Kivy - 添加和删除标签

Question

我是 Kivy 的新手，找不到任何关于添加和删除标签的真正答案。我完成了 Pong 教程（您可能已经猜到了），并将其改编为 4 名玩家。现在，我正在尝试添加一个标签来显示文本Winner!，并单击该文本以重新开始游戏。

到那里为止，它正在工作。问题是，我无法在新游戏开始后让标签再次消失。另外，我不明白格式 - 我似乎无法使我的标签更大或在面板中将其移动到更低的位置。

我将发布所有代码，因为希望您无论如何都想玩游戏（一旦它被修复），我很肯定有一种更好、更简洁的方式来添加和删除文本。

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.label import Label
from kivy.properties import NumericProperty, ReferenceListProperty,\
    ObjectProperty
from kivy.vector import Vector
from kivy.clock import Clock
from random import randint


class PongPaddle(Widget):
    score = NumericProperty(0)
    orientation = ObjectProperty([0, 0])
    can_move = ObjectProperty(0)

    def bounce_ball(self, ball):
        if self.collide_widget(ball):
            vx, vy = ball.velocity
            if self.orientation[0] == 25:                
                offset = (ball.center_y - self.center_y) / (self.height / 2)
                bounced = Vector(-1 * vx, vy)
                vel = bounced * 1.1
                ball.velocity = vel.x, vel.y + offset
            else:
                offset = (ball.center_x - self.center_x) / (self.width / 2)
                bounced = Vector(vx, -1 * vy)
                vel = bounced * 1.1
                ball.velocity = vel.x + offset, vel.y


class PongBall(Widget):
    velocity_x = NumericProperty(0)
    velocity_y = NumericProperty(0)
    velocity = ReferenceListProperty(velocity_x, velocity_y)

    def move(self):
        self.pos = Vector(*self.velocity) + self.pos

class PongGame(Widget):
    ball = ObjectProperty(None)
    player1 = ObjectProperty(None)
    player2 = ObjectProperty(None)
    player3 = ObjectProperty(None)
    player4 = ObjectProperty(None)

    def initialize(self):
        SCORE = 1
        self.player1.orientation = [25, 200]
        self.player2.orientation = [25, 200]
        self.player3.orientation = [200, 25]
        self.player4.orientation = [200, 25]
        self.player1.score = SCORE
        self.player2.score = SCORE
        self.player3.score = SCORE
        self.player4.score = SCORE
        self.player1.can_move = 1
        self.player2.can_move = 1
        self.player3.can_move = 1
        self.player4.can_move = 1
        self.serve_ball()

    def serve_ball(self, vel=(4, 0)):
        self.ball.center = self.center
        self.ball.velocity = vel

    def update(self, dt):
        self.ball.move()

        #bounce of paddles
        self.player1.bounce_ball(self.ball)
        self.player2.bounce_ball(self.ball)
        self.player3.bounce_ball(self.ball)
        self.player4.bounce_ball(self.ball)

        #bounce ball off bottom or top
        if ((self.ball.y < self.y) and not self.player3.can_move) \
           or ((self.ball.top > self.top) and not self.player4.can_move):
            self.ball.velocity_y *= -1
        if ((self.ball.x < self.x) and not self.player1.can_move) \
           or ((self.ball.right > self.width) and not self.player2.can_move):
            self.ball.velocity_x *= -1

        #went off to a side to score point?
        if self.ball.x < self.x and self.player1.can_move == 1:
            self.player1.score -= 1
            self.serve_ball(vel=(4, randint(1, 4)))
            if self.player1.score <= 0:
                self.player1.can_move = 0
        elif self.ball.x > self.width and self.player2.can_move == 1:
            self.player2.score -= 1
            self.serve_ball(vel=(-4, randint(1, 4)))
            if self.player2.score <= 0:
                self.player2.can_move = 0
        elif self.ball.y > self.height and self.player4.can_move == 1:
            self.player4.score -= 1
            self.serve_ball(vel = (randint(1, 4), -4))
            if self.player4.score <= 0:
                self.player4.can_move = 0
        elif self.ball.y < self.y and self.player3.can_move == 1:
            self.player3.score -= 1
            self.serve_ball(vel = (randint(1, 4), 4))
            if self.player3.score <= 0:
                self.player3.can_move = 0

        if self.player1.can_move + self.player2.can_move + \
           self.player3.can_move + self.player4.can_move == 1:
            self.ball.velocity = (0, 0)
            global win_label
            win_label = Label(size_hint=(None, None),
                              text='[ref=winner]Winner![/ref]',
                              markup=True, text_size=(70, None))
            #win_label.texture_update()
            win_label.pos = (self.width / 2, self.height / 2 - 70)
##            win_label.size =  win_label.texture_size[0] + 20, \
##                             win_label.texture_size[1] + 20
            win_label.bind(on_ref_press=self.click_win_label)
            win_label.texture_update()
            self.add_widget(win_label)

    def click_win_label(self, instance, value):
        self.initialize()
        self.remove_widget(win_label)


    def on_touch_move(self, touch):
        if touch.x < self.width / 3 and touch.y > self.height / 6 \
            and touch.y < 5 * self.height / 6 and self.player1.can_move:
            self.player1.center_y = touch.y
        if touch.x > self.width - self.width / 3 and touch.y > self.height / 6 \
            and touch.y < 5 * self.height / 6 and self.player2.can_move:
            self.player2.center_y = touch.y
        if touch.y < self.height / 3 and touch.x > self.width / 6 \
            and touch.x < 5 * self.width / 6 and self.player3.can_move:
            self.player3.center_x = touch.x
        if touch.y > 2* self.height / 3 and touch.x > self.width / 6 \
            and touch.x < 5 * self.width / 6 and self.player4.can_move:
            self.player4.center_x = touch.x


class PongApp(App):
    def build(self):
        game = PongGame()
        game.initialize()
        game.serve_ball()
        Clock.schedule_interval(game.update, 1.0 / 60.0)
        return game


if __name__ == '__main__':
    PongApp().run()

还有.kv文件：

#:kivy 1.0.9

<PongBall>:
    size: 50, 50 
    canvas:
        Ellipse:
            pos: self.pos
            size: self.size          

<PongPaddle>:
    size: root.orientation[0], root.orientation[1]
    canvas:
        Rectangle:
            pos:self.pos
            size:self.size

<PongGame>:
    ball: pong_ball
    player1: player_left
    player2: player_right
    player3: player_top
    player4: player_bottom


    Label:
        font_size: 50  
        center_x: root.width / 6
        top: root.top - root.height / 2 + 50
        text: str(root.player1.score)

    Label:
        font_size: 50  
        center_x: root.width * 5 / 6
        top: root.top - root.height / 2 + 50
        text: str(root.player2.score)

    Label:
        font_size: 50
        center_x: root.width / 2
        top: root.height / 6
        text: str(root.player3.score)

    Label:
        font_size: 50
        center_x: root.width / 2
        top: 5 * root.height / 6
        text: str(root.player4.score)

    PongBall:
        id: pong_ball
        center: self.parent.center

    PongPaddle:
        id: player_left
        x: root.x
        center_y: root.center_y

    PongPaddle:
        id: player_right
        x: root.width-self.width
        center_y: root.center_y

    PongPaddle:
        id: player_top
        y: root.y
        center_x: root.center_x

    PongPaddle:
        id: player_bottom
        y: root.height - self.height
        center_x: root.center_x

Answer 1

Label 正在被删除，问题是你添加了无数个 :) 因为更新方法计划在这里每 1/60 秒调用一次：

Clock.schedule_interval(game.update, 1.0 / 60.0)

如果不是您的计算机会死机，您需要在添加小部件之前取消计划：

Clock.unschedule(self.update)

下面的代码有效。我想建议不要使用全局变量（这只是一个非常糟糕的做法）。我也修改了那个。对于这种情况，您甚至不需要类属性，因为参数instance 包含与self.win_label 完全相同的内容。另外，我改变了你的居中方式（self.win_label.center = self.center）。最后，使用[Button][1] 而不是Label 会更容易，因为您可以绑定其他方法，例如on_press 或on_release。实际上，您不需要为此提供ref。你可以简单地绑定on_touch_down。

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.label import Label
from kivy.properties import NumericProperty, ReferenceListProperty,\
    ObjectProperty
from kivy.vector import Vector
from kivy.clock import Clock
from random import randint


class PongPaddle(Widget):
    score = NumericProperty(0)
    orientation = ObjectProperty([0, 0])
    can_move = ObjectProperty(0)

    def bounce_ball(self, ball):
        if self.collide_widget(ball):
            vx, vy = ball.velocity
            if self.orientation[0] == 25:                
                offset = (ball.center_y - self.center_y) / (self.height / 2)
                bounced = Vector(-1 * vx, vy)
                vel = bounced * 1.1
                ball.velocity = vel.x, vel.y + offset
            else:
                offset = (ball.center_x - self.center_x) / (self.width / 2)
                bounced = Vector(vx, -1 * vy)
                vel = bounced * 1.1
                ball.velocity = vel.x + offset, vel.y


class PongBall(Widget):
    velocity_x = NumericProperty(0)
    velocity_y = NumericProperty(0)
    velocity = ReferenceListProperty(velocity_x, velocity_y)

    def move(self):
        self.pos = Vector(*self.velocity) + self.pos

class PongGame(Widget):
    ball = ObjectProperty(None)
    player1 = ObjectProperty(None)
    player2 = ObjectProperty(None)
    player3 = ObjectProperty(None)
    player4 = ObjectProperty(None)

    def initialize(self):
        SCORE = 1
        self.player1.orientation = [25, 200]
        self.player2.orientation = [25, 200]
        self.player3.orientation = [200, 25]
        self.player4.orientation = [200, 25]
        self.player1.score = SCORE
        self.player2.score = SCORE
        self.player3.score = SCORE
        self.player4.score = SCORE
        self.player1.can_move = 1
        self.player2.can_move = 1
        self.player3.can_move = 1
        self.player4.can_move = 1
        self.serve_ball()

    def serve_ball(self, vel=(4, 0)):
        self.ball.center = self.center
        self.ball.velocity = vel

    def update(self, dt):
        self.ball.move()

        #bounce of paddles
        self.player1.bounce_ball(self.ball)
        self.player2.bounce_ball(self.ball)
        self.player3.bounce_ball(self.ball)
        self.player4.bounce_ball(self.ball)

        #bounce ball off bottom or top
        if ((self.ball.y < self.y) and not self.player3.can_move) \
           or ((self.ball.top > self.top) and not self.player4.can_move):
            self.ball.velocity_y *= -1
        if ((self.ball.x < self.x) and not self.player1.can_move) \
           or ((self.ball.right > self.width) and not self.player2.can_move):
            self.ball.velocity_x *= -1

        #went off to a side to score point?
        if self.ball.x < self.x and self.player1.can_move == 1:
            self.player1.score -= 1
            self.serve_ball(vel=(4, randint(1, 4)))
            if self.player1.score <= 0:
                self.player1.can_move = 0
        elif self.ball.x > self.width and self.player2.can_move == 1:
            self.player2.score -= 1
            self.serve_ball(vel=(-4, randint(1, 4)))
            if self.player2.score <= 0:
                self.player2.can_move = 0
        elif self.ball.y > self.height and self.player4.can_move == 1:
            self.player4.score -= 1
            self.serve_ball(vel = (randint(1, 4), -4))
            if self.player4.score <= 0:
                self.player4.can_move = 0
        elif self.ball.y < self.y and self.player3.can_move == 1:
            self.player3.score -= 1
            self.serve_ball(vel = (randint(1, 4), 4))
            if self.player3.score <= 0:
                self.player3.can_move = 0

        if self.player1.can_move + self.player2.can_move + \
           self.player3.can_move + self.player4.can_move == 1:
            self.ball.velocity = (0, 0)
            Clock.unschedule(self.update)

            self.win_label = Label(size_hint=(None, None),
                              text='[ref=winner]Winner![/ref]',
                              markup=True, font_size=70, color=[1,0,0,1])
            #win_label.texture_update()
            #self.win_label.pos = (self.width / 2, self.height / 2 - 70)
            self.win_label.center = self.center
##            win_label.size =  win_label.texture_size[0] + 20, \
##                             win_label.texture_size[1] + 20
            self.win_label.bind(on_ref_press=self.click_win_label)
            self.win_label.texture_update()
            self.add_widget(self.win_label)


    def click_win_label(self, instance, value):
        self.remove_widget(self.win_label)
        #self.remove_widget(instance) # this should also work:
        self.initialize()
        Clock.schedule_interval(self.update, 1.0 / 60.0)



    def on_touch_move(self, touch):
        if touch.x < self.width / 3 and touch.y > self.height / 6 \
            and touch.y < 5 * self.height / 6 and self.player1.can_move:
            self.player1.center_y = touch.y
        if touch.x > self.width - self.width / 3 and touch.y > self.height / 6 \
            and touch.y < 5 * self.height / 6 and self.player2.can_move:
            self.player2.center_y = touch.y
        if touch.y < self.height / 3 and touch.x > self.width / 6 \
            and touch.x < 5 * self.width / 6 and self.player3.can_move:
            self.player3.center_x = touch.x
        if touch.y > 2* self.height / 3 and touch.x > self.width / 6 \
            and touch.x < 5 * self.width / 6 and self.player4.can_move:
            self.player4.center_x = touch.x


class PongApp(App):
    def build(self):
        game = PongGame()
        game.initialize()
        #game.serve_ball()
        Clock.schedule_interval(game.update, 1.0 / 60.0)
        return game

if __name__ == '__main__':
    PongApp().run()