Added wtt clustering rule and supported Thai MS/MAC font layout.

2 files changed, 1192 insertions, 192 deletions

diff --git a/modules/thai/thai-x.c b/modules/thai/thai-x.c
index 6547250a..d6b2c44c 100644
--- a/modules/thai/thai-x.c
+++ b/modules/thai/thai-x.c
@@ -1,7 +1,14 @@
-/* Pango
+/* pANGO
  * thai.c:
  *
  * Copyright (C) 1999 Red Hat Software
+ * Author: Owen Taylor <otaylor@redhat.com>
+ *
+ * Software and Language Engineering Laboratory, NECTEC
+ * Author: Theppitak Karoonboonyanan <thep@links.nectec.or.th>
+ *
+ * Copyright (c) 1996-2000 by Sun Microsystems, Inc.
+ * Author: Chookij Vanatham <Chookij.Vanatham@Eng.Sun.COM>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -19,10 +26,63 @@
  * Boston, MA 02111-1307, USA.
  */
 
+
 #include <glib.h>
 #include "pango.h"
 #include "pangox.h"
 
+#define ucs2tis(wc)		(unsigned int)((unsigned int)(wc) - 0x0E00 + 0xA0)
+#define tis2uni(c)		((gunichar)(c) - 0xA0 + 0x0E00)
+
+#define MAX_CLUSTER_CHRS	256
+#define MAX_GLYPHS		256
+
+/* Define TACTIS character classes */
+#define CTRL			0
+#define NON			1
+#define CONS			2
+#define LV			3
+#define FV1			4
+#define FV2			5
+#define FV3			6
+#define BV1			7
+#define BV2			8
+#define BD			9
+#define TONE			10
+#define AD1			11
+#define AD2			12
+#define AD3			13
+#define AV1			14
+#define AV2			15
+#define AV3			16
+
+#define _ND			0
+#define _NC			1
+#define _UC			(1<<1)
+#define _BC			(1<<2)
+#define _SC			(1<<3)
+#define _AV			(1<<4)
+#define _BV			(1<<5)
+#define _TN			(1<<6)
+#define _AD			(1<<7)
+#define _BD			(1<<8)
+#define _AM			(1<<9)
+
+#define NoTailCons		_NC
+#define UpTailCons		_UC
+#define BotTailCons		_BC
+#define SpltTailCons		_SC
+#define Cons			(NoTailCons|UpTailCons|BotTailCons|SpltTailCons)
+#define AboveVowel		_AV
+#define BelowVowel		_BV
+#define Tone			_TN
+#define AboveDiac		_AD
+#define BelowDiac		_BD
+#define SaraAm			_AM
+
+#define char_class(wc)		TAC_char_class[(unsigned int)(wc)]
+#define is_char_type(wc, mask)	(char_type_table[ucs2tis ((wc))] & (mask))
+
 /* We handle the range U+0e01 to U+0e5b exactly
  */
 static PangoEngineRange thai_ranges[] = {
@@ -83,6 +143,8 @@ typedef enum {
   THAI_FONT_NONE,
   THAI_FONT_XTIS,
   THAI_FONT_TIS,
+  THAI_FONT_TIS_MAC,
+  THAI_FONT_TIS_WIN,
   THAI_FONT_ISO10646
 } ThaiFontType;
 
@@ -128,6 +190,160 @@ static const char group2_map[32] = {
   2, 3, 4, 5, 6, 7, 1, 0
 };
 
+static const gint char_type_table[256] = {
+  /*       0,   1,   2,   3,   4,   5,   6,   7,
+           8,   9,   A,   B,   C,   D,   E,   F  */
+
+  /*00*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*10*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*20*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*30*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*40*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*50*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*60*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*70*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*80*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*90*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+		
+  /*A0*/ _ND, _NC, _NC, _NC, _NC, _NC, _NC, _NC,
+         _NC, _NC, _NC, _NC, _NC, _SC, _BC, _BC,
+  /*B0*/ _SC, _NC, _NC, _NC, _NC, _NC, _NC, _NC,
+         _NC, _NC, _NC, _UC, _NC, _UC, _NC, _UC,
+  /*C0*/ _NC, _NC, _NC, _NC, _ND, _NC, _ND, _NC,
+         _NC, _NC, _NC, _NC, _UC, _NC, _NC, _ND,
+  /*D0*/ _ND, _AV, _ND, _AM, _AV, _AV, _AV, _AV,
+         _BV, _BV, _BD, _ND, _ND, _ND, _ND, _ND,
+  /*E0*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _AD,
+         _TN, _TN, _TN, _TN, _AD, _AD, _AD, _ND,
+  /*F0*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+};
+
+static const gint TAC_char_class[256] = {
+  /*	   0,   1,   2,   3,   4,   5,   6,   7,
+           8,   9,   A,   B,   C,   D,   E,   F  */
+
+  /*00*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*10*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*20*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*30*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*40*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*50*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*60*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*70*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON,CTRL,
+  /*80*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*90*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*A0*/  NON,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+         CONS,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+  /*B0*/ CONS,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+         CONS,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+  /*C0*/ CONS,CONS,CONS,CONS, FV3,CONS, FV3,CONS,
+         CONS,CONS,CONS,CONS,CONS,CONS,CONS, NON,
+  /*D0*/  FV1, AV2, FV1, FV1, AV1, AV3, AV2, AV3,
+          BV1, BV2,  BD, NON, NON, NON, NON, NON,
+  /*E0*/   LV,  LV,  LV,  LV,  LV, FV2, NON, AD2,
+         TONE,TONE,TONE,TONE, AD1, AD1, AD3, NON,
+  /*F0*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON,CTRL,
+};
+
+static const gchar TAC_compose_and_input_check_type_table[17][17] = {
+      /* Cn */ /* 0,   1,   2,   3,   4,   5,   6,   7,
+                  8,   9,   A,   B,   C,   D,   E,   F       */
+  /* Cn-1 00 */	'X', 'A', 'A', 'A', 'A', 'A', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 10 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 20 */      'X', 'A', 'A', 'A', 'A', 'S', 'A', 'C',
+                'C', 'C', 'C', 'C', 'C', 'C', 'C', 'C', 'C',
+  /* 30 */      'X', 'S', 'A', 'S', 'S', 'S', 'S', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 40 */      'X', 'S', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 50 */      'X', 'A', 'A', 'A', 'A', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 60 */      'X', 'A', 'A', 'A', 'S', 'A', 'S', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 70 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'C', 'R', 'R', 'R', 'R', 'R',
+  /* 80 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 90 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* A0 */      'X', 'A', 'A', 'A', 'A', 'A', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* B0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* C0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* D0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* E0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'C', 'R', 'R', 'R', 'R', 'R',
+  /* F0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'R', 'R', 'R', 'R', 'R', 'R',
+                'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'R', 'C', 'R', 'R', 'R', 'R'
+};
+
+typedef struct {
+  gint ShiftDown_TONE_AD[8];
+  gint ShiftDownLeft_TONE_AD[8];
+  gint ShiftLeft_TONE_AD[8];
+  gint ShiftLeft_AV[7];
+  gint ShiftDown_BV_BD[3];
+  gint TailCutCons[4];
+} ThaiShapeTable;
+
+#define shiftdown_tone_ad(c,tbl)      ((tbl)->ShiftDown_TONE_AD[(c)-0xE7])
+#define shiftdownleft_tone_ad(c,tbl)  ((tbl)->ShiftDownLeft_TONE_AD[(c)-0xE7])
+#define shiftleft_tone_ad(c,tbl)      ((tbl)->ShiftLeft_TONE_AD[(c)-0xE7])
+#define shiftleft_av(c,tbl)           ((tbl)->ShiftLeft_AV[(c)-0xD1])
+#define shiftdown_bv_bd(c,tbl)        ((tbl)->ShiftDown_BV_BD[(c)-0xD8])
+#define tailcutcons(c,tbl)            ((tbl)->TailCutCons[(c)-0xAD])
+
+/* Macintosh
+ */
+static const ThaiShapeTable Mac_shape_table = {
+  { 0xE7, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0xED, 0xEE },
+  { 0xE7, 0x83, 0x84, 0x85, 0x86, 0x87, 0x8F, 0xEE },
+  { 0x93, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x8F, 0xEE },
+  { 0x92, 0x00, 0x00, 0x94, 0x95, 0x96, 0x97 },
+  { 0xD8, 0xD9, 0xDA },
+  { 0xAD, 0x00, 0x00, 0xB0 }
+};
+
+/* Microsoft Window
+ */
+static const ThaiShapeTable Win_shape_table = {
+    { 0xE7, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0xED, 0xEE },
+    { 0xE7, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x99, 0xEE },
+    { 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0x99, 0xEE },
+    { 0x98, 0x00, 0x00, 0x81, 0x82, 0x83, 0x84 },
+    { 0xFC, 0xFD, 0xFE },
+    { 0x90, 0x00, 0x00, 0x80 }
+};
+
 /* Returns a structure with information we will use to rendering given the
  * #PangoFont. This is computed once per font and cached for later retrieval.
  */
@@ -135,24 +351,26 @@ static ThaiFontInfo *
 get_font_info (PangoFont *font)
 {
   static const char *charsets[] = {
+    "tis620-2",
+    "tis620-1",
+    "tis620-0",
     "xtis620.2529-1",
     "xtis-0",
-    "tis620.2533-0",
     "tis620.2533-1",
-    "tis620.2529-0",
     "tis620.2529-1",
     "iso8859-11",
     "iso10646-1",
   };
 
   static const int charset_types[] = {
+    THAI_FONT_TIS_WIN,
+    THAI_FONT_TIS_MAC,
+    THAI_FONT_TIS,
     THAI_FONT_XTIS,
     THAI_FONT_XTIS,
     THAI_FONT_TIS,
     THAI_FONT_TIS,
     THAI_FONT_TIS,
-    THAI_FONT_TIS,
-    THAI_FONT_TIS,
     THAI_FONT_ISO10646
   };
   
@@ -160,14 +378,15 @@ get_font_info (PangoFont *font)
   GQuark info_id = g_quark_from_string ("thai-font-info");
   
   font_info = g_object_get_qdata (G_OBJECT (font), info_id);
+
   if (!font_info)
     {
       /* No cached information not found, so we need to compute it
        * from scratch
        */
       PangoXSubfont *subfont_ids;
-      int *subfont_charsets;
-      int n_subfonts, i;
+      gint *subfont_charsets;
+      gint n_subfonts, i;
 
       font_info = g_new (ThaiFontInfo, 1);
       font_info->font = font;
@@ -202,12 +421,12 @@ get_font_info (PangoFont *font)
 static void
 add_glyph (ThaiFontInfo     *font_info, 
 	   PangoGlyphString *glyphs, 
-	   int               cluster_start, 
+	   gint              cluster_start, 
 	   PangoGlyph        glyph,
 	   gboolean          combining)
 {
   PangoRectangle ink_rect, logical_rect;
-  int index = glyphs->num_glyphs;
+  gint index = glyphs->num_glyphs;
 
   pango_glyph_string_set_size (glyphs, index + 1);
   
@@ -221,10 +440,25 @@ add_glyph (ThaiFontInfo     *font_info,
 
   if (combining)
     {
-      glyphs->glyphs[index].geometry.width = 
-	MAX (logical_rect.width, glyphs->glyphs[index - 1].geometry.width);
-      glyphs->glyphs[index - 1].geometry.width = 0;
-      glyphs->glyphs[index].geometry.x_offset = 0;
+      if (font_info->type == THAI_FONT_TIS ||
+	  font_info->type == THAI_FONT_TIS_MAC ||
+	  font_info->type == THAI_FONT_TIS_WIN)
+	{
+          glyphs->glyphs[index].geometry.width =
+		logical_rect.width + glyphs->glyphs[index - 1].geometry.width;
+          if (logical_rect.width > 0)
+	      glyphs->glyphs[index].geometry.x_offset = glyphs->glyphs[index - 1].geometry.width;
+          else
+	      glyphs->glyphs[index].geometry.x_offset = glyphs->glyphs[index].geometry.width;
+	  glyphs->glyphs[index - 1].geometry.width = 0;
+	}
+      else
+        {
+	  glyphs->glyphs[index].geometry.width =
+		MAX (logical_rect.width, glyphs->glyphs[index - 1].geometry.width);
+	  glyphs->glyphs[index - 1].geometry.width = 0;
+	  glyphs->glyphs[index].geometry.x_offset = 0;
+        }
     }
   else
     {
@@ -235,63 +469,362 @@ add_glyph (ThaiFontInfo     *font_info,
   glyphs->glyphs[index].geometry.y_offset = 0;
 }
 
-/* Return the glyph code within the font for the given Unicode Thai 
- * code pointer
- */
-static int
-get_glyph (ThaiFontInfo *font_info, gunichar wc)
+static gint
+get_adjusted_glyphs_list (ThaiFontInfo *font_info,
+		                  gunichar *cluster,
+		                  gint num_chrs,
+		                  PangoGlyph **glyph_lists,
+				  const ThaiShapeTable *shaping_table)
 {
+  switch (num_chrs)
+    {
+      case 1:
+        if (is_char_type (cluster[0], BelowVowel|BelowDiac|AboveVowel|AboveDiac|Tone))
+	  {
+            glyph_lists[0] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0x7F);
+            glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            return 2;
+          }
+	else
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            return 1;
+          }
+        break;
+        
+      case 2:
+        if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+            is_char_type (cluster[1], SaraAm))
+	  {
+            glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xED);
+            glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+            return 3;
+          }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+          	 is_char_type (cluster[1], SaraAm))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+					shiftleft_tone_ad (0xED, shaping_table));
+            glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+            return 3;
+          }
+	else if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+          	 is_char_type (cluster[1], AboveVowel))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    return 2;
+          }
+	else if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+          	 is_char_type (cluster[1], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    	shiftdown_tone_ad (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+	  }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+          	 is_char_type (cluster[1], AboveVowel))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    	shiftleft_av (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+          }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+          	 is_char_type (cluster[1], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdownleft_tone_ad (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+	  }
+	else if (is_char_type (cluster[0], NoTailCons|UpTailCons) &&
+          	 is_char_type (cluster[1], BelowVowel|BelowDiac))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    return 2;
+          }
+	else if (is_char_type (cluster[0], BotTailCons) &&
+		 is_char_type (cluster[1], BelowVowel|BelowDiac))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdown_bv_bd (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+	  }
+	else if (is_char_type (cluster[0], SpltTailCons) &&
+          	 is_char_type (cluster[1], BelowVowel|BelowDiac))
+	  {
+	    glyph_lists[0] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		tailcutcons (ucs2tis (cluster[0]), shaping_table));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    return 2;
+	  }
+	else
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, 0x7F);
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[2]));
+	    return 3;
+	  }
+        break;
+          
+      case 3:
+        if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+            is_char_type (cluster[1], Tone) &&
+            is_char_type (cluster[2], SaraAm))
+	  {
+            glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xED);
+            glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+            glyph_lists[3] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+            return 4;
+          }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+		 is_char_type (cluster[1], Tone) &&
+		 is_char_type (cluster[2], SaraAm))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+				shiftleft_tone_ad (0xED, shaping_table));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftleft_tone_ad (ucs2tis (cluster[1]), shaping_table));
+	    glyph_lists[3] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+	    return 4;
+	  }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+		 is_char_type (cluster[1], AboveVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+				shiftleft_av (ucs2tis (cluster[1]), shaping_table));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftleft_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdownleft_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], NoTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdown_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], SpltTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		tailcutcons (ucs2tis (cluster[0]), shaping_table));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftdown_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], BotTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftdown_bv_bd (ucs2tis (cluster[1]), shaping_table));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+				shiftdown_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[2]));
+	    return 3;
+	  }
+      break;
+    }
+
+    return 0;
+}
+
+static gint
+get_glyphs_list (ThaiFontInfo	*font_info,
+		 gunichar	*cluster,
+		 gint		num_chrs,
+		 PangoGlyph	**glyph_lists)
+{
+  PangoGlyph glyph;
+  gint xtis_index;
+  gint i;
+
   switch (font_info->type)
     {
-    case THAI_FONT_NONE:
-      return pango_x_get_unknown_glyph (font_info->font);
-    case THAI_FONT_XTIS:
-      return PANGO_X_MAKE_GLYPH (font_info->subfont, 0x100 * (wc - 0xe00 + 0x20) + 0x30);
-    case THAI_FONT_TIS:
-      return PANGO_X_MAKE_GLYPH (font_info->subfont, wc - 0xe00 + 0xA0);
-    case THAI_FONT_ISO10646:
-      return PANGO_X_MAKE_GLYPH (font_info->subfont, wc);
+      case THAI_FONT_NONE:
+        for (i=0; i < num_chrs; i++)
+	  glyph_lists[i] = pango_x_get_unknown_glyph (font_info->font);
+        return num_chrs;
+
+      case THAI_FONT_XTIS:
+        /* If we are rendering with an XTIS font, we try to find a precomposed
+         * glyph for the cluster.
+         */
+        xtis_index = 0x100 * (cluster[0] - 0xe00 + 0x20) + 0x30;
+        if (cluster[1])
+	    xtis_index +=8 * group1_map[cluster[1] - 0xe30];
+        if (cluster[2])
+	    xtis_index += group2_map[cluster[2] - 0xe30];
+        glyph = PANGO_X_MAKE_GLYPH (font_info->subfont, xtis_index);
+        if (pango_x_has_glyph (font_info->font, glyph)) {
+            glyph_lists[0] = glyph;
+            return 1;
+        }
+        for (i=0; i < num_chrs; i++)
+	  glyph_lists[i] =
+	      PANGO_X_MAKE_GLYPH (font_info->subfont,
+					0x100 * (cluster[i] - 0xe00 + 0x20) + 0x30);
+        return num_chrs;
+      
+      case THAI_FONT_TIS:
+        for (i=0; i < num_chrs; i++)
+          glyph_lists[i] =
+              PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[i]));
+        return num_chrs;
+      
+      case THAI_FONT_TIS_MAC:
+	/* MacIntosh Extension
+	 */
+        return get_adjusted_glyphs_list (font_info, cluster,
+			num_chrs, glyph_lists, &Mac_shape_table);
+      
+      case THAI_FONT_TIS_WIN:
+	/* Microsoft Extension
+	 */
+        return get_adjusted_glyphs_list (font_info, cluster,
+			num_chrs, glyph_lists, &Win_shape_table);
+      
+      case THAI_FONT_ISO10646:
+        for (i=0; i < num_chrs; i++)
+          glyph_lists[i] = PANGO_X_MAKE_GLYPH (font_info->subfont, cluster[i]);
+        return num_chrs;
     }
+
   return 0;			/* Quiet GCC */
 }
 
 static void
-add_cluster (ThaiFontInfo *font_info,
-	     PangoGlyphString *glyphs,
-	     int cluster_start,
-	     gunichar base, 
-	     gunichar group1,
-	     gunichar group2)
+add_cluster (ThaiFontInfo	*font_info,
+	     PangoGlyphString	*glyphs,
+	     gint		cluster_start,
+	     gunichar		*cluster,
+	     gint		num_chrs)
+	     
+{
+  PangoGlyph glyphs_list[MAX_GLYPHS];
+  gint num_glyphs;
+  gint i;
+  
+  num_glyphs = get_glyphs_list(font_info, cluster, num_chrs, &glyphs_list);
+  for (i=0; i<num_glyphs; i++)
+       add_glyph (font_info, glyphs, cluster_start, glyphs_list[i],
+	    		i == 0 ? FALSE : TRUE);
+}
+
+static gboolean
+is_wtt_composible (gunichar cur_wc, gunichar nxt_wc)
 {
-  /* If we are rendering with an XTIS font, we try to find a precomposed
-   * glyph for the cluster.
-   */
-  if (font_info->type == THAI_FONT_XTIS)
+  switch (TAC_compose_and_input_check_type_table[char_class (ucs2tis (cur_wc))]
+						[char_class (ucs2tis (nxt_wc))])
     {
-      PangoGlyph glyph;
-      int xtis_index = 0x100 * (base - 0xe00 + 0x20) + 0x30;
-      if (group1)
-	xtis_index +=8 * group1_map[group1 - 0xe30];
-      if (group2)
-	xtis_index += group2_map[group2 - 0xe30];
-      
-      glyph = PANGO_X_MAKE_GLYPH (font_info->subfont, xtis_index);
+      case 'A':
+      case 'S':
+      case 'R':
+      case 'X':
+        return FALSE;
+
+      case 'C':
+        return TRUE;
+    }
+}
 
-      if (pango_x_has_glyph (font_info->font, glyph))
+static const char *
+get_next_cluster(const char	*text,
+		 gint		length,
+		 gunichar	**cluster,
+		 gint		*num_chrs)
+{  
+  const char *p;
+  gint n_chars = 0;
+  
+  p = text;
+  while (p < text + length && n_chars < 3)  
+    {
+      gunichar current = g_utf8_get_char (p);
+      
+      if (n_chars == 0 ||
+	  is_wtt_composible ((gunichar)(cluster[n_chars - 1]), current) ||
+	  (n_chars == 1 &&
+	   is_char_type (cluster[0], Cons) && 
+	   is_char_type (current, SaraAm)) ||
+	  (n_chars == 2 &&
+	   is_char_type (cluster[0], Cons) &&
+	   is_char_type (cluster[1], Tone) &&
+	   is_char_type (current, SaraAm)))
 	{
-	  add_glyph (font_info, glyphs, cluster_start, glyph, FALSE);
-	  return;
+	  cluster[n_chars++] = current;
+	  p = g_utf8_next_char (p);
 	}
+      else
+	break;
     }
 
-  /* If that failed, then we add compose the cluster out of three 
-   * individual glyphs
-   */
-  add_glyph (font_info, glyphs, cluster_start, get_glyph (font_info, base), FALSE);
-  if (group1)
-    add_glyph (font_info, glyphs, cluster_start, get_glyph (font_info, group1), TRUE);
-  if (group2)
-    add_glyph (font_info, glyphs, cluster_start, get_glyph (font_info, group2), TRUE);
+  *num_chrs = n_chars;
+  return p;
 }
 
 static void 
@@ -303,54 +836,21 @@ thai_engine_shape (PangoFont        *font,
 {
   ThaiFontInfo *font_info;
   const char *p;
-
-  gunichar base = 0;
-  gunichar group1 = 0;
-  gunichar group2 = 0;
-  int cluster_start = 0;
+  const char *log_cluster;
+  gunichar cluster[MAX_CLUSTER_CHRS];
+  gint num_chrs;
 
   pango_glyph_string_set_size (glyphs, 0);
 
   font_info = get_font_info (font);
-  
+
   p = text;
   while (p < text + length)
     {
-      int group;
-      gunichar wc;
-
-      wc = g_utf8_get_char (p);
-
-      if (wc >= 0xe30 && wc < 0xe50)
-	group = groups[wc - 0xe30];
-      else
-	group = 0;
-
-      switch (group)
-	{
-	case 0:
-	  if (base)
-	    {
-	      add_cluster (font_info, glyphs, cluster_start, base, group1, group2);
-	      group1 = 0;
-	      group2 = 0;
-	    }
-	  cluster_start = p - text;
-	  base = wc;
-	  break;
-	case 1:
-	  group1 = wc;
-	  break;
-	case 2:
-	  group2 = wc;
-	  break;
-	}
-      
-      p = g_utf8_next_char (p);
+	log_cluster = p;
+	p = get_next_cluster (p, text + length - p, &cluster, &num_chrs);
+	add_cluster (font_info, glyphs, log_cluster - text, cluster, num_chrs);
     }
-
-  if (base)
-    add_cluster (font_info, glyphs, cluster_start, base, group1, group2);
 }
 
 static PangoCoverage *
@@ -382,7 +882,7 @@ thai_engine_x_new ()
   result = g_new (PangoEngineShape, 1);
 
   result->engine.id = "ThaiScriptEngine";
-  result->engine.type = PANGO_ENGINE_TYPE_LANG;
+  result->engine.type = PANGO_ENGINE_TYPE_SHAPE;
   result->engine.length = sizeof (result);
   result->script_shape = thai_engine_shape;
   result->get_coverage = thai_engine_get_coverage;
diff --git a/modules/thai/thai.c b/modules/thai/thai.c
index 6547250a..d6b2c44c 100644
--- a/modules/thai/thai.c
+++ b/modules/thai/thai.c
@@ -1,7 +1,14 @@
-/* Pango
+/* pANGO
  * thai.c:
  *
  * Copyright (C) 1999 Red Hat Software
+ * Author: Owen Taylor <otaylor@redhat.com>
+ *
+ * Software and Language Engineering Laboratory, NECTEC
+ * Author: Theppitak Karoonboonyanan <thep@links.nectec.or.th>
+ *
+ * Copyright (c) 1996-2000 by Sun Microsystems, Inc.
+ * Author: Chookij Vanatham <Chookij.Vanatham@Eng.Sun.COM>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -19,10 +26,63 @@
  * Boston, MA 02111-1307, USA.
  */
 
+
 #include <glib.h>
 #include "pango.h"
 #include "pangox.h"
 
+#define ucs2tis(wc)		(unsigned int)((unsigned int)(wc) - 0x0E00 + 0xA0)
+#define tis2uni(c)		((gunichar)(c) - 0xA0 + 0x0E00)
+
+#define MAX_CLUSTER_CHRS	256
+#define MAX_GLYPHS		256
+
+/* Define TACTIS character classes */
+#define CTRL			0
+#define NON			1
+#define CONS			2
+#define LV			3
+#define FV1			4
+#define FV2			5
+#define FV3			6
+#define BV1			7
+#define BV2			8
+#define BD			9
+#define TONE			10
+#define AD1			11
+#define AD2			12
+#define AD3			13
+#define AV1			14
+#define AV2			15
+#define AV3			16
+
+#define _ND			0
+#define _NC			1
+#define _UC			(1<<1)
+#define _BC			(1<<2)
+#define _SC			(1<<3)
+#define _AV			(1<<4)
+#define _BV			(1<<5)
+#define _TN			(1<<6)
+#define _AD			(1<<7)
+#define _BD			(1<<8)
+#define _AM			(1<<9)
+
+#define NoTailCons		_NC
+#define UpTailCons		_UC
+#define BotTailCons		_BC
+#define SpltTailCons		_SC
+#define Cons			(NoTailCons|UpTailCons|BotTailCons|SpltTailCons)
+#define AboveVowel		_AV
+#define BelowVowel		_BV
+#define Tone			_TN
+#define AboveDiac		_AD
+#define BelowDiac		_BD
+#define SaraAm			_AM
+
+#define char_class(wc)		TAC_char_class[(unsigned int)(wc)]
+#define is_char_type(wc, mask)	(char_type_table[ucs2tis ((wc))] & (mask))
+
 /* We handle the range U+0e01 to U+0e5b exactly
  */
 static PangoEngineRange thai_ranges[] = {
@@ -83,6 +143,8 @@ typedef enum {
   THAI_FONT_NONE,
   THAI_FONT_XTIS,
   THAI_FONT_TIS,
+  THAI_FONT_TIS_MAC,
+  THAI_FONT_TIS_WIN,
   THAI_FONT_ISO10646
 } ThaiFontType;
 
@@ -128,6 +190,160 @@ static const char group2_map[32] = {
   2, 3, 4, 5, 6, 7, 1, 0
 };
 
+static const gint char_type_table[256] = {
+  /*       0,   1,   2,   3,   4,   5,   6,   7,
+           8,   9,   A,   B,   C,   D,   E,   F  */
+
+  /*00*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*10*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*20*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*30*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*40*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*50*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*60*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*70*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*80*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+  /*90*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+		
+  /*A0*/ _ND, _NC, _NC, _NC, _NC, _NC, _NC, _NC,
+         _NC, _NC, _NC, _NC, _NC, _SC, _BC, _BC,
+  /*B0*/ _SC, _NC, _NC, _NC, _NC, _NC, _NC, _NC,
+         _NC, _NC, _NC, _UC, _NC, _UC, _NC, _UC,
+  /*C0*/ _NC, _NC, _NC, _NC, _ND, _NC, _ND, _NC,
+         _NC, _NC, _NC, _NC, _UC, _NC, _NC, _ND,
+  /*D0*/ _ND, _AV, _ND, _AM, _AV, _AV, _AV, _AV,
+         _BV, _BV, _BD, _ND, _ND, _ND, _ND, _ND,
+  /*E0*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _AD,
+         _TN, _TN, _TN, _TN, _AD, _AD, _AD, _ND,
+  /*F0*/ _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+         _ND, _ND, _ND, _ND, _ND, _ND, _ND, _ND,
+};
+
+static const gint TAC_char_class[256] = {
+  /*	   0,   1,   2,   3,   4,   5,   6,   7,
+           8,   9,   A,   B,   C,   D,   E,   F  */
+
+  /*00*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*10*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*20*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*30*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*40*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*50*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*60*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON, NON,
+  /*70*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON,CTRL,
+  /*80*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*90*/ CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+         CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,CTRL,
+  /*A0*/  NON,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+         CONS,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+  /*B0*/ CONS,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+         CONS,CONS,CONS,CONS,CONS,CONS,CONS,CONS,
+  /*C0*/ CONS,CONS,CONS,CONS, FV3,CONS, FV3,CONS,
+         CONS,CONS,CONS,CONS,CONS,CONS,CONS, NON,
+  /*D0*/  FV1, AV2, FV1, FV1, AV1, AV3, AV2, AV3,
+          BV1, BV2,  BD, NON, NON, NON, NON, NON,
+  /*E0*/   LV,  LV,  LV,  LV,  LV, FV2, NON, AD2,
+         TONE,TONE,TONE,TONE, AD1, AD1, AD3, NON,
+  /*F0*/  NON, NON, NON, NON, NON, NON, NON, NON,
+          NON, NON, NON, NON, NON, NON, NON,CTRL,
+};
+
+static const gchar TAC_compose_and_input_check_type_table[17][17] = {
+      /* Cn */ /* 0,   1,   2,   3,   4,   5,   6,   7,
+                  8,   9,   A,   B,   C,   D,   E,   F       */
+  /* Cn-1 00 */	'X', 'A', 'A', 'A', 'A', 'A', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 10 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 20 */      'X', 'A', 'A', 'A', 'A', 'S', 'A', 'C',
+                'C', 'C', 'C', 'C', 'C', 'C', 'C', 'C', 'C',
+  /* 30 */      'X', 'S', 'A', 'S', 'S', 'S', 'S', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 40 */      'X', 'S', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 50 */      'X', 'A', 'A', 'A', 'A', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 60 */      'X', 'A', 'A', 'A', 'S', 'A', 'S', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 70 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'C', 'R', 'R', 'R', 'R', 'R',
+  /* 80 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* 90 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* A0 */      'X', 'A', 'A', 'A', 'A', 'A', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* B0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* C0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* D0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
+  /* E0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'C', 'R', 'R', 'R', 'R', 'R',
+  /* F0 */      'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'R', 'R', 'R', 'R', 'R', 'R',
+                'X', 'A', 'A', 'A', 'S', 'S', 'A', 'R',
+                'R', 'R', 'C', 'R', 'C', 'R', 'R', 'R', 'R'
+};
+
+typedef struct {
+  gint ShiftDown_TONE_AD[8];
+  gint ShiftDownLeft_TONE_AD[8];
+  gint ShiftLeft_TONE_AD[8];
+  gint ShiftLeft_AV[7];
+  gint ShiftDown_BV_BD[3];
+  gint TailCutCons[4];
+} ThaiShapeTable;
+
+#define shiftdown_tone_ad(c,tbl)      ((tbl)->ShiftDown_TONE_AD[(c)-0xE7])
+#define shiftdownleft_tone_ad(c,tbl)  ((tbl)->ShiftDownLeft_TONE_AD[(c)-0xE7])
+#define shiftleft_tone_ad(c,tbl)      ((tbl)->ShiftLeft_TONE_AD[(c)-0xE7])
+#define shiftleft_av(c,tbl)           ((tbl)->ShiftLeft_AV[(c)-0xD1])
+#define shiftdown_bv_bd(c,tbl)        ((tbl)->ShiftDown_BV_BD[(c)-0xD8])
+#define tailcutcons(c,tbl)            ((tbl)->TailCutCons[(c)-0xAD])
+
+/* Macintosh
+ */
+static const ThaiShapeTable Mac_shape_table = {
+  { 0xE7, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0xED, 0xEE },
+  { 0xE7, 0x83, 0x84, 0x85, 0x86, 0x87, 0x8F, 0xEE },
+  { 0x93, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x8F, 0xEE },
+  { 0x92, 0x00, 0x00, 0x94, 0x95, 0x96, 0x97 },
+  { 0xD8, 0xD9, 0xDA },
+  { 0xAD, 0x00, 0x00, 0xB0 }
+};
+
+/* Microsoft Window
+ */
+static const ThaiShapeTable Win_shape_table = {
+    { 0xE7, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0xED, 0xEE },
+    { 0xE7, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x99, 0xEE },
+    { 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0x99, 0xEE },
+    { 0x98, 0x00, 0x00, 0x81, 0x82, 0x83, 0x84 },
+    { 0xFC, 0xFD, 0xFE },
+    { 0x90, 0x00, 0x00, 0x80 }
+};
+
 /* Returns a structure with information we will use to rendering given the
  * #PangoFont. This is computed once per font and cached for later retrieval.
  */
@@ -135,24 +351,26 @@ static ThaiFontInfo *
 get_font_info (PangoFont *font)
 {
   static const char *charsets[] = {
+    "tis620-2",
+    "tis620-1",
+    "tis620-0",
     "xtis620.2529-1",
     "xtis-0",
-    "tis620.2533-0",
     "tis620.2533-1",
-    "tis620.2529-0",
     "tis620.2529-1",
     "iso8859-11",
     "iso10646-1",
   };
 
   static const int charset_types[] = {
+    THAI_FONT_TIS_WIN,
+    THAI_FONT_TIS_MAC,
+    THAI_FONT_TIS,
     THAI_FONT_XTIS,
     THAI_FONT_XTIS,
     THAI_FONT_TIS,
     THAI_FONT_TIS,
     THAI_FONT_TIS,
-    THAI_FONT_TIS,
-    THAI_FONT_TIS,
     THAI_FONT_ISO10646
   };
   
@@ -160,14 +378,15 @@ get_font_info (PangoFont *font)
   GQuark info_id = g_quark_from_string ("thai-font-info");
   
   font_info = g_object_get_qdata (G_OBJECT (font), info_id);
+
   if (!font_info)
     {
       /* No cached information not found, so we need to compute it
        * from scratch
        */
       PangoXSubfont *subfont_ids;
-      int *subfont_charsets;
-      int n_subfonts, i;
+      gint *subfont_charsets;
+      gint n_subfonts, i;
 
       font_info = g_new (ThaiFontInfo, 1);
       font_info->font = font;
@@ -202,12 +421,12 @@ get_font_info (PangoFont *font)
 static void
 add_glyph (ThaiFontInfo     *font_info, 
 	   PangoGlyphString *glyphs, 
-	   int               cluster_start, 
+	   gint              cluster_start, 
 	   PangoGlyph        glyph,
 	   gboolean          combining)
 {
   PangoRectangle ink_rect, logical_rect;
-  int index = glyphs->num_glyphs;
+  gint index = glyphs->num_glyphs;
 
   pango_glyph_string_set_size (glyphs, index + 1);
   
@@ -221,10 +440,25 @@ add_glyph (ThaiFontInfo     *font_info,
 
   if (combining)
     {
-      glyphs->glyphs[index].geometry.width = 
-	MAX (logical_rect.width, glyphs->glyphs[index - 1].geometry.width);
-      glyphs->glyphs[index - 1].geometry.width = 0;
-      glyphs->glyphs[index].geometry.x_offset = 0;
+      if (font_info->type == THAI_FONT_TIS ||
+	  font_info->type == THAI_FONT_TIS_MAC ||
+	  font_info->type == THAI_FONT_TIS_WIN)
+	{
+          glyphs->glyphs[index].geometry.width =
+		logical_rect.width + glyphs->glyphs[index - 1].geometry.width;
+          if (logical_rect.width > 0)
+	      glyphs->glyphs[index].geometry.x_offset = glyphs->glyphs[index - 1].geometry.width;
+          else
+	      glyphs->glyphs[index].geometry.x_offset = glyphs->glyphs[index].geometry.width;
+	  glyphs->glyphs[index - 1].geometry.width = 0;
+	}
+      else
+        {
+	  glyphs->glyphs[index].geometry.width =
+		MAX (logical_rect.width, glyphs->glyphs[index - 1].geometry.width);
+	  glyphs->glyphs[index - 1].geometry.width = 0;
+	  glyphs->glyphs[index].geometry.x_offset = 0;
+        }
     }
   else
     {
@@ -235,63 +469,362 @@ add_glyph (ThaiFontInfo     *font_info,
   glyphs->glyphs[index].geometry.y_offset = 0;
 }
 
-/* Return the glyph code within the font for the given Unicode Thai 
- * code pointer
- */
-static int
-get_glyph (ThaiFontInfo *font_info, gunichar wc)
+static gint
+get_adjusted_glyphs_list (ThaiFontInfo *font_info,
+		                  gunichar *cluster,
+		                  gint num_chrs,
+		                  PangoGlyph **glyph_lists,
+				  const ThaiShapeTable *shaping_table)
 {
+  switch (num_chrs)
+    {
+      case 1:
+        if (is_char_type (cluster[0], BelowVowel|BelowDiac|AboveVowel|AboveDiac|Tone))
+	  {
+            glyph_lists[0] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0x7F);
+            glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            return 2;
+          }
+	else
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            return 1;
+          }
+        break;
+        
+      case 2:
+        if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+            is_char_type (cluster[1], SaraAm))
+	  {
+            glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xED);
+            glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+            return 3;
+          }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+          	 is_char_type (cluster[1], SaraAm))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+					shiftleft_tone_ad (0xED, shaping_table));
+            glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+            return 3;
+          }
+	else if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+          	 is_char_type (cluster[1], AboveVowel))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    return 2;
+          }
+	else if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+          	 is_char_type (cluster[1], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    	shiftdown_tone_ad (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+	  }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+          	 is_char_type (cluster[1], AboveVowel))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    	shiftleft_av (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+          }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+          	 is_char_type (cluster[1], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdownleft_tone_ad (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+	  }
+	else if (is_char_type (cluster[0], NoTailCons|UpTailCons) &&
+          	 is_char_type (cluster[1], BelowVowel|BelowDiac))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    return 2;
+          }
+	else if (is_char_type (cluster[0], BotTailCons) &&
+		 is_char_type (cluster[1], BelowVowel|BelowDiac))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdown_bv_bd (ucs2tis (cluster[1]), shaping_table));
+	    return 2;
+	  }
+	else if (is_char_type (cluster[0], SpltTailCons) &&
+          	 is_char_type (cluster[1], BelowVowel|BelowDiac))
+	  {
+	    glyph_lists[0] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		tailcutcons (ucs2tis (cluster[0]), shaping_table));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    return 2;
+	  }
+	else
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, 0x7F);
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[2]));
+	    return 3;
+	  }
+        break;
+          
+      case 3:
+        if (is_char_type (cluster[0], NoTailCons|BotTailCons|SpltTailCons) &&
+            is_char_type (cluster[1], Tone) &&
+            is_char_type (cluster[2], SaraAm))
+	  {
+            glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+            glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xED);
+            glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+            glyph_lists[3] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+            return 4;
+          }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+		 is_char_type (cluster[1], Tone) &&
+		 is_char_type (cluster[2], SaraAm))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+				shiftleft_tone_ad (0xED, shaping_table));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftleft_tone_ad (ucs2tis (cluster[1]), shaping_table));
+	    glyph_lists[3] = PANGO_X_MAKE_GLYPH (font_info->subfont, 0xD2);
+	    return 4;
+	  }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+		 is_char_type (cluster[1], AboveVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+				shiftleft_av (ucs2tis (cluster[1]), shaping_table));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftleft_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], UpTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdownleft_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], NoTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont,
+			shiftdown_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], SpltTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		tailcutcons (ucs2tis (cluster[0]), shaping_table));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftdown_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else if (is_char_type (cluster[0], BotTailCons) &&
+		 is_char_type (cluster[1], BelowVowel) &&
+		 is_char_type (cluster[2], AboveDiac|Tone))
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+		    		shiftdown_bv_bd (ucs2tis (cluster[1]), shaping_table));
+	    glyph_lists[2] = PANGO_X_MAKE_GLYPH (font_info->subfont,
+				shiftdown_tone_ad (ucs2tis (cluster[2]), shaping_table));
+	    return 3;
+	  }
+	else
+	  {
+	    glyph_lists[0] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[0]));
+	    glyph_lists[1] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[1]));
+	    glyph_lists[2] =
+		PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[2]));
+	    return 3;
+	  }
+      break;
+    }
+
+    return 0;
+}
+
+static gint
+get_glyphs_list (ThaiFontInfo	*font_info,
+		 gunichar	*cluster,
+		 gint		num_chrs,
+		 PangoGlyph	**glyph_lists)
+{
+  PangoGlyph glyph;
+  gint xtis_index;
+  gint i;
+
   switch (font_info->type)
     {
-    case THAI_FONT_NONE:
-      return pango_x_get_unknown_glyph (font_info->font);
-    case THAI_FONT_XTIS:
-      return PANGO_X_MAKE_GLYPH (font_info->subfont, 0x100 * (wc - 0xe00 + 0x20) + 0x30);
-    case THAI_FONT_TIS:
-      return PANGO_X_MAKE_GLYPH (font_info->subfont, wc - 0xe00 + 0xA0);
-    case THAI_FONT_ISO10646:
-      return PANGO_X_MAKE_GLYPH (font_info->subfont, wc);
+      case THAI_FONT_NONE:
+        for (i=0; i < num_chrs; i++)
+	  glyph_lists[i] = pango_x_get_unknown_glyph (font_info->font);
+        return num_chrs;
+
+      case THAI_FONT_XTIS:
+        /* If we are rendering with an XTIS font, we try to find a precomposed
+         * glyph for the cluster.
+         */
+        xtis_index = 0x100 * (cluster[0] - 0xe00 + 0x20) + 0x30;
+        if (cluster[1])
+	    xtis_index +=8 * group1_map[cluster[1] - 0xe30];
+        if (cluster[2])
+	    xtis_index += group2_map[cluster[2] - 0xe30];
+        glyph = PANGO_X_MAKE_GLYPH (font_info->subfont, xtis_index);
+        if (pango_x_has_glyph (font_info->font, glyph)) {
+            glyph_lists[0] = glyph;
+            return 1;
+        }
+        for (i=0; i < num_chrs; i++)
+	  glyph_lists[i] =
+	      PANGO_X_MAKE_GLYPH (font_info->subfont,
+					0x100 * (cluster[i] - 0xe00 + 0x20) + 0x30);
+        return num_chrs;
+      
+      case THAI_FONT_TIS:
+        for (i=0; i < num_chrs; i++)
+          glyph_lists[i] =
+              PANGO_X_MAKE_GLYPH (font_info->subfont, ucs2tis (cluster[i]));
+        return num_chrs;
+      
+      case THAI_FONT_TIS_MAC:
+	/* MacIntosh Extension
+	 */
+        return get_adjusted_glyphs_list (font_info, cluster,
+			num_chrs, glyph_lists, &Mac_shape_table);
+      
+      case THAI_FONT_TIS_WIN:
+	/* Microsoft Extension
+	 */
+        return get_adjusted_glyphs_list (font_info, cluster,
+			num_chrs, glyph_lists, &Win_shape_table);
+      
+      case THAI_FONT_ISO10646:
+        for (i=0; i < num_chrs; i++)
+          glyph_lists[i] = PANGO_X_MAKE_GLYPH (font_info->subfont, cluster[i]);
+        return num_chrs;
     }
+
   return 0;			/* Quiet GCC */
 }
 
 static void
-add_cluster (ThaiFontInfo *font_info,
-	     PangoGlyphString *glyphs,
-	     int cluster_start,
-	     gunichar base, 
-	     gunichar group1,
-	     gunichar group2)
+add_cluster (ThaiFontInfo	*font_info,
+	     PangoGlyphString	*glyphs,
+	     gint		cluster_start,
+	     gunichar		*cluster,
+	     gint		num_chrs)
+	     
+{
+  PangoGlyph glyphs_list[MAX_GLYPHS];
+  gint num_glyphs;
+  gint i;
+  
+  num_glyphs = get_glyphs_list(font_info, cluster, num_chrs, &glyphs_list);
+  for (i=0; i<num_glyphs; i++)
+       add_glyph (font_info, glyphs, cluster_start, glyphs_list[i],
+	    		i == 0 ? FALSE : TRUE);
+}
+
+static gboolean
+is_wtt_composible (gunichar cur_wc, gunichar nxt_wc)
 {
-  /* If we are rendering with an XTIS font, we try to find a precomposed
-   * glyph for the cluster.
-   */
-  if (font_info->type == THAI_FONT_XTIS)
+  switch (TAC_compose_and_input_check_type_table[char_class (ucs2tis (cur_wc))]
+						[char_class (ucs2tis (nxt_wc))])
     {
-      PangoGlyph glyph;
-      int xtis_index = 0x100 * (base - 0xe00 + 0x20) + 0x30;
-      if (group1)
-	xtis_index +=8 * group1_map[group1 - 0xe30];
-      if (group2)
-	xtis_index += group2_map[group2 - 0xe30];
-      
-      glyph = PANGO_X_MAKE_GLYPH (font_info->subfont, xtis_index);
+      case 'A':
+      case 'S':
+      case 'R':
+      case 'X':
+        return FALSE;
+
+      case 'C':
+        return TRUE;
+    }
+}
 
-      if (pango_x_has_glyph (font_info->font, glyph))
+static const char *
+get_next_cluster(const char	*text,
+		 gint		length,
+		 gunichar	**cluster,
+		 gint		*num_chrs)
+{  
+  const char *p;
+  gint n_chars = 0;
+  
+  p = text;
+  while (p < text + length && n_chars < 3)  
+    {
+      gunichar current = g_utf8_get_char (p);
+      
+      if (n_chars == 0 ||
+	  is_wtt_composible ((gunichar)(cluster[n_chars - 1]), current) ||
+	  (n_chars == 1 &&
+	   is_char_type (cluster[0], Cons) && 
+	   is_char_type (current, SaraAm)) ||
+	  (n_chars == 2 &&
+	   is_char_type (cluster[0], Cons) &&
+	   is_char_type (cluster[1], Tone) &&
+	   is_char_type (current, SaraAm)))
 	{
-	  add_glyph (font_info, glyphs, cluster_start, glyph, FALSE);
-	  return;
+	  cluster[n_chars++] = current;
+	  p = g_utf8_next_char (p);
 	}
+      else
+	break;
     }
 
-  /* If that failed, then we add compose the cluster out of three 
-   * individual glyphs
-   */
-  add_glyph (font_info, glyphs, cluster_start, get_glyph (font_info, base), FALSE);
-  if (group1)
-    add_glyph (font_info, glyphs, cluster_start, get_glyph (font_info, group1), TRUE);
-  if (group2)
-    add_glyph (font_info, glyphs, cluster_start, get_glyph (font_info, group2), TRUE);
+  *num_chrs = n_chars;
+  return p;
 }
 
 static void 
@@ -303,54 +836,21 @@ thai_engine_shape (PangoFont        *font,
 {
   ThaiFontInfo *font_info;
   const char *p;
-
-  gunichar base = 0;
-  gunichar group1 = 0;
-  gunichar group2 = 0;
-  int cluster_start = 0;
+  const char *log_cluster;
+  gunichar cluster[MAX_CLUSTER_CHRS];
+  gint num_chrs;
 
   pango_glyph_string_set_size (glyphs, 0);
 
   font_info = get_font_info (font);
-  
+
   p = text;
   while (p < text + length)
     {
-      int group;
-      gunichar wc;
-
-      wc = g_utf8_get_char (p);
-
-      if (wc >= 0xe30 && wc < 0xe50)
-	group = groups[wc - 0xe30];
-      else
-	group = 0;
-
-      switch (group)
-	{
-	case 0:
-	  if (base)
-	    {
-	      add_cluster (font_info, glyphs, cluster_start, base, group1, group2);
-	      group1 = 0;
-	      group2 = 0;
-	    }
-	  cluster_start = p - text;
-	  base = wc;
-	  break;
-	case 1:
-	  group1 = wc;
-	  break;
-	case 2:
-	  group2 = wc;
-	  break;
-	}
-      
-      p = g_utf8_next_char (p);
+	log_cluster = p;
+	p = get_next_cluster (p, text + length - p, &cluster, &num_chrs);
+	add_cluster (font_info, glyphs, log_cluster - text, cluster, num_chrs);
     }
-
-  if (base)
-    add_cluster (font_info, glyphs, cluster_start, base, group1, group2);
 }
 
 static PangoCoverage *
@@ -382,7 +882,7 @@ thai_engine_x_new ()
   result = g_new (PangoEngineShape, 1);
 
   result->engine.id = "ThaiScriptEngine";
-  result->engine.type = PANGO_ENGINE_TYPE_LANG;
+  result->engine.type = PANGO_ENGINE_TYPE_SHAPE;
   result->engine.length = sizeof (result);
   result->script_shape = thai_engine_shape;
   result->get_coverage = thai_engine_get_coverage;