While most platforms seem to have fractional scaling via QHighDpiScaling, Wayland is the first (and the only right now) platform that got fractional devicePixelRatio on QPA level. QHighDpiScaling doesn't handle that and the Wayland QPA just disables fractional scaling support when it sees the policy is not PassThrough.
It's good that it does that at least but I believe this could be done better. I have patches that make High DPI rounding policy to behave on Wayland the same as on other platforms, allowing applications using a rounding policy to render 1:1 with crsip fonts (currently the compositor downscales as QPA disables fractional scaling support) and actually respect the policy (downscaling means it's effectively always Ceil). Is there any interest in those changes? The code changes are quite small actually: the main patch changing mostly qhighdpiscaling.cpp is 179 lines long. The auxiliary qtwayland patch to provide fractional QWaylandScreen::devicePixelRatio (currently it provides only fractional QWaylandWindow::devicePixelRatio) is 111 lines long. -- Development mailing list Development@qt-project.org https://lists.qt-project.org/listinfo/development
