Return the DPR currently applied to renderer sizing.
A null override means "track the live ceiling" — the live
window.devicePixelRatio whenever high DPR is allowed, and the cap
otherwise. Keeping that meaning (rather than "track the live native")
is what preserves the no-reallocation fast path in
AdaptiveDPRManager.syncNativeDPR; see computePixelRatioOverride.
Return the DPR currently applied to renderer sizing.
A
nulloverride means "track the live ceiling" — the livewindow.devicePixelRatiowhenever high DPR is allowed, and the cap otherwise. Keeping that meaning (rather than "track the live native") is what preserves the no-reallocation fast path inAdaptiveDPRManager.syncNativeDPR; see computePixelRatioOverride.