(describe-char-display): New function.

(describe-char): Pay attention to display table on describing how
a character is displayed.

1 files changed, 114 insertions, 35 deletions

diff --git a/lisp/descr-text.el b/lisp/descr-text.el
index ff38c21ed50..8e9b1af2dde 100644
--- a/lisp/descr-text.el
+++ b/lisp/descr-text.el
@@ -434,6 +434,19 @@ otherwise."
 ;;;                                                (string-to-number
 ;;;                                                 (nth 13 fields) 16))
 ;;;                                               ??)))))))))))
+
+;; Return information about how CHAR is displayed at the buffer
+;; position POS.  If the selected frame is on a graphic display,
+;; return a cons (FONTNAME . GLYPH-CODE).  Otherwise, return a string
+;; describing the terminal codes for the character.
+(defun describe-char-display (pos char)
+  (if (display-graphic-p (selected-frame))
+      (internal-char-font pos char)
+    (let* ((coding (terminal-coding-system))
+           (encoded (encode-coding-char char coding)))
+      (if encoded
+          (encoded-string-description encoded coding)))))
+
 
 ;;;###autoload
 (defun describe-char (pos)
@@ -449,8 +462,11 @@ as well as widgets, buttons, overlays, and text properties."
          (charset (char-charset char))
          (buffer (current-buffer))
          (composition (find-composition pos nil nil t))
-         (composed (if composition (buffer-substring (car composition)
-                                                     (nth 1 composition))))
+         (component-chars nil)
+         (display-table (or (window-display-table)
+                            buffer-display-table
+                            standard-display-table))
+         (disp-vector (and display-table (aref display-table char)))
          (multibyte-p enable-multibyte-characters)
          item-list max-width unicode)
     (if (eq charset 'unknown)
@@ -514,15 +530,46 @@ as well as widgets, buttons, overlays, and text properties."
                              (format "(encoded by coding system %S)" coding))
                      (list "not encodable by coding system"
                            (symbol-name coding)))))
-              ,(if (display-graphic-p (selected-frame))
-                   (list "font" (or (internal-char-font pos)
-                                    "-- none --"))
-                 (list "terminal code"
-                       (let* ((coding (terminal-coding-system))
-                              (encoded (encode-coding-char char coding)))
-                         (if encoded
-                             (encoded-string-description encoded coding)
-                           "not encodable"))))
+              ("display"
+               ,(cond
+                 (disp-vector
+                  (setq disp-vector (copy-sequence disp-vector))
+                  (dotimes (i (length disp-vector))
+                    (setq char (aref disp-vector i))
+                    (aset disp-vector i
+                          (cons char (describe-char-display pos char))))
+                  (format "by display table entry [%s] (see below)"
+                          (mapconcat #'(lambda (x) (format "?%c" (car x)))
+                                     disp-vector " ")))
+                 (composition
+                  (let ((from (car composition))
+                        (to (nth 1 composition))
+                        (next (1+ pos))
+                        (components (nth 2 composition))
+                        ch)
+                    (setcar composition
+                            (and (< from pos) (buffer-substring from pos)))
+                    (setcar (cdr composition)
+                            (and (< next to) (buffer-substring next to)))
+                    (dotimes (i (length components))
+                      (if (integerp (setq ch (aref components i)))
+                          (push (cons ch (describe-char-display pos ch))
+                                component-chars)))
+                    (setq component-chars (nreverse component-chars))
+                    (format "composed to form \"%s\" (see below)"
+                            (buffer-substring from to))))
+                 (t
+                  (let ((display (describe-char-display pos char)))
+                    (if (display-graphic-p (selected-frame))
+                        (if display
+                            (concat
+                             "by this font (glyph code)\n"
+                             (format "     %s (0x%02X)"
+                                     (car display) (cdr display)))
+                          "no font avairable")
+                      (if display
+                          (format "terminal code %s" display)
+                        "not encodable for terminal"))))))
               ,@(let ((unicodedata (and unicode
                                         (describe-char-unicode-data unicode))))
                   (if unicodedata
@@ -547,31 +594,63 @@ as well as widgets, buttons, overlays, and text properties."
                   (indent-to (1+ max-width)))
                 (insert " " clm))
               (insert "\n"))))
+
+        (when disp-vector
+          (insert
+           "\nThe display table entry is displayed by ")
+          (if (display-graphic-p (selected-frame))
+              (progn
+                (insert "these fonts (glyph codes):\n")
+                (dotimes (i (length disp-vector))
+                  (insert (car (aref disp-vector i)) ?:
+                          (propertize " " 'display '(space :align-to 5))
+                          (if (cdr (aref disp-vector i))
+                              (format "%s (0x%02X)" (cadr (aref disp-vector i))
+                                      (cddr (aref disp-vector i)))
+                            "-- no font --")
+                          "\n ")))
+            (insert "these terminal codes:\n")
+            (dotimes (i (length disp-vector))
+              (insertf(car (aref disp-vector i)) 
+                      (propertize " " 'display '(space :align-to 5))
+                      (or (cdr (aref disp-vector i)) "-- not encodable --")
+                      "\n"))))
+
         (when composition
-          (insert "\nComposed with the "
-                  (cond
-                   ((eq pos (car composition)) "following ")
-                   ((eq (1+ pos) (cadr composition)) "preceding ")
-                   (t ""))
-                  "character(s) `"
-                  (cond
-                   ((eq pos (car composition)) (substring composed 1))
-                   ((eq (1+ pos) (cadr composition)) (substring composed 0 -1))
-                   (t (concat (substring composed 0 (- pos (car composition)))
-                              "' and `"
-                              (substring composed (- (1+ pos) (car composition))))))
-
-                  "' to form `" composed "'")
-          (if (nth 3 composition)
-              (insert ".\n")
-            (insert "\nby the rule ("
-                    (mapconcat (lambda (x)
-                                 (format (if (consp x) "%S" "?%c") x))
-                               (nth 2 composition)
-                               " ")
-                    ").\n"
-                    "See the variable `reference-point-alist' for "
-                    "the meaning of the rule.\n")))
+          (insert "\nComposed")
+          (if (car composition)
+              (if (cadr composition)
+                  (insert " with the surrounding characters \""
+                          (car composition) "\" and \""
+                          (cadr composition) "\"")
+                (insert " with the preceding character(s) \""
+                        (car composition) "\""))
+            (if (cadr composition)
+                (insert " with the following character(s) \""
+                        (cadr composition) "\"")))
+          (insert " by the rule:\n\t("
+                  (mapconcat (lambda (x)
+                               (format (if (consp x) "%S" "?%c") x))
+                             (nth 2 composition)
+                             " ")
+                  ")")
+          (insert  "\nThe component character(s) are displayed by ")
+          (if (display-graphic-p (selected-frame))
+              (progn
+                (insert "these fonts (glyph codes):")
+                (dolist (elt component-chars)
+                  (insert "\n " (car elt) ?:
+                          (propertize " " 'display '(space :align-to 5))
+                          (if (cdr elt)
+                              (format "%s (0x%02X)" (cadr elt) (cddr elt))
+                            "-- no font --"))))
+            (insert "these terminal codes:")
+            (dolist (elt component-chars)
+              (insert "\n  " (car elt) ":"
+                      (propertize " " 'display '(space :align-to 5))
+                      (or (cdr elt) "-- not encodable --"))))
+          (insert "\nSee the variable `reference-point-alist' for "
+                  "the meaning of the rule.\n"))
 
         (let ((output (current-buffer)))
           (with-current-buffer buffer