spatialreferencesystem.h

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#ifndef SPATIALREFERENCESYSTEM_H
#define SPATIALREFERENCESYSTEM_H
 
#include <QObject>
#include <QString>
 
// Forward-declare GDAL types to avoid polluting headers
class OGRSpatialReference;
class OGRCoordinateTransformation;
 
class SpatialReferenceSystem : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString authName   READ authName   NOTIFY propertyChanged)
    Q_PROPERTY(int     code       READ code       NOTIFY propertyChanged)
    Q_PROPERTY(QString description READ description WRITE setDescription NOTIFY propertyChanged)
    Q_PROPERTY(QString wkt        READ toWkt      NOTIFY propertyChanged)
    Q_PROPERTY(QString proj4      READ toProj4    NOTIFY propertyChanged)
    Q_PROPERTY(bool    isGeographic READ isGeographic NOTIFY propertyChanged)
    Q_PROPERTY(bool    isProjected  READ isProjected  NOTIFY propertyChanged)
    Q_PROPERTY(QString linearUnits  READ linearUnitsName NOTIFY propertyChanged)
 
public:
 
    explicit SpatialReferenceSystem(const QString &authName = "EPSG",
                                    int code = 4326,
                                    QObject *parent = nullptr);
 
    explicit SpatialReferenceSystem(const QString &wktOrProj,
                                    QObject *parent = nullptr);
 
    explicit SpatialReferenceSystem(const SpatialReferenceSystem &other,
                                    QObject *parent = nullptr);
 
    virtual ~SpatialReferenceSystem();
 
    // ----- Identity --------------------------------------------------------
 
    [[nodiscard]] QString authName() const;
 
    [[nodiscard]] int code() const;
 
    [[nodiscard]] QString description() const;
 
    void setDescription(const QString &description);
 
    // ----- Serialization ---------------------------------------------------
 
    [[nodiscard]] QString toWkt() const;
 
    [[nodiscard]] QString toProj4() const;
 
    [[nodiscard]] QString toAuthority() const;
 
    // ----- Type predicates -------------------------------------------------
 
    [[nodiscard]] bool isGeographic() const;
 
    [[nodiscard]] bool isProjected() const;
 
    [[nodiscard]] bool equals(const SpatialReferenceSystem &other) const;
 
    // ----- Units -----------------------------------------------------------
 
    [[nodiscard]] QString linearUnitsName() const;
 
    [[nodiscard]] double linearUnitsToMetres() const;
 
    [[nodiscard]] QString angularUnitsName() const;
 
    struct LinearUnitInfo
    {
        double  metresPerUnit = 1.0;
        QString name;
        bool    usable = false;
    };
 
    [[nodiscard]] LinearUnitInfo planarLinearUnit() const;
 
    // ----- GDAL interop ----------------------------------------------------
 
    [[nodiscard]] OGRSpatialReference *ogrSpatialReference() const;
 
    [[nodiscard]] OGRCoordinateTransformation *
    createTransformationTo(const SpatialReferenceSystem &target) const;
 
    // ----- Factory methods -------------------------------------------------
 
    [[nodiscard]] static SpatialReferenceSystem *fromWktOrProj(const QString &wktOrProj,
                                                               QObject *parent = nullptr);
 
    [[nodiscard]] static SpatialReferenceSystem *fromAuthCode(const QString &authName,
                                                              int code,
                                                              QObject *parent = nullptr);
 
    [[nodiscard]] static SpatialReferenceSystem *untitled(QObject *parent = nullptr);
 
    [[nodiscard]] static SpatialReferenceSystem *localFromMapUnits(const QString &mapUnits,
                                                                    QObject *parent = nullptr);
 
    // ----- Local-CS predicate ----------------------------------------------
 
    [[nodiscard]] bool isLocal() const;
 
signals:
    void propertyChanged(const QString &propertyName);
 
private:
    SpatialReferenceSystem(QObject *parent, Qt::Initialization);  // null-init for factory use
    void initFromAuthCode(const QString &authName, int code);
    void initFromWktOrProj(const QString &wktOrProj);
 
    OGRSpatialReference *m_ogrSRS = nullptr; 
    QString              m_authName;
    int                  m_code = -1;
    QString              m_description;
};
 
#endif // SPATIALREFERENCESYSTEM_H