• Peter Hutterer's avatar
    dix: leave last.valuators alone on slave switch · d7b1753d
    Peter Hutterer authored
    
    
    Terms:
    dev->last.valuator[] is the last value given to us by the driver
    dev->valuator.axisVal[] is the last value sent to the client
    dev->last.scroll[] is the abs value of the scroll axis as given by the driver,
            used for button emulation calculation (and the remainder)
    
    This function updates the device's last.valuator state based on the current
    master axis state. This way, relative motion continues fluidly when switching
    between devices. Before mouse 2 comes into effect, it's valuator state is
    updated to wherever the pointer currently is so the relative event applies on
    top of that.
    
    This can only work for x/y axes, all other axes aren't guaranteed to have the
    same meaning and/or may not be present:
    - xtest device: no valuator 2
    - mouse: valuator 2 is horizontal scroll axis
    - tablet: valuator 2 is pressure
    
    Scaling the current value from the pressure range into the range for
    horizontal scrolling makes no sense. And it causes scroll jumps:
    
    - scroll down, last.valuator == axisVal == 20
    - xdotool click 1, the XTest device doesn't have that valuator
    - scroll up
      - updateSlaveDeviceCoords reset last.valuator to 0 (axisVal == 20)
      - DeviceClassesChangedEvent includes value 20 for the axis
      - event is processed, last.value changes from 0 to -1
      - axisVal is updated to -1, causing a jump of -21
    
    The same applies when we switch from tablet to mouse wheel if the pressure
    value is 0 on proximity out (basically guaranteed). So let's drop this code
    altogether and only leave the scaling for the relative x/y motion.
    Signed-off-by: Peter Hutterer's avatarPeter Hutterer <peter.hutterer@who-t.net>
    d7b1753d
getevents.c 64.9 KB