path: root/src/pdf/qpdflinkmodel.cpp

// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qpdflink_p.h"
#include "qpdflinkmodel.h"
#include "qpdflinkmodel_p.h"
#include "qpdfdocument_p.h"

#include "third_party/pdfium/public/fpdf_doc.h"
#include "third_party/pdfium/public/fpdf_text.h"

#include <QLoggingCategory>
#include <QMetaEnum>

QT_BEGIN_NAMESPACE

Q_LOGGING_CATEGORY(qLcLink, "qt.pdf.links")

/*!
    \class QPdfLinkModel
    \since 6.6
    \inmodule QtPdf
    \inherits QAbstractListModel

    \brief The QPdfLinkModel class holds the geometry and the destination for
    each link that the specified \l page contains.

    This is used in PDF viewers to implement the hyperlink mechanism.
*/

/*!
    \enum QPdfLinkModel::Role

    \value Link A QPdfLink object.
    \value Rectangle Bounding rectangle around the link.
    \value Url If the link is a web link, the URL for that; otherwise an empty URL.
    \value Page If the link is an internal link, the page number to which the link should jump; otherwise \c {-1}.
    \value Location If the link is an internal link, the location on the page to which the link should jump.
    \value Zoom If the link is an internal link, the suggested zoom level on the destination page.
    \omitvalue NRoles
*/

/*!
    Constructs a new link model with parent object \a parent.
*/
QPdfLinkModel::QPdfLinkModel(QObject *parent)
    : QAbstractListModel(parent),
      d_ptr{std::make_unique<QPdfLinkModelPrivate>(this)}
{
    Q_D(QPdfLinkModel);
    QMetaEnum rolesMetaEnum = metaObject()->enumerator(metaObject()->indexOfEnumerator("Role"));
    for (int r = Qt::UserRole; r < int(Role::NRoles); ++r)
        d->roleNames.insert(r, QByteArray(rolesMetaEnum.valueToKey(r)).toLower());
}

/*!
    Destroys the model.
*/
QPdfLinkModel::~QPdfLinkModel() {}

QHash<int, QByteArray> QPdfLinkModel::roleNames() const
{
    Q_D(const QPdfLinkModel);
    return d->roleNames;
}

/*!
    \reimp
*/
int QPdfLinkModel::rowCount(const QModelIndex &parent) const
{
    Q_D(const QPdfLinkModel);
    Q_UNUSED(parent);
    return d->links.size();
}

/*!
    \reimp
*/
QVariant QPdfLinkModel::data(const QModelIndex &index, int role) const
{
    Q_D(const QPdfLinkModel);
    const auto &link = d->links.at(index.row());
    switch (Role(role)) {
    case Role::Link:
        return QVariant::fromValue(link);
    case Role::Rectangle:
        return link.rectangles().empty() ? QVariant() : link.rectangles().constFirst();
    case Role::Url:
        return link.url();
    case Role::Page:
        return link.page();
    case Role::Location:
        return link.location();
    case Role::Zoom:
        return link.zoom();
    case Role::NRoles:
        break;
    }
    if (role == Qt::DisplayRole)
        return link.toString();
    return QVariant();
}

/*!
    \property QPdfLinkModel::document
    \brief The document to load links from.
*/
QPdfDocument *QPdfLinkModel::document() const
{
    Q_D(const QPdfLinkModel);
    return d->document;
}

void QPdfLinkModel::setDocument(QPdfDocument *document)
{
    Q_D(QPdfLinkModel);
    if (d->document == document)
        return;
    if (d->document)
        disconnect(d->document, &QPdfDocument::statusChanged, this, &QPdfLinkModel::onStatusChanged);
    connect(document, &QPdfDocument::statusChanged, this, &QPdfLinkModel::onStatusChanged);
    d->document = document;
    emit documentChanged();
    if (page())
        setPage(0);
    else
        d->update();
}

/*!
    \property QPdfLinkModel::page
    \brief The page to load links from.
*/
int QPdfLinkModel::page() const
{
    Q_D(const QPdfLinkModel);
    return d->page;
}

void QPdfLinkModel::setPage(int page)
{
    Q_D(QPdfLinkModel);
    if (d->page == page)
        return;

    d->page = page;
    emit pageChanged(page);
    d->update();
}

/*!
    Returns a \l {QPdfLink::isValid()}{valid} link if found under the \a point
    (given in units of points, 1/72 of an inch), or an invalid link if it is
    not found. In other words, this function is useful for picking, to handle
    mouse click or hover.
*/
QPdfLink QPdfLinkModel::linkAt(QPointF point) const
{
    Q_D(const QPdfLinkModel);
    for (const auto &link : std::as_const(d->links)) {
        for (const auto &rect : link.rectangles()) {
            if (rect.contains(point))
                return link;
        }
    }
    return {};
}

void QPdfLinkModelPrivate::update()
{
    Q_Q(QPdfLinkModel);
    if (!document || !document->d->doc)
        return;
    auto doc = document->d->doc;
    const QPdfMutexLocker lock;
    FPDF_PAGE pdfPage = FPDF_LoadPage(doc, page);
    if (!pdfPage) {
        qCWarning(qLcLink) << "failed to load page" << page;
        return;
    }
    q->beginResetModel();
    links.clear();

    // Iterate the ordinary links
    int linkStart = 0;
    bool hasNext = true;
    while (hasNext) {
        FPDF_LINK linkAnnot;
        hasNext = FPDFLink_Enumerate(pdfPage, &linkStart, &linkAnnot);
        if (!hasNext)
            break;
        FS_RECTF rect;
        bool ok = FPDFLink_GetAnnotRect(linkAnnot, &rect);
        if (!ok) {
            qCWarning(qLcLink) << "skipping link with invalid bounding box";
            continue; // while enumerating links
        }
        // In case horizontal/vertical coordinates are flipped, swap them.
        if (rect.right < rect.left)
            std::swap(rect.right, rect.left);
        if (rect.bottom > rect.top)
            std::swap(rect.bottom, rect.top);

        QPdfLink linkData;
        // Use quad points if present; otherwise use the rect.
        if (int quadPointsCount = FPDFLink_CountQuadPoints(linkAnnot) > 0) {
            for (int i = 0; i < quadPointsCount; ++i) {
                FS_QUADPOINTSF point;
                if (FPDFLink_GetQuadPoints(linkAnnot, i, &point)) {
                    // Quadpoints are counter clockwise from bottom left (x1, y1)
                    QPolygonF poly;
                    poly << QPointF(point.x1, point.y1);
                    poly << QPointF(point.x2, point.y2);
                    poly << QPointF(point.x3, point.y3);
                    poly << QPointF(point.x4, point.y4);
                    QRectF bounds = poly.boundingRect();
                    bounds = document->d->mapPageToView(pdfPage, bounds.left(), bounds.top(), bounds.right(), bounds.bottom());
                    qCDebug(qLcLink) << "quadpoints" << i << "of" << quadPointsCount << ":" << poly << "mapped bounds" << bounds;
                    linkData.d->rects << bounds;
                    // QPdfLink could store polygons rather than rects, to get the benefit of quadpoints;
                    // so far we didn't bother. It would be an API change, and we'd need to use Shapes in PdfLinkDelegate.qml
                }
            }
        } else {
            linkData.d->rects << document->d->mapPageToView(pdfPage, rect.left, rect.top, rect.right, rect.bottom);
        }
        FPDF_DEST dest = FPDFLink_GetDest(doc, linkAnnot);
        FPDF_ACTION action = FPDFLink_GetAction(linkAnnot);
        switch (FPDFAction_GetType(action)) {
        case PDFACTION_UNSUPPORTED: // this happens with valid links in some PDFs
        case PDFACTION_GOTO: {
            linkData.d->page = FPDFDest_GetDestPageIndex(doc, dest);
            if (linkData.d->page < 0) {
                qCWarning(qLcLink) << "skipping link with invalid page number" << linkData.d->page;
                continue; // while enumerating links
            }
            FPDF_BOOL hasX, hasY, hasZoom;
            FS_FLOAT x, y, zoom;
            ok = FPDFDest_GetLocationInPage(dest, &hasX, &hasY, &hasZoom, &x, &y, &zoom);
            if (!ok) {
                qCWarning(qLcLink) << "link with invalid location and/or zoom @" << linkData.d->rects;
                break; // at least we got a page number, so the link will jump there
            }
            if (hasX && hasY)
                linkData.d->location = document->d->mapPageToView(pdfPage, x, y);
            if (hasZoom)
                linkData.d->zoom = zoom;
            break;
        }
        case PDFACTION_URI: {
            unsigned long len = FPDFAction_GetURIPath(doc, action, nullptr, 0);
            if (len < 1) {
                qCWarning(qLcLink) << "skipping link with empty URI @" << linkData.d->rects;
                continue; // while enumerating links
            } else {
                QByteArray buf(len, 0);
                unsigned long got = FPDFAction_GetURIPath(doc, action, buf.data(), len);
                Q_ASSERT(got == len);
                linkData.d->url = QString::fromLatin1(buf.data(), got - 1);
            }
            break;
        }
        case PDFACTION_LAUNCH:
        case PDFACTION_REMOTEGOTO: {
            unsigned long len = FPDFAction_GetFilePath(action, nullptr, 0);
            if (len < 1) {
                qCWarning(qLcLink) << "skipping link with empty file path @" << linkData.d->rects;
                continue; // while enumerating links
            } else {
                QByteArray buf(len, 0);
                unsigned long got = FPDFAction_GetFilePath(action, buf.data(), len);
                Q_ASSERT(got == len);
                linkData.d->url = QUrl::fromLocalFile(QString::fromLatin1(buf.data(), got - 1)).toString();

                // Unfortunately, according to comments in fpdf_doc.h, if it's PDFACTION_REMOTEGOTO,
                // we can't get the page and location without first opening the linked document
                // and then calling FPDFAction_GetDest() again.
            }
            break;
        }
        }
        links << linkData;
    }

    // Iterate the web links
    FPDF_TEXTPAGE textPage = FPDFText_LoadPage(pdfPage);
    if (textPage) {
        FPDF_PAGELINK webLinks = FPDFLink_LoadWebLinks(textPage);
        if (webLinks) {
            int count = FPDFLink_CountWebLinks(webLinks);
            for (int i = 0; i < count; ++i) {
                QPdfLink linkData;
                int len = FPDFLink_GetURL(webLinks, i, nullptr, 0);
                if (len < 1) {
                    qCWarning(qLcLink) << "skipping link" << i << "with empty URL";
                } else {
                    QList<unsigned short> buf(len);
                    int got = FPDFLink_GetURL(webLinks, i, buf.data(), len);
                    Q_ASSERT(got == len);
                    linkData.d->url = QString::fromUtf16(
                            reinterpret_cast<const char16_t *>(buf.data()), got - 1);
                }
                len = FPDFLink_CountRects(webLinks, i);
                for (int r = 0; r < len; ++r) {
                    double left, top, right, bottom;
                    bool success = FPDFLink_GetRect(webLinks, i, r, &left, &top, &right, &bottom);
                    if (success) {
                        linkData.d->rects << document->d->mapPageToView(pdfPage, left, top, right, bottom);
                        links << linkData;
                    }
                }
            }
            FPDFLink_CloseWebLinks(webLinks);
        }
        FPDFText_ClosePage(textPage);
    }

    // All done
    FPDF_ClosePage(pdfPage);
    if (Q_UNLIKELY(qLcLink().isDebugEnabled())) {
        for (const auto &l : links)
            qCDebug(qLcLink) << l;
    }
    q->endResetModel();
}

void QPdfLinkModel::onStatusChanged(QPdfDocument::Status status)
{
    Q_D(QPdfLinkModel);
    qCDebug(qLcLink) << "sees document statusChanged" << status;
    if (status == QPdfDocument::Status::Ready)
        d->update();
}

QT_END_NAMESPACE

#include "moc_qpdflinkmodel_p.cpp"