Qt数据库应用之实现图片转pdf

void DataOther::toPdf(const QPixmap &pixmap, const QString &fileName, int scale)
{
    QPrinter printer(QPrinter::HighResolution);
    if (scale > 1) {
        printer.setResolution(96);
    }
    printer.setFullPage(false);
    printer.setOutputFormat(QPrinter::PdfFormat);
    printer.setOutputFileName(fileName);
#if (QT_VERSION >= QT_VERSION_CHECK(5,3,0))
    printer.setPageSize(QPageSize(QPageSize::A4));
    printer.setPageOrientation(QPageLayout::Portrait);
#else
    printer.setPaperSize(QPrinter::A4);
    printer.setOrientation(QPrinter::Portrait);
#endif

    //调整图片大小比如等比例缩放拉伸填充等
    QRectF rect = printer.pageRect(QPrinter::DevicePixel);
    QPixmap pix = pixmap;

    //保存原图看下效果
#if 0
    QString file = fileName;
    file.replace("pdf", "png");
    pix.save(file, "png");
#endif

    if (scale == 0) {
        //pix = pix.scaled(rect.width(), rect.height(), Qt::KeepAspectRatio, Qt::FastTransformation);
        pix = pix.scaled(rect.width(), rect.height(), Qt::KeepAspectRatio, Qt::SmoothTransformation);
    } else if (scale == 1) {
        pix = pix.scaled(rect.width(), rect.height());
    }

    QPainter painter;
    painter.begin(&printer);

    int x = 0;
    int y = 0;
    //图片宽度小于绘制区域宽度没有缩放处理过的图片 才需要按照比例自动居中绘制
    if (pixmap.width() < rect.width() && scale > 1) {
        x = rect.center().x() - pix.width() / 2;
        //y = rect.center().y() - pix.height() / 2;
    }

    painter.drawPixmap(QPoint(x, y), pix);
    painter.end();
}

void DataOther::widgetToPdf(QWidget *widget, const QString &fileName, int scale)
{
#if (QT_VERSION >= QT_VERSION_CHECK(5,0,0))
    QPixmap pixmap = QApplication::primaryScreen()->grabWindow(widget->winId());
#else
    QPixmap pixmap = QPixmap::grabWindow(widget->winId());
#endif
    toPdf(pixmap, fileName, scale);
}

QString DataOther::imageToPdf(const QString &imageFile, const QString &pdfFile, int scale)
{
    //为空则同名文件
    QString fileName = pdfFile;
    if (fileName.isEmpty()) {
        fileName = imageFile;
        fileName.replace("." + QFileInfo(imageFile).suffix(), ".pdf");
    }

    //资源文件则当前目录下
    if (imageFile.startsWith(":/")) {
        fileName = qApp->applicationDirPath() + "/" + QFileInfo(imageFile).baseName() + ".pdf";
    }

    toPdf(QPixmap(imageFile), fileName, scale);
    return fileName;
}