PyQt：在其他操作运行时显示动画 GIF

Question

我有一个正在加载的 GIF，我想在特定方法完成之前将其显示为加载屏幕。我的问题是 GIF 不会保留运行因为还有另一个功能在工作，并且 GIF 应该保留运行直到该功能完成。

import sys
import time
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QMovie
from PyQt5.QtWidgets import QApplication, QLabel, QMainWindow

def wait_till_function_done():
    time.sleep(5)

class Window(QMainWindow):

    def __init__(self):
        super().__init__()


class Splash:

    def showSplash(self):
        label = QLabel()
        label.setWindowFlag(Qt.SplashScreen)

        # label for displaying GIF
        self.movie = QMovie(".../Loading.gif")
        label.setMovie(self.movie)

        self.movie.start()
        label.show()

        # -------
        # Simulate the operation that is talking about.
        # The GIF should keep working and playing till the following simulation is done.
        # -------
        # But The GIF stop running and that is because the following line block Qt event

        wait_function_is_done()  # this line simulate this sentence: "keep showing loading screen till the operation is done"


if __name__ == "__main__":
    app = QApplication(sys.argv)
    main_window = Window()
    splash_obj = Splash()
    # start the Splash screen
    splash_obj.showSplash()
    # when it's done, it will be closed and main_app showen
    main_window.show()
    app.exec_()

我尝试将 QThread 与加载 gif 一起使用，因此它会在 method/operation 为运行时更改 gif 帧（并且应该在该功能被关闭时关闭完毕）。但这没有成功：

框架没有改变。（我可以使用 app.processEvents() 这样可以更改帧）。
卡在了while循环中

class GIFThread(QThread):
    signal = pyqtSignal()

    def __init__(self):
        super(GIFThread, self).__init__()

class Splash:

    def showSplash(self):

        .....

        # init thread
        thread = GIFThread()
        thread.signal.connect(self.change_gif_frame)
        thread.start()

        # start changing GIF frames
        thread.signal.emit()

        # -------
        # Simulate the operation.
        time.sleep(5)

        # this should stop the thread and break the while loop
        thread.quit()

    def change_gif_frame(self):
        while True:
            self.movie.jumpToNextFrame()

Answer 1

可能最好使用 QSplashScreen for this, and use QThread 到运行应用程序在后台初始化。如有必要，可以通过自定义信号使用进度消息更新 splash-screen。这是一个基本演示，展示了如何实现它：

import sys
from PyQt5.QtCore import pyqtSignal, Qt, QThread
from PyQt5.QtGui import QMovie
from PyQt5.QtWidgets import QApplication, QSplashScreen, QMainWindow

class Worker(QThread):
    progressChanged = pyqtSignal(int)

    def run(self):
        for count in range(6):
            self.progressChanged.emit(count)
            self.sleep(1)
        self.progressChanged.emit(-1)

class Window(QMainWindow):
    def __init__(self):
        super().__init__()

class SplashScreen(QSplashScreen):
    def __init__(self, filepath, flags=0):
        super().__init__(flags=Qt.WindowFlags(flags))
        self.movie = QMovie(filepath, parent=self)
        self.movie.frameChanged.connect(self.handleFrameChange)
        self.movie.start()

    def updateProgress(self, count=0):
        if count == 0:
            message = 'Starting...'
        elif count > 0:
            message = f'Processing... {count}'
        else:
            message = 'Finished!'
        self.showMessage(
            message, Qt.AlignHCenter | Qt.AlignBottom, Qt.white)

    def handleFrameChange(self):
        pixmap = self.movie.currentPixmap()
        self.setPixmap(pixmap)
        self.setMask(pixmap.mask())

if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = Window()
    splash = SplashScreen('anim.gif', Qt.WindowStaysOnTopHint)
    worker = Worker()
    worker.progressChanged.connect(splash.updateProgress)
    worker.finished.connect(
        lambda: (splash.finish(window), window.show()))
    splash.show()
    worker.start()
    app.exec_()

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