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Revision as of 22:01, 10 October 2008 by extkbeditor1 (Talk | contribs)

Archived:Using Exif API for Symbian C++

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Article Metadata
Tested with
Devices(s): Nokia N95
Compatibility
Platform(s): S60 3rd Edition, MR
S60 3rd Edition FP1
Article
Keywords: CExifRead
Created: (20 May 2008)
Last edited: extkbeditor1 (10 Oct 2008)

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

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