The rectangle is defined by two opposite corners:
(x1, y1). The coordinates are in a
coordinate space that places (0,0) at the top-left corner of the page
and has 72 units per inch.
extractTextFromRect throws an error if text extraction is
prohibited by this PDF file.
See the "Setting parameters" section in the function list for settings that affect text extraction.
This function is identical to
extractTextFromRect2 except that it
takes points in a top-down coordinate space.