Android Flutter Code - How to Get the Native Size of the Bottom Bar

So what I wanted is to have the bottom bar extend here. This is not something you can do with flutter, it's also something which is done manually. So this way you can have a nice gradient. But if you're using like me something which is a great chance, it doesn't work anymore. You cannot do something like this. You have to extend the screen up until the bottom here. And so I've created a, sorry for not having the coloration here, or it's quickly, but I don't use it that much.I'm using some Android code here to get the real height and the real width of this bar here and this bar here on the bottom