FloodFill without a "Picture" object

Seems the only way to do a FloodFill is using the RGBSurface of a PICTURE object…
but what if you don’t have one… but all you have is the GRAPHICS object (from a Canvas, or Printer object?)

I know I could create a Picture the size of the Graphics object, and manipulate it that way, but that is moving a lot of bits around especially when I just want to flood an area that is relatively small compared to the whole image.