extentsRange
Computes the extents of a sub-portion of a glyph string.
The extents are relative to the start of the glyph string range (the origin of their coordinate system is at the start of the range, not at the start of the entire glyph string).
Parameters
start
start index
end
end index (the range is the set of bytes with indices such that start <= index < end)
font
a PangoFont
inkRect
rectangle used to store the extents of the glyph string range as drawn
logicalRect
rectangle used to store the logical extents of the glyph string range