Re: master e37eb7f: Add support for pixel wheel deltas on NS

[Po Lu <luangruo@yahoo.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Po Lu <luangruo@yahoo.com>
>> Cc: emacs-devel@gnu.org
>> Date: Sat, 27 Nov 2021 19:13:44 +0800
>> 
>> @cindex @code{wheel-up} event
>> @cindex @code{wheel-down} event
>> @item (wheel-up @var{position} @var{clicks} @var{lines} @var{pixel-delta})
>> @itemx (wheel-down @var{position})
>> These kinds of event are generated by moving a mouse wheel.  The
>> @var{position} element is a mouse position list (@pxref{Click
>> Events}), specifying the position of the mouse cursor when the event
>> occurred.
>> 
>> @var{clicks}, if present, is the number of times in quick succession
>> the wheel has been moved.

> By "if present", do you mean it can be absent, or do you mean it can
> be nil?  If the latter, then "present" is not the right word.

It can be absent, not nil.  Thanks.

> Also, can this CLICKS member really be anything but 1 when the wheel
> is used?

Yes, when the wheel is turned quickly it can be 2 or 3.  It can probably
go higher, but I can't turn my mouse wheel that fast.

>> @var{lines}, if present, is the number of screen lines that should
>> be scrolled.  @var{pixel-delta}, if present, is a pair of the form
>> @w{@code{(@var{x} . @var{y})}}, where @var{x} and @var{y} are the
>> number of pixels to scroll by in each axis.
>> 
>> WDYT?  Also, it seems that `lines' is only generated by the NS port, so
>> it should perhaps be worthwhile to mention that as well?

> Doesn't "if present" already handle that?

Yes, makes sense now, thanks.