handleScaleUpdate method

  1. @override
void handleScaleUpdate(
  1. double scaleFactor,
  2. Offset focalDelta
)
override

A two-plus finger gesture: scaleFactor is the incremental pinch factor since the last update (>1 spreading, <1 pinching) and focalDelta is the centroid movement in logical pixels.

Implementation

@override
void handleScaleUpdate(double scaleFactor, Offset focalDelta) {
  if (scaleFactor != 1.0) dollyBy(scaleFactor - 1.0);
  if (focalDelta != Offset.zero) {
    panBy(
      Offset(
        focalDelta.dx / viewportSize.height,
        focalDelta.dy / viewportSize.height,
      ),
    );
  }
}