Archived:Using Exif API for Symbian C++

Template:KBCS

ID	CS000968	Creation date	May 20, 2008
Platform	S60 3rd Edition, MR	Tested on devices	Nokia N95
Category	Symbian C++	Subcategory	Graphics

Keywords (APIs, classes, methods, functions): CExifRead

Overview

The CExifRead Interface class is used for parsing the Exif v2.2 file format. With this API you can read data from JPEG images, such as date, resolution, orientation, ISO speed, and exposure time.

MMP file

The following capabilities and libraries are required:

CAPABILITY        NONE
LIBRARY           efsrv.lib
LIBRARY           exiflib.lib

Header file

Class for reading Exif data.

#include <exifread.h>
#include <f32file.h>
 
class CMyExifReader : public CBase
    {
    public:
        static CMyExifReader* NewL();
        static CMyExifReader* NewLC();
        virtual ~CMyExifReader();
    private:
        CMyExifReader();
        void ConstructL();
    public:
        void ReadExifDataL(TDesC& aFilename);
 
    public:
        HBufC8* iImageDescription;
        HBufC8* iImageDate;
 
    };

Source file

CMyExifReader::CMyExifReader()
    {
    }
 
CMyExifReader* CMyExifReader::NewL()
    {
    CMyExifReader* self = NewLC();
    CleanupStack::Pop();
    return self;
    }
 
CMyExifReader* CMyExifReader::NewLC()
    {
    CMyExifReader* self = new (ELeave) CMyExifReader();
    CleanupStack::PushL( self );
    self->ConstructL();
    return self;
    }
 
void CMyExifReader::ConstructL()
    {
    }
 
CMyExifReader::~CMyExifReader()
    {
    delete iImageDescription;
    delete iImageDate;
    }
 
void CMyExifReader::ReadExifDataL(TDesC& aFilename)
    {
    // 1. Read Exif image from the file to a buffer
    RFile file;
    User::LeaveIfError( file.Open( CEikonEnv::Static()->FsSession(), aFilename, EFileRead ) );
    CleanupClosePushL( file );
    TInt size = 0;
    file.Size(size);
    HBufC8* exif = HBufC8::NewL( size );
    CleanupStack::PushL( exif );
    TPtr8 bufferDes( exif->Des() ); 
    User::LeaveIfError( file.Read( bufferDes ) );
    CleanupStack::Pop( exif );
    CleanupStack::PopAndDestroy(); // file
    CleanupStack::PushL( exif );
 
    // 2. Instantiate Exif reader...
    CExifRead* read = CExifRead::NewL( exif->Des() );
    CleanupStack::PushL( read );
 
    // 3. Get required data from the Exif image...
    TInt err = KErrNone;
    TRAP(err,iImageDescription = read->GetImageDescriptionL());
    TRAP(err,iImageDate = read->GetDateTimeL());
    // TODO: See CExifRead API for getting more data from image
 
    // 4. Delete the reader instance...
    CleanupStack::PopAndDestroy( read );
    CleanupStack::PopAndDestroy( exif );
    }

Postconditions

Exif data read from the given image.

See also

Exif API

File:GeoTagging Example.zip