detect when another view is touched - dragging with PanResponder in react native

Question

I have a card game where the user can drag cards around a screen.

How can I detect if the cards have been dragged over other View components? My draggable card code is like this:

// A draggable card
// drag drop code example used: https://github.com/brentvatne/react-native-animated-demo-tinder
// panresponder docs: https://facebook.github.io/react-native/docs/panresponder.html

class Card extends React.Component {
  componentWillMount() {
  this.state = {
    pan: new Animated.ValueXY(),
    enter: new Animated.Value(1),
  }

  this._panResponder = PanResponder.create({

    onMoveShouldSetResponderCapture: () => true,
    onMoveShouldSetPanResponderCapture: () => true,
    onPanResponderGrant: (e, gestureState) => {
               Animated.spring(this.state.enter, {
        toValue: .75,
      }).start()

      this.state.pan.setOffset({x: this.state.pan.x._value, 
                              y: this.state.pan.y._value});
      this.state.pan.setValue({x: 0, y: 0});
    },

    onPanResponderMove: Animated.event([
      null, {dx: this.state.pan.x, dy: this.state.pan.y},
    ]),

    onPanResponderRelease: (e, {vx, vy}) => {
      // do stuff when card released 
    }

    Animated.spring(this.state.enter, {
      toValue: 1,
    }).start()

    this.state.pan.flattenOffset();
    var velocity;

    if (vx >= 0) {
      velocity = clamp(vx, 3, 5);
    } else if (vx < 0) {
      velocity = clamp(vx * -1, 3, 5) * -1;
    }

    Animated.spring(this.state.pan, {
          toValue: {x: 0, y: toValue},
          friction: 4
    }).start()
    }
  })
}

Answer 1

I don't know if this would be the best way to go about it, but I would just get the onLayout of the target Views to get the x,y,width, and height...

<View onLayout={({nativeEvent: {layout: {x,y,width,height}}) => { })} />

The coordinates covered by the container would simply be (x, x+width) and (y, y+height)

onPanResponderGrant get the location of the draggable:

onPanResponderGrant: (e) => {
  this.originX = e.pageX - e.locationX;
  this.originY = e.pageY - e.locationY;
}

onPanResponderMove you can do something like this:

onPanResponderMove: (e, gestureState) => {
  const currentX0 = this.originX + gestureState.dx
  const currentY0 = this.originY + gestureState.dy 
}

The draggable now covers from currentX0 to currentX0 + width and from currentY0 to currentY0 + height ...

You can use these values to check to see whether it overlaps with the target view (x, x+width) and (y, y+height)