在QLabel中更新文本时出现问题

Question

所以我正在制作一个音乐播放器，我想要一个可以看到我的歌曲的部分，逐页。页面切换有效，但文本不会更新。我试过googleing但我找不到适合/工作的anwser。对于那些想要它的人来说，这就是我的闲聊所说的：

1
0
2
3
n1
n2
1
1
2
3

无论如何，这是我的代码：

import sys
import os
import pygame
from PyQt4 import QtGui, QtCore
from time import sleep

class Window(QtGui.QMainWindow):

    def __init__(self):
        super(Window, self).__init__()
        self.setGeometry(50, 50, 500, 300)
        self.setWindowTitle("Music Player Alpha")
        AutoPlay = True
        Song = os.listdir('/home/pi/Desktop/Muziek/' )
        Song = sorted(Song)
        self.Song = Song
        self.CurrentSong = 0
        self.PageNum = 0
        pygame.mixer.init()
        pygame.mixer.music.load('/home/pi/Desktop/Muziek/' + Song[0])
        pygame.mixer.music.play()
        self.home()

    def home(self):
        print("1")
        print(self.PageNum)
        btnQuit = QtGui.QPushButton("Quit", self)
        btnQuit.clicked.connect(self.close)
        btnQuit.move(400,270)
        btnPlay = QtGui.QPushButton("Play", self)
        btnPlay.clicked.connect(self.play)
        btnPlay.move(100, 270)
        btnPause = QtGui.QPushButton("Pause", self)
        btnPause.clicked.connect(self.pause)
        btnPause.move(200, 270)
        btnNext = QtGui.QPushButton("Next", self)
        btnNext.clicked.connect(self.next)
        btnNext.move(300, 270)
        btnPrevious = QtGui.QPushButton("Previous", self)
        btnPrevious.clicked.connect(self.previous)
        btnPrevious.move(0, 270)
        btnPrevPage = QtGui.QPushButton("Prev Page", self)
        btnPrevPage.clicked.connect(self.PrevPage)
        btnPrevPage.move(0,160)
        btnNextPage = QtGui.QPushButton("Next Page", self)
        btnNextPage.clicked.connect(self.NextPage)
        btnNextPage.move(100, 160)
        try:
            txtNum1 = QtGui.QLabel(self.Song[0 + 10*self.PageNum], self)
            txtNum1.resize(500, 30)
            txtNum2 = QtGui.QLabel(self.Song[1 + 10*self.PageNum], self)
            txtNum2.move(0, 15)
            txtNum2.resize(500, 30)
            txtNum3 = QtGui.QLabel(self.Song[2 + 10*self.PageNum], self)
            txtNum3.move(0, 30)
            txtNum3.resize(500, 30)
            txtNum4 = QtGui.QLabel(self.Song[3 + 10*self.PageNum], self)
            txtNum4.move(0, 45)
            txtNum4.resize(500, 30)
            txtNum5 = QtGui.QLabel(self.Song[4 + 10*self.PageNum], self)
            txtNum5.move(0, 60)
            txtNum5.resize(500, 30)
            txtNum6 = QtGui.QLabel(self.Song[5 + 10*self.PageNum], self)
            txtNum6.move(0, 75)
            txtNum6.resize(500, 30)
            txtNum7 = QtGui.QLabel(self.Song[6 + 10*self.PageNum], self)
            txtNum7.move(0, 90)
            txtNum7.resize(500, 30)
            txtNum8 = QtGui.QLabel(self.Song[7 + 10*self.PageNum], self)
            txtNum8.move(0, 105)
            txtNum8.resize(500, 30)
            txtNum9 = QtGui.QLabel(self.Song[8 + 10*self.PageNum], self)
            txtNum9.move(0, 120)
            txtNum9.resize(500, 30)
            txtNum10 = QtGui.QLabel(self.Song[9 + 10*self.PageNum], self)
            txtNum10.move(0, 135)
            txtNum10.resize(500, 30)
            print("2")
        except IndexError:
            print("2.5")
        self.show()
        print("3")

    def close(self):
        sys.exit()

    def play(self):
        pygame.mixer.music.unpause()

    def pause(self):
        pygame.mixer.music.pause()

    def next(self, event):
        self.CurrentSong = self.CurrentSong + 1
        if self.CurrentSong > len(self.Song) + 1:
            self.CurrentSong = 0
        pygame.mixer.music.load('/home/pi/Desktop/Muziek/' + self.Song[self.CurrentSong])
        pygame.mixer.music.play()
        return self.CurrentSong;

    def previous(self, event):
        self.CurrentSong = self.CurrentSong - 1
        if self.CurrentSong < 0:
            self.CurrentSong = len(self.Song) -1
        pygame.mixer.music.load('/home/pi/Desktop/Muziek/' + self.Song[self.CurrentSong])
        pygame.mixer.music.play()

    def PrevPage(self, event):
        print("p1")
        self.PageNum = self.PageNum - 1
        if self.PageNum < 0 :
            print("p<0")
            self.PageNum = 0
        print("p2")
        self.home()
        return self.PageNum;

    def NextPage(self, event):
        print("n1")
        self.PageNum = self.PageNum + 1
        if self.PageNum > len(self.Song) / 10:
            print("n>0")
        self.PageNum = self.PageNum - 1
        print("n2")
        self.home()
        return self.PageNum;

app = QtGui.QApplication(sys.argv)
GUI = Window()
sys.exit(app.exec_())

Answer 1

问题在于，每次调用home()函数时，您都在创建新标签，您只需更新文本，为此我们创建标签列表。避免使用try，除非程序可能有错误，否则最好验证列表的索引是否在范围内。

关闭窗口时，最好在关闭窗口之前使用pygame.mixer.quit()释放声音资源，为此最好覆盖closeEvent()。

import sys
import os
import pygame
from PyQt4 import QtGui, QtCore
from time import sleep


class Window(QtGui.QMainWindow):
    song_per_page = 10
    directory = '/home/pi/Desktop/Muziek/'

    def __init__(self):
        super(Window, self).__init__()
        self.setGeometry(50, 50, 500, 300)
        self.setWindowTitle("Music Player Alpha")
        AutoPlay = True
        Song = os.listdir(self.directory)
        Song = sorted(Song)
        self.Song = Song
        self.CurrentSong = 0
        self.PageNum = 0
        pygame.mixer.init()
        self.txtNums = []
        self.home()
        self.song()

    def home(self):
        btnQuit = QtGui.QPushButton("Quit", self)
        btnQuit.clicked.connect(self.close)
        btnQuit.move(400, 270)
        btnPlay = QtGui.QPushButton("Play", self)
        btnPlay.clicked.connect(self.play)
        btnPlay.move(100, 270)
        btnPause = QtGui.QPushButton("Pause", self)
        btnPause.clicked.connect(self.pause)
        btnPause.move(200, 270)
        btnNext = QtGui.QPushButton("Next", self)
        btnNext.clicked.connect(self.next)
        btnNext.move(300, 270)
        btnPrevious = QtGui.QPushButton("Previous", self)
        btnPrevious.clicked.connect(self.previous)
        btnPrevious.move(0, 270)
        btnPrevPage = QtGui.QPushButton("Prev Page", self)
        btnPrevPage.clicked.connect(self.PrevPage)
        btnPrevPage.move(0, 160)
        btnNextPage = QtGui.QPushButton("Next Page", self)
        btnNextPage.clicked.connect(self.NextPage)
        btnNextPage.move(100, 160)

        for i in range(self.song_per_page):
            txtNum = QtGui.QLabel(self)
            txtNum.resize(500, 30)
            txtNum.move(0, 15 * i)
            self.txtNums.append(txtNum)
        self.updateLabels()
        self.show()

    def updateLabels(self):
        print(self.CurrentSong, self.PageNum)
        for i in range(len(self.txtNums)):
            index = i + self.song_per_page * self.PageNum
            self.txtNums[i].clear()
            if index < len(self.Song):
                self.txtNums[i].setText(self.Song[i + self.song_per_page * self.PageNum])

    def closeEvent(self, event):
        pygame.mixer.quit()
        QtGui.QMainWindow.closeEvent(self, event)

    def play(self):
        pygame.mixer.music.unpause()

    def pause(self):
        pygame.mixer.music.pause()

    def song(self):
        try:
            pygame.mixer.music.load(self.directory + self.Song[self.CurrentSong])
            pygame.mixer.music.play()
        except pygame.error:
            print("Module format not recognized")

        self.updateLabels()

    def next(self, event):
        self.CurrentSong = (self.CurrentSong + 1) % len(self.Song)
        self.song()

    def previous(self, event):
        self.CurrentSong = (self.CurrentSong - 1) % len(self.Song)
        self.song()

    def PrevPage(self, event):
        self.PageNum = self.PageNum - 1
        if self.PageNum < 0:
            self.PageNum = 0
        self.updateLabels()

    def NextPage(self, event):
        if self.song_per_page * (self.PageNum + 1) - 1 < len(self.Song):
            self.PageNum = self.PageNum + 1
        self.updateLabels()


app = QtGui.QApplication(sys.argv)
GUI = Window()
sys.exit(app.exec_())