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Re: IE implementation of navigator.maxTouchPoints

From: David Bokan <bokan@google.com>
Date: Thu, 11 Sep 2014 14:36:54 -0400
Message-ID: <CANMmsAtBr-i=jF4Qi2NcSJBPbfHPhVsBZkXHt_pM1gq0rhzakA@mail.gmail.com>
To: Rick Byers <rbyers@chromium.org>
Cc: Sangwhan Moon <smoon@opera.com>, Jacob Rossi <Jacob.Rossi@microsoft.com>, "public-pointer-events@w3.org" <public-pointer-events@w3.org>
Beat me to the punch: https://codereview.chromium.org/563853002

On Thu, Sep 11, 2014 at 2:31 PM, Rick Byers <rbyers@chromium.org> wrote:

> Essentially yes (although I don't think that compiles - you mean
> IsTouchDevicePresent, not IsTouchEnabledDevice?).  I believe bokan@ plans
> to land something like this ASAP.
>
> Thanks,
>    Rick
>
>
> On Thu, Sep 11, 2014 at 1:29 AM, Sangwhan Moon <smoon@opera.com> wrote:
>
>> Makes sense, is was this what you had in mind?
>>
>> https://gist.github.com/cynthia/fe95daed5322109f567c
>>
>> (I didn't actually check if this compiles, my work environment is 100%
>> *nix. :-()
>>
>> Cheers,
>> Sangwhan
>>
>> On Thu, Sep 11, 2014 at 10:46 AM, Rick Byers <rbyers@chromium.org> wrote:
>>
>>> Thank you!  Indeed it looks like this is Windows 7 only, and unlike IE
>>> we do still want to support touchscreens on Windows 7 (a small but
>>> non-trivial fraction of our touchscreen users are still on Windows 7).  It
>>> looks like SM_DIGITIZER is false in these cases, so I think we can try
>>> looking at SM_MAXIMUMTOUCHES only when SM_DIGITIZER is true. Sound
>>> reasonable to you?
>>>
>>> Thanks,
>>> Rick
>>>
>>>
>>> On Wed, Sep 10, 2014 at 7:44 PM, Jacob Rossi <Jacob.Rossi@microsoft.com>
>>> wrote:
>>>
>>>>  Definitely happy to help here. Our code is roughly:
>>>>
>>>>
>>>>
>>>> lMaxTouchPoints = 0;
>>>>
>>>> if (Win8+)
>>>>
>>>> {
>>>>
>>>>     lMaxTouchPoints = GetSystemMetrics(SM_MAXIMUMTOUCHES);
>>>>
>>>> }
>>>>
>>>> return lMaxTouchPoints;
>>>>
>>>>
>>>>
>>>> The OS check is there because we don’t support touch in the IE platform
>>>> on Windows 7 and usage of touchscreen devices on Win7 is extremely low
>>>> (most have moved to Win8+).
>>>>
>>>> Have you seen reports of this on Windows 8/8.1 or just Windows 7?
>>>>
>>>>
>>>>
>>>> There definitely are touchpad drivers that like to install a fake touch
>>>> driver in order to fake zoom gestures (e.g. pinch to zoom). I don’t think
>>>> there’s a way for the Windows input stack to tell the difference between
>>>> that and an actual touchscreen. But if you’d like, I can loop you in with
>>>> our Win32 input team.
>>>>
>>>>
>>>>
>>>> -Jacob
>>>>
>>>>
>>>>
>>>> *From:* rbyers@google.com [mailto:rbyers@google.com] *On Behalf Of *Rick
>>>> Byers
>>>> *Sent:* Wednesday, September 10, 2014 10:26 AM
>>>> *To:* Jacob Rossi
>>>> *Cc:* public-pointer-events@w3.org; David Bokan
>>>> *Subject:* IE implementation of navigator.maxTouchPoints
>>>>
>>>>
>>>>
>>>> Hey Jacob,
>>>>
>>>> We're getting reports of some complaints of navigator.maxTouchPoints
>>>> returning 1 on Chrome when there is in fact no touchscreen.  IE11 correctly
>>>> returns 0.  http://crbug.com/352942.  Scott (from MS OpenTech) wrote the
>>>> code
>>>> <https://code.google.com/p/chromium/codesearch#chromium/src/ui/base/touch/touch_device_win.cc&q=MAXTOUCHPOINTS&sq=package:chromium&type=cs&l=17>
>>>> for this for us, basically just:
>>>>
>>>>
>>>>
>>>> int MaxTouchPoints() {
>>>>
>>>>   return GetSystemMetrics(SM_MAXIMUMTOUCHES);
>>>>
>>>> }
>>>>
>>>>
>>>>
>>>> Apparently, despite what we'd expect fro the MSDN docs, this is
>>>> insufficient.  Users report that it returns 1 in scenarios with both an
>>>> internal and external mouse plugged in - although we haven't been able to
>>>> reproduce it (and they've confirmed they see those values from the API
>>>> directly, so it's not some bug in chrome).
>>>>
>>>>
>>>>
>>>> Any chance you can share the algorithm with us that IE uses to compute
>>>> maxTouchPoints on windows?  Ideally Chrome and IE would always agree here,
>>>> and there's obviously some special cases.
>>>>
>>>>
>>>>
>>>> Thanks,
>>>>
>>>>    Rick
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>> --
>> Sangwhan Moon [Opera Software ASA]
>> Software Engineer | Tokyo, Japan
>>
>
>
Received on Thursday, 11 September 2014 18:37:25 UTC

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