Python - Pygame 不在按钮上显示文本

Question

I'm trying to make a simple menu for a game in pygame, but I'm struggling to display interactive text for the menu buttons. I have a very simple menu, with the 'Start' and 'Quit' options, and I'm trying to display them using a Button class I made.

For some reason the button background blits but the text doesn't appear. I get a bunch of rectangles which change colour correctly as I scroll over them but no text.

I looked at similar questions but can't seem to figure out why mine doesn't work. Any help or guidance would be appreciated.

Here is a code sample below. Colours are defined in a separate python file.

class Start(SceneBase):
    def __init__(self):
        SceneBase.__init__(self)

        self.options = ['Start', 'Quit']
        self.buttons = pygame.sprite.Group()

    def initGraphics(self, screen):
        SceneBase.initGraphics(self, screen)

        info = pygame.display.Info()
        screenWidth, screenHeight = info.current_w, info.current_h

        font = pygame.font.Font('freesansbold.ttf', 30)

        for i, option in enumerate(self.options):
            rect = pygame.Rect(int(screenWidth/2) - 50, int(screenHeight/2) - 100 + i*50, 100, 30)
            passive_color = colors.BLACK
            active_color = colors.RED

            button = Button(rect, font, active_color, option, colors.WHITE, passive_color, option, colors.WHITE)

            self.buttons.add(button)

    def ProcessInput(self, events, pressed_keys):
        pass

    def Update(self):
        self.buttons.update()

    def Render(self):
        self.screen.fill(colors.WHITE)
        self.buttons.draw(self.screen)
        pygame.display.flip()


class Button(pygame.sprite.Sprite):
    def __init__(self, rect, font, active_color, active_text, active_textcolor, passive_color, passive_text, passive_textcolor):
        # Call the parent class (Sprite) constructor
        pygame.sprite.Sprite.__init__(self)

        self.image = pygame.Surface((rect[2], rect[3]))

        self.rect = rect

        self.font = font

        self.active_color = active_color
        self.active_text = active_text
        self.active_textcolor = active_textcolor
        self.passive_color = passive_color
        self.passive_text = passive_text
        self.passive_textcolor = passive_textcolor

    def update(self):
        mouse = pygame.mouse.get_pos()

        if self.rect.x <= mouse[0] <= self.rect.x + self.rect.w and self.rect.y <= mouse[1] <= self.rect.y + self.rect.h:
            self.image.fill(self.active_color)
            self.renderButtonText(self.active_text, self.active_textcolor)
        else:
            self.image.fill(self.passive_color)
            self.renderButtonText(self.passive_text, self.passive_textcolor)

    def renderButtonText(self, text, color):
        textsurf = self.font.render(text, True, color)
        textrect = textsurf.get_rect()
        textrect.center = self.rect.center
        self.image.blit(textsurf, textrect)

This is the skeleton code for the SceneBase class:

pygame.init()


def run_game(width, height, fps, starting_scene):
    screen = pygame.display.set_mode((width, height))
    clock = pygame.time.Clock()

    active_scene = starting_scene

    initialized = False

    while active_scene:

        if not initialized:
            active_scene.initGraphics(screen)
            initialized = True

        pressed_keys = pygame.key.get_pressed()

        # Event filtering
        filtered_events = []
        for event in pygame.event.get():
            quit_attempt = False
            if event.type == pygame.QUIT:
                quit_attempt = True
            elif event.type == pygame.KEYDOWN:
                alt_pressed = pressed_keys[pygame.K_LALT] or \
                              pressed_keys[pygame.K_RALT]
                if event.key == pygame.K_ESCAPE:
                    quit_attempt = True
                elif event.key == pygame.K_F4 and alt_pressed:
                    quit_attempt = True

            if quit_attempt:
                active_scene.Terminate()
            else:
                filtered_events.append(event)

        active_scene.ProcessInput(filtered_events, pressed_keys)
        active_scene.Update()
        active_scene.Render()

        active_scene = active_scene.next

        pygame.display.flip()
        clock.tick(fps)

#==============================================================================
# The rest is code where you implement your game using the Scenes model


run_game(500, 500, 60, Start())

Answer 1

It seems that you're rendering the button text before you're rendering the background, so what is probably happening is that the text is being drawn, but the button is being drawn over it in the same frame, so it seems that there's no text. Try adding the update function's code to a new function called checkIfHovering, and have it write:

    def checkIfHovering(self):
        mouse = pygame.mouse.get_pos()

        if self.rect.x <= mouse[0] <= self.rect.x + self.rect.w and self.rect.y <= mouse[1] <= self.rect.y + self.rect.h:
            self.image.fill(self.active_color)
            self.renderButtonText(self.active_text, self.active_textcolor)
        else:
            self.image.fill(self.passive_color)
            self.renderButtonText(self.passive_text, self.passive_textcolor)

and in addition to that, change the Render function to have:

    def Render(self):
        self.screen.fill(colors.WHITE)
        self.buttons.draw(self.screen)
        self.buttons.checkIfHovering()
        pygame.display.flip()

That way it's printing the text after the button backgrounds are being drawn.