transformMatrix property

Matrix4 get transformMatrix

The total transformation matrix for the component. This matrix combines translation, rotation, reflection and scale transforms into a single entity. The matrix is cached and gets recalculated only as necessary.

The returned matrix must not be modified by the user.

Implementation

Matrix4 get transformMatrix {
  if (_recalculate) {
    // The transforms below are equivalent to:
    //   _transformMatrix = Matrix4.identity()
    //       .. translate(_position.x, _position.y)
    //       .. rotateZ(_angle)
    //       .. scale(_scale.x, _scale.y, 1)
    //       .. translate(_offset.x, _offset.y);
    final m = _transformMatrix.storage;
    final cosA = math.cos(_angle);
    final sinA = math.sin(_angle);
    m[0] = cosA * _scale.x;
    m[1] = sinA * _scale.x;
    m[4] = -sinA * _scale.y;
    m[5] = cosA * _scale.y;
    m[12] = _position.x + m[0] * _offset.x + m[4] * _offset.y;
    m[13] = _position.y + m[1] * _offset.x + m[5] * _offset.y;
    _recalculate = false;
  }
  return _transformMatrix;
}

set transformMatrix (Matrix4 value)

Implementation

set transformMatrix(Matrix4 value) {
  assert(
    value.storage[2] == 0 &&
        value.storage[3] == 0 &&
        value.storage[6] == 0 &&
        value.storage[7] == 0 &&
        value.storage[8] == 0 &&
        value.storage[9] == 0 &&
        value.storage[10] == 1 &&
        value.storage[11] == 0 &&
        value.storage[14] == 0 &&
        value.storage[15] == 1,
    'The provided matrix is not a valid 2D transformation',
  );
  _transformMatrix.setFrom(value);
  _recalculate = false;

  final storage = _transformMatrix.storage;
  _isBatchUpdating = true;
  final determinant = storage[0] * storage[5] - storage[1] * storage[4];
  _scale.x = math.sqrt(storage[0] * storage[0] + storage[1] * storage[1]);
  if (_scale.x == 0) {
    _angle = math.atan2(-storage[4], storage[5]);
    _scale.y = math.sqrt(storage[4] * storage[4] + storage[5] * storage[5]);
  } else {
    _angle = math.atan2(storage[1], storage[0]);
    _scale.y = determinant / _scale.x;
  }

  _position.x =
      storage[12] - (storage[0] * _offset.x + storage[4] * _offset.y);
  _position.y =
      storage[13] - (storage[1] * _offset.x + storage[5] * _offset.y);
  _isBatchUpdating = false;
  notifyListeners();
}