OpacityProvider class abstract
Interface for a component that can be affected by opacity effects. Value of opacity must be in the range of 0-1 (both inclusive).
It is allowed for implementers of this interface to use an integer for
internal representation. In such cases, opacity get/set are expected
to perform necessary conversions from integer to double and vice versa.
As a side effect of this, setting the opacity to some
x value would not
necessarily produce the same
x when reading it back.
See HasPaint for an example implementation.