The adjust pass and the readback both scale with pixel count, so a drag
paid full viewport cost on every frame it managed to produce. Halving
each edge while the gesture is moving is roughly a quarter of the work.
Detecting the gesture needed no new plumbing. No control reports a drag
boundary, and threading one out of every slider, curve point and crop
handle would be a lot of surface for what is a rendering concern. The
coalescing flag already carries the answer: a request that arrives while
a render is queued can only come from a control that moved again. A
click, a reset or a resize never coalesces, so those still render sharp
the first time and never show a draft frame.
A settle render restores full resolution 120 ms after the last change —
above the interval between events within a drag, so an ordinary gesture
never trips it mid-motion, and well under the point where waiting for
the sharp frame would be noticeable. Only one settle is ever queued.
The softness is therefore visible only while the image is moving too
fast to study.
dr-ui tests pass.
dtourolle
75ce3846c3