `mode-line'.  */
-
-#define CURRENT_MODE_LINE_HEIGHT(W)                             \
-     (current_mode_line_height >= 0                             \
-      ? current_mode_line_height                                \
-      : (MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix)          \
-         ? MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix)        \
-         : estimate_mode_line_height (XFRAME ((W)->frame),      \
-                                      CURRENT_MODE_LINE_FACE_ID (W))))
-
-/* Return the current height of the header line of window W.  If not
-   known from current_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'.  */
+/* Return the current height of the mode line of window W.  If not known
+   from W->mode_line_height, look at W's current glyph matrix, or return
+   a default based on the height of the font of the face `mode-line'.  */
+
+#define CURRENT_MODE_LINE_HEIGHT(W)                                     \
+  (W->mode_line_height >= 0                                             \
+   ? W->mode_line_height                                                \
+   : (W->mode_line_height                                               \
+      = (MATRIX_MODE_LINE_HEIGHT (W->current_matrix)                    \
+         ? MATRIX_MODE_LINE_HEIGHT (W->current_matrix)                  \
+         : estimate_mode_line_height                                    \
+             (XFRAME (W->frame), CURRENT_MODE_LINE_FACE_ID (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'.  */
 
 #define CURRENT_HEADER_LINE_HEIGHT(W)                           \
-      (current_header_line_height >= 0                          \
-       ? current_header_line_height                             \
-       : (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)))
+  (W->header_line_height >= 0                                   \
+   ? W->header_line_height                                      \
+   : (W->header_line_height                                     \
+      = (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))))
 
 /* Return the height of the desired mode line of window W.  */
 
@@ -3201,7 +3201,6 @@ int frame_mode_line_height (struct frame *);
 extern Lisp_Object Qtool_bar;
 extern bool redisplaying_p;
 extern int help_echo_showing_p;
-extern int current_mode_line_height, current_header_line_height;
 extern Lisp_Object help_echo_string, help_echo_window;
 extern Lisp_Object help_echo_object, previous_help_echo_string;
 extern ptrdiff_t help_echo_pos;