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QExifImageHeader Class Reference
[QtBaseModule]

The QExifImageHeader class provides functionality for reading and writing EXIF image headers. More...

    #include <QExifImageHeader>

This class is under development and is subject to change.

Public Types

Public Functions


Detailed Description

The QExifImageHeader class provides functionality for reading and writing EXIF image headers.

EXIF headers are a collection of properties that describe the image they're embedded in. Each property is identified by a tag of which there are three kinds. Image tags which mostly describe the format (dimensions, resolution, orientation) but also include some descriptive information (description, camera make and model, artist). EXIF extended tags which elaborate on some of the image tags and record the camera settings at time of capture among other things. Finally there are GPS tags which record the location the image was captured.

EXIF tags are typically found in JPEG images but may be found in other image formats. To read headers from a JPEG image QExifImageHeader provides the loadFromJpeg() function, and the complementary saveToJpeg() function for writing. To allow reading and writing arbitrary formats QExifImageHeader provides the read() and write() functions which work with just the EXIF header data itself.


Member Type Documentation

enum QExifImageHeader::ExifExtendedTag

Enumerates the extended EXIF tag IDs defined in the EXIF specification.

ConstantValue
QExifImageHeader::ExifVersion0x9000
QExifImageHeader::FlashPixVersion0xA000
QExifImageHeader::ColorSpace0xA001
QExifImageHeader::ComponentsConfiguration0x9101
QExifImageHeader::CompressedBitsPerPixel0x9102
QExifImageHeader::PixelXDimension0xA002
QExifImageHeader::PixelYDimension0xA003
QExifImageHeader::MakerNote0x927C
QExifImageHeader::UserComment0x9286
QExifImageHeader::RelatedSoundFile0xA004
QExifImageHeader::DateTimeOriginal0x9003
QExifImageHeader::DateTimeDigitized0x9004
QExifImageHeader::SubSecTime0x9290
QExifImageHeader::SubSecTimeOriginal0x9291
QExifImageHeader::SubSecTimeDigitized0x9292
QExifImageHeader::ImageUniqueId0xA420
QExifImageHeader::ExposureTime0x829A
QExifImageHeader::FNumber0x829D
QExifImageHeader::ExposureProgram0x8822
QExifImageHeader::SpectralSensitivity0x8824
QExifImageHeader::ISOSpeedRatings0x8827
QExifImageHeader::Oecf0x8828
QExifImageHeader::ShutterSpeedValue0x9201
QExifImageHeader::ApertureValue0x9202
QExifImageHeader::BrightnessValue0x9203
QExifImageHeader::ExposureBiasValue0x9204
QExifImageHeader::MaxApertureValue0x9205
QExifImageHeader::SubjectDistance0x9206
QExifImageHeader::MeteringMode0x9207
QExifImageHeader::LightSource0x9208
QExifImageHeader::Flash0x9209
QExifImageHeader::FocalLength0x920A
QExifImageHeader::SubjectArea0x9214
QExifImageHeader::FlashEnergy0xA20B
QExifImageHeader::SpatialFrequencyResponse0xA20C
QExifImageHeader::FocalPlaneXResolution0xA20E
QExifImageHeader::FocalPlaneYResolution0xA20F
QExifImageHeader::FocalPlaneResolutionUnit0xA210
QExifImageHeader::SubjectLocation0xA214
QExifImageHeader::ExposureIndex0xA215
QExifImageHeader::SensingMethod0xA217
QExifImageHeader::FileSource0xA300
QExifImageHeader::SceneType0xA301
QExifImageHeader::CfaPattern0xA302
QExifImageHeader::CustomRendered0xA401
QExifImageHeader::ExposureMode0xA402
QExifImageHeader::WhiteBalance0xA403
QExifImageHeader::DigitalZoomRatio0xA404
QExifImageHeader::FocalLengthIn35mmFilm0xA405
QExifImageHeader::SceneCaptureType0xA406
QExifImageHeader::GainControl0xA407
QExifImageHeader::Contrast0xA408
QExifImageHeader::Saturation0xA409
QExifImageHeader::Sharpness0xA40A
QExifImageHeader::DeviceSettingDescription0xA40B
QExifImageHeader::SubjectDistanceRange0x40C

enum QExifImageHeader::GpsTag

Enumerates the GPS tag IDs from the EXIF specification.

ConstantValue
QExifImageHeader::GpsVersionId0x0000
QExifImageHeader::GpsLatitudeRef0x0001
QExifImageHeader::GpsLatitude0x0002
QExifImageHeader::GpsLongitudeRef0x0003
QExifImageHeader::GpsLongitude0x0004
QExifImageHeader::GpsAltitudeRef0x0005
QExifImageHeader::GpsAltitude0x0006
QExifImageHeader::GpsTimeStamp0x0007
QExifImageHeader::GpsSatellites0x0008
QExifImageHeader::GpsStatus0x0009
QExifImageHeader::GpsMeasureMode0x000A
QExifImageHeader::GpsDop0x000B
QExifImageHeader::GpsSpeedRef0x000C
QExifImageHeader::GpsSpeed0x000D
QExifImageHeader::GpsTrackRef0x000E
QExifImageHeader::GpsTrack0x000F
QExifImageHeader::GpsImageDirectionRef0x0010
QExifImageHeader::GpsImageDirection0x0011
QExifImageHeader::GpsMapDatum0x0012
QExifImageHeader::GpsDestLatitudeRef0x0013
QExifImageHeader::GpsDestLatitude0x0014
QExifImageHeader::GpsDestLongitudeRef0x0015
QExifImageHeader::GpsDestLongitude0x0016
QExifImageHeader::GpsDestBearingRef0x0017
QExifImageHeader::GpsDestBearing0x0018
QExifImageHeader::GpsDestDistanceRef0x0019
QExifImageHeader::GpsDestDistance0x001A
QExifImageHeader::GpsProcessingMethod0x001B
QExifImageHeader::GpsAreaInformation0x001C
QExifImageHeader::GpsDateStamp0x001D
QExifImageHeader::GpsDifferential0x001E

enum QExifImageHeader::ImageTag

Enumerates the TIFF image tag IDs defined in the EXIF specification.

ConstantValue
QExifImageHeader::ImageWidth0x0100
QExifImageHeader::ImageLength0x0101
QExifImageHeader::BitsPerSample0x0102
QExifImageHeader::Compression0x0103
QExifImageHeader::PhotometricInterpretation0x0106
QExifImageHeader::Orientation0x0112
QExifImageHeader::SamplesPerPixel0x0115
QExifImageHeader::PlanarConfiguration0x011C
QExifImageHeader::YCbCrSubSampling0x0212
QExifImageHeader::XResolution0x011A
QExifImageHeader::YResolution0x011B
QExifImageHeader::ResolutionUnit0x0128
QExifImageHeader::StripOffsets0x0111
QExifImageHeader::RowsPerStrip0x0116
QExifImageHeader::StripByteCounts0x0117
QExifImageHeader::TransferFunction0x012D
QExifImageHeader::WhitePoint0x013E
QExifImageHeader::PrimaryChromaciticies0x013F
QExifImageHeader::YCbCrCoefficients0x0211
QExifImageHeader::ReferenceBlackWhite0x0214
QExifImageHeader::DateTime0x0132
QExifImageHeader::ImageDescription0x010E
QExifImageHeader::Make0x010F
QExifImageHeader::Model0x0110
QExifImageHeader::Software0x0131
QExifImageHeader::Artist0x013B
QExifImageHeader::Copyright0x8298


Member Function Documentation

QExifImageHeader::QExifImageHeader ()

Constructs a new EXIF image data editor.

QExifImageHeader::QExifImageHeader ( const QString & fileName )

Constructs a new EXIF image data editor and reads the meta-data from a JPEG image with the given fileName.

QExifImageHeader::~QExifImageHeader ()

Destroys an EXIF image data editor.

QSysInfo::Endian QExifImageHeader::byteOrder () const

Returns the byte order of EXIF file.

void QExifImageHeader::clear ()

Clears all image meta-data.

bool QExifImageHeader::contains ( ImageTag tag ) const

Returns true if an EXIf header contains a value for an image tag and false otherwise.

bool QExifImageHeader::contains ( ExifExtendedTag tag ) const

This is an overloaded member function, provided for convenience.

Returns true if a header contains a a value for an extended EXIF tag and false otherwise.

bool QExifImageHeader::contains ( GpsTag tag ) const

This is an overloaded member function, provided for convenience.

Returns true if an EXIf header contains a value for a GPS tag and false otherwise.

QList<ExifExtendedTag> QExifImageHeader::extendedTags () const

Returns a list of all extended EXIF tags in a header.

QList<GpsTag> QExifImageHeader::gpsTags () const

Returns a list of all GPS tags in an EXIF header.

QList<ImageTag> QExifImageHeader::imageTags () const

Returns a list of all image tags in an EXIF header.

bool QExifImageHeader::loadFromJpeg ( const QString & fileName )

Reads meta-data from a JPEG image with the given fileName.

Returns true if the data was successfully parsed and false otherwise.

bool QExifImageHeader::loadFromJpeg ( QIODevice * device )

This is an overloaded member function, provided for convenience.

Reads meta-data from an I/O device containing a JPEG image.

Returns true if the data was successfully parsed and false otherwise.

bool QExifImageHeader::read ( QIODevice * device )

Reads the contents of an EXIF header from an I/O device.

Returns true if the header was read and false otherwise.

See also loadFromJpeg() and write().

void QExifImageHeader::remove ( ImageTag tag )

Removes the value for an image tag.

void QExifImageHeader::remove ( ExifExtendedTag tag )

This is an overloaded member function, provided for convenience.

Removes the value for an extended EXIF tag.

void QExifImageHeader::remove ( GpsTag tag )

This is an overloaded member function, provided for convenience.

Removes the value for a GPS tag.

bool QExifImageHeader::saveToJpeg ( const QString & fileName ) const

Saves meta-data to a JPEG image with the given fileName.

Returns true if the data was successfully written.

bool QExifImageHeader::saveToJpeg ( QIODevice * device ) const

This is an overloaded member function, provided for convenience.

Save meta-data to the given I/O device.

The device must be non-sequential and already contain a valid JPEG image.

Returns true if the data was successfully written.

void QExifImageHeader::setThumbnail ( const QImage & thumbnail )

Sets the image thumbnail.

See also thumbnail().

void QExifImageHeader::setValue ( ImageTag tag, const QExifValue & value )

Sets the value for an image tag.

See also value().

void QExifImageHeader::setValue ( ExifExtendedTag tag, const QExifValue & value )

This is an overloaded member function, provided for convenience.

Sets the value for an extended EXIF tag.

void QExifImageHeader::setValue ( GpsTag tag, const QExifValue & value )

This is an overloaded member function, provided for convenience.

Sets the value for an GPS tag.

qint64 QExifImageHeader::size () const

Returns the size of EXIF data in bytes.

QImage QExifImageHeader::thumbnail () const

Returns the image thumbnail.

See also setThumbnail().

QExifValue QExifImageHeader::value ( ImageTag tag ) const

Returns the value for an image tag.

See also setValue().

QExifValue QExifImageHeader::value ( ExifExtendedTag tag ) const

This is an overloaded member function, provided for convenience.

Returns the value for an extended EXIF tag.

QExifValue QExifImageHeader::value ( GpsTag tag ) const

This is an overloaded member function, provided for convenience.

Returns the value for a GPS tag.

qint64 QExifImageHeader::write ( QIODevice * device ) const

Writes an EXIF header to an I/O device.

Returns the total number of bytes written.


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Qt Extended 4.4.3