OEM Priority Project

  1. Bug #1672619
  2. Comment #8

Comment 8 for bug 1672619

Revision history for this message
Leon Liao (lihow731) wrote : Re: touch pad on xps 13 need better palm detection mechanism

More information about the BTN_TOOL_FINGER event.
I found the BTN_TOOL_FINGER definition in https://www.kernel.org/doc/Documentation/input/event-codes.txt.

There are four events: BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP, BTN_TOOL_TRIPLETAP, BTN_TOOL_QUADTAP.
One of these events will be sent when click down and click up.
Only one finger touched the touchpad, the BTN_TOOL_FINGER is sent.
Two fingers touched, the BTN_TOOL_DOUBLETAP is sent.
Three fingers touched, the BTN_TOOL_TRIPLETAP is sent.
Four fingers touched, the BTN_TOOL_QUADTAP is sent.

In the xserver-xorg-input-synaptics, the driver knows how many finger is touching via these events.

In the source code, the number of the touching finger is saved in hw->numFingers.
And, the "numFingers == 1" only be used in "Two finger emulation".