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How to read images to Symbian bitmap

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Created: symbianyucca (20 Mar 2007)
Last edited: hamishwillee (18 Sep 2012)


The CImage_Reader implementation illustrates how to use CImageDecoder to open and read different types of images (jpeg, png, depending on the device) and how to convert them to the Symbian bitmap format, which then can be used to draw the image to the screen.

Tip.pngTip: This is a basic example. There is more thorough example in Nokia Developer, which enables you to also load different types of image files, as well as rotate, scale and save them back in different formats.

S60 Platform: Image Converter Example


The GetFileType function is used to determine the type of the image file, and if the image type is not recognized by the system it will be indicated by the iError variable. The MImageReadyCallBack callback interface is used to notify of the completion of the image loading.

Image_Reader.cpp

#include <APMREC.H>
#include <APGCLI.H>
 
 
CImage_Reader::CImage_Reader(MImageReadyCallBack& aNotify)
:CActive(0),iNotify(aNotify)
{
}
 
CImage_Reader::~CImage_Reader()
{
Cancel();
delete iFrame;
delete iImageDecoder;
}
 
 
void CImage_Reader::ConstructL(const TDesC& aFileName)
{
CActiveScheduler::Add(this);
 
iImageName.Copy(aFileName);
 
TBuf8<255> ImageType;
GetFileType(aFileName, ImageType);
 
if(ImageType.Length() && iImageName.Length())
{
iImageDecoder = CImageDecoder::FileNewL(CCoeEnv::Static()->FsSession(),aFileName,ImageType);
 
delete iFrame;
iFrame = NULL;
iFrame = new(ELeave)CFbsBitmap();
iFrame->Create(iImageDecoder->FrameInfo(0).iOverallSizeInPixels,iImageDecoder->FrameInfo(0).iFrameDisplayMode);
 
iImageDecoder->Convert(&iStatus,*iFrame,0);
SetActive();
}
else
{
TRequestStatus* status=&iStatus;
User::RequestComplete(status, KErrNotSupported);
SetActive();
}
}
 
void CImage_Reader::GetFileType(const TDesC& aFileName, TDes8& aFileType)
{
TEntry FileEntry;
 
if(CCoeEnv::Static()->FsSession().Entry(aFileName,FileEntry) == KErrNone)
{
TBuf8<255> FileBuffer;
 
if(!FileEntry.IsDir())
{
TInt FileSize = FileEntry.iSize;
 
if(FileSize > 255)
{
FileSize = 255;
}
 
if(CCoeEnv::Static()->FsSession().ReadFileSection(aFileName,0,FileBuffer,FileSize) == KErrNone)
{
RApaLsSession RSession;
if(RSession.Connect() == KErrNone)
{
TDataRecognitionResult FileDataType;
 
RSession.RecognizeData(aFileName,FileBuffer,*&FileDataType);
 
aFileType.Copy(FileDataType.iDataType.Des8());
 
RSession.Close();
}
}
}
}
}
 
void CImage_Reader::DoCancel()
{
iImageDecoder->Cancel();
}
 
CFbsBitmap* CImage_Reader::Bitmap()
{
return iFrame;
}
 
 
void CImage_Reader::RunL()
{
iNotify.ImageReadyL(iStatus.Int());
}

Image_Reader.h

#include <e32base.h>
#include <coecntrl.h>
#include <w32std.h>
#include <e32std.h>
#include <cntdef.h>
#include <cntdb.h>
#include <ImageConversion.h>
 
class CFbsBitmap;
 
class MImageReadyCallBack
{
public:
virtual void ImageReadyL(const TInt& aError) = 0;
};
 
class CImage_Reader : public CActive
{
public:
CImage_Reader(MImageReadyCallBack& aNotify);
void ConstructL(const TDesC& aFileName);
~CImage_Reader();
public:
CFbsBitmap* Bitmap();
protected:
void DoCancel();
void RunL();
private:
void GetFileType(const TDesC& aFileName, TDes8& aFileType);
private:
MImageReadyCallBack& iNotify;
CImageDecoder* iImageDecoder;
CFbsBitmap* iFrame;
TFileName iImageName;
};


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This page was last modified on 18 September 2012, at 08:48.
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