Trackpad reporting Absolute co-ordinates

NTDEV
1

Hi Guys,

I went through working of a mice and figured out that mouse reports relative changes in position.

I have a requirement from a customer that is asking for a trackpad that reports absolute co-ordinates and can still function as a mouse. Is it possible to use the generic HID mouse driver for this?

Any pointers for this will be really helpful!

Thank you

2

Are you trying to alter the behavior of a trackpad after market or do you control the HW itself?

d

Bent from my phone

From: xxxxx@gmail.commailto:xxxxx
Sent: ?4/?24/?2014 7:03 PM
To: Windows System Software Devs Interest Listmailto:xxxxx
Subject: [ntdev] Trackpad reporting Absolute co-ordinates

Hi Guys,

I went through working of a mice and figured out that mouse reports relative changes in position.

I have a requirement from a customer that is asking for a trackpad that reports absolute co-ordinates and can still function as a mouse. Is it possible to use the generic HID mouse driver for this?

Any pointers for this will be really helpful!

Thank you

—
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3

I do control the HW but the HW will be used with other hosts as well that need absolute co-ordinates. So, it is a requirement that the trackpad reports absolute values.

The other requirement is to make it work on PC as a generic trackpad.

4

AFAIK, all trackpads report absolute coordinates. But on the ones I’ve
used, it can take 3-6 swipes to move the cursor from full-left to
full-right (absolute velocity is used to scale the motion). There are
some clever algorithms that convert absolute deltas to relative offsets.
Play with any trackpad for ten minutes and you should be able to
reverse-engineer the bulk of the behavior. I did this for an optical
trackpad back in 1989, and it worked pretty well, but I have none of the
code (it ran on an embedded 68020, 2MHz, and the code was developed on an
Iris (MIPS-based) workstation running, IIRC, bsd 4.3 Unix).
joe

I do control the HW but the HW will be used with other hosts as well that
need absolute co-ordinates. So, it is a requirement that the trackpad
reports absolute values.

The other requirement is to make it work on PC as a generic trackpad.

NTDEV is sponsored by OSR

Visit the list at: http://www.osronline.com/showlists.cfm?list=ntdev

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5

Thank you Joe.

The trackpad I’ve is reporting absolute co-ordinates and the mouse cursor
doesn’t work properly with that. Is there something special you did in the
driver to get it working?

Anshul

On Fri, Apr 25, 2014 at 5:25 PM, wrote:

> AFAIK, all trackpads report absolute coordinates. But on the ones I’ve
> used, it can take 3-6 swipes to move the cursor from full-left to
> full-right (absolute velocity is used to scale the motion). There are
> some clever algorithms that convert absolute deltas to relative offsets.
> Play with any trackpad for ten minutes and you should be able to
> reverse-engineer the bulk of the behavior. I did this for an optical
> trackpad back in 1989, and it worked pretty well, but I have none of the
> code (it ran on an embedded 68020, 2MHz, and the code was developed on an
> Iris (MIPS-based) workstation running, IIRC, bsd 4.3 Unix).
> joe
>
> >
> > I do control the HW but the HW will be used with other hosts as well that
> > need absolute co-ordinates. So, it is a requirement that the trackpad
> > reports absolute values.
> >
> > The other requirement is to make it work on PC as a generic trackpad.
> >
> > —
> > NTDEV is sponsored by OSR
> >
> > Visit the list at: http://www.osronline.com/showlists.cfm?list=ntdev
> >
> > OSR is HIRING!! See http://www.osr.com/careers
> >
> > For our schedule of WDF, WDM, debugging and other seminars visit:
> > http://www.osr.com/seminars
> >
> > To unsubscribe, visit the List Server section of OSR Online at
> > http://www.osronline.com/page.cfm?name=ListServer
> >
>
>
>
> —
> NTDEV is sponsored by OSR
>
> Visit the list at: http://www.osronline.com/showlists.cfm?list=ntdev
>
> OSR is HIRING!! See http://www.osr.com/careers
>
> For our schedule of WDF, WDM, debugging and other seminars visit:
> http://www.osr.com/seminars
>
> To unsubscribe, visit the List Server section of OSR Online at
> http://www.osronline.com/page.cfm?name=ListServer
>