The HTML table length and width is not taken in consideration when printing

Question

Using Pyside6, I am trying to print an HTML Table. The HTML table format looks good in browser. However, when I open it up in print preview in Pyside6, the length and width of the table are not considered and the table collapses.

Devlopment Environment:

1. Ubuntu 20.04
2. Python 3.8.10 (using python virtual environment)
3. PySide6 version 6.1.3

I also tried the same code in Windows with Python 3.9.7 and Pyside6 version 6.2, and got the same result.

Expected:

Actual:

main.py

from PySide6.QtGui import (
    QPageSize,
    QPageLayout,
    QTextBlockFormat,
    QTextCursor,
    QTextDocument,
    QTextFormat,
)
from PySide6.QtWidgets import QApplication
from PySide6.QtPrintSupport import QPrinter, QPrintPreviewDialog

app = QApplication()

dialog = QPrintPreviewDialog()


def handle_paint_requested(printer):
    document = QTextDocument()
   
    f = open("template.html", "r")
    billTemplate = f.read()

    document.setHtml(billTemplate)
    document.print_(printer)


dialog.paintRequested.connect(handle_paint_requested)
dialog.exec()

template.html

<p>&nbsp;</p>
<table style="border-collapse: collapse; width: 300px;" border="1">
    <tbody>
        <tr>
            <td style="width: 50%; height: 50px;">test1</td>
            <td style="width: 50%; height: 50px;">&nbsp;</td>
        </tr>
    </tbody>
</table>

Answer 1

Since QTextDocument only supports a subset of HTML4 properties it causes the observed error.

One workaround is to use QtWebEngine which was reintroduced in Qt 6.2. Currently only the windows .whl is available in pypi (See here and here for more information) so we can install the Linux and MacOs package you must execute:

python -m pip install pyside6 \
   --index-url=http://download.qt.io/official_releases/QtForPython

So translating my previous answer to PySide6:

import os
from pathlib import Path

from PySide6.QtCore import (
    QCoreApplication,
    QEventLoop,
    QObject,
    QPointF,
    Qt,
    QUrl,
    Slot,
)
from PySide6.QtGui import QKeySequence, QPainter, QShortcut
from PySide6.QtPrintSupport import QPrintDialog, QPrinter, QPrintPreviewDialog
from PySide6.QtWebEngineWidgets import QWebEngineView
from PySide6.QtWidgets import (
    QApplication,
    QDialog,
    QProgressBar,
    QProgressDialog,
)

CURRENT_DIRECTORY = Path(__file__).resolve().parent


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)

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

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

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

        def printPreview(success):
            nonlocal result
            result = success
            loop.quit()

        view = QWebEngineView.forPage(self.m_page)
        view.printFinished.connect(printPreview)
        progressbar = QProgressDialog(view)
        progressbar.findChild(QProgressBar).setTextVisible(False)
        progressbar.setLabelText("Wait please...")
        progressbar.setRange(0, 0)
        progressbar.show()
        progressbar.canceled.connect(loop.quit)
        view.print(printer)
        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")

    filename = CURRENT_DIRECTORY / "template.html"
    url = QUrl.fromLocalFile(os.fspath(filename))

    view = QWebEngineView()
    view.setUrl(url)
    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()

After pressing Ctrl + P you get: