Besides X Input 2.2 multi-touch
, within the X.Org / Linux input world, one of the recent patch-sets going through several revisions with comments has been for introducing ClickPad support in the Synaptics driver.
The patch-set, which is comprised of ten patches, was originally authored by Chase Douglas at Canonical (yes, an upstream contribution from Canonical! Albeit, it's already found in Ubuntu 12.04's package
). These patches enable support within the xf86-input-synaptics X.Org driver for supporting ClickPad.
ClickPad is described by Synaptics
as a "Button-Less Design, Enhanced User Experience." Without any physical buttons, a ClickPad can support scrolling, pointing, navigation, and selection. ClickPad isn't new but has been around since 2009 and can be found in Apple products, among other OEMs. ClickPads use image-sensing hardware to provide finger tracking support for gestures.
The patches for the xf86-input-synaptics driver to allow for press-and-drag with two-fingers support on capable ClickPad hardware. The implementation relies upon cumulative relative touch motion for determining the direction. There's also support now for "soft buttons" on ClickPad devices that have special button areas painted on them. A current limitation is that the ClickPad support currently collides with the click action support and right button support. "Clickpad press-and-drag with two fingers will break click actions."
The xf86-input-synaptics ClickPad patch-set is now up to its fourth revision and can be found on the mailing list