Returns the bounding rectangle within which the given text block containing the glyph at the given index is to be laid out.
- macOS 10.4+
The text block whose bounding rectangle is returned.
Index of the glyph.
NULL, on output, the range for all glyphs in the text block.
The bounding rectangle of the text block, or
NSZero if no rectangle has been set for the specified block since the last invalidation.
This method causes glyph generation but not layout. Block layout rectangles and bounds rectangles are always in container coordinates.