Afaik Chrome fires scroll events with raf timing so additional throttling is not needed. And that's why you saw header-panel worked fine in Chrome. But on other browsers we still need to throttle events to that timing. In Polymer we care about all supporting browsers and if header-panel doesn't work well in iOS then is just a bug.
Btw, my understanding is iOS (mobile Safari) fires scroll events only after scrolling has stopped. So code in the scroll handler shouldn't affect smooth scrolling in iOS. You mentioned about "flooded with mouse move events and take 60ms" and that may indicate some other issues causing the scrolling to misbehave. On Sat, Aug 30, 2014 at 9:44 AM, <[email protected]> wrote: > *I am on vacation, so sorry for the 'not-so-professional' post. Once I am > back I will dig more into this and hopefully will find out what exactly is > misbehaving. * > > I have big time issues with touch events interfering with smooth scrolling > in iOS and started digging, found out some disturbing stuff. > > For example in core-header-panel I see code like this: > > <div on-scroll="{{scroll}}">...</div> > > where the scroll handler is not really bound to any frame timing or > throttling but instead is directly executing code and also is directly > accessing scrollTop. > > When we were little kids the big guys at Google used to teach us NOT to do > that, but instead wait for the next animationFrame (in Polymer this > translates to 'this.async(..)') and then do as little work as possible and > let it go. > > Now, I start to wonder: are the guys at Google considering this to > a) not be part of the best practices anymore (things tend to evolve and > they should know how it works internally), > b) not needed because of some magic going on with declarative event > handlers that take care of this timing/frame issues or > c) simply do not care/think that this is not important in this case... > > Or is this may be simply a bug/omission? > > Interesting fact - in iOS when I have core-header-panel inside > core-header-panel inside core-header panel the console is flooded with > mouse move events and take ~ 60 ms which completely breaks the scrolling. > Another interesting fact - if I have 10 core-header panels as siblings > (actually section elements being the siblings of core-animated-pages) the > scrolling is completely trashed in Safari mobile but just fine in Chrome. I > know Google cares mostly about Chrome but a nice 'do not do X if you want > to be running fine in other browsers' could help penetration of the project > a lot. > > Follow Polymer on Google+: plus.google.com/107187849809354688692 > --- > You received this message because you are subscribed to the Google Groups > "Polymer" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/polymer-dev/8631bdcd-ca4f-4ed3-91c8-42f44a47a05f%40googlegroups.com > <https://groups.google.com/d/msgid/polymer-dev/8631bdcd-ca4f-4ed3-91c8-42f44a47a05f%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > Follow Polymer on Google+: plus.google.com/107187849809354688692 --- You received this message because you are subscribed to the Google Groups "Polymer" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/polymer-dev/CAAGTQkBWMR9e2qbOi8hwuA9a_ZQ43icSa8AZ-T3-t-p57XjwKw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
