[minutes] Web Performance WG Teleconference #117 2013-08-21

Meeting Summary:



1.     Element Visibility

There are two main use cases where element visibility is useful: power efficient animations and advertisement impressions. The former refers to the ability to stop animations on elements that are below the fold, and the latter to allow cross-origin iframes to query if they are above the fold. We can solve the first problem in an Element Visibility spec that defines this behavior, whereas the second problem will need to be solved in a Page Visibility L2 spec, as iframe will be a document. For the cross-origin iframe issue, we need to determine if providing additional data here has an increased security or privacy concern.



2.     Resource Priorities

Based on feedback from the mailing list, we have updated the Resource Priorities spec: https://dvcs.w3.org/hg/webperf/raw-file/tip/specs/ResourcePriorities/Overview.html. Please review and provide feedback.



3.     Test Cases

We need to review the Resource Timing test cases to check if there are test bugs, spec bugs, or implementer bugs. I'll review these test cases.



4.     Next Conference Call

Due to a number of vacations, we will schedule our next conference call for September 4th.




W3C Web Performance WG Teleconference #117 2013-08-21





IRC log: http://www.w3.org/2013/08/21-webperf-irc



Meeting Minutes: http://www.w3.org/2013/08/21-webperf-minutes.html



Attendees

Jatinder Mann, Philippe Le Hegaret, Alois Reitbauer, Dan Austin, Arvind Jain, James Simonsen, Rob Dickenson, Ganesh Rao, Aaron Heady


Scribe

Jatinder Mann



Agenda

1.     Element Visibility

2.     Resource Priorities

3.     Test Cases

4.     Next Meeting

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Minutes:
Element Visibility

Arvind: I've seen a few different types of requests: one is to see visibility on an element level. Today visibility is for top level browsing context. One ask is to see if it can be made at an element level. E.g., if an iframe is scrolled below the fold, it wants to know if its visible or not.
... In one case the JavaScript on the main page can query the visibility of elements. The other case is third party advertisers want to be able to query when their ad is viewed or not.
... Mozilla has a interface to give the iframe the screen coordinates to determine screen coordinates. See https://www.w3.org/Bugs/Public/show_bug.cgi?id=22931.

Jatinder: If we are giving screen coordinates, we can just do the math and avoid the developer doing the math.
... Let's put together an Element Visibility to answer the first part of the question. I'll share a draft with you Arvind. Arvind, also send me any thoughts or proposals.
... We need to determine whether Chrome or IE for cross origin iframes share the top level parent or not.

Arvind: I'll follow up with Chrome behavior.

Jatinder: I can follow up with IE behavior.
Resource Priorities

<plh> http://www.w3.org/2013/08/results-user-timing-tests.html

Jatinder: Please review the Resource Priorities spec updates and raise issues. Thanks!
Test Cases

Plh: IE and Chrome both pass the tests.

<plh> http://www.w3.org/2013/08/results-google-resource-timing-tests.html

Plh: Do we need any additional tests?

James: I don't believe there are new tests we need to write.

Plh: Jatinder, can you check for the IE test failures?

Jatinder: I'll review all the test cases. I think this is a good opportunity to find test case issues, browser issues, or potentially spec issues.

Plh: I think we can move User Timing and Performance Timeline to PR and rAF to CR, based on this information. Resource Timing will just have to come in after.
Next meeting

James: I'm out next week.

Plh: Me too.

Jatinder: Let's schedule our next meeting for two weeks out.