Character Clusters

Character clusters are glyph sequences that cannot be split between lines. Some languages, for example Thai and Indic, restrict caret placement to points between clusters. This applies to caret movement initiated with keyboard or mouse actions(hit testing).

Uniscribe provides cluster information in both the visual and logical attributes. After calling ScriptShape, the cluster information is represented both by sequences of the same value in the pwLogClust array, and by the fClusterStart member in the psva SCRIPT_VISATTR array.

ScriptBreak also returns the fCharStop member in the SCRIPT_LOGATTR array to identify cluster positions.