QWebEngineView. Can't replace html code and print new pdf

0x5FB5

I have 2 small html files. I've printed the first page successfully, but if I call ...->setHtml again and place html code from another file and call printToPdf with a little modified filename, I see only the first file that was saved before. I've tested and on first pass it prints both htmls successfully. What's wrong?

Here's the code:

QFile file("://cards_src/dentist_043_header.html");
file.open(QIODevice::ReadOnly);

QTextStream input(&file);
QString html = input.readAll();

file.close();

QFile file1("://cards_src/second_page_test.html");
file1.open(QIODevice::ReadOnly);

QTextStream input1(&file1);
QString html1 = input1.readAll();

file1.close();

// do some things
 ...

webView->setHtml(html);

QString path = QFileDialog::getSaveFileName(nullptr, "Сохранить в PDF", fileName + ".pdf", "PDF (*.pdf)");

if (QFileInfo(path).suffix().isEmpty())
    path.append(".pdf");

webView->page()->printToPdf(path);
webView->setHtml(html1);

path.replace(".pdf", "_1.pdf");

webView->page()->printToPdf(path);

0x5FB5

@JonB Yep, I've just found that I need to wait for loading page before printing and the solution is connect loadFinished signal to method I need, that do printToPdf() in it. I thought that WebEngineView does not need to wait for the local html file to load, but it was mistaken.

UPD: Also, I've found a way to print multiple pdfs. You need to make a QEventLoop obj, connect loadFinished signal to QEventLoop::quit and after setHtml just call loop.exec() and you can guarantee that file you need will load and prints correctly only after loading of the previous page code.

Example:

// Header
class MyClass : public QObject
{
    Q_OBJECT

private:
    QEventLoop loop;
    QWebEngineView *webView;

public:
    void saveCardPdf();

// Cpp
MyClass::MyClass(QObject *parent ): QObject(parent)
{
    webView = new QWebEngineView();
    connect(webView, &QWebEngineView::loadFinished, &loop, &QEventLoop::quit);
}

...
void MyClass::saveCardPdf()
{
    ...
    // Load your html code..

    webView->setHtml(html); // html - string of one page
    loop.exec();

    webView->page()->printToPdf(path);

    // Modify name for another file
    path.replace(".pdf", "_1.pdf");

    webView->setHtml(html1); // html1 - string of another page
    loop.exec();

    webView->page()->printToPdf(path);
}

It's not perfect solution, but I think you understand the idea

JonB

@0x5FB5
I don't use QWebView so this is a guess. I wonder whether printToPdf() doesn't happen in the backgroubnd/asynchronously? In which case the web view's HTML must stay the same until the printing has finished? Only then can you change to a new HTML and print that. See e.g. https://stackoverflow.com/questions/59274653/how-to-print-from-qwebengineview. Use QWebEngineView::loadFinished to wait for HTML to be loaded before printing? Or is there a "print finished" signal from printToPdf() which you must wait for before proceeding with the second page?

0x5FB5

@JonB Yep, I've just found that I need to wait for loading page before printing and the solution is connect loadFinished signal to method I need, that do printToPdf() in it. I thought that WebEngineView does not need to wait for the local html file to load, but it was mistaken.

UPD: Also, I've found a way to print multiple pdfs. You need to make a QEventLoop obj, connect loadFinished signal to QEventLoop::quit and after setHtml just call loop.exec() and you can guarantee that file you need will load and prints correctly only after loading of the previous page code.

Example:

// Header
class MyClass : public QObject
{
    Q_OBJECT

private:
    QEventLoop loop;
    QWebEngineView *webView;

public:
    void saveCardPdf();

// Cpp
MyClass::MyClass(QObject *parent ): QObject(parent)
{
    webView = new QWebEngineView();
    connect(webView, &QWebEngineView::loadFinished, &loop, &QEventLoop::quit);
}

...
void MyClass::saveCardPdf()
{
    ...
    // Load your html code..

    webView->setHtml(html); // html - string of one page
    loop.exec();

    webView->page()->printToPdf(path);

    // Modify name for another file
    path.replace(".pdf", "_1.pdf");

    webView->setHtml(html1); // html1 - string of another page
    loop.exec();

    webView->page()->printToPdf(path);
}

It's not perfect solution, but I think you understand the idea