Creates a partially transparent render object.
The opacity argument must be between 0.0 and 1.0, inclusive.
Source
RenderOpacity({ double opacity: 1.0, RenderBox child })
: _opacity = opacity, _alpha = _getAlphaFromOpacity(opacity), super(child) {
assert(opacity != null);
assert(opacity >= 0.0 && opacity <= 1.0);
}