Massive/AppFab.tsx

import { ComponentProps, useMemo } from "react";
import { FAB, useTheme } from "react-native-paper";
import { CombinedDarkTheme, CombinedDefaultTheme } from "./App";
import { lightColors } from "./colors";

export default function AppFab(props: Partial<ComponentProps<typeof FAB>>) {
  const { colors } = useTheme();

  const fabColor = useMemo(
    () =>
      lightColors.map((color) => color.hex).includes(colors.primary)
        ? CombinedDarkTheme.colors.background
        : CombinedDefaultTheme.colors.background,
    [colors.primary]
  );

  return (
    <FAB
      icon="add"
      testID="add"
      color={fabColor}
      style={{
        position: "absolute",
        right: 20,
        bottom: 20,
        backgroundColor: colors.primary,
      }}
      {...props}
    />
  );
}