https://bugs.kde.org/show_bug.cgi?id=398056
--- Comment #24 from Andrew Crouthamel <andrew.croutha...@kdemail.net> --- (In reply to Fabian Vogt from comment #19) > (In reply to Friedrich W. H. Kossebau from comment #15) > > (In reply to Christoph Feck from comment #13) > > > What exactly is the difference between Qt::AA_UseHighDpiPixmaps and > > > Qt::AA_EnableHighDpiScaling, and should both be enabled for proper HiDPI > > > support? Most applications I see only set the former property. > > > > Good question. > > Not exactly sure, but I would bet both should be set for really good looking > > UI currently for our legacy-based applications like KDevelop, which rely on > > code done around low-dpi pixel sizes (think icon sizes referring to 16, 32 > > or 64 pixels per dimension), as still relied on in all(?) the QtWidget-based > > KDE Frameworks modules. > > From what I understood by reading the docs, Qt::AA_EnableHighDpiScaling > > cares for scaling any QPainter commands and other pixel-based geometries. > > While Qt::AA_UseHighDpiPixmaps makes sure that pixmaps which are rendered > > for the unscaled pixel sizes are internally prepared for the real pixels > > sizes when rendered in the end onto the real display. > > But we indeed should consult some experts, not putting my hand here close to > > any fire. > > > > (Adding fvogt as potential expoert to cc: list) > > Fabian, can you tell more? > > It's complicated. > > QPainter etc. scale all the time, but by default the devicePixelRatio is 1 so > it has no effect (except on OS X). All AA_EnableHighDpiScaling does is set > the > devicePixelRatio according to the DPI of the monitor the application is on. > > On Plasma on X11, where AA_EnableHighDpiScaling has no effect at all as it's > overwritten using environment variables (QT_AUTO_SCREEN_SCALE_FACTOR and > QT_SCREEN_SCALE_FACTORS). > > AA_UseHighDpiPixmaps is important as it allows QPixmap with a > devicePixelRatio > of > 1. > > So your guess is correct, both is the best option here. > > > (In reply to Saverio from comment #9) > > > Oh, ok. Sorry, I didn't understand xD > > > So, I'll wait other possible solutions, thanks anyway :) > > > > Saverio, as Kevin asked and linked, please test the Nigthly build of the > > Windows version created after my commit. My fix was done as blind fix, just > > done based on documentation and given it did not break things for me on my > > lowdpi system :) Should we start submitting patches to include both lines on all apps? Or is there a list of "legacy" apps I could tackle? -- You are receiving this mail because: You are watching all bug changes.
