[pango/fix-cluster-accounting: 2/4] wip: glyph item: get more info

[Matthias Clasen <matthiasc src gnome org>]

commit 9ae51bf8ee1e8c225221aea7e57b256a77208219
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Nov 10 23:45:00 2021 -0500

    wip: glyph item: get more info
    
    This needs to be made properly private.

 pango/pango-glyph-item.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 pango/pango-glyph-item.h |  5 +++++
 2 files changed, 53 insertions(+)
---
diff --git a/pango/pango-glyph-item.c b/pango/pango-glyph-item.c
index 7eb1737d..93645d34 100644
--- a/pango/pango-glyph-item.c
+++ b/pango/pango-glyph-item.c
@@ -860,3 +860,51 @@ pango_glyph_item_get_logical_widths (PangoGlyphItem *glyph_item,
        }
     }
 }
+
+void
+pango_glyph_item_get_logical_widths_and_clusters (PangoGlyphItem *glyph_item,
+                                                  const char     *text,
+                                                  int            *logical_widths,
+                                                  int            *clusters)
+{
+  PangoGlyphItemIter iter;
+  gboolean has_cluster;
+  int dir;
+
+  dir = glyph_item->item->analysis.level % 2 == 0 ? +1 : -1;
+  for (has_cluster = pango_glyph_item_iter_init_start (&iter, glyph_item, text);
+       has_cluster;
+       has_cluster = pango_glyph_item_iter_next_cluster (&iter))
+    {
+      int glyph_index, char_index, num_chars, cluster_width = 0, char_width;
+
+      for (glyph_index  = iter.start_glyph;
+          glyph_index != iter.end_glyph;
+          glyph_index += dir)
+        {
+         cluster_width += glyph_item->glyphs->glyphs[glyph_index].geometry.width;
+       }
+
+      num_chars = iter.end_char - iter.start_char;
+      if (num_chars == 1)
+        {
+          logical_widths[char_index] = cluster_width;
+          clusters[char_index] = 0;
+        }
+      else if (num_chars > 0) /* pedantic */
+        {
+         char_width = cluster_width / num_chars;
+
+         for (char_index = iter.start_char;
+              char_index < iter.end_char;
+              char_index++)
+           {
+             logical_widths[char_index] = char_width;
+              clusters[char_index] = char_index - iter.start_char + 1;
+           }
+
+         /* add any residues to the first char */
+         logical_widths[iter.start_char] += cluster_width - (char_width * num_chars);
+       }
+    }
+}
diff --git a/pango/pango-glyph-item.h b/pango/pango-glyph-item.h
index fd8951d2..fc18ca02 100644
--- a/pango/pango-glyph-item.h
+++ b/pango/pango-glyph-item.h
@@ -85,6 +85,11 @@ void           pango_glyph_item_get_logical_widths (PangoGlyphItem *glyph_item,
                                               const char     *text,
                                               int            *logical_widths);
 
+void      pango_glyph_item_get_logical_widths_and_clusters (PangoGlyphItem *glyph_item,
+                                                            const char     *text,
+                                                            int            *logical_widths,
+                                                            int            *clusters);
+
 
 /**
  * PangoGlyphItemIter: