第 x 页，共 y 页，使用 QPrinter

page x of y using QPrinter

本文关键字：使用 QPrinter      更新时间：2023-10-16

im 使用 qt 从 HTML 代码生成 PDF 文件：

QTextDocument *document = new QTextDocument();
document->setHtml(htmlContent);
QPrinter printer(QPrinter::HighResolution);
printer.setPageSize(QPrinter::A4);
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setOutputFileName("filename.pdf");
document->print(printer);

是否可以拥有页面信息"第 X 页，共 Y 页"，而不仅仅是页码？如果是，如何？

我提出的解决方案基于此代码。我添加了对高分辨率的必要支持

static const int textMargins = 12; // in millimeters
static const int borderMargins = 10; // in millimeters
static double mmToPixels(QPrinter& printer, int mm)
{
    return mm * 0.039370147 * printer.resolution();
}
static void paintPage(int pageNumber, int pageCount,
                      QPainter* painter, QTextDocument* doc,
                      const QRectF& textRect, qreal footerHeight)
{

    painter->save();
    // textPageRect is the rectangle in the coordinate system of the QTextDocument, in pixels,
    // and starting at (0,0) for the first page. Second page is at y=doc->pageSize().height().
    const QRectF textPageRect(0, pageNumber * doc->pageSize().height(), doc->pageSize().width(), doc->pageSize().height());
    // Clip the drawing so that the text of the other pages doesn't appear in the margins
    painter->setClipRect(textRect);
    // Translate so that 0,0 is now the page corner
    painter->translate(0, -textPageRect.top());
    // Translate so that 0,0 is the text rect corner
    painter->translate(textRect.left(), textRect.top());
    doc->drawContents(painter);
    painter->restore();
    QRectF footerRect = textRect;
    footerRect.setTop(textRect.bottom());
    footerRect.setHeight(footerHeight);
    painter->drawText(footerRect, Qt::AlignVCenter | Qt::AlignRight, QObject::tr("Page %1 of %2").arg(pageNumber+1).arg(pageCount));
}
static void printDocument(QPrinter& printer, QTextDocument* doc)
{
    QPainter painter( &printer );
    doc->documentLayout()->setPaintDevice(&printer);
    doc->setPageSize(printer.pageRect().size());
    QSizeF pageSize = printer.pageRect().size(); // page size in pixels
    // Calculate the rectangle where to lay out the text
    const double tm = mmToPixels(printer, textMargins);
    const qreal footerHeight = painter.fontMetrics().height();
    const QRectF textRect(tm, tm, pageSize.width() - 2 * tm, pageSize.height() - 2 * tm - footerHeight);
    doc->setPageSize(textRect.size());
    const int pageCount = doc->pageCount();
    bool firstPage = true;
    for (int pageIndex = 0; pageIndex < pageCount; ++pageIndex) {
        if (!firstPage)
            printer.newPage();
        paintPage(pageIndex, pageCount, &painter, doc, textRect, footerHeight );
        firstPage = false;
    }
}

例：

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QTextDocument *document = new QTextDocument();
    QTextCursor cursor(document);
    QTextBlockFormat blockFormat;

    for(int i=0; i < 10; i++){
        cursor.insertBlock(blockFormat);
        cursor.insertHtml(QString("<h1>This is the %1 page</h1>").arg(i+1));
        blockFormat.setPageBreakPolicy(QTextFormat::PageBreak_AlwaysBefore);
    }

    QPrinter printer(QPrinter::HighResolution);
    printer.setPageSize(QPrinter::A4);
    printer.setOutputFormat(QPrinter::PdfFormat);
    printer.setOutputFileName("filename.pdf");;
    printDocument(printer, document);
    return app.exec();
}
以上

是一个很好的解决方案，但如果在打印后使用它，则会破坏您的 QTextDocument 对象。我有一个QTextDocument，它是对话框的成员，当提供打印机(paintDevice(的调用函数失去范围时，它会使文档崩溃。

我建议在函数开始时获取当前 paintDevice 的指针，然后在结束时恢复它。

    static void printDocument(QPrinter& printer, QTextDocument* doc)
{
    QPaintDevice * oldDevice=doc->documentLayout()->paintDevice();
    doc->documentLayout()->setPaintDevice(&printer);    
    doc->documentLayout()->setPaintDevice(oldDevice);
}
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