Bar class useful for progress or health bars

bar.py

import pygame
from pygame import Vector2
from pygame import Vector3
from typing import Tuple

class Bar:
    def __init__(self,
                 pos: Tuple[int, int],
                 size: Tuple[int, int],
                 color: Tuple[int, int, int],
                 bg_color: Tuple[int, int, int]=(0,0,0,30),
                 border_color: Tuple[int, int, int]=(0,0,0),
                 anchor: str='center',
                 vertical: bool=False) -> None:
        self.pos = Vector2(pos)
        self.size = Vector2(size)
        self.color = color
        self.bg_color = bg_color
        self.border_color = border_color
        self.anchor = anchor
        self.vertical = vertical
        self._progress = 0
        self.progress = 0
        self.surf = None

    def draw(self, surface: pygame.Surface) -> None:
        if not self.surf or self._progress != self.progress:
            surf = pygame.Surface(self.size, pygame.SRCALPHA)
            size = self.size - Vector2(2)
            if self.vertical:
                size.y = max(0, min(size.y * self.progress, size.y))
            else:
                size.x = max(0, min(size.x * self.progress, size.x))
            pygame.draw.rect(surf, self.bg_color, (Vector2(), self.size), border_radius=4)
            y_pos = 1
            if self.vertical:
                y_pos = self.size.y - size.y
            pygame.draw.rect(surf, self.color, (Vector2(1, y_pos), size), border_radius=1)
            pygame.draw.rect(surf, self.border_color, (Vector2(), self.size), 1, border_radius=4)
            self.surf = surf
            self._progress = self.progress
        pos = self.pos - self.get_anchor_offset()
        surface.blit(self.surf, pos)

    def get_anchor_offset(self) -> None:
        if self.anchor == 'top_left':
            return Vector2()
        elif self.anchor == 'top_center':
            return Vector2(self.size.x/2, 0)
        elif self.anchor == 'top_right':
            return Vector2(self.size.x, 0)
        elif self.anchor == 'middle_left':
            return Vector2(0, self.size.y/2)
        elif self.anchor == 'center':
            return Vector2(self.size.x/2, self.size.y/2)
        elif self.anchor == 'middle_right':
            return Vector2(self.size.x, self.size.y/2)
        elif self.anchor == 'bottom_left':
            return Vector2(0, self.size.y)
        elif self.anchor == 'bottom_center':
            return Vector2(self.size.x/2, self.size.y)
        elif self.anchor == 'bottom_right':
            return size
        return Vector2()