On Jun 8, 2010, at 7:50 PM, Andy Estes wrote:
> Hi Nathan,
>
> It is true that Safari now emits mousewheel events in increments of 120 for
> compatibility reasons. However, there is no loss of granularity in the sense
> that events are generated on fractional wheel ticks and are accelerated on
> platforms that support it. The only difference is that you will see
> increments of 120 rather than increments of 1. It's been a few months since
> I've checked (and I can't look at the URL you attached on my phone), but I
> believe you'll see the same behavior in Chrome and IE.
I will not have access to IE for some time, but I think the old behaviour was
more compatible. I am not the original author of the OpenLayers code (just made
some un-integrated improvements, not shown below, to deal with WebKit's
wheelDelta acting like wheelDeltaX at times) but I think it demonstrates the
previous state of scroll wheel delta across browsers:
var delta; // one scroll wheel "click" (corresponds to zoom level
zoom level)
if (e.wheelDelta) {
delta = e.wheelDelta/120;
if (window.opera && window.opera.version() < 9.2) {
delta = -delta;
}
} else if (e.detail) {
delta = -e.detail / 3;
}
Webkit, IE and Opera seemed to be giving a wheelDelta in pixels or something
where one "line" was about 40 units, while Gecko gave a detail where one line
corresponds to 1 unit (assuming one old-school mouse wheel "click" scrolled ~3
lines).
What Safari 4 seemed to do was simply provide much greater precision, where
scrolling half a line simply yielded about 20 units instead of being ignored.
So the above code would yield integral deltas in browsers that only fired
events in 3-line increments, but nice fractional deltas in WebKit.
What Safari 5's WebKit does is turn one "line" into 4800 (!) units instead of
40. For Safari 5 the code above needs to read as follows to work the same. You
can see it isn't really "more compatible" at all:
var delta; // one scroll wheel "click" (corresponds to zoom level
zoom level)
if (isSafari5) {
delta = e.wheelDelta / 120 / 120;
} else if (e.wheelDelta) {
delta = e.wheelDelta/120;
if (window.opera && window.opera.version() < 9.2) {
delta = -delta;
}
} else if (e.detail) {
delta = -e.detail / 3;
}
It sounds like this was a well-intentioned change, but missed the fact that
that the values that are now being re-multiplied by 120 were *already* scaled
to the "1 'click' = 120 units" range.
hope this helps,
-natevw
> I would also point out that in DOM Level 3 Events, mousewheel events are
> considered deprecated and the unit of wheelDelta is left up to the
> implementor. IE set this increment to 120 some time ago, and we chose to
> match this behavior to be compatible with sites that expect it. As you can
> imagine, the opposite problem occurs on those sites (extremely slow
> scrolling). Unfortunately any decision we made here was bound to break some
> sites.
>
> -Andy
>
> Sent from my iPhone
>
> On Jun 8, 2010, at 19:09, Nathan Vander Wilt <[email protected]> wrote:
>
>> In Safari 4, the following event handler would log nice smooth values when
>> scrolling:
>> // logs: -3, -9, -6, -48, ...
>> document.addEventListener("mousewheel", function(e) {
>> console.log(e.wheelDeltaY); });
>>
>> In Safari 5, the mousewheel events have lost all precision, and are now big
>> ugly integral multiples of 120:
>> // logs: -120, -240, -120, -480, ... (no correspondence with above values,
>> of course)
>> document.addEventListener("mousewheel", function(e) {
>> console.log(e.wheelDeltaY); });
>>
>> This is a serious loss of precision, and brings us back to the primitive
>> days when a mouse a had 1-axis clicky scroll wheel if it had one at all, and
>> Firefox was the top browser. Compare the smooth, precise scroll zooming of
>> http://calftrail.com/Share/multitouch/ in Safari 4 to the jerky,
>> way-too-fast zooming in Safari 5.
>>
>> Is this a regression introduced directly in recent WebKit builds, or is it
>> Safari-specific? If the former, was it really necessary and can it please be
>> rolled back?
>>
>> thanks,
>> -natevw
>> _______________________________________________
>> webkit-dev mailing list
>> [email protected]
>> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
_______________________________________________
webkit-dev mailing list
[email protected]
http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
