pango:glyph-string-logical-widths (glyphs text len level)

glyphs -- a pango:glyph-string instance
text -- a string for the text of the run
len -- an integer for the number of bytes in text
level -- an integer for hte embedding level of the string

The array whose length is the number of characters in text with the resulting character widths.

Given a glyph string and corresponding text, determine the width corresponding to each character. When multiple characters compose a single cluster, the width of the entire cluster is divided equally among the characters. See also the pango:glyph-item-logical-widths function.