- From: Rick Byers via GitHub <sysbot+gh@w3.org>
- Date: Thu, 28 Jul 2016 15:43:09 +0000
- To: public-pointer-events@w3.org
Here's a summary of the argument and data I presented on this at the [implementation hackathon](https://docs.google.com/document/d/1b8aJOJcGXakstFJslKl87QwvlFHhHwGbQfJwnUTBBHg/edit#): We (Chrome team) feel apps being able to deliver reliable 60fps JS-driven dragging on mobile devices is essential for the web to effectively compete with native mobile platforms. In such scenarios there's 16ms per frame to get work done, and we generally aim to leave at least 2/3rds of that for developer-written JS. That gives the engine a budget of 6ms per frame. Chrome Android data from the field (see below) indicates a median hit-test time of 0.5ms, which would be a substantial 8% of this 6ms budget. Worse, the 95th percentile is 6ms and the 99th percentile hit-test time is 20ms - so in many scenarios the hit-test time alone would make it impossible to meet this budget. Therefore we feel it's critical that developers aren't subject to this cost unless they explicitly opt-into it by requesting a feature that requires it. It's possible that we could reduce this time dramatically by a complete re-write of our hit-test system, but that would be a major undertaking - probably delaying our ability to ship pointer events by at least a year. Even then we'd be unlikely to see such a huge improvement that we'd be comfortable imposing this penalty on the web when Android and iOS don't have such a design.  -- GitHub Notification of comment by RByers Please view or discuss this issue at https://github.com/w3c/pointerevents/issues/8#issuecomment-235935356 using your GitHub account
Received on Thursday, 28 July 2016 15:43:22 UTC