Version of OQColorGetComponents that goes through a linear RGB color space

OQColor.m

OQLinearRGBA OQGetColorComponents(NSColor *c)
{
    static dispatch_once_t once;
    static NSColorSpace *linearRGBColorSpace;
    dispatch_once(&once, ^{
        CGColorSpaceRef cgColorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGBLinear);
        linearRGBColorSpace = [[NSColorSpace alloc] initWithCGColorSpace:cgColorSpace];
        CGColorSpaceRelease(cgColorSpace);
        
        OBASSERT_NOTNULL(linearRGBColorSpace);
        OBASSERT([linearRGBColorSpace colorSpaceModel] == NSRGBColorSpaceModel);
        OBASSERT([linearRGBColorSpace numberOfColorComponents] == 3);
    });
    
    OQLinearRGBA l;
    if (c) {
        CGFloat components[3];
        [[c colorUsingColorSpace:linearRGBColorSpace] getComponents:components];
        l.r = components[0];
        l.g = components[1];
        l.b = components[2];
        l.a = [c alphaComponent];
    } else
        memset(&l, 0, sizeof(l)); // Treat nil as clear.
    return l;
}