fix: mouse wheel responds on the first tick after a direction change - #21807
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Arecsu wants to merge 1 commit into
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fix: mouse wheel responds on the first tick after a direction change#21807Arecsu wants to merge 1 commit into
Arecsu wants to merge 1 commit into
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The discrete scroll accumulators (both the event controller proxy used by bauhaus sliders/dropdowns and dt_gui_get_scroll_unit_deltas) kept the signed fractional remainder from the previous scroll direction. After reversing direction, the first tick was silently spent cancelling that stale remainder, so it did nothing and a second tick was needed before the value changed. Drop the accumulated remainder when the incoming scroll delta changes sign, so the new direction takes effect on its very first tick.
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Need help to test if this solves #21390 |
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Mouse wheel scrolling of bauhaus sliders and dropdowns ignored the first tick after a direction change: scroll down three notches, then one notch up — the up notch does nothing, and only the second one moves the value back. Same in reverse, and it affects dropdown popups and the alt/ctrl/shift zoom-range shortcuts too.
The new discrete scroll proxy accumulates attenuated wheel deltas and only emits a step once the accumulator crosses ±1.0, keeping the fractional remainder from the previous direction. On a direction change that remainder has to be cancelled first, so the first tick of the new direction is spent doing nothing. Released versions handled mouse wheel notches as exact ±1 cardinal events that never went through the accumulator, which is why this never happened before.
The fix drops the accumulated remainder as soon as the incoming delta changes sign:
dt_gui_get_scroll_unit_deltas()(thumbtable, gradientslider, darkroom scroll-zoom, scroll shortcuts) gets the same handling for smooth/touchpad input, which had the identical lag.No behavior changes for scrolling within a single direction.
Could fix #21390