Add pinch/zoom

[muirandy]

I'd like to be able to zoom in and out using the pinch gesture.

This should be optional, and I should be able to specify a range for the zoom.

[graknol]

I'd like to be able to zoom in and out using the pinch gesture.

This should be optional, and I should be able to specify a range for the zoom.

I would say that this wouldn't be appropriate for this library.

For this use case, I would use matrix_gesture_detector.

It does everything you want, pan, zoom and even rotation.
And you even get finer control over how you want it to behave.
Want to implement clamping? Great, implement it in onMatrixUpdate.
After all, it's all just matrices. 😄