setBackgroundColor method
Set background color. https://github.com/wang-bin/mdk-sdk/wiki/Player-APIs#void-setbackgroundcolorfloat-r-float-g-float-b-float-a-void-vo_opaque--nullptr
Implementation
void setBackgroundColor(double r, double g, double b, double a) =>
_player.ref.setBackgroundColor.asFunction<
void Function(Pointer<mdkPlayer>, double, double, double, double,
Pointer<Void>)>()(
_player.ref.object, r, g, b, a, Pointer.fromAddress(0));