Cppcheck - HTML report - digiKam-master-rev-960d3ce42d

# Cppcheck report - digiKam-master-rev-960d3ce42d: ../../core/utilities/geolocation/engine/projections/CylindricalProjection.cpp

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    /* ============================================================
     *
     * This file is a part of digiKam project
     * https://www.digikam.org
     *
     * Date        : 2023-05-15
     * Description : geolocation engine based on Marble.
     *               (c) 2007-2022 Marble Team
     *               https://invent.kde.org/education/marble/-/raw/master/data/credits_authors.html
     *
     * SPDX-FileCopyrightText: 2023-2026 by Gilles Caulier <caulier dot gilles at gmail dot com>
     *
     * SPDX-License-Identifier: LGPL-2.1-or-later
     *
     * ============================================================ */

    #include "CylindricalProjection.h"
    #include "CylindricalProjection_p.h"

    // Qt includes

    #include <QPainterPath>

    // Local includes

    #include "GeoDataLinearRing.h"
    #include "GeoDataLineString.h"
    #include "GeoDataCoordinates.h"
    #include "GeoDataLatLonAltBox.h"
    #include "ViewportParams.h"

    // Maximum amount of nodes that are created automatically between actual nodes.
    static const int maxTessellationNodes = 200;

    namespace Marble
    {

    CylindricalProjection::CylindricalProjection()
        : AbstractProjection(new CylindricalProjectionPrivate(this))
    {
    }

    CylindricalProjection::CylindricalProjection(CylindricalProjectionPrivate* dd)
        : AbstractProjection(dd)
    {
    }

    CylindricalProjection::~CylindricalProjection()
    {
    }

    CylindricalProjectionPrivate::CylindricalProjectionPrivate(CylindricalProjection* parent)
        : AbstractProjectionPrivate(parent),
          q_ptr                    (parent)
    {
    }

    QPainterPath CylindricalProjection::mapShape(const ViewportParams* viewport) const
    {
        // Convenience variables

        int  width  = viewport->width();
        int  height = viewport->height();

        qreal  yTop;
        qreal  yBottom;
        qreal  xDummy;

        // Get the top and bottom coordinates of the projected map.

        screenCoordinates(0.0, maxLat(), viewport, xDummy, yTop);
        screenCoordinates(0.0, minLat(), viewport, xDummy, yBottom);

        // Don't let the map area be outside the image

        if (yTop < 0)
        {
            yTop = 0;
        }

        if (yBottom > height)
        {
            yBottom =  height;
        }

        QPainterPath mapShape;
        mapShape.addRect(0,
                         yTop,
                         width,
                         yBottom - yTop);

        return mapShape;
    }

    bool CylindricalProjection::screenCoordinates(const GeoDataLineString& lineString,
                                                  const ViewportParams* viewport,
                                                  QVector<QPolygonF*>& polygons) const
    {
        Q_D(const CylindricalProjection);

        // Compare bounding box size of the line string with the angularResolution
        // Immediately return if the latLonAltBox is smaller.

        if (!viewport->resolves(lineString.latLonAltBox()))
        {
            // qCDebug(DIGIKAM_GEOENGINE_LOG) << "Object too small to be resolved";

            return false;
        }

        QVector<QPolygonF*> subPolygons;
        d->lineStringToPolygon(lineString, viewport, subPolygons);
        polygons << subPolygons;

        return polygons.isEmpty();
    }

    int CylindricalProjectionPrivate::tessellateLineSegment(const GeoDataCoordinates& aCoords,
                                                            qreal ax, qreal ay,
                                                            const GeoDataCoordinates& bCoords,
                                                            qreal bx, qreal by,
                                                            const QVector<QPolygonF*>& polygons,
                                                            const ViewportParams* viewport,
                                                            TessellationFlags f,
                                                            int mirrorCount,
                                                            qreal repeatDistance) const<--- Shadow argument
    {
        // We take the manhattan length as a distance approximation
        // that can be too big by a factor of sqrt(2)

        qreal distance = fabs((bx - ax)) + fabs((by - ay));

    #ifdef SAFE_DISTANCE

        // Interpolate additional nodes if the line segment that connects the
        // current or previous nodes might cross the viewport.
        // The latter can pretty safely be excluded for most projections if both points
        // are located on the same side relative to the viewport boundaries and if they are
        // located more than half the line segment distance away from the viewport.

        const qreal safeDistance = - 0.5 * distance;

        if (
               !( (bx < safeDistance) && (ax < safeDistance))
            || !( (by < safeDistance) && (ay < safeDistance))
            || !(((bx + safeDistance) > viewport->width())
              && ((ax + safeDistance) > viewport->width()))
            || !(((by + safeDistance) > viewport->height())
              && ((ay + safeDistance) > viewport->height()))
           )
        {

    #endif

            int maxTessellationFactor            = (viewport->radius() < 20000) ? 10 : 20;
            int const finalTessellationPrecision = qBound(2, viewport->radius() / 200, maxTessellationFactor) * tessellationPrecision;

            // Let the line segment follow the spherical surface
            // if the distance between the previous point and the current point
            // on screen is too big

            if (distance > finalTessellationPrecision)
            {
                const int tessellatedNodes = qMin<int>(distance / finalTessellationPrecision, maxTessellationNodes);

                mirrorCount                = processTessellation(aCoords, bCoords,
                                                                 tessellatedNodes,
                                                                 polygons,
                                                                 viewport,
                                                                 f,
                                                                 mirrorCount,
                                                                 repeatDistance);
            }
            else
            {
                mirrorCount = crossDateLine(aCoords, bCoords, bx, by, polygons, mirrorCount, repeatDistance);
            }

    #ifdef SAFE_DISTANCE

        }

    #endif

        return mirrorCount;
    }

    int CylindricalProjectionPrivate::processTessellation(const GeoDataCoordinates& previousCoords,
                                                          const GeoDataCoordinates& currentCoords,
                                                          int tessellatedNodes,
                                                          const QVector<QPolygonF*>& polygons,
                                                          const ViewportParams* viewport,
                                                          TessellationFlags f,
                                                          int mirrorCount,
                                                          qreal repeatDistance) const<--- Shadow argument
    {
        const bool clampToGround        = f.testFlag(FollowGround);
        const bool followLatitudeCircle = f.testFlag(RespectLatitudeCircle)
                                          && (previousCoords.latitude() == currentCoords.latitude());

        // Calculate steps for tessellation: lonDiff and altDiff

        qreal lonDiff = 0.0;

        if (followLatitudeCircle)
        {
            const int previousSign = (previousCoords.longitude() > 0) ? 1 : -1;
            const int currentSign  = (currentCoords.longitude()  > 0) ? 1 : -1;

            lonDiff                = currentCoords.longitude() - previousCoords.longitude();

            if ((previousSign != currentSign)
                && (fabs(previousCoords.longitude()) + fabs(currentCoords.longitude()) > M_PI))
            {
                if (previousSign > currentSign)
                {
                    // going eastwards ->

                    lonDiff += 2 * M_PI ;
                }
                else
                {
                    // going westwards ->

                    lonDiff -= 2 * M_PI;
                }
            }

            if (fabs(lonDiff) == (2 * M_PI))
            {
                return mirrorCount;
            }
        }

        // Create the tessellation nodes.

        GeoDataCoordinates previousTessellatedCoords = previousCoords;

        for (int i = 1 ; i <= tessellatedNodes ; ++i)
        {
            const qreal t = (qreal)(i) / (qreal)(tessellatedNodes + 1);

            GeoDataCoordinates currentTessellatedCoords;

            if (followLatitudeCircle)
            {
                // To tessellate along latitude circles use the
                // linear interpolation of the longitude.
                // interpolate the altitude, too

                const qreal altDiff      = currentCoords.altitude() - previousCoords.altitude();
                const qreal altitude     = altDiff * t + previousCoords.altitude();
                const qreal lon          = lonDiff * t + previousCoords.longitude();
                const qreal lat          = previousTessellatedCoords.latitude();

                currentTessellatedCoords = GeoDataCoordinates(lon, lat, altitude);
            }
            else
            {
                // To tessellate along great circles use the
                // normalized linear interpolation ("NLERP") for latitude and longitude.

                currentTessellatedCoords = previousCoords.nlerp(currentCoords, t);
            }

            if (clampToGround)
            {
                currentTessellatedCoords.setAltitude(0);
            }

            Q_Q(const CylindricalProjection);

            qreal bx, by;
            q->screenCoordinates(currentTessellatedCoords, viewport, bx, by);
            mirrorCount               = crossDateLine(previousTessellatedCoords, currentTessellatedCoords, bx, by, polygons,
                                                      mirrorCount, repeatDistance);
            previousTessellatedCoords = currentTessellatedCoords;
        }

        // For the clampToGround case add the "current" coordinate after adding all other nodes.

        GeoDataCoordinates currentModifiedCoords(currentCoords);

        if (clampToGround)
        {
            currentModifiedCoords.setAltitude(0.0);
        }

        Q_Q(const CylindricalProjection);

        qreal bx, by;
        q->screenCoordinates(currentModifiedCoords, viewport, bx, by);
        mirrorCount = crossDateLine(previousTessellatedCoords, currentModifiedCoords, bx, by, polygons,
                                    mirrorCount, repeatDistance);

        return mirrorCount;
    }

    int CylindricalProjectionPrivate::crossDateLine(const GeoDataCoordinates& aCoord,
                                                    const GeoDataCoordinates& bCoord,
                                                    qreal bx,
                                                    qreal by,
                                                    const QVector<QPolygonF*>& polygons,
                                                    int mirrorCount,
                                                    qreal repeatDistance)<--- Shadow argument
    {
        qreal aLon  = aCoord.longitude();
        qreal aSign = (aLon > 0) ? 1 : -1;
        qreal bLon  = bCoord.longitude();
        qreal bSign = (bLon > 0) ? 1 : -1;
        qreal delta = 0;

        if ((aSign != bSign) && ((fabs(aLon) + fabs(bLon)) > M_PI))
        {
            int sign     = (aSign > bSign) ? 1 : -1;
            mirrorCount += sign;
        }

        delta = repeatDistance * mirrorCount;
        *polygons.last() << QPointF(bx + delta, by);

        return mirrorCount;
    }

    bool CylindricalProjectionPrivate::lineStringToPolygon(const GeoDataLineString& lineString,
                                                           const ViewportParams* viewport,
                                                           QVector<QPolygonF*>& polygons) const
    {
        const TessellationFlags f = lineString.tessellationFlags();
        bool const tessellate     = lineString.tessellate();
        const bool noFilter       = f.testFlag(PreventNodeFiltering);

        qreal x                   = 0;
        qreal y                   = 0;
        qreal previousX           = -1.0;
        qreal previousY           = -1.0;
        int mirrorCount           = 0;
        qreal distance            = repeatDistance(viewport);

        QPolygonF* polygon        = new QPolygonF;

        if (!tessellate)
        {
            polygon->reserve(lineString.size());
        }

        polygons.append(polygon);

        GeoDataLineString::ConstIterator itCoords         = lineString.constBegin();
        GeoDataLineString::ConstIterator itPreviousCoords = lineString.constBegin();

        GeoDataLineString::ConstIterator itBegin          = lineString.constBegin();
        GeoDataLineString::ConstIterator itEnd            = lineString.constEnd();

        bool processingLastNode = false;

        // We use a while loop to be able to cover linestrings as well as linear rings:
        // Linear rings require to tessellate the path from the last node to the first node
        // which isn't really convenient to achieve with a for loop ...

        const bool isLong       = lineString.size() > 10;
        const int maximumDetail = levelForResolution(viewport->angularResolution());

        // The first node of optimized linestrings has a non-zero detail value.

        const bool hasDetail    = (itBegin->detail() != 0);

        bool isStraight         = (lineString.latLonAltBox().height() == 0) || (lineString.latLonAltBox().width() == 0);

        Q_Q(const CylindricalProjection);

        bool const isClosed     = lineString.isClosed();

        while (itCoords != itEnd)
        {
            // Optimization for line strings with a big amount of nodes

            bool skipNode = (hasDetail ? (itCoords->detail() > maximumDetail)
                                       : isLong && !processingLastNode && (itCoords != itBegin) &&
                                         !viewport->resolves(*itPreviousCoords, *itCoords));

            if (!skipNode || noFilter)
            {
                q->screenCoordinates(*itCoords, viewport, x, y);

                // Initializing variables that store the values of the previous iteration

                if (!processingLastNode && (itCoords == itBegin))
                {
                    itPreviousCoords = itCoords;
                    previousX        = x;
                    previousY        = y;
                }

                // This if-clause contains the section that tessellates the line
                // segments of a linestring. If you are about to learn how the code of
                // this class works you can safely ignore this section for a start.

                if (tessellate && !isStraight)
                {
                    mirrorCount = tessellateLineSegment(*itPreviousCoords, previousX, previousY,
                                                        *itCoords, x, y,
                                                        polygons, viewport,
                                                        f, mirrorCount, distance);
                }
                else
                {
                    // special case for polys which cross dateline but have no Tessellation Flag
                    // the expected rendering is a screen coordinates straight line between
                    // points, but in projections with repeatX things are not smooth

                    mirrorCount = crossDateLine(*itPreviousCoords, *itCoords, x, y, polygons, mirrorCount, distance);
                }

                itPreviousCoords = itCoords;
                previousX        = x;
                previousY        = y;
            }

            // Here we modify the condition to be able to process the
            // first node after the last node in a LinearRing.

            if (processingLastNode)
            {
                break;
            }

            ++itCoords;

            if (isClosed && itCoords == itEnd)
            {
                itCoords           = itBegin;
                processingLastNode = true;
            }
        }

        // Closing e.g. in the Antarctica case.
        // This code makes the assumption that
        // - the first node is located at 180 E
        // - and the last node is located at 180 W
        // TODO: add a similar pattern in the crossDateLine() code.
    /*
        GeoDataLatLonAltBox box = lineString.latLonAltBox();

        if (lineString.isClosed() && (box.width() == 2*M_PI))
        {
            QPolygonF* poly = polygons.last();

            if (box.containsPole(NorthPole))
            {
                qreal topMargin = 0.0;
                qreal dummy     = 0.0;
                q_ptr->screenCoordinates(0.0, q_ptr->maxLat(), viewport, topMargin, dummy );
                poly->push_back( QPointF( poly->last().x(), topMargin ) );
                poly->push_back( QPointF( poly->first().x(), topMargin ) );
            }
            else
            {
                qreal bottomMargin = 0.0;
                qreal dummy        = 0.0;
                q_ptr->screenCoordinates(0.0, q_ptr->minLat(), viewport, bottomMargin, dummy );
                poly->push_back( QPointF( poly->last().x(), bottomMargin ) );
                poly->push_back( QPointF( poly->first().x(), bottomMargin ) );
            }
        }
    */

        repeatPolygons(viewport, polygons);

        return polygons.isEmpty();
    }

    void CylindricalProjectionPrivate::translatePolygons(const QVector<QPolygonF*>& polygons,
                                                         QVector<QPolygonF*>& translatedPolygons,
                                                         qreal xOffset)
    {
        // qCDebug(DIGIKAM_GEOENGINE_LOG) << "Translation: " << xOffset;

        translatedPolygons.reserve(polygons.size());

        QVector<QPolygonF*>::const_iterator itPolygon = polygons.constBegin();
        QVector<QPolygonF*>::const_iterator itEnd     = polygons.constEnd();

        for ( ; itPolygon != itEnd ; ++itPolygon)
        {
            QPolygonF* polygon = new QPolygonF;
            *polygon           = **itPolygon;
            polygon->translate(xOffset, 0);
            translatedPolygons.append(polygon);
        }
    }

    void CylindricalProjectionPrivate::repeatPolygons(const ViewportParams* viewport,
                                                      QVector<QPolygonF*>& polygons) const
    {
        Q_Q(const CylindricalProjection);

        qreal xEast = 0;
        qreal xWest = 0;
        qreal y     = 0;

        // Choose a latitude that is inside the viewport.

        const qreal centerLatitude = viewport->viewLatLonAltBox().center().latitude();

        const GeoDataCoordinates westCoords(-M_PI, centerLatitude);
        const GeoDataCoordinates eastCoords(+M_PI, centerLatitude);

        q->screenCoordinates(westCoords, viewport, xWest, y);
        q->screenCoordinates(eastCoords, viewport, xEast, y);

        if ((xWest <= 0) && (xEast >= viewport->width()) - 1)
        {
            // qCDebug(DIGIKAM_GEOENGINE_LOG) << "No repeats";

            return;
        }

        const qreal repeatXInterval = xEast - xWest;
        const int repeatsLeft       = (xWest > 0)                 ? (int)(xWest                       / repeatXInterval) + 1 : 0;
        const int repeatsRight      = (xEast < viewport->width()) ? (int)((viewport->width() - xEast) / repeatXInterval) + 1 : 0;

        QVector<QPolygonF*> repeatedPolygons;

        for (int it = repeatsLeft ; it > 0 ; --it)
        {
            const qreal xOffset = -it * repeatXInterval;
            QVector<QPolygonF*> translatedPolygons;
            translatePolygons(polygons, translatedPolygons, xOffset);
            repeatedPolygons << translatedPolygons;
        }

        repeatedPolygons << polygons;

        for (int it = 1 ; it <= repeatsRight ; ++it)
        {
            const qreal xOffset = +it * repeatXInterval;
            QVector<QPolygonF*> translatedPolygons;
            translatePolygons(polygons, translatedPolygons, xOffset);
            repeatedPolygons << translatedPolygons;
        }

        polygons = repeatedPolygons;

        // qCDebug(DIGIKAM_GEOENGINE_LOG) << Q_FUNC_INFO << "Coordinates: " << xWest << xEast
        //                                << "Repeats: " << repeatsLeft << repeatsRight;
    }

    qreal CylindricalProjectionPrivate::repeatDistance(const ViewportParams* viewport) const
    {
        // Choose a latitude that is inside the viewport.

        qreal centerLatitude = viewport->viewLatLonAltBox().center().latitude();

        GeoDataCoordinates westCoords(-M_PI, centerLatitude);
        GeoDataCoordinates eastCoords(+M_PI, centerLatitude);
        qreal xWest, xEast, dummyY;

        Q_Q(const AbstractProjection);

        q->screenCoordinates(westCoords, viewport, xWest, dummyY);
        q->screenCoordinates(eastCoords, viewport, xEast, dummyY);

        return (xEast - xWest);
    }

    } // namespace Marble