def METHOD_NAME(self, roi):
    for tile in roi.gen_tiles():
        gridinfo = self.grid.gridinfo_at_tilename(tile)
        for block_type in gridinfo.bits:
            bits = gridinfo.bits[block_type]
            for frame in range(bits.base_address,
                               bits.base_address + bits.frames):
                self.frames_in_use.add(frame)