cairo-scaled-font-text-extents (scaled-font utf8 extents)

scaled-font -- a cairo-scaled-font-t instance
utf8 -- a string of text, encoded in UTF-8
extents -- a cairo-text-extents-t instance which to store the retrieved extents

Gets the extents for a string of text. The extents describe a user-space rectangle that encloses the "inked" portion of the text drawn at the origin (0,0), as it would be drawn by the function cairo-show-text if the Cairo graphics state were set to the same font-face, font-matrix, ctm, and font-options as scaled-font. Additionally, the x-advance and y-advance values indicate the amount by which the current point would be advanced by the function cairo-show-text.

Note that whitespace characters do not directly contribute to the size of the rectangle (extents.width and extents.height). They do contribute indirectly by changing the position of non-whitespace characters. In particular, trailing whitespace characters are likely to not affect the size of the rectangle, though they will affect the x-advance and y-advance values.