Modifies @orig to cover only the text after @split_index, and
returns a new item that covers the text before @split_index that
used to be in @orig.
You can think of @split_index as the length of the returned item.
@split_index may not be 0, and it may not be greater than or equal
to the length of @orig (that is, there must be at least one byte
assigned to each item, you can't create a zero-length item).
@split_offset is the length of the first item in chars, and must be
provided because the text used to generate the item isn't available,
so pango_item_split() can't count the char length of the split items
itself.
Modifies @orig to cover only the text after @split_index, and returns a new item that covers the text before @split_index that used to be in @orig.
You can think of @split_index as the length of the returned item. @split_index may not be 0, and it may not be greater than or equal to the length of @orig (that is, there must be at least one byte assigned to each item, you can't create a zero-length item). @split_offset is the length of the first item in chars, and must be provided because the text used to generate the item isn't available, so pango_item_split() can't count the char length of the split items itself.