Perform a Pinch gesture on the object.
- The scale for the pinch gesture. This number is the ratio between the start distance and the end distance between the two touch point used for the pinch. For example, if you were to touch a screen with your fingers 6 cm apart, and pinch until your fingers were 3 cm, apart, the scale would be 0.5
- PinchArgs arguments that define the behavior of the pinch operation.