Orientation Class Reference

Encapsulates Exif orientation processing. More...

#include <libmythmetadata/imagemetadata.h>

Collaboration diagram for Orientation:

Public Member Functions
	Orientation (int composite)
	Orientation (int current, int file)
int	Composite () const
	Encode original & current orientation to a single Db field. More...
int	Transform (int transform)
	Adjust orientation to apply a transform to an image. More...
int	GetCurrent (bool compensate)
	Determines orientation required for an image. More...
QString	Description () const
	Generate text description of orientation. More...

Static Public Member Functions
static int	FromRotation (const QString &degrees)
	Convert degrees of rotation into Exif orientation code. More...

Private Types
using	Matrix = QHash< int, QHash< int, int > >

Private Member Functions
int	Apply (int transform) const
	Adjust current orientation code to apply a transform to an image. More...

Static Private Member Functions
static QString	AsText (int orientation)
	Converts orientation code to text description for info display. More...
static Matrix	InitOrientationMatrix ()
	Initialises conversion matrix for Qt 5.4.1. More...

Private Attributes
int	m_current
	The orientation to use: the file orientation with user transformations applied. More...
int	m_file
	The orientation of the raw file image, as specified by the camera. More...

Static Private Attributes
static const bool	krunningQt541 = (strcmp(qVersion(), "5.4.1") == 0)
	True when using Qt 5.4.1 with its deviant orientation behaviour. More...
static const Matrix	kQt541_orientation
	Orientation conversions for proper display on Qt 5.4.1. More...

Detailed Description

Encapsulates Exif orientation processing.

The exif code indicates how the raw image should be rotated/mirrored in order to display correctly. This manipulation is expensive, so done once only. User transformations are applied to the code to achieve the required effect. Both file orientation and current orientation are stored in the Db (together) to cope with deviant Qt versions. This composite code is 2-digits where 1st = current orientation, 2nd = original file orientation

Definition at line 62 of file imagemetadata.h.

Member Typedef Documentation

Matrix

using Orientation::Matrix = QHash<int, QHash<int, int> >

private

Definition at line 83 of file imagemetadata.h.

Constructor & Destructor Documentation

Orientation() [1/2]

Orientation::Orientation ( int  composite )

inlineexplicit

Definition at line 66 of file imagemetadata.h.

Orientation() [2/2]

Orientation::Orientation ( int  current, int  file  )

inline

Definition at line 68 of file imagemetadata.h.

Member Function Documentation

Composite()

int Orientation::Composite ( ) const

inline

Encode original & current orientation to a single Db field.

Definition at line 71 of file imagemetadata.h.

Referenced by ImageScanThread< ImageDbSg >::SyncFile(), and Transform().

Transform()

int Orientation::Transform

(

int

transform

)

Adjust orientation to apply a transform to an image.

Parameters

transform

Rotation/flip/reset to apply

Returns

int Adjusted composite orientation of the image

Definition at line 26 of file imagemetadata.cpp.

Referenced by ImageHandler< ImageDbSg >::HandleTransform().

GetCurrent()

int Orientation::GetCurrent

(

bool

compensate

)

Determines orientation required for an image.

Some Qt versions automatically apply file orientation when an image is loaded. This compensates for that to ensure images are always orientated correctly.

Parameters

compensate

Whether to compensate for Qt auto-rotation

Returns

Exif orientation code to apply after the image has been loaded.

Definition at line 83 of file imagemetadata.cpp.

Referenced by ThumbThread< ImageDbSg >::CreateThumbnail(), Slide::LoadSlide(), and ImageScanThread< ImageDbSg >::SyncFile().

Description()

QString Orientation::Description

(

)

const

Generate text description of orientation.

Reports code & its interpretation of file orientation and, if different, the Db orientation

Returns

Text description of orientation

Definition at line 226 of file imagemetadata.cpp.

Referenced by ReadMetaThread::run().

FromRotation()

int Orientation::FromRotation ( const QString &  degrees )

static

Convert degrees of rotation into Exif orientation code.

Parameters

degrees

CW rotation required to show video correctly

Returns

QString Orientation code as per Exif spec.

Definition at line 210 of file imagemetadata.cpp.

Referenced by VideoMetaData::GetOrientation().

AsText()

QString Orientation::AsText ( int  orientation )

staticprivate

Converts orientation code to text description for info display.

Parameters

orientation

Exif code

Returns

QString Description text

Definition at line 240 of file imagemetadata.cpp.

Referenced by Description().

Apply()

int Orientation::Apply ( int  transform ) const

private

Adjust current orientation code to apply a transform to an image.

When displayed the image will be orientated iaw its orientation code. The transform is effected by applying the reverse transform to the orientation code.

See also

http://jpegclub.org/exif_orientation.html

Parameters

transform

Rotation/flip to apply

Returns

int New orientation code that will apply the transform to the image

Definition at line 112 of file imagemetadata.cpp.

Referenced by Transform().

InitOrientationMatrix()

Orientation::Matrix Orientation::InitOrientationMatrix ( )

staticprivate

Initialises conversion matrix for Qt 5.4.1.

Returns

Matrix of orientation codes such that: Qt 5.4.1 orientation = matrix(file orientation, current orientation)

Definition at line 38 of file imagemetadata.cpp.

Member Data Documentation

krunningQt541

const bool Orientation::krunningQt541 = (strcmp(qVersion(), "5.4.1") == 0)

staticprivate

True when using Qt 5.4.1 with its deviant orientation behaviour.

Definition at line 86 of file imagemetadata.h.

Referenced by GetCurrent(), and InitOrientationMatrix().

kQt541_orientation

const Orientation::Matrix Orientation::kQt541_orientation

staticprivate

Initial value:

=
        Orientation::InitOrientationMatrix()

Orientation conversions for proper display on Qt 5.4.1.

Definition at line 88 of file imagemetadata.h.

Referenced by GetCurrent().

m_current

int Orientation::m_current

private

The orientation to use: the file orientation with user transformations applied.

Definition at line 92 of file imagemetadata.h.

Referenced by Apply(), Description(), GetCurrent(), and Transform().

m_file

int Orientation::m_file

private

The orientation of the raw file image, as specified by the camera.

Definition at line 94 of file imagemetadata.h.

Referenced by Apply(), Description(), and GetCurrent().

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The documentation for this class was generated from the following files:

• mythtv/libs/libmythmetadata/imagemetadata.h
• mythtv/libs/libmythmetadata/imagemetadata.cpp