Re: Smoother macOS touchpad scrolling

[Tak Kunihiro <homeros.misasa@gmail.com>]

>> > +          int lineHeight = default_line_pixel_height(XWINDOW (FRAME_SELECTED_WINDOW (emacsframe)));
>> 
>> A buffer with images has lines with different height.
>> I think lineHeight should be
>>  - height of 1 line (or sum of 5 lines) at the top on a screen
>>    when scrolling up
>>  - height of unseen 1 line (or sum of unseen 5 lines) above the
>>    top out of screen when scrolling down.
>
> I also don’t think it’s too important as we’re not doing real
> pixelwise scrolling. I considered just using a constant value, like
> 10, as I think that would still provide a better experience than we
> have currently.

Once customization is allowed, touchpad can scroll slow with following
setup.

  (require 'pixel-scroll)
  (pixel-scroll-mode 1)
  (setq pixel-resolution-fine-flag t)

Although this should not be advertised because C-n and C-p after
scrolling redo the scroll less than a line (in other word,
implementation is incomplete), this works as pixelwise scrolling.  Thus
please have an option to let touchpad send each event by each pixel.