Flutter InteractiveViewer 将缩放限制为一维

Question

How could I make scaling only possible on one dimension, eg the y dimension and have eg the x dimension fixed. I am trying to make a (vertical) ruler, the user can scale (zoom) and the values of the ruler will change. But the widths of the ruler lines should remain fixed. thx

Answer 1

I have found the following way. Not sure if there is a better way:

onInteractionUpdate: (details) {
      final M = _transformationController.value;
      V.Vector3 translation = V.Vector3.zero();
      V.Quaternion rotation = V.Quaternion.identity();
      V.Vector3 scale = V.Vector3.zero();
      M.decompose(translation, rotation, scale);
      _transformationController.value.scale(1 / scale.x, 1, 1 / scale.z);
    },