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;;; bdf.el --- BDF font file handler for ps-print.
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;; Copyright (C) 1998 Electrotechnical Laboratory, JAPAN.
;; Licensed to the Free Software Foundation.

;; Keywords: BDF, font, PostScript

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; Functions for getting bitmap information from X's BDF font file are
;; provided.

;;; Code:

(eval-when-compile (require 'ps-print))

(defvar bdf-directory-list
  nil
  "*List of directories to search for `BDF' font files.")

(defun bdf-expand-file-name (bdfname)
  "Return an abosolute path name of a `BDF' font file BDFNAME.
It searches directories listed in the variable `bdf-directory-list'
for BDFNAME."
  (if (file-name-absolute-p bdfname)
      (if (file-readable-p bdfname)
	  bdfname)
    (let ((l bdf-directory-list))
      (catch 'tag
	(while l
	  (if (file-readable-p (expand-file-name bdfname (car l)))
	      (throw 'tag (expand-file-name bdfname (car l))))
	  (setq l (cdr l)))))))

(defsubst bdf-file-mod-time (filename)
  "Return modification time of FILENAME.
The value is a list of two integers, the first integer has high-order
16 bits, the second has low 16 bits."
  (nth 5 (file-attributes filename)))

(defun bdf-file-newer-than-time (filename mod-time)
  "Return non-nil if and only if FILENAME is newer than MOD-TIME.
MOD-TIME is a modification time as a list of two integers, the first
integer has high-order 16 bits, the second has low 16 bits."
  (let ((new-mod-time (bdf-file-mod-time (bdf-expand-file-name filename))))
    (or (> (car new-mod-time) (car mod-time))
	(and (= (car new-mod-time) (car mod-time))
	     (> (nth 1 new-mod-time) (nth 1 mod-time))))))

(defun bdf-find-file (bdfname)
  "Return a buffer visiting a bdf file BDFNAME.
If BDFNAME is not an absolute path, directories listed in
`bdf-directory-list' is searched.
If BDFNAME doesn't exist, return nil."
  (let ((buf (generate-new-buffer " *bdf-work*"))
	(coding-system-for-read 'no-conversion))
    (save-excursion
      (set-buffer buf)
      (insert-file-contents (bdf-expand-file-name bdfname))
    buf)))

(defvar bdf-cache-file "~/.bdfcache.el"
  "Name of cache file which contains information of `BDF' font files.")

(defvar bdf-cache nil
  "Cached information of `BDF' font files.  It is a list of FONT-INFO.
FONT-INFO is a list of the following format:
    (BDFFILE ABSOLUTE-PATH MOD-TIME SIZE FONT-BOUNDING-BOX
     RELATIVE-COMPOSE BASELINE-OFFSET CODE-RANGE MAXLEN OFFSET-VECTOR)
See the documentation of the function `bdf-read-font-info' for more detail.")

(defun bdf-read-cache ()
  "Return a cached information about `BDF' font files from a cache file.
The variable `bdf-cache-file' holds the cache file name.
If the cache file is not readable, this return nil."
  (setq bdf-cache nil)
  (condition-case nil
      (if (file-readable-p bdf-cache-file)
	  (load-file bdf-cache-file))
    (error nil))
  (if (not (listp bdf-cache))
      (setq bdf-cache nil)))

(defun bdf-write-cache ()
  "Write out cached information of `BDF' font file to a file.
The variable `bdf-cache-file' holds the cache file name.
The file is written if and only if the file alreay exists and writable."
  (if (and bdf-cache
	   (file-exists-p bdf-cache-file)
	   (file-writable-p bdf-cache-file))
      (write-region (format "(setq bdf-cache '%S)\n" bdf-cache)
		    nil bdf-cache-file)))

(defun bdf-set-cache (font-info)
  "Cache FONT-INFO as information about one `BDF' font file.
FONT-INFO is a list of the following format:
    (BDFFILE ABSOLUTE-PATH MOD-TIME SIZE FONT-BOUNDING-BOX
     RELATIVE-COMPOSE BASELINE-OFFSET CODE-RANGE MAXLEN OFFSET-VECTOR)
See the documentation of the function `bdf-read-font-info' for more detail."
  (let ((slot (assoc (car font-info) bdf-cache)))
    (if slot
	(setcdr slot (cdr font-info))
      (setq bdf-cache (cons font-info bdf-cache)))))

(defun bdf-initialize ()
  "Initialize `bdf' library."
  (if (bdf-read-cache)
      (add-hook 'kill-emacs-hook 'bdf-write-cache)))

(defun bdf-compact-code (code code-range)
  (if (or (< code (aref code-range 4))
	  (> code (aref code-range 5)))
      (setq code (aref code-range 6)))
  (+ (* (- (lsh code -8) (aref code-range 0))
	(1+ (- (aref code-range 3) (aref code-range 2))))
     (- (logand code 255) (aref code-range 2))))

(defun bdf-expand-code (code code-range)
  (let ((code0-range (1+ (- (aref code-range 3) (aref code-range 2)))))
    (+ (* (+ (/ code code0-range) (aref code-range 0)) 256)
       (+ (% code code0-range) (aref code-range 2)))))

(defun bdf-read-font-info (bdfname)
  "Read `BDF' font file BDFNAME and return information (FONT-INFO) of the file.
FONT-INFO is a list of the following format:
    (BDFFILE ABSOLUTE-PATH MOD-TIME FONT-BOUNDING-BOX
     RELATIVE-COMPOSE BASELINE-OFFSET CODE-RANGE MAXLEN OFFSET-VECTOR)

BDFFILE is a name of a font file (excluding directory part).

ABSOLUTE-PATH is an absolute path of the font file.

MOD-TIME is last modification time as a list of two integers, the
first integer has high-order 16 bits, the second has low 16 bits.

SIZE is a size of the font.  This value is got from SIZE record of the
font.

FONT-BOUNDING-BOX is the font bounding box as a list of four integers,
BBX-WIDTH, BBX-HEIGHT, BBX-XOFF, and BBX-YOFF.

RELATIVE-COMPOSE is an integer value of the font's property
`_MULE_RELATIVE_COMPOSE'.  If the font doesn't have this property, the
value is 0.

BASELINE-OFFSET is an integer value of the font's property
`_MULE_BASELINE_OFFSET'.  If the font doesn't have this property, the
value is 0.

CODE-RANGE is a vector of minimum 1st byte, maximum 1st byte, minimum
2nd byte, maximum 2nd byte, minimum code, maximum code, and default
code.  For 1-byte fonts, the first two elements are 0.

MAXLEN is a maximum bytes of one glyph informaion in the font file.

OFFSET-VECTOR is a vector of a file position which starts bitmap data
of the glyph in the font file.

Nth element of OFFSET-VECTOR is a file position for the glyph of code
CODE, where N and CODE are in the following relation:
    (bdf-compact-code CODE) => N, (bdf-expand-code N) => CODE"
  (let ((absolute-path (bdf-expand-file-name bdfname))
	(maxlen 0)
	size
	font-bounding-box 
	(relative-compose 'false)
	(baseline-offset 0)
	default-char
	code-range
	offset-vector
	buf)
    (if absolute-path
	(message "Reading %s..." bdfname)
	(error "BDF file %s doesn't exist" bdfname))
    (setq buf (bdf-find-file absolute-path))
    (unwind-protect
	(save-excursion
	  (set-buffer buf)
	  (goto-char (point-min))
	  (search-forward "\nFONTBOUNDINGBOX")
	  (setq font-bounding-box (vector (read (current-buffer))
					  (read (current-buffer))
					  (read (current-buffer))
					  (read (current-buffer))))
	  ;; The following kludgy code is to avoid bugs of fonts
	  ;; jiskan16.bdf and jiskan24.bdf distributed with X.
	  ;; They contain wrong FONTBOUNDINGBOX.
	  (if (and (> (aref font-bounding-box 3) 0)
		   (string-match "jiskan\\(16\\|24\\)" bdfname))
	      (aset font-bounding-box 3
		    (- (aref font-bounding-box 3))))

	  (goto-char (point-min))
	  (search-forward "\nSIZE ")
	  (setq size (read (current-buffer)))
	  ;; The following kludgy code is t avoid bugs of several
	  ;; fonts which have wrong SIZE record.
	  (if (<= size (/ (aref font-bounding-box 1) 2))
	      (setq size (aref font-bounding-box 1)))

	  (goto-char (point-min))
	  (if (search-forward "\nDEFAULT_CHAR" nil t)
	      (setq default-char (read (current-buffer))))

	  (search-forward "\nSTARTCHAR")
	  (forward-line -1)
	  (let ((limit (point)))
	    (goto-char (point-min))
	    (if (search-forward "\n_MULE_RELATIVE_COMPOSE" limit t)
		(progn
		  (goto-char (match-end 0))
		  (setq relative-compose (read (current-buffer)))))
	    (goto-char (point-min))
	    (if (search-forward "\n_MULE_BASELINE_OFFSET" limit t)
		(progn
		  (goto-char (match-end 0))
		  (setq baseline-offset (read (current-buffer))))))

	  (let ((min-code0 256) (min-code1 256) (max-code0 0) (max-code1 0)
		(min-code 65536)
		(max-code 0)
		(glyph-list nil)
		code bbx offset)
	    (while (search-forward "\nSTARTCHAR" nil t)
	      (setq offset (line-beginning-position))
	      (search-forward "\nENCODING")
	      (setq code (read (current-buffer)))
	      (let ((code0 (lsh code -8))
		    (code1 (logand code 255)))
		(if (< code0 min-code0) (setq min-code0 code0)
		  (if (> code0 max-code0) (setq max-code0 code0)))
		(if (< code1 min-code1) (setq min-code1 code1)
		  (if (> code1 max-code1) (setq max-code1 code1))))
	      (if (< code min-code)
		  (setq min-code code)
		(if (> code max-code)
		    (setq max-code code)))
	      (search-forward "ENDCHAR")
	      (if (< maxlen (- (point) offset))
		  (setq maxlen (- (point) offset)))
	      (setq glyph-list (cons (cons code offset) glyph-list)))
	    (setq code-range
		  (vector min-code0 max-code0 min-code1 max-code1
			  min-code max-code (or default-char min-code)))
	    (setq offset-vector
		  (make-vector (1+ (bdf-compact-code max-code code-range))
			       nil))
	    (while glyph-list
	      (let ((glyph (car glyph-list)))
		(aset offset-vector
		      (bdf-compact-code (car glyph) code-range)
		      (cdr glyph)))
	      (setq glyph-list (cdr glyph-list)))))
      (kill-buffer buf))
    (message "Reading %s...done" bdfname)
    (list bdfname absolute-path (bdf-file-mod-time absolute-path)
	  size font-bounding-box relative-compose baseline-offset
	  code-range maxlen offset-vector)))

(defsubst bdf-info-absolute-path (font-info) (nth 1 font-info))
(defsubst bdf-info-mod-time (font-info) (nth 2 font-info))
(defsubst bdf-info-size (font-info) (nth 3 font-info))
(defsubst bdf-info-font-bounding-box (font-info) (nth 4 font-info))
(defsubst bdf-info-relative-compose (font-info) (nth 5 font-info))
(defsubst bdf-info-baseline-offset (font-info) (nth 6 font-info))
(defsubst bdf-info-code-range (font-info) (nth 7 font-info))
(defsubst bdf-info-maxlen (font-info) (nth 8 font-info))
(defsubst bdf-info-offset-vector (font-info) (nth 9 font-info))

(defun bdf-get-font-info (bdfname)
  "Return information about `BDF' font file BDFNAME.
The value FONT-INFO is a list of the following format:
    (BDFFILE ABSOLUTE-PATH MOD-TIME SIZE FONT-BOUNDING-BOX
     RELATIVE-COMPOSE BASELINE-OFFSET CODE-RANGE MAXLEN OFFSET-VECTOR)
See the documentation of the function `bdf-read-font-info' for more detail."
  (or bdf-cache
      (bdf-read-cache))
  (let ((font-info (assoc bdfname bdf-cache)))
    (if (or (not font-info)
	    (not (file-readable-p (bdf-info-absolute-path font-info)))
	    (bdf-file-newer-than-time bdfname (bdf-info-mod-time font-info)))
	(progn
	  (setq font-info (bdf-read-font-info bdfname))
	  (bdf-set-cache font-info)))
    font-info))

(defun bdf-read-bitmap (bdfname offset maxlen)
  "Read `BDF' font file BDFNAME to get bitmap data at file poistion OFFSET.
BDFNAME is an abosolute path name of the font file.
MAXLEN specifies how many bytes we should read at least.
The value is a list of DWIDTH, BBX, and BITMAP-STRING.
DWIDTH is a pixel width of a glyph.
BBX is a bounding box of the glyph.
BITMAP-STRING is a string representing bits by hexadecimal digits."
  (let ((coding-system-for-read 'no-conversion)
	dwidth bbx height yoff bitmap-string)
    (condition-case nil
	(with-temp-buffer
	  (insert-file-contents bdfname nil offset (+ offset maxlen))
	  (goto-char (point-min))
	  (search-forward "\nDWIDTH")
	  (setq dwidth (read (current-buffer)))
	  (goto-char (point-min))
	  (search-forward "\nBBX")
	  (setq bbx (vector (read (current-buffer)) (read (current-buffer))
			    (read (current-buffer)) (read (current-buffer))))
	  (setq height (aref bbx 1) yoff (aref bbx 3))
	  (search-forward "\nBITMAP")
	  (forward-line 1)
	  (delete-region (point-min) (point))
	  (if (looking-at "\\(0+\n\\)+")
	      (progn
		(setq height
		      (- height (count-lines (point) (match-end 0))))
		(delete-region (point) (match-end 0))))
	  (or (looking-at "ENDCHAR")
	      (progn
		(search-forward "ENDCHAR" nil 'move)
		(forward-line -1)
		(while (looking-at "0+$")
		  (setq yoff (1+ yoff) height (1- height))
		  (forward-line -1))
		(forward-line 1)))
	  (aset bbx 1 height)
	  (aset bbx 3 yoff)
	  (delete-region (point) (point-max))
	  (goto-char (point-min))
	  (while (not (eobp))
	    (end-of-line)
	    (delete-char 1))
	  (setq bitmap-string (buffer-string)))
      (error nil))
    (list dwidth bbx bitmap-string)))

(defun bdf-get-bitmaps (bdfname codes)
  "Return bitmap information of glyphs of CODES in `BDF' font file BDFNAME.
CODES is a list of encoding number of glyphs in the file.
The value is a list of CODE, DWIDTH, BBX, and BITMAP-STRING.
DWIDTH is a pixel width of a glyph.
BBX is a bounding box of the glyph.
BITMAP-STRING is a string representing bits by hexadecimal digits."
  (let* ((font-info (bdf-get-font-info bdfname))
	 (absolute-path (bdf-info-absolute-path font-info))
	 (font-bounding-box (bdf-info-font-bounding-box font-info))
	 (maxlen (bdf-info-maxlen font-info))
	 (code-range (bdf-info-code-range font-info))
	 (offset-vector (bdf-info-offset-vector font-info)))
    (mapcar (function
	     (lambda (x)
	       (cons x (bdf-read-bitmap
			absolute-path
			(aref offset-vector (bdf-compact-code x code-range))
			maxlen))))
	    codes)))

;;; Interface to ps-print.el

;; Called from ps-mule-init-external-library.
(defun bdf-generate-prologue ()
  (or bdf-cache
      (bdf-initialize))
  (ps-mule-generate-bitmap-prologue))

;; Called from ps-mule-generate-font.
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(defun bdf-generate-font (charset font-spec)
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  (let* ((font-name (ps-mule-font-spec-name font-spec))
	 (font-info (bdf-get-font-info font-name)))
    (ps-mule-generate-bitmap-font font-name
				  (ps-mule-font-spec-bytes font-spec)
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				  (charset-width charset)
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				  (bdf-info-size font-info)
				  (bdf-info-relative-compose font-info)
				  (bdf-info-baseline-offset font-info)
				  (bdf-info-font-bounding-box font-info))))

;; Called from ps-mule-generate-glyphs.
(defun bdf-generate-glyphs (font-spec code-list bytes)
  (let ((font-name (ps-mule-font-spec-name font-spec)))
    (mapcar (function
	     (lambda (x)
	       (apply 'ps-mule-generate-bitmap-glyph font-name x)))
	    (bdf-get-bitmaps font-name code-list))))

(provide 'bdf)

;;; bdf.el ends here