**Feature request:** support per-window scale factors Motivation ---------- Not all apps support scaling properly. Some (particularly fullscreen games) might have internal settings for scaling, but ignore the compositor-given scale factor. Some might simply not *need* scaling (at low screen scale factors) or be better forced to use 200% scaling where other windows are using 150-175%. Details ------- Kwin already has "window rules" for forcing initial position etc. Allow these to force a scale factor too. Complication: coordinate systems. A little linear arithmetic and rounding is needed to translate window positions and sizes. I believe this is solvable. Complication: if the desktop already uses multiple screens with multiple scale factors, forcing some window to use a single scale factor everywhere makes less sense. Still, this is the simplest approach and often good enough. At most, there should be a per-screen look-up table of forced scales or an additional qualifier to the rule (which screen the window is on).
Per-window is not technically feasible, but per-app is, and is likely to be just as good, since apps typically don't vary in scale quality on a per-window basis. *** This bug has been marked as a duplicate of bug 460394 ***