Created attachment 107579 [details] screenshot showing the problem Have a look at the attached screenshot. The word 'annotation' is a freehand annotation; it has been drawn in regular page view mode. The word 'presentation' has been drawn in presentation mode. Note how it is of much worse quality. This screenshot was taken with the current gsoc_2017_hidpi branch. On git master, both words look equally bad. I have QT_SCREEN_SCALE_FACTORS set to 1.5.
Patch at https://phabricator.kde.org/D21836
Git commit 19f22098e67dba5d06df170b32b9074b17b1ae6e by Oliver Sander. Committed on 22/06/2019 at 19:55. Pushed by sander into branch 'master'. Mind the devicePixelRatio when drawing on-screen in presentation mode Previously, when using a screen scaling factor larger than 1, the drawings by mouse or stylus in presentation mode were slightly blocky. The underlying cause was a) a few integer types used for non-integer coordinates b) the intermediate use of a QPixmap without the correct devicePixelRatio Additionally, this patch uses a QPainterPath to draw the path, rather than a sequence of individual lines. This improves the line quality a tiny bit, because the lines are properly joined. Differential Revision: https://phabricator.kde.org/D21836 M +4 -5 ui/annotationtools.cpp M +11 -5 ui/presentationwidget.cpp https://invent.kde.org/kde/okular/commit/19f22098e67dba5d06df170b32b9074b17b1ae6e