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RE: Exposing high-frequency mouse/touch movement?

From: Jacob Rossi <Jacob.Rossi@microsoft.com>
Date: Fri, 30 May 2014 19:17:52 +0000
To: Rick Byers <rbyers@google.com>, "public-pointer-events@w3.org" <public-pointer-events@w3.org>
Message-ID: <b0f5b60348bb4e4c9b19d3a21abe58ab@BY2PR03MB457.namprd03.prod.outlook.com>
What scenarios do you have in mind for this?

On Windows, the primary scenario we see this used for is pen inking for higher stroke fidelity (e.g. go back and look at the pointer history to collect more points for the stroke path).  But in actuality, I suspect it’s used by very few applications.

Touch is a rather coarse input device while pens can be very fine as on graphics artist tablets or devices like Surface Pro 3. So I think this is less useful for touch. For pen, correct me if I’m wrong, but I haven’t seen much interest from browser vendors other than Microsoft in targeting pen scenarios.

-Jacob

From: Rick Byers [mailto:rbyers@google.com]
Sent: Friday, May 30, 2014 12:48 PM
To: public-pointer-events@w3.org
Subject: Exposing high-frequency mouse/touch movement?

Platforms typically coalesce movement events, eg. possibly limiting them to reporting at most 1 per video frame.  Some applications want additional data, for example high-precision drawing and some games.  Windows 8 has a GetPointerTouchInfoHistory<http://msdn.microsoft.com/en-us/library/windows/desktop/hh454891(v=vs.85).aspx> API [1] for this (why is this just touch and not all pointers?), and Android has methods on MotionEvent<http://developer.android.com/reference/android/view/MotionEvent.html> [2] for getting historical data out of the event batch.

Should we be exposing something similar to the web?

Other platforms take the approach of having an API to disable coalescing/batching - eg. setMouseCoalescingEnabled<https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSEvent_Class/Reference/Reference.html#//apple_ref/occ/clm/NSEvent/setMouseCoalescingEnabled:> [3] on Mac OS X.  One big disadvantage I see to this approach is that it treats all event consumers the same.  For a particular event, there may be one consumer that wants high-resolution data (and can process it efficiently) while other consumers may get backlogged by an unusually high event reporting rate.

Thanks,
  Rick

[1] http://msdn.microsoft.com/en-us/library/windows/desktop/hh454891(v=vs.85).aspx
[2] http://developer.android.com/reference/android/view/MotionEvent.html

[3] https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSEvent_Class/Reference/Reference.html#//apple_ref/occ/clm/NSEvent/setMouseCoalescingEnabled:

Received on Friday, 30 May 2014 19:18:25 UTC

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