@Override
    public void onPinch(int source, Node target, float scaleFactor, PinchState pinchState) {
        VRTComponent node = weakComponent.get();
        if (node == null){
            return;
        }

        WritableMap event = Arguments.createMap();
        event.putInt("source", source);
        event.putDouble("scaleFactor", scaleFactor);
        event.putInt("pinchState", pinchState.getTypeId());

        node.getReactContext().getJSModule(RCTEventEmitter.class).receiveEvent(
                node.getId(),
                ViroEvents.ON_PINCH,
                event);
    }
Represents all java-to-javascript calls that can be triggered from an EventDelegate.
android/viro_bridge/src/main/java/com/viromedia/bridge/utility/ComponentEventDelegate.java