How can I prevent a QTextTable row being split over page breaks?

l3u_

Hi all!

I'm implementing a small program to print lists of items with QR codes containing item-specific data. The following happens both when using Qt 5.15.8 and 6.4.2.

I use a QTextDocument and several QTextTables, in separate QTextBlocks. This is the first time I mess with printing, so maybe, It's some beginner issue. However, I have no idea why the following happens or how to prevent it:

At a specific size of the QR codes, everything is fine. The printed PDF looks like it should:

But as soon as I slightly increase the size of the QR codes, rows at the end of a page are split and appear on two pages. Also the text is displaced:

How can I prevent this?

Thanks for all help!

SGaist

Hi,

Can you provide a minimal compilable example that shows this behaviour ?

In the old days, I remember implementing the tables using html and doing checks to learn when the split would happen and ensure rows would break at the right time.

l3u_

@SGaist Hi :-)

The following minimal example produces a split up row:

#include <QApplication>
#include <QImage>
#include <QPrinter>
#include <QTextDocument>
#include <QTextCursor>
#include <QTextTableFormat>
#include <QTextImageFormat>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QPrinter printer(QPrinter::HighResolution);
    printer.setPageSize(QPageSize::A4);
    printer.setOutputFormat(QPrinter::PdfFormat);
    printer.setOutputFileName(QStringLiteral("/tmp/demo.pdf"));

    QTextDocument document;
    QTextCursor cursor(&document);

    QTextTableFormat tableFormat;
    tableFormat.setWidth(QTextLength(QTextLength::PercentageLength, 100));
    tableFormat.setCellPadding(10);
    tableFormat.setBorderCollapse(true);
    tableFormat.setBorderBrush(QBrush(Qt::SolidPattern));
    cursor.insertTable(16, 3, tableFormat);

    for (int i = 0; i < 16; i++) {
        cursor.insertText(QStringLiteral("Some text"));
        cursor.movePosition(QTextCursor::NextCell);
        cursor.insertText(QStringLiteral("Some price"));
        cursor.movePosition(QTextCursor::NextCell);
        QImage image(57, 57, QImage::Format_RGB32);
        image.fill(qRgb(0, 0, 0));
        const auto url = QStringLiteral("mydata://%1.png").arg(i);
        document.addResource(QTextDocument::ImageResource, QUrl(url), QVariant(image));
        QTextImageFormat pictureFormat;
        pictureFormat.setName(url);
        pictureFormat.setHeight(90);
        pictureFormat.setWidth(90);
        cursor.insertImage(pictureFormat);
        cursor.movePosition(QTextCursor::NextCell);
    }

    document.print(&printer);

    return app.exec();
}

The output /tmp/demo.pdf renders als follows (at least here …):

l3u_

Okay. While it still would be interesting how to fix this:

For my use-case, it actually seems to be easier to generate a HTML file (HTML 5 with full CSS) and let a browser print it. This way, the browser has to mess with all the page layouting, and the result looks good. Also creating it seems to be easier …