The cairo_text_cluster_t structure holds information about a single text cluster. A text cluster is a minimal mapping of some glyphs corresponding to some UTF-8 text.

For a cluster to be valid, both num_bytes and num_glyphs should be non-negative, and at least one should be non-zero. Note that clusters with zero glyphs are not as well supported as normal clusters. For example, PDF rendering applications typically ignore those clusters when PDF text is being selected.

See cairo_show_text_glyphs() for how clusters are used in advanced text operations.