Vfrdtyky

I have no prior experience with Qt/PyQt.
I'm just trying to use PyQt for the web engine capabilities, to 'convert' a folder of html files to pdf documents.

The code works well if there is only 1 html file, but when there are multiple html files it only generates a pdf for the last file in the loop.

I think the issue must be to do with Qt stuff, looping, events etc - but I have no idea where to begin to sort this out. As you can tell I'm only Qt to produce html->pdf, I'm not interested in building a GUI.

I read about using QApplication.processEvents() at the end of the loop may fix this, but the result was the same.
I tried adding a sleep/pause to the code, also the same.

import sys

import os



from PyQt5.QtWidgets import QApplication

from PyQt5.QtWebEngineWidgets import QWebEngineView

from PyQt5.QtCore import QDir, QUrl



# read somewhere this is needed to load local html, works without for me though

sys.argv.append("--disable-web-security")

app = QApplication(sys.argv)



iter_num = 0



directory = 'my_webfile_directory'

for filename in os.listdir(directory):

    if filename.endswith(".htm") or filename.endswith(".html"):

        with open(os.path.join(directory, filename), 'r') as myfile:



            print(filename)

            raw_html = myfile.read()

            # init qt web view

            view = QWebEngineView()

            view.setHtml(raw_html)



            # set to close web view after pdf is created

            view.page().pdfPrintingFinished.connect(view.close)

            # generate filename

            iter_num += 1

            outputfilename = str(iter_num) + ".pdf"

            outputfullpath = os.path.join(directory, outputfilename)



            def save_pdf(finished):

                view.page().printToPdf(outputfullpath)

            # when web view is ready, save the pdf

            view.loadFinished.connect(save_pdf)

            # QApplication.processEvents()



app.exec()

I think QWebEngineView is not thread-safe because I was able to make it work consistently by creating a queue of files to be processed and executing one after the other using a signal, here is a demo application:

import sys

import os



from PyQt5.QtWidgets import QApplication, QMainWindow, QMessageBox

from PyQt5.QtWebEngineWidgets import QWebEngineView

from PyQt5.QtCore import QObject, QDir, QUrl, pyqtSignal





class HtmlToPdfConverter(QObject):



    queueProcessed = pyqtSignal()



    def __init__(self):

        super().__init__()



        self._queue = 

        self._current = None



    def queue(self, html_file, output_file):

        self._queue.append((html_file, output_file))



    def process_queue(self):

        if self._queue:

            raw_html = ''

            self._current = self._queue.pop(0)

            with open(self._current[0], 'r') as my_file:

                raw_html = my_file.read()



            view = QWebEngineView()

            view.loadFinished.connect(self._get_load_finished_event(view))

            view.page().pdfPrintingFinished.connect(self._get_printing_finished_event(view))

            view.setHtml(raw_html)

        else:

            self.queueProcessed.emit()



    def _get_load_finished_event(self, view):

        def _load_finished(success):

            if success:

                view.page().printToPdf(self._current[1])

        return _load_finished



    def _get_printing_finished_event(self, view):

        def _printing_finished(file, success):

            view.close()

            self.process_queue()

        return _printing_finished





class App(QApplication):

    def __init__(self, sys_argv):

        super().__init__(sys_argv)



        self.dummy_window = QMainWindow()

        self.dummy_window.show()



    def generate_pdfs(self, directory):

        converter = HtmlToPdfConverter()

        converter.queueProcessed.connect(self._queue_processed)



        iter_num = 0



        for filename in os.listdir(directory):

            if filename.endswith(".htm") or filename.endswith(".html"):

                iter_num += 1

                out_filename = os.path.join(directory, str(iter_num) + ".pdf")

                converter.queue(os.path.join(directory, filename), out_filename)



        converter.process_queue()



    def _queue_processed(self):

        QMessageBox.information(self.dummy_window, 'Pdf Generator', 'All PDF files have been generated.')





if __name__ == '__main__':

    app = App(sys.argv)

    app.generate_pdfs('c:/temp/test')



    sys.exit(app.exec_())