如何在 PyQt5 中创建 QWebEngineView 的打印预览？

Question

我正在尝试创建 QWebEngineView 的打印预览，但我无法让它工作。

这是我的代码：

...
self.view = QWebEngineView()
...

def handle_preview(self):
    dialog = QPrintPreviewDialog()
    dialog.paintRequested.connect(self.view.print_)
    dialog.exec_()

代码给了我这个错误：

AttributeError: 'QWebEngineView' 对象没有属性 'print_'

当我使用 QTextEdit 时，代码运行良好。但这不是我想要的。我想使用 QWebEngineView。

Answer 1

Based on the official example: WebEngine Widgets PrintMe Example you can implement the preview using the following code.

from PyQt5.QtCore import (QCoreApplication, QEventLoop, QObject, QPointF, Qt,
                       QUrl, pyqtSlot)
from PyQt5.QtGui import QKeySequence, QPainter
from PyQt5.QtPrintSupport import QPrintDialog, QPrinter, QPrintPreviewDialog
from PyQt5.QtWebEngineWidgets import QWebEnginePage, QWebEngineView
from PyQt5.QtWidgets import QApplication, QDialog, QLabel, QProgressBar, QProgressDialog, QShortcut


class PrintHandler(QObject):
    def __init__(self, parent = None):
        super().__init__(parent)
        self.m_page = None
        self.m_inPrintPreview = False

    def setPage(self, page):
        assert not self.m_page
        self.m_page = page
        self.m_page.printRequested.connect(self.printPreview)

    @pyqtSlot()
    def print(self):
        printer = QPrinter(QPrinter.HighResolution)
        dialog = QPrintDialog(printer, self.m_page.view())
        if dialog.exec_() != QDialog.Accepted:
            return
        self.printDocument(printer)

    @pyqtSlot()
    def printPreview(self):
        if not self.m_page:
            return
        if self.m_inPrintPreview:
            return
        self.m_inPrintPreview = True
        printer = QPrinter()
        preview = QPrintPreviewDialog(printer, self.m_page.view())
        preview.paintRequested.connect(self.printDocument)
        preview.exec()
        self.m_inPrintPreview = False

    @pyqtSlot(QPrinter)
    def printDocument(self, printer):
        loop = QEventLoop()
        result = False

        def printPreview(success):
            nonlocal result
            result = success
            loop.quit()
        progressbar = QProgressDialog(self.m_page.view())
        progressbar.findChild(QProgressBar).setTextVisible(False)
        progressbar.setLabelText("Wait please...")
        progressbar.setRange(0, 0)
        progressbar.show()
        progressbar.canceled.connect(loop.quit)
        self.m_page.print(printer, printPreview)
        loop.exec_()
        progressbar.close()
        if not result:
            painter = QPainter()
            if painter.begin(printer):
                font = painter.font()
                font.setPixelSize(20)
                painter.setFont(font)
                painter.drawText(QPointF(10, 25), "Could not generate print preview.")
                painter.end()


def main():
    import sys

    QCoreApplication.setAttribute(Qt.AA_EnableHighDpiScaling)
    app = QApplication(sys.argv)
    app.setApplicationName("Previewer")

    view = QWebEngineView()
    view.setUrl(QUrl("https://stackoverflow.com/questions/59438021"))
    view.resize(1024, 750)
    view.show()

    handler = PrintHandler()
    handler.setPage(view.page())

    printPreviewShortCut = QShortcut(QKeySequence(Qt.CTRL + Qt.Key_P), view)
    printShortCut = QShortcut(QKeySequence(Qt.CTRL + Qt.SHIFT + Qt.Key_P), view)

    printPreviewShortCut.activated.connect(handler.printPreview)
    printShortCut.activated.connect(handler.print)

    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

Note: For PySide2 you only have to change pyqtSlot to Slot.