addPointerPanZoom method Null safety

void addPointerPanZoom(
  1. PointerPanZoomStartEvent event
)

Registers a new pointer pan/zoom that might be relevant to this gesture detector.

A pointer pan/zoom is a stream of events that conveys data covering pan, zoom, and rotate data from a multi-finger trackpad gesture.

The owner of this gesture recognizer calls addPointerPanZoom() with the PointerPanZoomStartEvent of each pointer that should be considered for this gesture.

It's the GestureRecognizer's responsibility to then add itself to the global pointer router (see PointerRouter) to receive subsequent events for this pointer, and to add the pointer to the global gesture arena manager (see GestureArenaManager) to track that pointer.

This method is called for each and all pointers being added. In most cases, you want to override addAllowedPointerPanZoom instead.

Implementation

void addPointerPanZoom(PointerPanZoomStartEvent event) {
  _pointerToKind[event.pointer] = event.kind;
  if (isPointerPanZoomAllowed(event)) {
    addAllowedPointerPanZoom(event);
  } else {
    handleNonAllowedPointerPanZoom(event);
  }
}