x, y in struct _SynapticsSHM is ABS_X, ABS_Y, why not ABS_MT_POSITION_X, ABS_MT_POSITION_Y?

[Zhai Xiang]

Hi Peter,

Sorry for my late reply because I wen to Beijing for a short business
travel.

Yes, I read about the source code about 1.7.x by apt-get source
xserver-xorg-input-synaptics under Linux Deepin 2014, the SHM has been
completely removed.
And I do not want to hack the 1.6.x source code under Linux Deepin 2013 to
support ABS_MT_SLOT, ABS_MT_POSITION_X && ABS_MT_POSITION_Y sort of
multitouch support, even it supports multitouch and gesture recognition,
such as 2 fingers to zoom out/in, 4 fingers swipe up to show all open
windows, 4 fingers swipe right to switch to 2nd work space, 4 fingers swipe
left to switch to 1st work space, 3 fingers to move active window, the demo
video shown as http://v.youku.com/v_show/id_XNjU5MTk4MTk2.html

You said you are writing the driver with multitouch support using a
different base design, can I ask whether or not the driver`s source code
will be accepted by xorg official maintainer?
Would it be OK for you if I also contribute to your driver? If it is OK,
may I have your driver source code version control link such as github or
something else?

Looking forward to your reply.

Cheers,
Leslie

2014/1/6 Peter Hutterer <peter.hutterer at who-t.net>

> On Sat, Jan 04, 2014 at 04:25:51PM +0800, Leslie Zhai wrote:
> > Hi xorg developers,
> >
> > in xserver-xorg-input-synaptics-1.6.2/include/synaptics.h
> > the struct _SynapticsSHM is shown as below:
>
> SHM has been completely removed in synaptics 1.7, it's largely a leftover
> from before device properties where it was needed for run-time
> configuration. it had't been updated in a while, so any code that deals
> with
> it is likely outdated.
>
> updating synaptics to support multitouch properly is a bit of a larger
> issue, it's likely easier to write the driver from scratch using a
> different
> base design (which I'm currently in the process of doing).
>
> Cheers,
>    Peter
>
> > ```
> > typedef struct _SynapticsSHM {
> > int version; /* Driver version */
> >
> > /* Current device state */
> > int x, y; /* actual x, y coordinates */
> > int z; /* pressure value */
> > int numFingers; /* number of fingers */
> > int fingerWidth; /* finger width value */
> > int left, right, up, down; /* left/right/up/down buttons */
> > Bool multi[8];
> > Bool middle;
> > } SynapticsSHM;
> > ```
> >
> > there are x and y, because I want to know what they are, then read about
> > src/eventcomm.c
> > ```
> > if (ev.code < ABS_MT_SLOT) {
> > switch (ev.code) {
> > case ABS_X:
> > hw->x = apply_st_scaling(proto_data, ev.value, 0);
> > break;
> > case ABS_Y:
> > hw->y = apply_st_scaling(proto_data, ev.value, 1);
> > break;
> > case ABS_PRESSURE:
> > hw->z = ev.value;
> > break;
> > case ABS_TOOL_WIDTH:
> > hw->fingerWidth = ev.value;
> > break;
> > }
> > }
> > ```
> >
> > Why use ABS_X for hw->x?
> > I want to recognize multi-touch gesture, such as zoom in/out, with
> > ABS_MT_SLOT, ABS_MT_POSITION_X and ABS_MT_POSITION_Y based on Linux
> > Multi-touch (MT) Protocol.
> > But struct _SynapticsSHM only provides ABS_X and ABS_Y, even there is
> > numFingers, it is still unable to distinguish which finger touching the
> > point1, point2 or pointN...
> >
> > So I hacked the struct _SynapticsSHM, added int slot, mt_x, mt_y, shown
> > as below:
> > ```
> > typedef struct _SynapticsSHM {
> > int version; /* Driver version */
> >
> > /* Current device state */
> > int x, y; /* actual x, y coordinates */
> > int z; /* pressure value */
> > int numFingers; /* number of fingers */
> > int fingerWidth; /* finger width value */
> > int left, right, up, down; /* left/right/up/down buttons */
> > Bool multi[8];
> > Bool middle;
> >
> > int slot;
> > int mt_x;
> > int mt_y;
> > } SynapticsSHM;
> > ```
> >
> > and also hacked src/eventcomm.c, using ABS_MT_POSITION_X for mt_x, shown
> > as below:
> > ```
> > case EV_ABS:
> > if (ev.code == ABS_MT_SLOT)
> > hw->slot = ev.value;
> > if (ev.code == ABS_MT_POSITION_X)
> > hw->mt_x = ev.value;
> > if (ev.code == ABS_MT_POSITION_Y)
> > hw->mt_y = ev.value;
> > ```
> >
> > Then I can use slot, mt_x, mt_y to recognize multi-touch gesture such as
> > zoom in, rotate ... but that is hacking way, perhaps there are some
> > synaptics developers already considered about multi-touch gesture
> > recognization requirement, it might be in TODO list.
> >
> > Please someone give me some advice, thanks a lot!
> >
> > Leslie Zhai
> > _______________________________________________
> > xorg-devel at lists.x.org: X.Org development
> > Archives: http://lists.x.org/archives/xorg-devel
> > Info: http://lists.x.org/mailman/listinfo/xorg-devel
> >
>
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