Render.cc

#include <QImage>
#include <QImageReader>
#include <poppler-qt5.h>
#include <cmath>
#include "Render.hh"

void DisplayRenderer::adjustImage(QImage& image, int brightness, int contrast, bool invert) const {
    if(brightness == 0 && contrast == 0 && !invert) {
        return;
    }

    double kBr = 1.0 - std::abs(brightness / 200.0);
    double dBr = brightness > 0 ? 255.0 : 0.0;

    double kCn = contrast * 2.55;
    double FCn = (259.0 * (kCn + 255.0)) / (255.0 * (259.0 - kCn));

    int nLinePixels = image.bytesPerLine() / 4;
    int nLines = image.height();
    #pragma omp parallel for
    for(int line = 0; line < nLines; ++line) {
        QRgb* rgb = reinterpret_cast<QRgb*>(image.scanLine(line));
        for(int i = 0; i < nLinePixels; ++i) {
            int red = qRed(rgb[i]);
            int green = qGreen(rgb[i]);
            int blue = qBlue(rgb[i]);
            // Brighntess
            red = dBr * (1.0 - kBr) + red * kBr;
            green = dBr * (1.0 - kBr) + green * kBr;
            blue = dBr * (1.0 - kBr) + blue * kBr;
            // Contrast
            red = std::max(0.0, std::min(FCn * (red - 128.0) + 128.0, 255.0));
            green = std::max(0.0, std::min(FCn * (green - 128.0) + 128.0, 255.0));
            blue = std::max(0.0, std::min(FCn * (blue - 128.0) + 128.0, 255.0));
            // Invert
            if(invert) {
                red = 255 - red;
                green = 255 - green;
                blue = 255 - blue;
            }

            rgb[i] = qRgb(red, green, blue);
        }
    }
}

ImageRenderer::ImageRenderer(const QString& filename) : DisplayRenderer(filename) {
    m_pageCount = QImageReader(m_filename).imageCount();
}

QImage ImageRenderer::render(int page, double resolution) const {
    QImageReader reader(m_filename);
    reader.jumpToImage(page - 1);
    reader.setBackgroundColor(Qt::white);
    reader.setScaledSize(reader.size() * resolution / 100.0);
    return reader.read().convertToFormat(QImage::Format_RGB32);
}

PDFRenderer::PDFRenderer(const QString& filename, const QByteArray& password) : DisplayRenderer(filename) {
    m_document = Poppler::Document::load(filename);
    if(m_document) {
        if(m_document->isLocked()) {
            m_document->unlock(password, password);
        }

        m_document->setRenderHint(Poppler::Document::Antialiasing);
        m_document->setRenderHint(Poppler::Document::TextAntialiasing);
    }
}

PDFRenderer::~PDFRenderer() {
    delete m_document;
}

QImage PDFRenderer::render(int page, double resolution) const {
    if(!m_document) {
        return QImage();
    }
    m_mutex.lock();
    Poppler::Page* poppage = m_document->page(page - 1);
    m_mutex.unlock();
    QImage image = poppage->renderToImage(resolution, resolution);
    delete poppage;
    return image.convertToFormat(QImage::Format_RGB32);
}

int PDFRenderer::getNPages() const {
    return m_document ? m_document->numPages() : 1;
}