PySide6 我可以将回调与其调用方方法同步吗？

Question

这是我的代码。

from PySide6 import QtGui,QtCore,QtWidgets,QtWebEngineWidgets
from PySide6.QtWebEngineCore import QWebEngineDownloadRequest, QWebEnginePage

# all these are in some class
self.myView = QtWebEngineWidgets.QWebEngineView()

def getValue(self):
    self.myView.page().runJavaScript(
        '''
        (function () {
            finds = document.getElementsByClassName('ps');
            if (finds.length > 0) return finds[0].offsetWidth;
            return -1;
        })();
        ''', 0, self._getvalueCallback)
    # i want to wait for the callback and return the value.
    # want to make it to work synchronously.

def _getvalueCallback(self, value):
    if type(value) is float:
        self._value = int(value)
    else:
        self._value = -1

这可能吗..？ 我尝试使用threading.Event但没有工作，因为event.waiting()只是阻塞了线程和回调。

Answer 1

您可以使用 QEventLoop：

from collections import deque
from functools import partial

from PySide6 import QtGui, QtCore, QtWidgets, QtWebEngineWidgets


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.myView = QtWebEngineWidgets.QWebEngineView()
        self.setCentralWidget(self.myView)
        self.myView.load(QtCore.QUrl("https://stackoverflow.com/"))

        QtCore.QTimer.singleShot(4000, self.handle_timeout)

    def handle_timeout(self):
        value = self.getValue()
        print("value:", value)

    def getValue(self):
        q = deque()
        loop = QtCore.QEventLoop()
        self.myView.page().runJavaScript(
            """
            (function () {
                finds = document.getElementsByClassName('ps');
                if (finds.length > 0) return finds[0].offsetWidth;
                return -1;
            })();
            """,
            0,
            partial(self._getvalueCallback, loop, q),
        )
        loop.exec()
        return q.pop()

    def _getvalueCallback(self, loop, q, value):
        q.append(int(value) if isinstance(value, float) else -1)
        loop.quit()


if __name__ == "__main__":
    app = QtWidgets.QApplication()
    mw = MainWindow()
    mw.show()
    app.exec()