A #PangoGlyphItemIter is an iterator over the clusters in a
#PangoGlyphItem. The <firstterm>forward direction</firstterm> 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 <literal>@glyph_item->item->analysis.level</literal> 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 of
pango_glyph_item_iter_init_start() and
pango_glyph_item_iter_init_end(), for forward and backward iteration
respectively, and walked over using any desired mixture of
pango_glyph_item_iter_next_cluster() and
pango_glyph_item_iter_prev_cluster(). A common idiom for doing a
forward iteration over the clusters is:
<programlisting>
PangoGlyphItemIter cluster_iter;
gboolean have_cluster;
Note that @text is the start of the text for layout, which is then
indexed by <literal>@glyph_item->item->offset</literal> 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 #PangoGlyphItemIter should be modified manually.
PangoGlyphItemIter:
A #PangoGlyphItemIter is an iterator over the clusters in a #PangoGlyphItem. The <firstterm>forward direction</firstterm> 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 <literal>@glyph_item->item->analysis.level</literal> 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 of pango_glyph_item_iter_init_start() and pango_glyph_item_iter_init_end(), for forward and backward iteration respectively, and walked over using any desired mixture of pango_glyph_item_iter_next_cluster() and pango_glyph_item_iter_prev_cluster(). A common idiom for doing a forward iteration over the clusters is: <programlisting> 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)) { ... } </programlisting>
Note that @text is the start of the text for layout, which is then indexed by <literal>@glyph_item->item->offset</literal> 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 #PangoGlyphItemIter should be modified manually.