Callback Events

Call back events related to the main callback function TBApiRegisterEvent() and upddapi.h.

This document covers additional points related to the Callback Events.


For UPDD V6 a new callback type has been introduced:

#define _EventTypeDigitiserEvent 0x4000000 

This provides a single event for touch information. This is intended to be a replacement for XY and PhysicalEvents and Flags events typically used in V5.
Flags events are no longer supported, but  XY and PhysicalEvents will be retained. For new code _EventTypeDigitiserEvent offers a more complete / easier to implement solution.

The struct and related flags are shown below.

Some points to note:

digitizerType indicates if the device that generated this event is a pen or a touch device eg digitizerType == DIGITIZER_TYPE_PEN
The struct  penEvent OR touchEvent is used dependant on digitizerType.
validBits indicates which bits are supported by the sending device (unsupported bits will be zero so this is only needed if a behavior change is needed based on supported bits)
screen / y provide co-ordinates scaled to the associated monitor
Z values are in the field z. HID also defines “tip pressure” but I’ve not seen a pen that uses this yet so for now I’m passing z or pressure values in z on the assumption that one or the other will be used; not both.


#define PEN_BIT_FLAGS_TIP 0x1



    struct  _digitiserEvent
      union  _de
        struct _penEvent
          uint8_t tipSwitch : 1;        // bit flags relating to pen devices, relates to TOUCH_BIT_FLAGS_XXX above
          uint8_t barrelSwitch : 1;
          uint8_t invert : 1;
          uint8_t inrange : 1;
          uint8_t reserved1 : 1;
          uint8_t reserved2 : 1;
          uint8_t reserved3 : 1;
          uint8_t reserved4 : 1;
          uint32_t reserved5;
        struct _touchEvent
          uint8_t touchingLeft : 1; // bit flags relating to regular touch devices, relates to TOUCH_BIT_FLAGS_XXX above
          uint8_t touchingRight : 1;
      uint8_t deltaBits;               // a bit mask to indicate which bits are changed since last _digitiserEvent
      uint8_t validBits;               // a bit mask to indicate which bits are supported by the originating hardware
      long screenx;                     // screen co-ordinate values, these values are in screen pixels and take account of the co-ordinate range of the associated monitors
      long screeny;                     // so for example with 2 monitors, resolution 1024 x 768 side by side; with the left monitor bieng the primary,
      // touching the centre of the right gives about 1536,384
      long internalx;                   // the corresponding windows co-ordinate value, the primary monitor has the range 0xffff, and other monitors are scaled from that
      long internaly;                   // so in the example given above the result is 0x17fee,0x7fff
      long calx;                          // the calibrated co-ordinates values; a value from 0 - 0xffff, giving the absolute position of touch in the range of the originating hardware
      long caly;                          // so for example touching the centre of a screen will give  around 7ff regardless of the associated monitor
      TBBOOL zSupport;             // set to TRUE (1) if the originating hardware supports z values
      unsigned long z;                // the raw z value reported by the controller, typically this is used to indicate pressure 

      TBBOOL isTimed;              // set to TRUE (1) if the event is triggered by a timeout (eg liftoff time) 
      TBBOOL isToolbar;             // set to TRUE (1) if the event is for a touch start started in a toolbar
      TBBOOL stylusSupport;     // set to TRUE (1) if the originating hardware supports stylus values
      uint8_t digitizerType;        // see DIGITIZER_TYPE_xxx