请问如何把这样动态的方块改成动态text字

想把这三个移动的方块改成两个分别移动的英文，比如HELLO和WORLD，请问怎么改？

编码是这样的：

Python code

import pygame, sys, time
from pygame.locals import *

# set up pygame
pygame.init()

# set up the window
WINDOWWIDTH = 400
WINDOWHEIGHT = 400
windowSurface = pygame.display.set_mode((WINDOWWIDTH, WINDOWHEIGHT), 0, 32)
pygame.display.set_caption('Animation')

# set up direction variables
DOWNLEFT = 1
DOWNRIGHT = 3
UPLEFT = 7
UPRIGHT = 9

MOVESPEED = 4

# set up the colors
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

# set up the block data structure
b1 = {'rect':pygame.Rect(300, 80, 50, 100), 'color':RED, 'dir':UPRIGHT}
b2 = {'rect':pygame.Rect(200, 200, 20, 20), 'color':GREEN, 'dir':UPLEFT}
b3 = {'rect':pygame.Rect(100, 150, 60, 60), 'color':BLUE, 'dir':DOWNLEFT}
blocks = [b1, b2, b3]

# run the game loop
while True:
    # check for the QUIT event
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    # draw the black background onto the surface
    windowSurface.fill(BLACK)

    for b in blocks:
        # move the block data structure
        if b['dir'] == DOWNLEFT:
            b['rect'].left -= MOVESPEED
            b['rect'].top += MOVESPEED
        if b['dir'] == DOWNRIGHT:
            b['rect'].left += MOVESPEED
            b['rect'].top += MOVESPEED
        if b['dir'] == UPLEFT:
            b['rect'].left -= MOVESPEED
            b['rect'].top -= MOVESPEED
        if b['dir'] == UPRIGHT:
            b['rect'].left += MOVESPEED
            b['rect'].top -= MOVESPEED

        # check if the block has move out of the window
        if b['rect'].top < 0:
            # block has moved past the top
            if b['dir'] == UPLEFT:
                b['dir'] = DOWNLEFT
            if b['dir'] == UPRIGHT:
                b['dir'] = DOWNRIGHT
        if b['rect'].bottom > WINDOWHEIGHT:
            # block has moved past the bottom
            if b['dir'] == DOWNLEFT:
                b['dir'] = UPLEFT
            if b['dir'] == DOWNRIGHT:
                b['dir'] = UPRIGHT
        if b['rect'].left < 0:
            # block has moved past the left side
            if b['dir'] == DOWNLEFT:
                b['dir'] = DOWNRIGHT
            if b['dir'] == UPLEFT:
                b['dir'] = UPRIGHT
        if b['rect'].right > WINDOWWIDTH:
            # block has moved past the right side
            if b['dir'] == DOWNRIGHT:
                b['dir'] = DOWNLEFT
            if b['dir'] == UPRIGHT:
                b['dir'] = UPLEFT

        # draw the block onto the surface
        pygame.draw.rect(windowSurface, b['color'], b['rect'])

    # draw the window onto the screen
    pygame.display.update()
    time.sleep(0.02)

是不是要改这一部分呢？

Python code

# set up the block data structure
b1 = {'rect':pygame.Rect(300, 80, 50, 100), 'color':RED, 'dir':UPRIGHT}
b2 = {'rect':pygame.Rect(200, 200, 20, 20), 'color':GREEN, 'dir':UPLEFT}
b3 = {'rect':pygame.Rect(100, 150, 60, 60), 'color':BLUE, 'dir':DOWNLEFT}
blocks = [b1, b2, b3]

可是要怎么改呢？
我乱写了一通，都不行，麻烦高手帮忙啦~~~ 

改了两个地方。
其一：
Python code

# set up the block data structure
font = pygame.font.SysFont(pygame.font.get_default_font(), 32)
b1 = {'text':font.render('A', 1, RED),   'rect':pygame.Rect(300, 80, 50, 100), 'dir':UPRIGHT}
b2 = {'text':font.render('B', 1, GREEN), 'rect':pygame.Rect(200, 200, 20, 20), 'dir':UPLEFT}
b3 = {'text':font.render('C', 1, BLUE),  'rect':pygame.Rect(100, 150, 60, 60), 'dir':DOWNLEFT}
blocks = [b1, b2, b3]

其二：
Python code

        # draw the block onto the surface
        windowSurface.blit(b['text'], b['rect'])

完整代码：
Python code

import pygame, sys, time
from pygame.locals import *

# set up pygame
pygame.init()

# set up the window
WINDOWWIDTH = 400
WINDOWHEIGHT = 400
windowSurface = pygame.display.set_mode((WINDOWWIDTH, WINDOWHEIGHT), 0, 32)
pygame.display.set_caption('Animation')

# set up direction variables
DOWNLEFT = 1
DOWNRIGHT = 3
UPLEFT = 7
UPRIGHT = 9

MOVESPEED = 4

# set up the colors
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

# set up the block data structure
font = pygame.font.SysFont(pygame.font.get_default_font(), 32)
b1 = {'text':font.render('A', 1, RED),   'rect':pygame.Rect(300, 80, 50, 100), 'dir':UPRIGHT}
b2 = {'text':font.render('B', 1, GREEN), 'rect':pygame.Rect(200, 200, 20, 20), 'dir':UPLEFT}
b3 = {'text':font.render('C', 1, BLUE),  'rect':pygame.Rect(100, 150, 60, 60), 'dir':DOWNLEFT}
blocks = [b1, b2, b3]

# run the game loop
while True:
    # check for the QUIT event
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    # draw the black background onto the surface
    windowSurface.fill(BLACK)

    for b in blocks:
        # move the block data structure
        if b['dir'] == DOWNLEFT:
            b['rect'].left -= MOVESPEED
            b['rect'].top += MOVESPEED
        if b['dir'] == DOWNRIGHT:
            b['rect'].left += MOVESPEED
            b['rect'].top += MOVESPEED
        if b['dir'] == UPLEFT:
            b['rect'].left -= MOVESPEED
            b['rect'].top -= MOVESPEED
        if b['dir'] == UPRIGHT:
            b['rect'].left += MOVESPEED
            b['rect'].top -= MOVESPEED

        # check if the block has move out of the window
        if b['rect'].top < 0:
            # block has moved past the top
            if b['dir'] == UPLEFT:
                b['dir'] = DOWNLEFT
            if b['dir'] == UPRIGHT:
                b['dir'] = DOWNRIGHT
        if b['rect'].bottom > WINDOWHEIGHT:
            # block has moved past the bottom
            if b['dir'] == DOWNLEFT:
                b['dir'] = UPLEFT
            if b['dir'] == DOWNRIGHT:
                b['dir'] = UPRIGHT
        if b['rect'].left < 0:
            # block has moved past the left side
            if b['dir'] == DOWNLEFT:
                b['dir'] = DOWNRIGHT
            if b['dir'] == UPLEFT:
                b['dir'] = UPRIGHT
        if b['rect'].right > WINDOWWIDTH:
            # block has moved past the right side
            if b['dir'] == DOWNRIGHT:
                b['dir'] = DOWNLEFT
            if b['dir'] == UPRIGHT:
                b['dir'] = UPLEFT

        # draw the block onto the surface
        windowSurface.blit(b['text'], b['rect'])

    # draw the window onto the screen
    pygame.display.update()
    time.sleep(0.02)

不过前面那个碰撞效果不太好，因为是按照rect碰撞的，但是rect和文字大小不一致。
可以把rect修正为和文字一样大小：
Python code

# set up the block data structure
font = pygame.font.SysFont(pygame.font.get_default_font(), 32)
b1 = {'text':font.render('A', 1, RED),   'rect':pygame.Rect(300, 80, 50, 100), 'dir':UPRIGHT}
b2 = {'text':font.render('B', 1, GREEN), 'rect':pygame.Rect(200, 200, 20, 20), 'dir':UPLEFT}
b3 = {'text':font.render('C', 1, BLUE),  'rect':pygame.Rect(100, 150, 60, 60), 'dir':DOWNLEFT}
blocks = [b1, b2, b3]
for b in blocks:
    b['rect'].width = b['text'].get_width()
    b['rect'].height = b['text'].get_height()