multi-touch-dev team mailing list archive

[Rafi Rubin <rafi@xxxxxxxxxxxxxx>]

Moving to the mailing list.

> Where is the best place to learn about:
>
>   - X events and input handling, generally
>   - The current state of conversations in the FLOSS community re MT
>   - The state of the art in MT, even in proprietary software?

Not what you asked, but should mention for reference.  The hid spec 
lives at usb.org http://www.usb.org/developers/hidpage/  The "HID Usage 
Tables" was perhaps the most useful document that I discovered early on. 
 There are additions under review (or maybe already approved) to 
specify the codes for MT.


kernel <-> userspace is (incompletely) defined in the kernel tree 
Documentation/input.  The structure of the stream from the event devices 
is specified near the end of input.txt.  However it does not really 
cover anything about which events and the ordering.

multi-touch-protocol.txt describes the events for mt devices including 
specifying the minimum set of events to represent each finger and the 
complete mt group.


For input protocol to the X drivers, I found no documentation aside from 
the driver source.  I don't claim it doesn't exist, but I found what I 
was looking for rather quickly and did not dig much further.  In the 
case of the n-trig, the supported features were very close to what the 
drivers were looking for and I only needed to read a little to figure 
out why certain things went wrong.  For example, -wacom wants to see 
"doubleclick" instead of just "touch" to indicate your finger is 
touching the screen and evdev incorrectly identifies the device as a 
digitizer if BTN_TOOL_PEN is claimed and touchpad if BTN_TOOL_FINGER is 
defined, requiring clearing those bits when the input devices are setup.

X protocol docs (the answer to your question):
http://www.x.org/wiki/XInputSpec
http://cgit.freedesktop.org/xorg/proto/inputproto/tree/XI2proto.txt
http://www.x.org/wiki/Development/Documentation/MPX


The mpx doc is really pretty light and I don't feel particularly 
enlightened as to what support we should expect to see from general X 
apps.  And as Stephane points out, there are still several high level 
concepts that are still being ironed out.

Rafi