Initial delegate for colourslider

ColourSliderDelagate1.dart

class _ColourSliderDelegate extends MultiChildLayoutDelegate {
  @override
  void performLayout(Size size) {
    layoutChild(ColourSlider.track, BoxConstraints.loose(size));
    positionChild(ColourSlider.track, Offset(0, 0));
    layoutChild(ColourSlider.thumb, BoxConstraints.loose(size));
    positionChild(ColourSlider.thumb, Offset(0, 0));
  }

  @override
  bool shouldRelayout(MultiChildLayoutDelegate oldDelegate) {
    return false;
  }
}