Scrolling iframe inside scrollable div does not work with trackpad

[Anders Johansson]

Created attachment 263154 [details]
Testcase source

Open http://output.jsbin.com/zetevuyaqa in Safari 9 or nightly and try to scroll the iframe (picture) with a MacBook trackpad. The frame will not scroll.

Scroll down the outer div to the bottom position and try to scroll the iframe again. The iframe can now be scrolled down, but not up.

If the outer div's scroll position is not an any of the top or bottom endpoints the iframe can not be scrolled at all.

It is not entirely consistent and sometimes the areas can be scrolled with quick and slightly angled scroll gestures.


Using a mouse with a wheel works as expected. Other browsers (FF, Chrome) including Safari 8 does not have the problem with a trackpad.

[Anders Johansson]

Previous testpage apparently stopped working due to being created anonymously at JSBin. Here is a new one that hopefully will continue to work.

https://output.jsbin.com/mudada

It needs to be viewed on a full page since nesting inside other iframes won't show the problem.

[Radar WebKit Bug Importer]

<rdar://problem/23143931>

[Martin Hecko]

I can verify that this is also happening on Safari 9.0.1 (10601.2.7.2) on OS X 10.10.5 as well as one of the recent nightlies r191902.

[Wenson Hsieh]

Created attachment 264957 [details]
Patch

[Brent Fulgham]

Comment on attachment 264957 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=264957&action=review

r=me. I had a suggestion for improving the test (to avoid flakiness on the test bots).

> LayoutTests/fast/scrolling/latching/scroll-iframe-in-overflow-expected.txt:2
> +The wrapper's scroll position is: 0

I would suggest these be PASS/FAIL results, to avoid flakiness due to different test machine resolutions and settings.

> LayoutTests/fast/scrolling/latching/scroll-iframe-in-overflow.html:30
> +        debug("The wrapper's scroll position is: " + wrapper.scrollTop);

I would suggest something like:
if (iframe.contentWindow.scrollY && !wrapper.scrollTop) {
    testPassed("The iframe scrolled but the wrapper did not.");
} else {
    testFailed("The iframe's scroll position is: " + iframe.contentWindow.scrollY + ", and the wrapper's scroll position is: " + wrapper.scrollTop);
}

> LayoutTests/fast/scrolling/latching/scroll-iframe-in-overflow.html:50
> +        eventSender.callAfterScrollingCompletes(checkForScroll);

Someday we should make this into a test library function so we can remove all this duplicate code! :-)

[Wenson Hsieh]

Comment on attachment 264957 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=264957&action=review

>> LayoutTests/fast/scrolling/latching/scroll-iframe-in-overflow-expected.txt:2
>> +The wrapper's scroll position is: 0
> 
> I would suggest these be PASS/FAIL results, to avoid flakiness due to different test machine resolutions and settings.

Will do.

>> LayoutTests/fast/scrolling/latching/scroll-iframe-in-overflow.html:30
>> +        debug("The wrapper's scroll position is: " + wrapper.scrollTop);
> 
> I would suggest something like:
> if (iframe.contentWindow.scrollY && !wrapper.scrollTop) {
>     testPassed("The iframe scrolled but the wrapper did not.");
> } else {
>     testFailed("The iframe's scroll position is: " + iframe.contentWindow.scrollY + ", and the wrapper's scroll position is: " + wrapper.scrollTop);
> }

Got it. Fixed!

>> LayoutTests/fast/scrolling/latching/scroll-iframe-in-overflow.html:50
>> +        eventSender.callAfterScrollingCompletes(checkForScroll);
> 
> Someday we should make this into a test library function so we can remove all this duplicate code! :-)

I agree -- maybe something like sendMomentumScroll(positionX, positionY, dragCount, momentumCount, dragDeltaX, dragDeltaY, momentumDeltaX, momentumDeltaY, handleScrollingComplete) that handles everything in scrollTest() here.

[Wenson Hsieh]

Committed r192124: <http://trac.webkit.org/changeset/192124>

[Michael Kuryshev]

Is it fixed yet? I've tried both Safari on the latest Mac OS Sierra and nightly build of webkit and scrolling down inside iframe doesn't work. Scrolling up works fine though.

[Anders Johansson]

Yes, works for me now, Safari on Sierra.

Updated my last test case with a working image.

[Wenson Hsieh]

(In reply to comment #8)
> Is it fixed yet? I've tried both Safari on the latest Mac OS Sierra and
> nightly build of webkit and scrolling down inside iframe doesn't work.
> Scrolling up works fine though.

Hi Michael,

Scrolling Anders' test case seems to be working for me as well. If you are still seeing an issue, could you file a followup bug and attach a video clip showing the problem you're seeing?

Thanks!
Wenson

[Michael Kuryshev]

Hi Wenson, Anders,

I've created followup bug report with minimal test case. Thanks.

https://bugs.webkit.org/show_bug.cgi?id=169129