How to reduce output file size and printing time?

[deleted385]

Tried to follow this thread for page footer and it draws page footer correctly:

BUT takes much longer time and produces much larger file size than necessary. Also, not sure whether I've screwed up the actual process anywhere in code! Here's the code:

Window::Window(QWidget *parent) : QWidget(parent){
    document = new QTextDocument();
    document->setUndoRedoEnabled(false);
    printer = new QPrinter();
    printer->setPageSize(QPageSize::A4);
    printer->setPageMargins(QMarginsF(72,72,72,72), QPageLayout::Point);
    printer->setResolution(fontMetrics().fontDpi());
    auto pageRect = printer->pageRect(QPrinter::DevicePixel).size();
    document->setPageSize(QSizeF(pageRect.width(), pageRect.height()));
    createDocument();
    auto lay = new QVBoxLayout(this);
    auto button = new QPushButton("Pint PDF", this);
    lay->addWidget(button);
    connect(button, &QPushButton::clicked, [=]{
        QElapsedTimer timer;
        timer.start();
        printer->setOutputFormat(QPrinter::PdfFormat);
        printer->setOutputFileName("test.pdf");
        //document->print(printer);
        bool firstPage = true;
        int pageCount = document->pageCount();
        QRectF textRect(0, 0, pageRect.width(), pageRect.height());
        QPainter painter(printer);
        for (int pageNo = 0; pageNo < pageCount; pageNo++) {
            if (!firstPage) printer->newPage();
            const QRectF textPageRect(0, pageNo * document->pageSize().height(), document->pageSize().width(), document->pageSize().height());
            painter.save();
            painter.setClipRect(textRect);
            painter.translate(0, -textPageRect.top());
            document->drawContents(&painter);
            painter.restore();
            QRectF footerRect(0, textRect.height(), textRect.width(), fontMetrics().height());
            painter.drawLine(footerRect.left(),footerRect.top(),footerRect.right(),footerRect.top());
            painter.drawText(footerRect, Qt::AlignVCenter | Qt::AlignRight, QObject::tr("Page %1/%2").arg(pageNo+1).arg(pageCount));
            firstPage = false;
        }
        qDebug() << timer.elapsed();
    });
}
void Window::addHeader(QTextCursor& cursor){
    QTextTableCellFormat cellFormat;
    cellFormat.setTopBorder(1);
    cellFormat.setBottomBorder(1);
    cellFormat.setBorderBrush(Qt::black);
    cellFormat.setTopBorderStyle(QTextFrameFormat::BorderStyle_Solid);
    cellFormat.setBottomBorderStyle(QTextFrameFormat::BorderStyle_Solid);
    QTextCharFormat textFormat;
    textFormat.setFontWeight(QFont::Bold);
    for (int i = 0; i < 4; i++) {
        auto cell = cursor.currentTable()->cellAt(0, i);
        cell.setFormat(cellFormat);
        cursor.insertText("Column " + QString::number(i + 1), textFormat);
        cursor.movePosition(QTextCursor::NextCell);
    }
}
QTextTableFormat Window::format(){
    QTextTableFormat tableFormat;
    tableFormat.setBorder(0);
    tableFormat.setCellSpacing(0);
    tableFormat.setCellPadding(0);
    tableFormat.setHeaderRowCount(1);
    QVector<QTextLength> columnLengths;
    columnLengths.append(QTextLength(QTextLength::PercentageLength, 40));
    columnLengths.append(QTextLength(QTextLength::PercentageLength, 20));
    columnLengths.append(QTextLength(QTextLength::PercentageLength, 20));
    columnLengths.append(QTextLength(QTextLength::PercentageLength, 20));
    tableFormat.setColumnWidthConstraints(columnLengths);
    return tableFormat;
}
void Window::createDocument(){
    int row = 2500, column = 4;
    QTextCursor cursor(document);
    cursor.insertTable(1, 4, format());
    addHeader(cursor);
    for (int r = 1; r < row; r++) {
        cursor.currentTable()->appendRows(1);
        cursor = cursor.currentTable()->rowStart(cursor);
        cursor.movePosition(QTextCursor::NextCell);
        for (int c = 0; c < column; c++) {
            cursor.insertText("Row " + QString::number(r) + " Column " + QString::number(c));
            cursor.movePosition(QTextCursor::NextCell);
        }
    }
}

It produces 2.4MB pdf and takes ~35/40sec to print. If I uncomment //document->print(printer); in the lambda in constructor and comment out rest of the code up to qDebug() << timer.elapsed(); it takes ~5/6sec to print and produces 107KB pdf.

[artwaw]

@Emon-Haque But have you tried to actually comment out setClipRect() and put it as a param to the drawContents()? Long shot but I don't see anything off with your code so it must be something internal to Qt rather.

[artwaw]

@Emon-Haque said in How to reduce output file size and printing time?:

this thread

In the same thread OP gives a hint: https://forum.qt.io/post/366382

[deleted385]

@artwaw, I've that painter.setClipRect(textRect);

EDIT
@artwaw, oh drawContent also takes clipRect in addition to painter's! With that:

document->drawContents(&painter, QRectF(0, textPageRect.top(), textRect.width(), textRect.height()));

it's ok. painter.setClipRect(textRect); isn't necessary.

[artwaw]

@Emon-Haque But have you tried to actually comment out setClipRect() and put it as a param to the drawContents()? Long shot but I don't see anything off with your code so it must be something internal to Qt rather.

[deleted385]

@artwaw, now it's ok. See the edited part.