基于javafx如何用线程完成移动一个圆？

Posted 2023-04-19

运用JavaFX技术设计如图3所示简单动画（动画效果见视频 移动的圆.avi）。窗口宽400，高200，圆半径50，圆心纵坐标100，圆边框黑色线宽3像素。移动速度：1像素/20毫秒。

利用“绘图”菜单可以插入线段，方法如下： 1、单击“绘图”菜单下的“自选图形”，选择“线条”菜单下的“直线” 2、屏幕中出现“在此处创建图形”，我们不利用这个文本框调整线条的位置，在这个文本档的下方绘制线段 3、在文本框的下方，按住鼠标左键同时. 参考技术A 可以在“按钮点击事件”中写上读取fmxl为节点对象 Parent root = FXMLLoader.load(getClass().getResource("fxml_example.fxml")); 然后把父节点放入某个new Scene(root,320,200); 然后在显示在所用的舞台stage上。

我如何用 pafy 为进度条制作线程

【中文标题】我如何用 pafy 为进度条制作线程

【英文标题】：how i can make thread for progress bar with pafy

【发布时间】：2019-01-04 14:55:11

【问题描述】：

我正在尝试解决我的程序中的问题，这个问题是当我开始下载视频时，程序没有响应，我也看不到进度条移动，所以我尝试使用线程模块，但我无法解决问题所以我该如何解决问题

通过此代码，我可以下载视频并将数据发送到另一个函数，以检索我用来将其连接到进度条的信息

def video(self):
    video_url = self.lineEdit_4.text()
    video_save = self.lineEdit_3.text()

    pafy_video = pafy.new(video_url)
    type_video = pafy_video.videostreams

    quality = self.comboBox.currentIndex()

    start_download = type_video[quality].download(filepath=video_save,callback=self.video_progressbar)

此代码是从视频功能接收信息以连接进度条

def video_progressbar(self,total, recvd, ratio, rate, eta):
    self.progressBar_2.setValue(ratio * 100)

我用;python3.5 pyqt5 pafy

【参考方案1】：

移动到另一个线程的一种方法是创建一个位于另一个线程中的QObject，并在一个槽中执行该任务。并且该槽必须通过QMetaObject::invokeMethod 或信号调用。

with QThread and QMetaObject::invokeMethod:

import pafy
from PyQt5 import QtCore, QtWidgets

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        central_widget = QtWidgets.QWidget()
        self.setCentralWidget(central_widget)

        self.le_url = QtWidgets.QLineEdit("https://www.youtube.com/watch?v=bMt47wvK6u0")
        path = QtCore.QStandardPaths.writableLocation(QtCore.QStandardPaths.DownloadLocation)
        self.le_output = QtWidgets.QLineEdit(path)
        self.btn_quality = QtWidgets.QPushButton("Get qualities")
        self.combo_quality = QtWidgets.QComboBox()
        self.btn_download = QtWidgets.QPushButton("Download")
        self.progressbar = QtWidgets.QProgressBar(maximum=100)

        self.downloader = DownLoader()
        thread = QtCore.QThread(self)
        thread.start()
        self.downloader.moveToThread(thread)

        self.btn_quality.clicked.connect(self.on_clicked_quality)
        self.btn_download.clicked.connect(self.download)
        self.btn_download.setDisabled(True)
        self.downloader.progressChanged.connect(self.progressbar.setValue)
        self.downloader.qualitiesChanged.connect(self.update_qualityes)
        self.downloader.finished.connect(self.on_finished)

        form_lay = QtWidgets.QFormLayout(central_widget)
        form_lay.addRow("Url: ", self.le_url)
        form_lay.addRow(self.btn_quality)
        form_lay.addRow("qualities: ", self.combo_quality)
        form_lay.addRow("Output: ", self.le_output) 
        form_lay.addRow(self.btn_download)  
        form_lay.addRow(self.progressbar)

    @QtCore.pyqtSlot()
    def on_finished(self):
        self.update_disables(False)

    @QtCore.pyqtSlot()
    def on_clicked_quality(self):
        video_url = self.le_url.text()
        QtCore.QMetaObject.invokeMethod(self.downloader, "get_qualities",
            QtCore.Qt.QueuedConnection,
            QtCore.Q_ARG(str, video_url))

    @QtCore.pyqtSlot(list)
    def update_qualityes(self, types_of_video):
        for t in types_of_video:
            self.combo_quality.addItem(str(t), t)
        self.btn_download.setDisabled(False)

    @QtCore.pyqtSlot()
    def download(self):
        video_save = self.le_output.text()
        d = self.combo_quality.currentData()
        QtCore.QMetaObject.invokeMethod(self.downloader, "start_download",
            QtCore.Qt.QueuedConnection,
            QtCore.Q_ARG(object, d),
            QtCore.Q_ARG(str, video_save))
        self.update_disables(True)

    def update_disables(self, state):
        self.combo_quality.setDisabled(state)
        self.btn_quality.setDisabled(state)
        self.le_output.setDisabled(state)
        self.le_url.setDisabled(state)
        self.btn_download.setDisabled(not state)

class DownLoader(QtCore.QObject):
    progressChanged = QtCore.pyqtSignal(int)
    qualitiesChanged = QtCore.pyqtSignal(list)
    finished = QtCore.pyqtSignal()

    @QtCore.pyqtSlot(str)
    def get_qualities(self, video_url):
        pafy_video = pafy.new(video_url)
        types_of_video = pafy_video.allstreams # videostreams
        self.qualitiesChanged.emit(types_of_video)

    @QtCore.pyqtSlot(object, str)
    def start_download(self, d, filepath):
        d.download(filepath=filepath, callback=self.callback)

    def callback(self, total, recvd, ratio, rate, eta):
        val = int(ratio * 100)
        self.progressChanged.emit(val)
        if val == 100:
            self.finished.emit()

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.resize(320, 480)
    w.show()
    sys.exit(app.exec_())

with threading.Thread:

import pafy
import threading
from PyQt5 import QtCore, QtWidgets

class MainWindow(QtWidgets.QMainWindow):
    qualitiesChanged = QtCore.pyqtSignal(list)
    progressChanged = QtCore.pyqtSignal(int)
    finished = QtCore.pyqtSignal()

    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        central_widget = QtWidgets.QWidget()
        self.setCentralWidget(central_widget)

        self.le_url = QtWidgets.QLineEdit("https://www.youtube.com/watch?v=bMt47wvK6u0")
        path = QtCore.QStandardPaths.writableLocation(QtCore.QStandardPaths.DownloadLocation)
        self.le_output = QtWidgets.QLineEdit(path)
        self.btn_quality = QtWidgets.QPushButton("Get qualities")
        self.combo_quality = QtWidgets.QComboBox()
        self.btn_download = QtWidgets.QPushButton("Download")
        self.progressbar = QtWidgets.QProgressBar(maximum=100)

        self.btn_quality.clicked.connect(self.on_clicked_quality)
        self.btn_download.clicked.connect(self.download)
        self.btn_download.setDisabled(True)
        self.progressChanged.connect(self.progressbar.setValue)
        self.qualitiesChanged.connect(self.update_qualityes)
        self.finished.connect(self.on_finished)

        form_lay = QtWidgets.QFormLayout(central_widget)
        form_lay.addRow("Url: ", self.le_url)
        form_lay.addRow(self.btn_quality)
        form_lay.addRow("qualities: ", self.combo_quality)
        form_lay.addRow("Output: ", self.le_output) 
        form_lay.addRow(self.btn_download)  
        form_lay.addRow(self.progressbar)

    @QtCore.pyqtSlot()
    def on_finished(self):
        self.update_disables(False)

    @QtCore.pyqtSlot()
    def on_clicked_quality(self):
        video_url = self.le_url.text()
        threading.Thread(target=self.get_qualities, args=(video_url,)).start()

    def get_qualities(self, video_url):
        pafy_video = pafy.new(video_url)
        types_of_video = pafy_video.allstreams # videostreams
        self.qualitiesChanged.emit(types_of_video)

    @QtCore.pyqtSlot(list)
    def update_qualityes(self, types_of_video):
        for t in types_of_video:
            self.combo_quality.addItem(str(t), t)
        self.btn_download.setDisabled(False)

    @QtCore.pyqtSlot()
    def download(self):
        video_save = self.le_output.text()
        d = self.combo_quality.currentData()
        threading.Thread(target=d.download, kwargs='filepath': video_save, 'callback': self.callback, daemon=True).start()

    def callback(self, total, recvd, ratio, rate, eta):
        print(ratio)
        val = int(ratio * 100)
        self.progressChanged.emit(val)
        if val == 100:
            self.finished.emit()

    def update_disables(self, state):
        self.combo_quality.setDisabled(state)
        self.btn_quality.setDisabled(state)
        self.le_output.setDisabled(state)
        self.le_url.setDisabled(state)
        self.btn_download.setDisabled(not state)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.resize(320, 480)
    w.show()
    sys.exit(app.exec_())

【讨论】：

感谢您的代码运行良好，但我的代码无法使用 qthread，我使用的是 QmainWindow

因为我理解你是50%的代码所以我尝试使用qthread，并没有成功解决无响应问题

你刚换了课

我会把我的代码交给你解决我的问题，并将 qthread 放在正确的位置

谢谢你，我再次尝试阅读你的代码，我现在明白了如何使用线程