opacity property
final
How much of the surface shows, 0 to 1: a surface fading in or out, such as a popover's platter while it opens.
A control fades its glass through this value rather than an
Opacity above the painter's widget: an opacity layer hands a
backdrop-sampling surface the empty layer instead of what lies
behind it. A painter fades everything it draws by it, the flat fill
of MorphGlassPainter.buildFill included.
Implementation
final double opacity;