721787 - Double tap zoom takes too long to respond

Status: RESOLVED DUPLICATE of bug 741565

(Firefox for Android Graveyard :: General, defect, P3)

Description

[Wesley Johnston (:wesj)]

When the user double taps to zoom we should start responding instantly. Right now we have to send messages across the bridge and wait for a response with the appropriate rect to zoom to. If there's anything else hogging the queue, that can take seconds.

We could start a guessy zoom and then adjust midway through, but that assumes that we hear back from content within a few 10s of ms I think. Since we can't count on that, I think we may need to prioritize these messages. Maybe even write a special no-JSON conversion path for them? Would be good to get some profiling to know exactly where the slowdown is as well.

Comment 1

[Kartikaya Gupta (email:[e-mail])]

Part of the problem here might also be that the first thing in a double-tap is a onDown, which sends the same Gesture:ShowPress as in bug 741228. I haven't verified this but it shouldn't be too hard to check, I will do that and report back here.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

FWIW, Chrome zooms in by a fixed amount on double tap so they don't need to do as much work.

Comment 3

[Kartikaya Gupta (email:[e-mail])]

It is in fact sending a Gesture:ShowPress on the first touch-down of the double-tap. It also sends a second Gesture:ShowPress on the second touch-down, but fortunately that happens after onDoubleTap (at least on the GN; it might be dependent on how manufacturers have modified the android GestureDetector).

Comment 4

[Kartikaya Gupta (email:[e-mail])]

Also, the 200ms delay in the LayerController touch event code is coming into play here.

Comment 5

[Kartikaya Gupta (email:[e-mail])]

FWIW, I don't see the JSON serialization taking any significant amount of time here. I don't think that's the problem. It seems to be a combination of waiting the 200ms for the touch event handlers to run (bug 741565), followed by running the Gesture:ShowPress handler (bug 741228) before we get to the Gesture:DoubleTap. The DoubleTap handler itself probably takes a bit of time to run since it also does a anyElementFromPoint call.

Comment 6

[Mark Finkle (:mfinkle) (use needinfo?)]

Is bug 741228 the real issue here? Is this bug even a blocker on it's own?

Comment 7

[Kartikaya Gupta (email:[e-mail])]

I think fixing 741565 mostly took care of this. It can be improved further, but right now the delay is not really noticeable to the user. Marking as fixed.

Comment 8

[Paul Feher]

Verified/fixed on:
Nightly Fennec 15.0a1 (2012-04-25)
Device: HTC Desire Z