pango.glyph_item_iter

A [pango.glyph_item_iter.GlyphItemIter] is an iterator over the clusters in a [pango.glyph_item.GlyphItem].

The forward direction of the iterator is the logical direction of text. That is, with increasing @start_index and @start_char values. If @glyph_item is right-to-left (that is, if glyph_item->item->analysis.level is odd), then @start_glyph decreases as the iterator moves forward. Moreover, in right-to-left cases, @start_glyph is greater than @end_glyph.

An iterator should be initialized using either [pango.glyph_item_iter.GlyphItemIter.initStart] or [pango.glyph_item_iter.GlyphItemIter.initEnd], for forward and backward iteration respectively, and walked over using any desired mixture of [pango.glyph_item_iter.GlyphItemIter.nextCluster] and [pango.glyph_item_iter.GlyphItemIter.prevCluster].

A common idiom for doing a forward iteration over the clusters is:

PangoGlyphItemIter cluster_iter;
gboolean have_cluster;

for (have_cluster = pango_glyph_item_iter_init_start (&cluster_iter,
                                                     glyph_item, text);
    have_cluster;
    have_cluster = pango_glyph_item_iter_next_cluster (&cluster_iter))
{
 ...
}

Note that @text is the start of the text for layout, which is then indexed by glyph_item->item->offset to get to the text of @glyph_item. The @start_index and @end_index values can directly index into @text. The @start_glyph, @end_glyph, @start_char, and @end_char values however are zero-based for the @glyph_item. For each cluster, the item pointed at by the start variables is included in the cluster while the one pointed at by end variables is not.

None of the members of a [pango.glyph_item_iter.GlyphItemIter] should be modified manually.