bug#38187: 27.0.50; No mouse-wheel scaling on images

[Lars Ingebrigtsen]

Juri Linkov <juri@linkov.net> writes:

> I noticed that using the mouse-wheel on images is not responsive enough.
> It takes too much time when every step of the mouse scrolling wheel
> needs to scale the image separately for every consecutive rescaling.

Yeah, users are more likely to issue a bunch of scroll wheel events
rapidly than hitting `+' at the same rate, I guess.

> So I experimented with debouncing - a new macro 'debounce' swallows
> all intermediate calls in quick succession to 'image--change-size',
> and executes only the last call in sequence.
>
> But actually it requires another better macro 'debounce-reduce'
> that accumulates the state from all calls by multiplying all
> intermediate scaling factors, and using the result on the final call:

Makes sense to me.

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   bloggy blog: http://lars.ingebrigtsen.no