koreader/koreader — pull request #1191 by hwhw (2014-11-17 09:05:19+00:00)
Title: (really?) fix refresh viewport calculations

This adds more documentation about the viewport offset calculations
for refreshing rotated viewports.

The old behaviour also was (still) buggy, even after the latest round
of fixes. Now, the offsets when rotated are hopefully calculated correct.