sampleLuminance static method
Average WCAG relative luminance (0.0 dark – 1.0 light) of the content
behind rect (in global/screen coordinates).
Returns null when there is no enclosing GlassContentAwareScope, no GlassContentAwareContent registered with it, or no capture has completed yet (the first frame or two after the scope mounts).
Implementation
static double? sampleLuminance(BuildContext context, Rect rect) {
return GlassContentAwareScope.maybeOf(context)?.luminanceAt(rect);
}