onScaleUpdate method

void onScaleUpdate(ScaleUpdateDetails details)

Implementation

void onScaleUpdate(ScaleUpdateDetails details) {
  if (!_isZooming || _controllerReset.isAnimating) {
    return;
  }

  final translationDelta = details.focalPoint - _startFocalPoint;

  final translate = Matrix4.translation(
    v3.Vector3(translationDelta.dx, translationDelta.dy, 0),
  );

  final renderBox = context.findRenderObject() as RenderBox;
  final focalPoint = renderBox.globalToLocal(
    details.focalPoint - translationDelta,
  );

  var scaleby = details.scale;
  if (widget.minScale != null && scaleby < widget.minScale!) {
    scaleby = widget.minScale ?? 0;
  }

  if (widget.maxScale != null && scaleby > widget.maxScale!) {
    scaleby = widget.maxScale ?? 0;
  }

  final dx = (1 - scaleby) * focalPoint.dx;
  final dy = (1 - scaleby) * focalPoint.dy;

  final scale =
      Matrix4(scaleby, 0, 0, 0, 0, scaleby, 0, 0, 0, 0, 1, 0, dx, dy, 0, 1);

  _matrix = translate * scale;

  if (_transformWidget.currentState != null) {
    _transformWidget.currentState!.setMatrix(_matrix);
  }
}