199107 - Smooth scrolling on long pages doesn't stop immediately when key is released

Status: RESOLVED FIXED

(Core :: Web Painting, defect)

Description

[Stefan Borggraefe]

Using Build 2003032408 with smooth-scrolling enabled (see bug 174049).

Steps to reproduce:
1. Set key repeat in Windows to the highest rate.
2. Enable Smooth-Scroll in Mozilla (set general.smoothScroll to true)
3. Visit a long page (i.e. http://www.taglinesgalore.com/tags/quotes.html)
4. Scroll the page by holding down a key (Space/PgUp/PgDown/Cursor-keys) a few
seconds

Result:
After the key is released the page continues to scroll for awhile.

Expected Result:
Scrolling should stop immediatly after the key is released.

This probably happens because the key repeat interval is shorter than the
duration of one smooth-scroll step.

Comment 1

[Stefan Borggraefe]

Also happens with Linux: Changing OS to All.

Comment 2

[Hixie (not reading bugmail)]

This is not a trivial bug. IMHO this is a complete blocker for smooth scrolling.
It is one of the most annoying aspects of IE's implementation too.

Comment 3

[Waheed Islam]

this should be fixed when patch in bug 199607 is checked in.


*** This bug has been marked as a duplicate of 199607 ***

Comment 4

[Stefan Borggraefe]

While the check-in for bug 199607 improved the situation, this bug is still not
entirely fixed. The scrolling stops earlier now, but not immediatly.

With PgUp/PgDown I counted between 5 and 8 scroll steps after the key was released.
With Cursor Up/Down most of the time 2 or 3 additional steps are performed.

Tested with Build 2003040622 on Windows XP and the following pages:
http://www.taglinesgalore.com/tags/a.html
http://lxr.mozilla.org/mozilla/source/layout/html/style/src/nsCSSFrameConstructor.cpp

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

It's impossible to stop *instantly* when the key is released. (That would make
smooth scrolling in response to a single keypress impossible.) There should be
200ms or so of delay before scrolling stops.  If you see more delay than that,
that's a bug, otherwise it's expected.

Comment 6

[Stefan Borggraefe]

The behaviour of the cursor keys is ok, I think (scrolling stops after the 200ms
limit you gave).
In the case of PgUp/PgDown the page continues to scroll for about 2 seconds.
This is what I did to test this:

1. Place a clock right next to the monitor
2. Load http://www.taglinesgalore.com/tags/a.html
3. Hold down the PgDown-Key for 5 seconds
4. Keep an eye on the clock to measure how long it takes till the scrolling stops

(Just for the record: I performed this test with IE 6 and it scrolls for about
40 seconds after the key is released and is completely unresponsive during this
period of time. So your implementation is already much better. :-) )

Comment 7

[Neil Cronin]

Releasing pg down key on that page stops scrolling after 1 or 2 more pages,
which is the expected behaviour.

I think you are timing the elapsed time to do these sclolls, which does indeed
take longer.  keep in mind that this page is easily an order of magnitude larger
than most web pages, and you might expect that working with pages that large
will never be as snappy as with normal-sized pages.

I'm not saying there isn't room for further improvement, but this is clearly a
99% improvement over the original patch, and this bug should probably be "fixed."  

Comment 8

[Stefan Borggraefe]

> I think you are timing the elapsed time to do these sclolls

No, I´m not. The 2 seconds I´m talking about in comment #6 is the time between
the release of the PgDown-key and the actual stop of the scrolling.

Comment 9

[Neil Cronin]

resolving fixed.  outside of the extreme stress test, the scrolling is
responsive enough. (+/- 1000 ms, even over remote x.)