How can I print a QWidget in Qt?

Question

I need to know how to print a QWidget as a PDF file. The Widget (QDialog) contains a lot of labels, some QPlainTextEdit and a background image. The Dialog shows a receipt with all of its field already filled.

I already tried using QTextDocument and html for this purpose, but the complexity of the receipt(lots of image and format customisation) makes the html output completely messed up.

This is the document.

Receipt image

You can show a [Minimal, Complete, and Verifiable example](https://stackoverflow.com/help/mcve) of your widget. — eyllanesc, Aug 02 '17 at 18:16
I tried QWidget::render() solution but didn't work, showing me this errors: "QPainter::begin: Paint device returned engine == 0, type: 2" "QWidget::render: Cannot render with an inactive painter" — Alexey Smirnov, Aug 02 '17 at 18:32
[Edit](https://stackoverflow.com/posts/45467942/edit) your question and show what you have tried even if it does not work, plus a [mvce](https://stackoverflow.com/help/mcve) of your problem. — eyllanesc, Aug 02 '17 at 18:37
I used the same method explained on [QWidget::render()](http://doc.qt.io/qt-4.8/printing.html) — Alexey Smirnov, Aug 02 '17 at 18:37
I think you have used the following in some part of your code: `QPainter(object)`, what object did you use? — eyllanesc, Aug 02 '17 at 18:41

eyllanesc · Accepted Answer · 2018-10-07T19:52:34.120

You have to use QPrinter and this is the object that you must use and requires QPainter to draw the widget in QPrinter.

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QDialog w;

    w.setLayout(new QVBoxLayout());
    w.layout()->addWidget(new QLineEdit("text"));
    w.layout()->addWidget(new QPushButton("btn"));
    w.layout()->addWidget(new QPlainTextEdit("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Mauris rutrum magna semper nisi faucibus, at auctor dolor ullamcorper. Phasellus facilisis blandit augue sit amet placerat. Aliquam nec imperdiet diam. Proin dignissim vulputate metus, nec tincidunt magna vulputate ac. Praesent vel felis ac dolor viverra tempus eu vitae neque. Nulla efficitur gravida arcu id suscipit. Maecenas placerat egestas velit quis interdum. Nulla diam massa, hendrerit vitae mi et, placerat aliquam nisl. Donec tincidunt lobortis orci, quis egestas augue tempus sed. Nulla vel dolor eget ipsum accumsan placerat ut at magna."));
    w.show();

    QPushButton btn("print");
    btn.show();

    QObject::connect(&btn, &QPushButton::clicked, [&w](){
        QPrinter printer(QPrinter::HighResolution);
        printer.setOutputFormat(QPrinter::PdfFormat);
        printer.setOutputFileName("output.pdf");
        printer.setPageMargins(12, 16, 12, 20, QPrinter::Millimeter);
        printer.setFullPage(false);

        QPainter painter(&printer);

        double xscale = printer.pageRect().width() / double(w.width());
        double yscale = printer.pageRect().height() / double(w.height());
        double scale = qMin(xscale, yscale);
        painter.translate(printer.paperRect().center());
        painter.scale(scale, scale);
        painter.translate(-w.width()/ 2, -w.height()/ 2);
        w.render(&painter);
    });

    return a.exec();
}

Widget:

output.pdf

This worked perfectly, thank you so much. I'm almost sure I tried this too, but by some reason it didn't work, maybe I wrote some wrong arguments. Answer tagged as accepted. — Alexey Smirnov, Aug 02 '17 at 19:30
@AlexeySmirnov Please place arguments that you had placed erroneously but this question is closed because they will think it is duplicated. — eyllanesc, Aug 02 '17 at 19:36

score 0 · Answer 2 · answered Jun 27 '23 at 14:16

Eyllanesc's solution works perfectly but I have warnings on the pageRect() and paperRect() functions. This function seems obsolete. Below is the before and after code without the deprecated functions.

//-------------------------- Code BEFORE --------------------------//
double xscale = printer.pageRect().width() / double(w.width());
double yscale = printer.pageRect().height() / double(w.height());
double scale = qMin(xscale, yscale);
painter.translate(printer.paperRect().center());
painter.scale(scale, scale);
painter.translate(-w.width()/ 2, -w.height()/ 2);
w.render(&painter);
//-----------------------------------------------------------------//

//-------------------------- Code AFTER ---------------------------//
double pageRectWidth  = printer.pageLayout().pageSize().sizePixels(96).width()-printer.pageLayout().marginsPixels(96).left()-printer.pageLayout().marginsPixels(96).right();
double pageRectHeight = printer.pageLayout().pageSize().sizePixels(96).height()-printer.pageLayout().marginsPixels(96).top()-printer.pageLayout().marginsPixels(96).bottom();

double xscale = pageRectWidth / double(w.width());
double yscale = pageRectHeight / double(w.height());
double scale = qMin(xscale, yscale);
painter.translate(QPoint(printer.pageLayout().pageSize().sizePixels(96).width()/2,printer.pageLayout().pageSize().sizePixels(96).height()/2));
painter.scale(scale, scale);
painter.translate(-w.width()/ 2, -w.height()/ 2);
w.render(&painter);
//-----------------------------------------------------------------//

I used 96 in the sizePixels() functions because it's the default resolution.
Hope this code can help :)

How can I print a QWidget in Qt?

2 Answers2

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