updateScalebyDelta method

void updateScalebyDelta(
  1. double delta, {
  2. Offset? focalPoint,
})

Increment or decrement the scale by an additive delta value. Clamps to the zoom limits while preserving the focal point.

Implementation

void updateScalebyDelta(double delta, {Offset? focalPoint}) {
  stopAnimation();
  // added focalPoint param
  focalPoint ??= Offset(canvasSize.width / 2, canvasSize.height / 2);
  final newScale = _clampScale(_scale + delta);
  _gsTopLeftOffset = newGsTopLeftOnScaling(
    _gsTopLeftOffset,
    focalPoint,
    _scale,
    newScale,
  );
  _scale = newScale;
  markDirty();
}