Implement other tab alignments. Bug #325547, Itai Bar-Haim.

2006-01-28  Behdad Esfahbod  <behdad@gnome.org>

        Implement other tab alignments. Bug #325547, Itai Bar-Haim.

        * docs/tmpl/tab-stops.sgml: Documented new tab alignment enum vals.

        * pango/pango-tabs.h, pango/pango-tabs.c: Added support for tab
        alignments PANGO_TAB_RIGHT and PANGO_TAB_CENTER.

        * examples/renderdemo.h, examples/renderdemo.c: Added support for
        --tab-spec.

        * examples/GLASS.utf8, examples/HELLO.utf8: Cleaned up tabs.

3 files changed, 49 insertions, 16 deletions

diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index 50143387..5dc3a0ce 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -109,6 +109,8 @@ struct _PangoLayoutLinePrivate
 {
   PangoLayoutLine line;
   guint ref_count;
+  PangoGlyphString *last_tab_glyph;
+  PangoTabAlign last_tab_alignment;
 };
 
 struct _PangoLayoutClass
@@ -2495,11 +2497,8 @@ ensure_tab_width (PangoLayout *layout)
     }
 }
 
-/* For now we only need the tab position, we assume
- * all tabs are left-aligned.
- */
 static int
-get_tab_pos (PangoLayout *layout, int index)
+get_tab_pos (PangoLayout *layout, int index, PangoTabAlign *alignment)
 {
   gint n_tabs;
   gboolean in_pixels;
@@ -2519,7 +2518,7 @@ get_tab_pos (PangoLayout *layout, int index)
     {
       gint pos = 0;
 
-      pango_tab_array_get_tab (layout->tabs, index, NULL, &pos);
+      pango_tab_array_get_tab (layout->tabs, index, alignment, &pos);
 
       if (in_pixels)
         return pos * PANGO_SCALE;
@@ -2536,10 +2535,10 @@ get_tab_pos (PangoLayout *layout, int index)
       int next_to_last_pos = 0;
       int tab_width;
       
-      pango_tab_array_get_tab (layout->tabs, n_tabs - 1, NULL, &last_pos);
+      pango_tab_array_get_tab (layout->tabs, n_tabs - 1, alignment, &last_pos);
 
       if (n_tabs > 1)
-        pango_tab_array_get_tab (layout->tabs, n_tabs - 2, NULL, &next_to_last_pos);
+        pango_tab_array_get_tab (layout->tabs, n_tabs - 2, alignment, &next_to_last_pos);
       else
         next_to_last_pos = 0;
 
@@ -2597,6 +2596,8 @@ shape_tab (PangoLayoutLine  *line,
 {
   int i;
 
+  PangoTabAlign tab_alignment;
+
   int current_width = line_width (line);
 
   pango_glyph_string_set_size (glyphs, 1);
@@ -2610,13 +2611,16 @@ shape_tab (PangoLayoutLine  *line,
 
   for (i=0;;i++)
     {
-      int tab_pos = get_tab_pos (line->layout, i);
+      int tab_pos = get_tab_pos (line->layout, i, &tab_alignment);
       if (tab_pos > current_width)
 	{
 	  glyphs->glyphs[0].geometry.width = tab_pos - current_width;
 	  break;
 	}
     }
+  PangoLayoutLinePrivate *private = (PangoLayoutLinePrivate *)line;
+  private->last_tab_glyph = glyphs;
+  private->last_tab_alignment =  tab_alignment;
 }
 
 static inline gboolean
@@ -2689,6 +2693,16 @@ struct _ParaBreakState
 				 * to the remaining portion of the first item */
 };
 
+static int
+glyphstring_width (PangoGlyphString* glyphs)
+{
+  int i;
+  int width = 0;
+  for (i=0; i < glyphs->num_glyphs; i++)
+    width += glyphs->glyphs[i].geometry.width;
+  return width;
+}
+
 static PangoGlyphString *
 shape_run (PangoLayoutLine *line,
 	   ParaBreakState  *state,
@@ -2701,6 +2715,10 @@ shape_run (PangoLayoutLine *line,
     shape_tab (line, glyphs);
   else
     {
+      PangoLayoutLinePrivate *private = (PangoLayoutLinePrivate *)line;
+      
+      g_return_val_if_fail (line != NULL, glyphs);
+      
       if (state->properties.shape_set)
 	imposed_shape (layout->text + item->offset, item->num_chars,
 		       state->properties.shape_ink_rect, state->properties.shape_logical_rect,
@@ -2708,6 +2726,21 @@ shape_run (PangoLayoutLine *line,
       else 
 	pango_shape (layout->text + item->offset, item->length, &item->analysis, glyphs);
 
+	if (private->last_tab_glyph != NULL)
+	{
+	if (private->last_tab_glyph->num_glyphs > 0)
+	{
+	  int w = private->last_tab_glyph->glyphs[0].geometry.width;
+	  if (private->last_tab_alignment == PANGO_TAB_RIGHT)
+	    w -= glyphstring_width (glyphs);
+	  else if (private->last_tab_alignment == PANGO_TAB_CENTER)
+	    w -= glyphstring_width (glyphs) / 2;
+	  
+	  if (w < 0) w = 0;
+	  private->last_tab_glyph->glyphs[0].geometry.width = w;
+	}
+	}
+
       if (state->properties.letter_spacing)
 	{
 	  PangoGlyphItem glyph_item;
@@ -4034,6 +4067,8 @@ pango_layout_line_new (PangoLayout *layout)
   private->line.layout = layout;
   private->line.runs = 0;
   private->line.length = 0;
+  private->last_tab_glyph = NULL;
+  private->last_tab_alignment = PANGO_TAB_LEFT;
 
   /* Note that we leave start_index, resolved_dir, and is_paragraph_start
    *  uninitialized */
diff --git a/pango/pango-tabs.c b/pango/pango-tabs.c
index aedd9bce..73343bc4 100644
--- a/pango/pango-tabs.c
+++ b/pango/pango-tabs.c
@@ -257,13 +257,12 @@ pango_tab_array_resize (PangoTabArray *tab_array,
 /**
  * pango_tab_array_set_tab:
  * @tab_array: a #PangoTabArray
- * @tab_index: the index of a tab stop
+ * @tab_index: the index of a tab stop, starting from zero
  * @alignment: tab alignment
  * @location: tab location in Pango units
  *
- * Sets the alignment and location of a tab stop.
- * @alignment must always be #PANGO_TAB_LEFT in the current
- * implementation.
+ * Sets the alignment and location of a tab stop.  Resizes the
+ * tab array if needed.
  * 
  **/
 void
@@ -274,7 +273,6 @@ pango_tab_array_set_tab  (PangoTabArray *tab_array,
 {
   g_return_if_fail (tab_array != NULL);
   g_return_if_fail (tab_index >= 0);
-  g_return_if_fail (alignment == PANGO_TAB_LEFT);
   g_return_if_fail (location >= 0);
 
   if (tab_index >= tab_array->size)
diff --git a/pango/pango-tabs.h b/pango/pango-tabs.h
index f60949e8..c2ec7eff 100644
--- a/pango/pango-tabs.h
+++ b/pango/pango-tabs.h
@@ -30,13 +30,13 @@ typedef struct _PangoTabArray PangoTabArray;
 
 typedef enum
 {
-  PANGO_TAB_LEFT
+  PANGO_TAB_LEFT,
+  PANGO_TAB_RIGHT,
+  PANGO_TAB_CENTER
 
   /* These are not supported now, but may be in the
    * future.
    *
-   *  PANGO_TAB_RIGHT,
-   *  PANGO_TAB_CENTER,
    *  PANGO_TAB_NUMERIC
    */
 } PangoTabAlign;