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
static constexpr const char* EXIF_TAG_ORIENTATION      { "Exif.Image.Orientation" };
static constexpr const char* EXIF_TAG_DATETIME         { "Exif.Image.DateTime" };
static constexpr const char* EXIF_TAG_DATE_FORMAT      { "yyyy:MM:dd hh:mm:ss" };
static constexpr const char* EXIF_TAG_IMAGEDESCRIPTION { "Exif.Image.ImageDescription" };
static constexpr const char* EXIF_TAG_USERCOMMENT      { "Exif.Photo.UserComment" };
static constexpr uint16_t EXIF_PRINT_IMAGE_MATCHING    { 0xc4a5 };
 
// ffmpeg video tags
static constexpr const char* FFMPEG_TAG_ORIENTATION    { "rotate" };
static constexpr const char* FFMPEG_TAG_DATETIME       { "creation_time" };
static constexpr const char* FFMPEG_TAG_DATE_FORMAT    { "yyyy-MM-dd hh:mm:ss" };
 
// Pseudo keys for passing Myth data as metadata tags.
static constexpr const char* EXIF_MYTH_HOST   { "Myth.host" };
static constexpr const char* EXIF_MYTH_PATH   { "Myth.path" };
static constexpr const char* EXIF_MYTH_NAME   { "Myth.name" };
static constexpr const char* EXIF_MYTH_SIZE   { "Myth.size" };
static constexpr const char* EXIF_MYTH_ORIENT { "Myth.orient" };
 
 
enum ImageFileTransform : std::uint8_t {
    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() const { return (m_current * 10) + m_file; }
    int Transform(int transform);
    int GetCurrent() const;
    QString Description() const;
 
    static int FromRotation(const QString &degrees);
 
private:
    static QString AsText(int orientation);
 
    int Apply(int transform) const;
 
    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 = QMultiMap<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