pscroll – pixel scrolling with X.org, GTK and QT

pscroll attempts to add support for pixel-resolution scrolling to the Linux
graphics stack.

Currently, scroll events are implemented as button presses, which does not
scale well for higher-resolution devices (either you loose the resolution or
you create an overhead of button events). Furthermore, the interpretation of
these button events is left to the client software (i.e. GTK or QT).

Rationale

pscroll proposes using a new valuator to report wheel events, which gives
accurate scrolling information in addition to the old button interface, to
keep the compability with current clients. The resolution field of the
valuator (needs XI2) specifies how many valuator ticks make up one
old scroll “click” so that toolkits can calculate how much to scroll.

Current status

• xorg-server was changed to allow blocking of valuator axis integration.
  I have experienced no problems with it so far, but I don’t know if it is
  done the “right” way as I have no experience with Xorg.
• There is a patch for QT 4.6 that adds pscroll support.
  • Modifiers are not handled correctly (e.g. scrolling while holding down
    ctrl)
• xserver-xorg-input-evdev sends high precision data.
• xserver-xorg-input-synaptics sends high precision data.
  • Circular scrolling is disabled, needs some work.
  • Coasting is also disabled, scrolling speed is kept internally in
    scroll clicks per sec (Eww).

Repository layout

• patches/ contains patches for HEAD versions of xorg & co
• ubuntu-patches/ contains patches for the ubuntu packages (may not be
  up to date)
• pscrolltest/ is a small utility for listening to the high precision
  wheel events

What needs to be done?

• Graphics frameworks need to be changed to use the new events
• Some client software (e.g. firefox) handle scrolling internally and need
  to be changed too.