GII_PMOVE_EVENT(9gii)

NAME
gii_pmove_event - LibGII pointer movement events

SYNOPSIS

#include <ggi/events.h>

DESCRIPTION

The gii_pmove_event structure is used to report change of pointer position. Depending on the event type, the values are either absolute or relative.

GENERATED EVENTS

This structure is used for evPtrRelative and evPtrAbsolute events.

STRUCTURE MEMBERS

typedef struct gii_pmove_event {
        COMMON_DATA;
        sint32  x, y;           /* absolute/relative position   */
        sint32  z, wheel;
} gii_pmove_event;

The gii_pmove_event structure describes pointer (mice, etc.) motion in terms of the x, y, z coordinates and the wheel values of the device. The motion described may be relative (offset from the current location) or absolute (a specific location on the 'screen'), depending on whether the event is of type evPtrRelative or evPtrAbsolute, respectively.

LibGII does not attempt to interpolate or keep track of the 'current' pointer position. (This is the application's responsability.) LibGII may also report both relative and absolute pointer motion for the same input, which may happen when the mouse is being emulated using a keyboard on an input/target that is normally reports absolute motion.

EXAMPLES

  INPUT HANDLING FOR APPLICATIONS EXPECTING ABSOLUTE POINTER POSITION

{
  static int mousex,mousey;
  ggiEventPoll(vis, emKey|emPointer, NULL);
  events = ggiEventsQueued(vis, emKey|emPointer);
  while (events--) {
    ggiEventRead(vis, &event, emKey|emPointer);
    switch(event.any.type) {
      case evPtrButtonPress:
        switch(event.pbutton.button) {
          case GII_PBUTTON_FIRST:
            do_something_as_appropriate(mousex,mousey);
            break;
          case GII_PBUTTON_SECOND:
            ...
        }
        break;
      case evPtrButtonRelease:
        ... if needed ...
        break;
      case evPtrAbsolute:
        mousex = event.pmove.x;
        mousey = event.pmove.y;
        break;
      case evPtrRelative:
        mousex += event.pmove.x;
        mousey += event.pmove.y;
        break;
    }
    /* Constrain mouse in any case */
    if (mousex < 0) mousex = 0;
    if (mousey < 0) mousey = 0;
    if (mousex > xmax) mousex = xmax;
    if (mousey > ymax) mousey = ymax;
  } /* while */
}

SEE ALSO
gii_event(9)