Core Text - Get Pixel Coordinates from NSRange

Question

How would I get a CGRect from an NSRange for text rendered with Core Text?

I am using Core Text with an NSAttributedString .

Answer 1

It is an absolute pain but can be done.

You need to get all of the lines in the frame using CTFrameGetLines() , check if their character range is in the range you're looking for using CTLineGetStringRange() , use CTLineGetTypographicBounds() to find how big the line itself would render as, and use CTLineGetOffsetForStringIndex() to determine the actual position of the start/end character of the range (if the line is just a subrange of the desired range).

Combining all of this and adding up offsets and heights and such can get you what you want. Note that CTLineGetImageBounds() doesn't work without a graphics context (and, from what I gather, it is pretty expensive anyway) and is not necessary to solve this problem.

Answer 2

FIrst determine the line(s) in which the range you are interested in lies is. Then call CTLineGetOffsetForStringIndex() to get an offset of a specific string position from the start of the line. Together with CTLineGetImageBounds() , it should be possible to calculate a CGPoint position of the first and last characters in your range.