So if the entire buffer uses just a single font, like TUTORIAL.he
does, you do the test only once, at the first character of the buffer
text? But that could produce incorrect results, because the text
further into the buffer could have both RTL and LTR paragraphs
intermixed, and the correct display will show each of these at their
correct base direction. For example, most of the paragraphs in
TUTORIAL.he have right-to-left base direction, but the last paragraph,
with the Local Variables, is left-to-right, so its display starts at
the left edge of the window.
Intermixed paragraphs are fine though mixed text is slightly problematic (see attachment).
The window positioning information can only be obtained for the part
of the buffer text actually visible in a window; for buffer positions
outside of the viewport posn-at-point will give you nil. How do you
work around this limitation to allow printing text of the entire
buffer?
You are correct with your doubts. And unfortunately, I don't have all the answers. That's why in all my communication I've always maintained "Basic" WYSIWYG. Maybe somebody else can improve upon the algorithm.
rtl1.png