touch down event and beginning of a touch sequence
A new touch point has appeared on the surface. This touch point is
assigned a unique ID. Future events from this touch point reference
this ID. The ID ceases to be valid after a touch up event and may be
reused in the future.
touch down event and beginning of a touch sequence
A new touch point has appeared on the surface. This touch point is assigned a unique ID. Future events from this touch point reference this ID. The ID ceases to be valid after a touch up event and may be reused in the future.