When handling overstrikes, try to guess a bit better how overstrike glyphs

Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>

	* modules/basic/basic.c (basic_engine_shape): When
	handling overstrikes, try to guess a bit better
	how overstrike glyphs are positioned in the font.
	(Now works with more of glyphs from clearlyu, though
	not the Hebrew accents in that font)

	* examples/HELLO.utf8: Insert tab characters to
	keep the columns in the right order for either
	global direction. Insert left-to-right marks in
	a few places to keep leading and trailing punctuation
	in the right place.

	* modules/basic/basic.c (basic_engine_shape): Don't
	show RLM and LRM

	* pango/glyphstring.c (pango_glyph_string_extents): Use
	the logical width set in the glyph string rather than
	that from the font's metrics.

	* pango/pangox.c (pango_x_render): Treat glyph index
	0 as special - representing invisible, 0 size
	character. We need this sometimes, and it is
	easier and faster to have this special case
	than to shape a space.

	* pango/pango-context.c (pango_itemize): Put
	tabs into separate items. (Sort of lame hack,
	we do this to make line breaking with tab
	handling simpler)

	* examples/viewer.c (checkbutton_toggled): Notify
	all the layouts that the context has changed so
	the RTL base dir change actually takes effect.

16 files changed, 443 insertions, 89 deletions

diff --git a/ChangeLog b/ChangeLog
index 0dfd6c7f..8a23fa5c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,39 @@
+Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>
+
+	* modules/basic/basic.c (basic_engine_shape): When
+	handling overstrikes, try to guess a bit better
+	how overstrike glyphs are positioned in the font.
+	(Now works with more of glyphs from clearlyu, though
+	not the Hebrew accents in that font)
+
+	* examples/HELLO.utf8: Insert tab characters to 
+	keep the columns in the right order for either
+	global direction. Insert left-to-right marks in
+	a few places to keep leading and trailing punctuation
+	in the right place.
+
+	* modules/basic/basic.c (basic_engine_shape): Don't
+	show RLM and LRM
+
+	* pango/glyphstring.c (pango_glyph_string_extents): Use
+	the logical width set in the glyph string rather than 
+	that from the font's metrics.
+
+	* pango/pangox.c (pango_x_render): Treat glyph index
+	0 as special - representing invisible, 0 size
+	character. We need this sometimes, and it is
+	easier and faster to have this special case
+	than to shape a space.
+
+	* pango/pango-context.c (pango_itemize): Put
+	tabs into separate items. (Sort of lame hack,
+	we do this to make line breaking with tab
+	handling simpler)
+
+	* examples/viewer.c (checkbutton_toggled): Notify
+	all the layouts that the context has changed so 
+	the RTL base dir change actually takes effect.
+
 Fri May  5 18:56:45 2000  Owen Taylor  <otaylor@redhat.com>
 
 	* pango/break.c (pango_break): Add ZWS to hacky 
diff --git a/ChangeLog.pre-1-0 b/ChangeLog.pre-1-0
index 0dfd6c7f..8a23fa5c 100644
--- a/ChangeLog.pre-1-0
+++ b/ChangeLog.pre-1-0
@@ -1,3 +1,39 @@
+Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>
+
+	* modules/basic/basic.c (basic_engine_shape): When
+	handling overstrikes, try to guess a bit better
+	how overstrike glyphs are positioned in the font.
+	(Now works with more of glyphs from clearlyu, though
+	not the Hebrew accents in that font)
+
+	* examples/HELLO.utf8: Insert tab characters to 
+	keep the columns in the right order for either
+	global direction. Insert left-to-right marks in
+	a few places to keep leading and trailing punctuation
+	in the right place.
+
+	* modules/basic/basic.c (basic_engine_shape): Don't
+	show RLM and LRM
+
+	* pango/glyphstring.c (pango_glyph_string_extents): Use
+	the logical width set in the glyph string rather than 
+	that from the font's metrics.
+
+	* pango/pangox.c (pango_x_render): Treat glyph index
+	0 as special - representing invisible, 0 size
+	character. We need this sometimes, and it is
+	easier and faster to have this special case
+	than to shape a space.
+
+	* pango/pango-context.c (pango_itemize): Put
+	tabs into separate items. (Sort of lame hack,
+	we do this to make line breaking with tab
+	handling simpler)
+
+	* examples/viewer.c (checkbutton_toggled): Notify
+	all the layouts that the context has changed so 
+	the RTL base dir change actually takes effect.
+
 Fri May  5 18:56:45 2000  Owen Taylor  <otaylor@redhat.com>
 
 	* pango/break.c (pango_break): Add ZWS to hacky 
diff --git a/ChangeLog.pre-1-10 b/ChangeLog.pre-1-10
index 0dfd6c7f..8a23fa5c 100644
--- a/ChangeLog.pre-1-10
+++ b/ChangeLog.pre-1-10
@@ -1,3 +1,39 @@
+Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>
+
+	* modules/basic/basic.c (basic_engine_shape): When
+	handling overstrikes, try to guess a bit better
+	how overstrike glyphs are positioned in the font.
+	(Now works with more of glyphs from clearlyu, though
+	not the Hebrew accents in that font)
+
+	* examples/HELLO.utf8: Insert tab characters to 
+	keep the columns in the right order for either
+	global direction. Insert left-to-right marks in
+	a few places to keep leading and trailing punctuation
+	in the right place.
+
+	* modules/basic/basic.c (basic_engine_shape): Don't
+	show RLM and LRM
+
+	* pango/glyphstring.c (pango_glyph_string_extents): Use
+	the logical width set in the glyph string rather than 
+	that from the font's metrics.
+
+	* pango/pangox.c (pango_x_render): Treat glyph index
+	0 as special - representing invisible, 0 size
+	character. We need this sometimes, and it is
+	easier and faster to have this special case
+	than to shape a space.
+
+	* pango/pango-context.c (pango_itemize): Put
+	tabs into separate items. (Sort of lame hack,
+	we do this to make line breaking with tab
+	handling simpler)
+
+	* examples/viewer.c (checkbutton_toggled): Notify
+	all the layouts that the context has changed so 
+	the RTL base dir change actually takes effect.
+
 Fri May  5 18:56:45 2000  Owen Taylor  <otaylor@redhat.com>
 
 	* pango/break.c (pango_break): Add ZWS to hacky 
diff --git a/ChangeLog.pre-1-2 b/ChangeLog.pre-1-2
index 0dfd6c7f..8a23fa5c 100644
--- a/ChangeLog.pre-1-2
+++ b/ChangeLog.pre-1-2
@@ -1,3 +1,39 @@
+Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>
+
+	* modules/basic/basic.c (basic_engine_shape): When
+	handling overstrikes, try to guess a bit better
+	how overstrike glyphs are positioned in the font.
+	(Now works with more of glyphs from clearlyu, though
+	not the Hebrew accents in that font)
+
+	* examples/HELLO.utf8: Insert tab characters to 
+	keep the columns in the right order for either
+	global direction. Insert left-to-right marks in
+	a few places to keep leading and trailing punctuation
+	in the right place.
+
+	* modules/basic/basic.c (basic_engine_shape): Don't
+	show RLM and LRM
+
+	* pango/glyphstring.c (pango_glyph_string_extents): Use
+	the logical width set in the glyph string rather than 
+	that from the font's metrics.
+
+	* pango/pangox.c (pango_x_render): Treat glyph index
+	0 as special - representing invisible, 0 size
+	character. We need this sometimes, and it is
+	easier and faster to have this special case
+	than to shape a space.
+
+	* pango/pango-context.c (pango_itemize): Put
+	tabs into separate items. (Sort of lame hack,
+	we do this to make line breaking with tab
+	handling simpler)
+
+	* examples/viewer.c (checkbutton_toggled): Notify
+	all the layouts that the context has changed so 
+	the RTL base dir change actually takes effect.
+
 Fri May  5 18:56:45 2000  Owen Taylor  <otaylor@redhat.com>
 
 	* pango/break.c (pango_break): Add ZWS to hacky 
diff --git a/ChangeLog.pre-1-4 b/ChangeLog.pre-1-4
index 0dfd6c7f..8a23fa5c 100644
--- a/ChangeLog.pre-1-4
+++ b/ChangeLog.pre-1-4
@@ -1,3 +1,39 @@
+Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>
+
+	* modules/basic/basic.c (basic_engine_shape): When
+	handling overstrikes, try to guess a bit better
+	how overstrike glyphs are positioned in the font.
+	(Now works with more of glyphs from clearlyu, though
+	not the Hebrew accents in that font)
+
+	* examples/HELLO.utf8: Insert tab characters to 
+	keep the columns in the right order for either
+	global direction. Insert left-to-right marks in
+	a few places to keep leading and trailing punctuation
+	in the right place.
+
+	* modules/basic/basic.c (basic_engine_shape): Don't
+	show RLM and LRM
+
+	* pango/glyphstring.c (pango_glyph_string_extents): Use
+	the logical width set in the glyph string rather than 
+	that from the font's metrics.
+
+	* pango/pangox.c (pango_x_render): Treat glyph index
+	0 as special - representing invisible, 0 size
+	character. We need this sometimes, and it is
+	easier and faster to have this special case
+	than to shape a space.
+
+	* pango/pango-context.c (pango_itemize): Put
+	tabs into separate items. (Sort of lame hack,
+	we do this to make line breaking with tab
+	handling simpler)
+
+	* examples/viewer.c (checkbutton_toggled): Notify
+	all the layouts that the context has changed so 
+	the RTL base dir change actually takes effect.
+
 Fri May  5 18:56:45 2000  Owen Taylor  <otaylor@redhat.com>
 
 	* pango/break.c (pango_break): Add ZWS to hacky 
diff --git a/ChangeLog.pre-1-6 b/ChangeLog.pre-1-6
index 0dfd6c7f..8a23fa5c 100644
--- a/ChangeLog.pre-1-6
+++ b/ChangeLog.pre-1-6
@@ -1,3 +1,39 @@
+Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>
+
+	* modules/basic/basic.c (basic_engine_shape): When
+	handling overstrikes, try to guess a bit better
+	how overstrike glyphs are positioned in the font.
+	(Now works with more of glyphs from clearlyu, though
+	not the Hebrew accents in that font)
+
+	* examples/HELLO.utf8: Insert tab characters to 
+	keep the columns in the right order for either
+	global direction. Insert left-to-right marks in
+	a few places to keep leading and trailing punctuation
+	in the right place.
+
+	* modules/basic/basic.c (basic_engine_shape): Don't
+	show RLM and LRM
+
+	* pango/glyphstring.c (pango_glyph_string_extents): Use
+	the logical width set in the glyph string rather than 
+	that from the font's metrics.
+
+	* pango/pangox.c (pango_x_render): Treat glyph index
+	0 as special - representing invisible, 0 size
+	character. We need this sometimes, and it is
+	easier and faster to have this special case
+	than to shape a space.
+
+	* pango/pango-context.c (pango_itemize): Put
+	tabs into separate items. (Sort of lame hack,
+	we do this to make line breaking with tab
+	handling simpler)
+
+	* examples/viewer.c (checkbutton_toggled): Notify
+	all the layouts that the context has changed so 
+	the RTL base dir change actually takes effect.
+
 Fri May  5 18:56:45 2000  Owen Taylor  <otaylor@redhat.com>
 
 	* pango/break.c (pango_break): Add ZWS to hacky 
diff --git a/ChangeLog.pre-1-8 b/ChangeLog.pre-1-8
index 0dfd6c7f..8a23fa5c 100644
--- a/ChangeLog.pre-1-8
+++ b/ChangeLog.pre-1-8
@@ -1,3 +1,39 @@
+Sun May  7 00:00:00 2000  Owen Taylor  <otaylor@redhat.com>
+
+	* modules/basic/basic.c (basic_engine_shape): When
+	handling overstrikes, try to guess a bit better
+	how overstrike glyphs are positioned in the font.
+	(Now works with more of glyphs from clearlyu, though
+	not the Hebrew accents in that font)
+
+	* examples/HELLO.utf8: Insert tab characters to 
+	keep the columns in the right order for either
+	global direction. Insert left-to-right marks in
+	a few places to keep leading and trailing punctuation
+	in the right place.
+
+	* modules/basic/basic.c (basic_engine_shape): Don't
+	show RLM and LRM
+
+	* pango/glyphstring.c (pango_glyph_string_extents): Use
+	the logical width set in the glyph string rather than 
+	that from the font's metrics.
+
+	* pango/pangox.c (pango_x_render): Treat glyph index
+	0 as special - representing invisible, 0 size
+	character. We need this sometimes, and it is
+	easier and faster to have this special case
+	than to shape a space.
+
+	* pango/pango-context.c (pango_itemize): Put
+	tabs into separate items. (Sort of lame hack,
+	we do this to make line breaking with tab
+	handling simpler)
+
+	* examples/viewer.c (checkbutton_toggled): Notify
+	all the layouts that the context has changed so 
+	the RTL base dir change actually takes effect.
+
 Fri May  5 18:56:45 2000  Owen Taylor  <otaylor@redhat.com>
 
 	* pango/break.c (pango_break): Add ZWS to hacky 
diff --git a/examples/HELLO.utf8 b/examples/HELLO.utf8
index 7c624392..281c1be1 100644
--- a/examples/HELLO.utf8
+++ b/examples/HELLO.utf8
@@ -5,43 +5,42 @@ This is a list of ways to say hello in various languages. Its purpose is to illu
 (Converted into UTF-8)
 
 ---------------------------------------------------------
-Arabic  السلام عليكم
-Czech (česky)  Dobrý den
-Danish (Dansk)  Hej, Goddag
-English   Hello
-Esperanto  Saluton
-Estonian  Tere, Tervist
-FORTRAN   PROGRAM
-Finnish (Suomi)  Hei
-French (Français) Bonjour, Salut
-German (Deutsch Nord) Guten Tag
-German (Deutsch Süd) Grüß Gott
-Greek (Ελληνικά) Γειά σας
-Hebrew   שלום
-Hindi    नमस्ते, नमस्कार।
-Italiano  Ciao, Buon giorno
-Maltese   Ċaw, Saħħa
-Nederlands, Vlaams Hallo, Dag
-Norwegian (Norsk) Hei, God dag
-Polish   Dzień dobry, Hej
-Russian (Русский) Здравствуйте!
-Slovak   Dobrý deň
-Spanish (Español) ¡Hola!
-Swedish (Svenska) Hej, Goddag
-Thai (ภาษาไทย)  สวัสดีครับ, สวัสดีค่ะ
-Turkish (Türkçe) Merhaba
-Vietnamese (Tiếng Việt) Xin Chào
-Yiddish (ײַדישע) דאָס הײַזעלע 
+Arabic	السلام عليكم
+Czech	(česky)	Dobrý den
+Danish	(Dansk)	Hej, Goddag
+English	Hello
+Esperanto	Saluton
+Estonian	Tere, Tervist
+FORTRAN	PROGRAM
+Finnish	(Suomi)	Hei
+French	(Français)	Bonjour, Salut
+German	(Deutsch Nord)	Guten Tag
+German	(Deutsch Süd)	Grüß Gott
+Greek	(Ελληνικά)	Γειά σας
+Hebrew	שלום
+Hindi	नमस्ते, नमस्कार।
+Italiano	Ciao, Buon giorno
+Maltese	Ċaw, Saħħa
+Nederlands, Vlaams	Hallo, Dag
+Norwegian	(Norsk)	Hei, God dag
+Polish	Dzień dobry, Hej
+Russian	(Русский)	Здравствуйте!‎
+Slovak	Dobrý deň
+Spanish	(Español)	‎¡Hola!‎
+Swedish	(Svenska)	Hej, Goddag
+Thai	(ภาษาไทย)	สวัสดีครับ, สวัสดีค่ะ
+Turkish	(Türkçe)	Merhaba
+Vietnamese	(Tiếng Việt)	Xin Chào
+Yiddish	(ײַדישע)	דאָס הײַזעלע 
 
-Japanese (日本語)  こんにちは, ｺﾝﾆﾁﾊ
-Chinese (中文,普通话,汉语) 你好
-Cantonese (粵語,廣東話)  早晨, 你好
-Korean (한글)   안녕하세요, 안녕하십니까
-
-Difference among chinese characters in GB, JIS, KSC, BIG5:
- GB   -- 元气  开发
- JIS  -- 元気  開発
- KSC  -- 元氣  開發
- BIG5 -- 元氣  開發
+Japanese	(日本語)	こんにちは, ｺﾝﾆﾁﾊ
+Chinese	(中文,普通话,汉语)	你好
+Cantonese	(粵語,廣東話)	早晨, 你好
+Korean	(한글)	안녕하세요, 안녕하십니까
 
+Difference among chinese characters in GB, JIS, KSC, BIG5:‎
+ GB	--	元气	开发
+ JIS	--	元気	開発
+ KSC	--	元氣	開發
+ BIG5	--	元氣	開發
 
diff --git a/examples/viewer.c b/examples/viewer.c
index ccff0b77..61beceab 100644
--- a/examples/viewer.c
+++ b/examples/viewer.c
@@ -372,7 +372,19 @@ button_press (GtkWidget *layout, GdkEventButton *event)
 static void
 checkbutton_toggled (GtkWidget *widget, gpointer data)
 {
+  GSList *para_list;
+  
   pango_context_set_base_dir (context, GTK_TOGGLE_BUTTON (widget)->active ? PANGO_DIRECTION_RTL : PANGO_DIRECTION_LTR);
+
+  para_list = paragraphs;
+  while (para_list)
+    {
+      Paragraph *para = para_list->data;
+
+      pango_layout_context_changed (para->layout);
+      para_list = para_list->next;
+    }
+
   gtk_widget_queue_resize (layout);
 }
 
diff --git a/modules/basic/basic-x.c b/modules/basic/basic-x.c
index 6c851228..e78aa384 100644
--- a/modules/basic/basic-x.c
+++ b/modules/basic/basic-x.c
@@ -401,16 +401,9 @@ basic_engine_shape (PangoFont        *font,
 	    input = buf;
 	  }
 
-      if (wc == 0x200B)		/* Zero-width space */
+      if (wc == 0x200B || wc == 0x200E || wc == 0x200F)	/* Zero-width characters */
 	{
-	  index = find_char (cache, font, ' ', input);
-	  if (index)
-	    {
-	      set_glyph (font, glyphs, i, p - text, index);
-	      glyphs->glyphs[i].geometry.width = 0;
-	    }
-	  else
-	    set_glyph (font, glyphs, i, p - text, pango_x_get_unknown_glyph (font));
+	  set_glyph (font, glyphs, i, p - text, 0);
 	}
       else
 	{
@@ -423,10 +416,19 @@ basic_engine_shape (PangoFont        *font,
 		{
 		  if (i > 0)
 		    {
+		      PangoRectangle logical_rect, ink_rect;
+		      
 		      glyphs->glyphs[i].geometry.width = MAX (glyphs->glyphs[i-1].geometry.width,
 							      glyphs->glyphs[i].geometry.width);
 		      glyphs->glyphs[i-1].geometry.width = 0;
 		      glyphs->log_clusters[i] = glyphs->log_clusters[i-1];
+
+		      /* Some heuristics to try to guess how overstrike glyphs are
+		       * done and compensate
+		       */
+		      pango_font_get_glyph_extents (font, glyphs->glyphs[i].glyph, &ink_rect, &logical_rect);
+		      if (logical_rect.width == 0 && ink_rect.x == 0)
+			glyphs->glyphs[i].geometry.x_offset = (glyphs->glyphs[i].geometry.width - ink_rect.width) / 2;
 		    }
 		}
 	    }
diff --git a/modules/basic/basic.c b/modules/basic/basic.c
index 6c851228..e78aa384 100644
--- a/modules/basic/basic.c
+++ b/modules/basic/basic.c
@@ -401,16 +401,9 @@ basic_engine_shape (PangoFont        *font,
 	    input = buf;
 	  }
 
-      if (wc == 0x200B)		/* Zero-width space */
+      if (wc == 0x200B || wc == 0x200E || wc == 0x200F)	/* Zero-width characters */
 	{
-	  index = find_char (cache, font, ' ', input);
-	  if (index)
-	    {
-	      set_glyph (font, glyphs, i, p - text, index);
-	      glyphs->glyphs[i].geometry.width = 0;
-	    }
-	  else
-	    set_glyph (font, glyphs, i, p - text, pango_x_get_unknown_glyph (font));
+	  set_glyph (font, glyphs, i, p - text, 0);
 	}
       else
 	{
@@ -423,10 +416,19 @@ basic_engine_shape (PangoFont        *font,
 		{
 		  if (i > 0)
 		    {
+		      PangoRectangle logical_rect, ink_rect;
+		      
 		      glyphs->glyphs[i].geometry.width = MAX (glyphs->glyphs[i-1].geometry.width,
 							      glyphs->glyphs[i].geometry.width);
 		      glyphs->glyphs[i-1].geometry.width = 0;
 		      glyphs->log_clusters[i] = glyphs->log_clusters[i-1];
+
+		      /* Some heuristics to try to guess how overstrike glyphs are
+		       * done and compensate
+		       */
+		      pango_font_get_glyph_extents (font, glyphs->glyphs[i].glyph, &ink_rect, &logical_rect);
+		      if (logical_rect.width == 0 && ink_rect.x == 0)
+			glyphs->glyphs[i].geometry.x_offset = (glyphs->glyphs[i].geometry.width - ink_rect.width) / 2;
 		    }
 		}
 	    }
diff --git a/pango/glyphstring.c b/pango/glyphstring.c
index c2964704..d9d7c87b 100644
--- a/pango/glyphstring.c
+++ b/pango/glyphstring.c
@@ -139,6 +139,12 @@ pango_glyph_string_extents (PangoGlyphString *glyphs,
       if (i == 0)
 	{
 	  pango_font_get_glyph_extents (font, glyphs->glyphs[i].glyph, ink_rect, logical_rect);
+
+	  if (logical_rect)
+	    {
+	      logical_rect->x = 0;
+	      logical_rect->width = geometry->width;
+	    }
 	}
       else
 	{
@@ -163,14 +169,11 @@ pango_glyph_string_extents (PangoGlyphString *glyphs,
 
 	  if (logical_rect)
 	    {
-	      new_pos = MIN (logical_rect->x, x_pos + glyph_logical.x + geometry->x_offset);
-	      logical_rect->width = MAX (logical_rect->x + logical_rect->width,
-				     x_pos + glyph_logical.x + glyph_logical.width + geometry->x_offset) - new_pos;
-	      logical_rect->x = new_pos;
+	      logical_rect->width += geometry->width;
 
 	      new_pos = MIN (logical_rect->y, glyph_logical.y + geometry->y_offset);
 	      logical_rect->height = MAX (logical_rect->y + logical_rect->height,
-				      glyph_logical.y + glyph_logical.height + geometry->y_offset) - new_pos;
+					  glyph_logical.y + glyph_logical.height + geometry->y_offset) - new_pos;
 	      logical_rect->y = new_pos;
 	    }
 	}
diff --git a/pango/mapping.c b/pango/mapping.c
index 3ed47c66..57a438d9 100644
--- a/pango/mapping.c
+++ b/pango/mapping.c
@@ -300,6 +300,3 @@ pango_glyph_string_x_to_index (PangoGlyphString *glyphs,
 	*trailing = (cp - (int)cp > 0.5) ? 1 : 0;
     }
 }
-
-
-
diff --git a/pango/pango-context.c b/pango/pango-context.c
index 0c2e3dcf..a0134eb4 100644
--- a/pango/pango-context.c
+++ b/pango/pango-context.c
@@ -582,6 +582,7 @@ pango_itemize (PangoContext   *context,
       next = unicode_next_utf8 (p);
       
       if (i == 0 ||
+	  text_ucs4[i] == '\t' || text_ucs4[i-1] == '\t' ||
 	  embedding_levels[i] != embedding_levels[i-1] ||
 	  shape_engines[i] != shape_engines[i-1] ||
 	  lang_engines[i] != lang_engines[i-1] ||
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index 30a872da..b3ce1c89 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -46,6 +46,8 @@ struct _PangoLayout
   gint n_chars;		        /* Total number of characters in layout */
   PangoLogAttr *log_attrs;	/* Logical attributes for layout's text */
 
+  int tab_width;		/* Cached width of a tab. -1 == not yet calculated */
+
   GSList *lines;
 };
 
@@ -104,6 +106,8 @@ pango_layout_new (PangoContext *context)
   layout->log_attrs = NULL;
   layout->lines = NULL;
 
+  layout->tab_width = -1;
+
   return layout;
 }
 
@@ -437,6 +441,7 @@ void
 pango_layout_context_changed (PangoLayout *layout)
 {
   pango_layout_clear_lines (layout);
+  layout->tab_width = -1;
 }
 
 /**
@@ -1381,6 +1386,81 @@ free_run (PangoLayoutRun *run, gboolean free_item)
   g_free (run);
 }
 
+static int
+get_tab_pos (PangoLayout *layout, int index)
+{
+  if (layout->tab_width == -1)
+    {
+      /* Find out how wide 8 spaces are in the context's default font. Utter
+       * performance killer. :-( 
+       */
+      PangoGlyphString *glyphs = pango_glyph_string_new ();
+      PangoItem *item;
+      GList *items;
+      int i;
+
+      PangoAttrList *attrs = pango_attr_list_new ();
+      items = pango_itemize (layout->context, " ", 1, attrs);
+      pango_attr_list_unref (attrs);
+
+      item = items->data;
+      pango_shape ("        ", 8, &item->analysis, glyphs);
+      
+      pango_item_free (item);
+      g_list_free (items);
+
+      layout->tab_width = 0;
+      for (i=0; i < glyphs->num_glyphs; i++)
+	layout->tab_width += glyphs->glyphs[i].geometry.width;
+
+      pango_glyph_string_free (glyphs);
+    }
+  
+  return layout->tab_width * index;
+}
+
+static void
+shape_tab (PangoLayoutLine  *line,
+	   PangoGlyphString *glyphs)
+{
+  int i;
+  GSList *tmp_list;
+
+  int current_width = 0;
+
+  /* Compute the width of the line currently - inefficient, but easier
+   * than keeping the current width of the line up to date everywhere
+   */
+  tmp_list = line->runs;
+  while (tmp_list)
+    {
+      PangoLayoutRun *run = tmp_list->data;
+      for (i=0; i < run->glyphs->num_glyphs; i++)
+	current_width += run->glyphs->glyphs[i].geometry.width;
+      
+      tmp_list = tmp_list->next;
+    }
+  
+  pango_glyph_string_set_size (glyphs, 1);
+  
+  glyphs->glyphs[0].glyph = 0;
+  glyphs->glyphs[0].geometry.x_offset = 0;
+  glyphs->glyphs[0].geometry.y_offset = 0;
+  glyphs->glyphs[0].attr.is_cluster_start = 1;
+  
+  glyphs->log_clusters[0] = 0;
+
+  for (i=0;;i++)
+    {
+      int tab_pos = get_tab_pos (line->layout, i);
+      if (tab_pos > current_width)
+	{
+	  glyphs->glyphs[0].geometry.width = tab_pos - current_width;
+	  break;
+	}
+    }
+}
+
 static gboolean
 process_item (PangoLayoutLine *line,
 	      PangoItem       *item,
@@ -1397,7 +1477,10 @@ process_item (PangoLayoutLine *line,
   if (*remaining_width == 0)
     return FALSE;
   
-  pango_shape (text + item->offset, item->length, &item->analysis, glyphs);
+  if (text[item->offset] == '\t')
+    shape_tab (line, glyphs);
+  else
+    pango_shape (text + item->offset, item->length, &item->analysis, glyphs);
 
   if (*remaining_width < 0)
     {
@@ -1579,7 +1662,7 @@ pango_layout_check_lines (PangoLayout *layout)
 	{
 	  PangoItem *item = tmp_list->data;
 	  gboolean fits;
-	  int old_num_chars = item->num_chars;
+ 	  int old_num_chars = item->num_chars;
 
 	  fits = process_item (line, item, start,
 			       layout->log_attrs + start_offset, current_cant_end,
diff --git a/pango/pangox.c b/pango/pangox.c
index c35e614e..34cd0d46 100644
--- a/pango/pangox.c
+++ b/pango/pangox.c
@@ -1413,32 +1413,35 @@ pango_x_render  (Display           *display,
   
   for (i=0; i<glyphs->num_glyphs; i++)
     {
-      guint16 index = PANGO_X_GLYPH_INDEX (glyphs->glyphs[i].glyph);
-      guint16 subfont_index = PANGO_X_GLYPH_SUBFONT (glyphs->glyphs[i].glyph);
-      PangoXSubfontInfo *subfont;
-      
-      XChar2b c;
-
-      subfont = pango_x_find_subfont (font, subfont_index);
-      if (subfont)
+      if (glyphs->glyphs[i].glyph)
 	{
-	  c.byte1 = index / 256;
-	  c.byte2 = index % 256;
-
-	  fs = pango_x_get_font_struct (font, subfont);
-	  if (!fs)
-	    continue;
+	  guint16 index = PANGO_X_GLYPH_INDEX (glyphs->glyphs[i].glyph);
+	  guint16 subfont_index = PANGO_X_GLYPH_SUBFONT (glyphs->glyphs[i].glyph);
+	  PangoXSubfontInfo *subfont;
+      
+	  XChar2b c;
 	  
-	  if (fs->fid != old_fid)
+	  subfont = pango_x_find_subfont (font, subfont_index);
+	  if (subfont)
 	    {
-	      XSetFont (display, gc, fs->fid);
-	      old_fid = fs->fid;
+	      c.byte1 = index / 256;
+	      c.byte2 = index % 256;
+	      
+	      fs = pango_x_get_font_struct (font, subfont);
+	      if (!fs)
+		continue;
+	      
+	      if (fs->fid != old_fid)
+		{
+		  XSetFont (display, gc, fs->fid);
+		  old_fid = fs->fid;
+		}
+	      
+	      XDrawString16 (display, d, gc,
+			     x + (x_off + glyphs->glyphs[i].geometry.x_offset) / PANGO_SCALE,
+			     y + glyphs->glyphs[i].geometry.y_offset / PANGO_SCALE,
+			     &c, 1);
 	    }
-	  
-	  XDrawString16 (display, d, gc,
-			 x + (x_off + glyphs->glyphs[i].geometry.x_offset) / PANGO_SCALE,
-			 y + glyphs->glyphs[i].geometry.y_offset / PANGO_SCALE,
-			 &c, 1);
 	}
 
       x_off += glyphs->glyphs[i].geometry.width;
@@ -1454,7 +1457,7 @@ pango_x_font_get_glyph_extents  (PangoFont      *font,
   XCharStruct *cs;
   PangoXSubfontInfo *subfont;
 
-  if (pango_x_find_glyph (font, glyph, &subfont, &cs))
+  if (glyph && pango_x_find_glyph (font, glyph, &subfont, &cs))
     {
       if (ink_rect)
 	{
@@ -2019,7 +2022,7 @@ pango_x_list_subfonts (PangoFont        *font,
 }
 
 gboolean
-pango_x_has_glyph (PangoFont       *font,
+pango_x_has_glyph (PangoFont  *font,
 		   PangoGlyph  glyph)
 {
   g_return_val_if_fail (font != NULL, FALSE);