imagemetadata.h

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#ifndef IMAGEMETADATA_H
#define IMAGEMETADATA_H

#include <utility>

// Qt headers
#include <QCoreApplication> // for tr()
#include <QDateTime>
#include <QStringBuilder>
#include <QStringList>

// MythTV headers
#include "mythmetaexp.h"


// Exif 2.3 standard tag names, see http://www.exiv2.org/tags.html
#define EXIF_TAG_ORIENTATION      "Exif.Image.Orientation"
#define EXIF_TAG_DATETIME         "Exif.Image.DateTime"
#define EXIF_TAG_DATE_FORMAT      "yyyy:MM:dd hh:mm:ss"
#define EXIF_TAG_IMAGEDESCRIPTION "Exif.Image.ImageDescription"
#define EXIF_TAG_USERCOMMENT      "Exif.Photo.UserComment"
#define EXIF_PRINT_IMAGE_MATCHING 0xc4a5

// ffmpeg video tags
#define FFMPEG_TAG_ORIENTATION    "rotate"
#define FFMPEG_TAG_DATETIME       "creation_time"
#define FFMPEG_TAG_DATE_FORMAT    "yyyy-MM-dd hh:mm:ss"

// Pseudo keys for passing Myth data as metadata tags.
#define EXIF_MYTH_HOST   "Myth.host"
#define EXIF_MYTH_PATH   "Myth.path"
#define EXIF_MYTH_NAME   "Myth.name"
#define EXIF_MYTH_SIZE   "Myth.size"
#define EXIF_MYTH_ORIENT "Myth.orient"


enum ImageFileTransform {
    kResetToExif    = 0, 
    kRotateCW       = 1, 
    kRotateCCW      = 2, 
    kFlipHorizontal = 3, 
    kFlipVertical   = 4  
};


class META_PUBLIC Orientation
{
    Q_DECLARE_TR_FUNCTIONS(Orientation)
public:
    explicit Orientation(int composite)
        : m_current(composite / 10), m_file(composite % 10) {}
    Orientation(int current, int file) : m_current(current), m_file(file) {}

    int Composite() { return m_current * 10 + m_file; }
    int Transform(int transform);
    int GetCurrent(bool compensate);
    QString Description();

    static int FromRotation(const QString &degrees);

private:
    static QString AsText(int orientation);

    int Apply(int transform);

    using Matrix = QHash<int, QHash<int, int> >;

    static const bool krunningQt541;
    static const Matrix kQt541_orientation;
    static Matrix InitOrientationMatrix();

    int m_current;
    int m_file;
};


class META_PUBLIC ImageMetaData
{
    Q_DECLARE_TR_FUNCTIONS(ImageMetaData);
public:
    static ImageMetaData* FromPicture(const QString &filePath);
    static ImageMetaData* FromVideo(const QString &filePath);

    virtual ~ImageMetaData() = default;

    static const QString kSeparator;

    static QString ToString(const QString &name, const QString &label, const QString &value)
    { return name % kSeparator % label % kSeparator % value; }

    static QStringList FromString(const QString &str)
    { return str.split(kSeparator); }

    using TagMap = QMap<QString, QStringList>;
    static TagMap ToMap(const QStringList &tags);

    virtual bool        IsValid()                                = 0;
    virtual QStringList GetAllTags()                             = 0;
    virtual int         GetOrientation(bool *exists = nullptr)      = 0;
    virtual QDateTime   GetOriginalDateTime(bool *exists = nullptr) = 0;
    virtual QString     GetComment(bool *exists = nullptr)          = 0;

protected:
    explicit ImageMetaData(QString filePath)
        : m_filePath(std::move(filePath)) {}

    QString m_filePath;
};


#endif // IMAGEMETADATA_H