I want to access progress bar's (which is in the Ui_MainWindow() class) setMaximum() from another class/thread (DownloadThread() class).

我嘗試讓 DownloadThread() 類繼承自 Ui_MainWindow:DownloadThread(Ui_MainWindow).但是當(dāng)我嘗試設(shè)置最大進(jìn)度條值時(shí):

I tried making DownloadThread() class inherit from Ui_MainWindow: DownloadThread(Ui_MainWindow). But when I try to set the maximum progress bar value:

Ui_MainWindow.progressBar.setMaximum(100)

我收到此錯(cuò)誤:

AttributeError:類型對(duì)象Ui_MainWindow"沒(méi)有屬性progressBar"

AttributeError: type object 'Ui_MainWindow' has no attribute 'progressBar'

我的代碼:

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        # ...
        self.updateButton = QtGui.QPushButton(self.centralwidget)
        self.progressBar = QtGui.QProgressBar(self.centralwidget)
        self.updateStatusText = QtGui.QLabel(self.centralwidget)
        # ...
        self.updateButton.clicked.connect(self.download_file)
        # ...

    def download_file(self):
        self.thread = DownloadThread()
        self.thread.data_downloaded.connect(self.on_data_ready)
        self.thread.start()

    def on_data_ready(self, data):
        self.updateStatusText.setText(str(data))


class DownloadThread(QtCore.QThread, Ui_MainWindow):

    data_downloaded = QtCore.pyqtSignal(object)

    def run(self):
        self.data_downloaded.emit('Status: Connecting...')

        ftp = FTP('example.com')
        ftp.login(user='user', passwd='pass')

        ftp.cwd('/some_directory/')

        filename = '100MB.bin'
        totalsize = ftp.size(filename)
        print(totalsize)

        # SET THE MAXIMUM VALUE OF THE PROGRESS BAR
        Ui_MainWindow.progressBar.setMaximum(totalsize)          

        self.data_downloaded.emit('Status: Downloading...')

        global localfile
        with open(filename, 'wb') as localfile:
            ftp.retrbinary('RETR ' + filename, self.file_write)

        ftp.quit()
        localfile.close()

        self.data_downloaded.emit('Status: Updated!')

    def file_write(self, data):
        global localfile
        localfile.write(data)
        print(len(data))

推薦答案

直接的問(wèn)題是 Ui_MainWindow 是一個(gè)類，而不是類的實(shí)例.您必須將窗口"self 傳遞給 DownloadThread.但這無(wú)論如何都不是正確的解決方案.您不能從另一個(gè)線程訪問(wèn) PyQt 小部件.相反，使用您已經(jīng)使用的相同技術(shù)來(lái)更新?tīng)顟B(tài)文本(FTP 下載，帶有顯示當(dāng)前狀態(tài)的文本標(biāo)簽下載).

The immediate problem is that Ui_MainWindow is a class, not an instance of the class. You would have to pass your "window" self to the DownloadThread. But that's not the right solution anyway. You cannot access PyQt widgets from another thread. Instead, use the same technique as you already do, to update the status text (FTP download with text label showing the current status of the download).

class Ui_MainWindow(object):
    def download_file(self):
        self.thread = DownloadThread()
        self.thread.data_downloaded.connect(self.on_data_ready)
        self.thread.data_progress.connect(self.on_progress_ready)
        self.progress_initialized = False
        self.thread.start()

    def on_progress_ready(self, data):
        # The first signal sets the maximum, the other signals increase a progress
        if self.progress_initialized:
            self.progressBar.setValue(self.progressBar.value() + int(data))
        else:
            self.progressBar.setMaximum(int(data))
            self.progress_initialized = True

class DownloadThread(QtCore.QThread):

    data_downloaded = QtCore.pyqtSignal(object)
    data_progress = QtCore.pyqtSignal(object)

    def run(self):
        self.data_downloaded.emit('Status: Connecting...')

        with FTP('example.com') as ftp:
            ftp.login(user='user', passwd='pass')

            ftp.cwd('/some_directory/')

            filename = '100MB.bin'
            totalsize = ftp.size(filename)
            print(totalsize)

            # The first signal sets the maximum
            self.data_progress.emit(str(totalsize))

            self.data_downloaded.emit('Status: Downloading...')

            with open(filename, 'wb') as self.localfile:
                ftp.retrbinary('RETR ' + filename, self.file_write)

        self.data_downloaded.emit('Status: Updated!')

    def file_write(self, data):
        self.localfile.write(data)
        # The other signals increase a progress
        self.data_progress.emit(str(len(data)))

對(duì)代碼的其他更改:

• global localfile 是一種不好的做法.請(qǐng)改用 self.localfile.
• 不需要 localfile.close()，with 可以解決這個(gè)問(wèn)題.
• 類似地，ftp.quit() 應(yīng)該替換為 with.
• DownloadThread 無(wú)需從 Ui_MainWindow 繼承.

• global localfile is a bad practice. Use self.localfile instead.
• There's no need for localfile.close(), with takes care of that.
• Similarly ftp.quit() should be replaced with with.
• There's no need for DownloadThread to inherit from Ui_MainWindow.

這篇關(guān)于從另一個(gè)運(yùn)行 FTP 下載的線程更新 PyQt 進(jìn)度的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！