Improve Hebrew rendering.

4 files changed, 169 insertions, 24 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index e988b6bdef4..3d8648c86b6 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,11 @@
+2010-07-12  Kenichi Handa  <handa@m17n.org>
+
+        * language/hebrew.el: Remove no-byte-compile declaration.  Change
+        coding: tag to utf-8.  Register hebrew-shape-gstring in
+        composition-function-table for 3-character looking back.
+        (hebrew-font-get-precomposed): New function.
+        (hebrew-shape-gstring): Utilize precomposed glyphs if available.
+
 2010-07-11  Chong Yidong  <cyd@stupidchicken.com>
 
         * mouse.el (mouse-drag-track): Handle select-active-regions
diff --git a/lisp/language/hebrew.el b/lisp/language/hebrew.el
index f024251c60b..89a22d2d238 100644
--- a/lisp/language/hebrew.el
+++ b/lisp/language/hebrew.el
@@ -1,4 +1,4 @@
-;;; hebrew.el --- support for Hebrew -*- coding: iso-2022-7bit; no-byte-compile: t -*-
+;;; hebrew.el --- support for Hebrew -*- coding: utf-8 -*-
 
 ;; Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
 ;;   Free Software Foundation, Inc.
@@ -59,7 +59,7 @@
             (nonascii-translation . iso-8859-8)
             (input-method . "hebrew")
             (unibyte-display . hebrew-iso-8bit)
-            (sample-text . "Hebrew      ,Hylem(B")
+            (sample-text . "Hebrew      שלום")
             (documentation . "Bidirectional editing is supported.")))
 
 (set-language-info-alist
@@ -85,33 +85,167 @@ Bidirectional editing is supported.")))
   :mime-charset 'cp862)
 (define-coding-system-alias 'ibm862 'cp862)
 
-;; Composition function for hebrew.
+;; Return a nested alist of Hebrew character sequences vs the
+;; corresponding glyph of FONT-OBJECT.
+(defun hebrew-font-get-precomposed (font-object)
+  (let ((precomposed (font-get font-object 'hebrew-precomposed))
+        ;; Vector of Hebrew precomposed charaters.
+        (chars [#xFB2A #xFB2B #xFB2C #xFB2D #xFB2E #xFB2F #xFB30 #xFB31
+                #xFB32 #xFB33 #xFB34 #xFB35 #xFB36 #xFB38 #xFB39 #xFB3A
+                #xFB3B #xFB3C #xFB3E #xFB40 #xFB41 #xFB43 #xFB44 #xFB46
+                #xFB47 #xFB48 #xFB49 #xFB4A #xFB4B #xFB4C #xFB4D #xFB4E])
+        ;; Vector of decomposition character sequences corresponding
+        ;; to the above vector.
+        (decomposed 
+         [[#x05E9 #x05C1]
+          [#x05E9 #x05C2]
+          [#x05E9 #x05BC #x05C1]
+          [#x05E9 #x05BC #x05C2]
+          [#x05D0 #x05B7]
+          [#x05D0 #x05B8]
+          [#x05D0 #x05BC]
+          [#x05D1 #x05BC]
+          [#x05D2 #x05BC]
+          [#x05D3 #x05BC]
+          [#x05D4 #x05BC]
+          [#x05D5 #x05BC]
+          [#x05D6 #x05BC]
+          [#x05D8 #x05BC]
+          [#x05D9 #x05BC]
+          [#x05DA #x05BC]
+          [#x05DB #x05BC]
+          [#x05DC #x05BC]
+          [#x05DE #x05BC]
+          [#x05E0 #x05BC]
+          [#x05E1 #x05BC]
+          [#x05E3 #x05BC]
+          [#x05E4 #x05BC]
+          [#x05E6 #x05BC]
+          [#x05E7 #x05BC]
+          [#x05E8 #x05BC]
+          [#x05E9 #x05BC]
+          [#x05EA #x05BC]
+          [#x05D5 #x05B9]
+          [#x05D1 #x05BF]
+          [#x05DB #x05BF]
+          [#x05E4 #x05BF]]))
+    (unless precomposed
+      (setq precomposed (list t))
+      (let ((gvec (font-get-glyphs font-object 0 (length chars) chars)))
+        (dotimes (i (length chars))
+          (if (aref gvec i)
+              (set-nested-alist (aref decomposed i) (aref gvec i)
+                                precomposed))))
+      ;; Cache the result in FONT-OBJECT's property.
+      (font-put font-object 'hebrew-precomposed precomposed))
+    precomposed))
+
+;; Composition function for hebrew.  GSTRING is made of a Hebrew base
+;; character followed by Hebrew diacritical marks, or is made of
+;; single Hebrew diacritical mark.  Adjust GSTRING to display that
+;; sequence properly.  The basic strategy is:
+;;
+;; (1) If there's single diacritical, add padding space to the left
+;; and right of the glyph.
+;;
+;; (2) If the font has OpenType features for Hebrew, ask the OTF
+;; driver the whole work.
+;;
+;; (3) If the font has precomposed glyphs, use them as far as
+;; possible.  Adjust the remaining glyphs artificially.
+
 (defun hebrew-shape-gstring (gstring)
-  (setq gstring (font-shape-gstring gstring))
-  (let ((header (lgstring-header gstring))
-        (nchars (lgstring-char-len gstring))
-        (nglyphs (lgstring-glyph-len gstring))
-        (base-width (lglyph-width (lgstring-glyph gstring 0))))
-    (while (and (> nglyphs 1)
-                (not (lgstring-glyph gstring (1- nglyphs))))
-      (setq nglyphs (1- nglyphs)))
-    (while (> nglyphs 1)
-      (setq nglyphs (1- nglyphs))
-      (let* ((glyph (lgstring-glyph gstring nglyphs))
-             (adjust (and glyph (lglyph-adjustment glyph))))
-        (if adjust
-            (setq nglyphs 0)
-          (if (>= (lglyph-lbearing glyph) 0)
-              (lglyph-set-adjustment glyph (- base-width) 0 0))))))
-  gstring)
+  (let* ((font (lgstring-font gstring))
+         (otf (font-get font :otf))
+         (nchars (lgstring-char-len gstring))
+         header nglyphs base-width glyph precomposed val idx)
+    (cond
+     ((= nchars 1)
+      ;; Independent diacritical mark.  Add padding space to left or
+      ;; right so that the glyph doesn't overlap with the surrounding
+      ;; chars.
+      (setq glyph (lgstring-glyph gstring 0))
+      (let ((width (lglyph-width glyph))
+            bearing)
+        (if (< (setq bearing (lglyph-lbearing glyph)) 0)
+            (lglyph-set-adjustment glyph bearing 0 (- width bearing)))
+        (if (> (setq bearing (lglyph-rbearing glyph)) width)
+            (lglyph-set-adjustment glyph 0 0 bearing))))
+
+     ((or (assq 'hebr (car otf)) (assq 'hebr (cdr otf)))
+      ;; FONT has OpenType features for Hebrew.
+      (font-shape-gstring gstring))
+
+     (t
+      ;; FONT doesn't have OpenType features for Hebrew.
+      ;; Try a precomposed glyph.
+      ;; Now GSTRING is in this form:
+      ;;   [[FONT CHAR1 CHAR2 ... CHARn] nil GLYPH1 GLYPH2 ... GLYPHn nil ...]
+      (setq precomposed (hebrew-font-get-precomposed font)
+            header (lgstring-header gstring)
+            val (lookup-nested-alist header precomposed nil 1))
+      (if (and (consp val) (vectorp (car val)))
+          ;; All characters can be displayed by a single precomposed glyph.
+          ;; Reform GSTRING to [HEADER nil PRECOMPOSED-GLYPH nil ...]
+          (let ((glyph (copy-sequence (car val))))
+            (lglyph-set-from-to glyph 0 (1- nchars))
+            (lgstring-set-glyph gstring 0 glyph)
+            (lgstring-set-glyph gstring 1 nil))
+        (if (and (integerp val) (> val 2)
+                 (setq glyph (lookup-nested-alist header precomposed val 1))
+                 (consp glyph) (vectorp (car glyph)))
+            ;; The first (1- VAL) characters can be displayed by a
+            ;; precomposed glyph.  Provided that VAL is 3, the first
+            ;; two glyphs should be replaced by the precomposed glyph.
+            ;; In that case, reform GSTRING to:
+            ;;   [HEADER nil PRECOMPOSED-GLYPH GLYPH3 ... GLYPHn nil ...]
+            (let* ((ncmp (1- val))      ; number of composed glyphs
+                   (diff (1- ncmp)))    ; number of reduced glyphs
+              (setq glyph (copy-sequence (car glyph)))
+              (lglyph-set-from-to glyph 0 (1- nchars))
+              (lgstring-set-glyph gstring 0 glyph)
+              (setq idx ncmp)
+              (while (< idx nchars)
+                (setq glyph (lgstring-glyph gstring idx))
+                (lglyph-set-from-to glyph 0 (1- nchars))
+                (lgstring-set-glyph gstring (- idx diff) glyph)
+                (setq idx (1+ idx)))
+              (lgstring-set-glyph gstring (- idx diff) nil)
+              (setq idx (- ncmp diff)
+                    nglyphs (- nchars diff)))
+          (setq glyph (lgstring-glyph gstring 0))
+          (lglyph-set-from-to glyph 0 (1- nchars))
+          (setq idx 1 nglyphs nchars))
+        ;; Now IDX is an index to the first non-precomposed glyph.
+        ;; Adjust positions of the remaining glyphs artificially.
+        (setq base-width (lglyph-width (lgstring-glyph gstring 0)))
+        (while (< idx nglyphs)
+          (setq glyph (lgstring-glyph gstring idx))
+          (lglyph-set-from-to glyph 0 (1- nchars))
+          (if (>= (lglyph-lbearing glyph) (lglyph-width glyph))
+              ;; It seems that this glyph is designed to be rendered
+              ;; before the base glyph.
+              (lglyph-set-adjustment glyph (- base-width) 0 0)
+            (if (>= (lglyph-lbearing glyph) 0)
+                ;; Align the horizontal center of this glyph to the
+                ;; horizontal center of the base glyph.
+                (let ((width (- (lglyph-rbearing glyph)
+                                (lglyph-lbearing glyph))))
+                  (lglyph-set-adjustment glyph
+                                         (- (/ (- base-width width) 2)
+                                            (lglyph-lbearing glyph)
+                                            base-width) 0 0))))
+          (setq idx (1+ idx))))))
+    gstring))
 
 (let ((pattern1 "[\u05D0-\u05F2][\u0591-\u05BF\u05C1-\u05C5\u05C7]+")
       (pattern2 "[\u05D0-\u05F2]\u200D[\u0591-\u05BF\u05C1-\u05C5\u05C7]+"))
   (set-char-table-range
    composition-function-table '(#x591 . #x5C7)
-   (list (vector pattern2 2 'hebrew-shape-gstring)
+   (list (vector pattern2 3 'hebrew-shape-gstring)
+         (vector pattern2 2 'hebrew-shape-gstring)
          (vector pattern1 1 'hebrew-shape-gstring)
-         ["[\u0591-\u05C7]" 0 font-shape-gstring]))
+         [nil 0 hebrew-shape-gstring]))
   (set-char-table-range
    composition-function-table #x5C0 nil)
   (set-char-table-range
diff --git a/src/ChangeLog b/src/ChangeLog
index 5acf42608e4..c7e5c5c3ef2 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,8 @@
 2010-07-12  Kenichi Handa  <handa@m17n.org>
 
+        * Makefile.in (lisp): Change hebrew.el to hebrew.elc.
+        (shortlisp): Likewise.
+
         * font.h (enum font_property_index): New member FONT_ENTITY_INDEX.
 
         * font.c (font_open_entity): Record ENTITY in FONT_OBJECT's slot
diff --git a/src/Makefile.in b/src/Makefile.in
index 933ec98a8d5..6a60b1d1ffe 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -426,7 +426,7 @@ lisp= \
         ${lispsource}language/slovak.el \
         ${lispsource}language/romanian.el \
         ${lispsource}language/greek.el \
-        ${lispsource}language/hebrew.el \
+        ${lispsource}language/hebrew.elc \
         ${lispsource}language/japanese.el \
         ${lispsource}language/korean.el \
         ${lispsource}language/lao.el \
@@ -517,7 +517,7 @@ shortlisp= \
         ../lisp/language/slovak.el \
         ../lisp/language/romanian.el \
         ../lisp/language/greek.el \
-        ../lisp/language/hebrew.el \
+        ../lisp/language/hebrew.elc \
         ../lisp/language/japanese.el \
         ../lisp/language/korean.el \
         ../lisp/language/lao.el \