/*

* Copyright (c) 2006 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  

*	CDCDithering 

*		Dithering by H263 algorithm developed in NMP/Oulu.

*

*/

//  Include Files  

#include <e32std.h>   // The basic definitions

#include <fbs.h>      // For FBS bitmap

#include "DCDithering.h"     // The DCDithering class

//  MEMBER FUNCTIONS

//=============================================================================

/*

-----------------------------------------------------------------------------

    CDCDithering

    Constructor

    Default constructor

    Return Values:  none

-----------------------------------------------------------------------------

*/

CDCDithering::CDCDithering()

{

	// This function is intentionally left blank.

}

/*

-----------------------------------------------------------------------------

    CDCDithering

    NewLC

    Factory function to instantiate the class.

    This function leaves the class pointer to the cleanup stack

    May leave with KErrNoMemory if no memory available

    Return Values:  CDCDithering* self:  pointer to the class instance

-----------------------------------------------------------------------------

*/

CDCDithering* CDCDithering::NewLC()

{

    CDCDithering* self = new (ELeave) CDCDithering();

    CleanupStack::PushL(self);

    self->ConstructL();

    return self;

}

/*

-----------------------------------------------------------------------------

    CDCDithering

    NewL

    Factory function to instantiate the class.

    May leave with KErrNoMemory if no memory available

    Return Values:  CDCDithering* self:  pointer to the class instance

-----------------------------------------------------------------------------

*/

CDCDithering* CDCDithering::NewL()

{

    CDCDithering* self = CDCDithering::NewLC();

    CleanupStack::Pop();

    return self;

}

/*

-----------------------------------------------------------------------------

    CDCDithering

    ConstructL

    Second phase constructor. Does nothing at the moment

    Return Values:  none

-----------------------------------------------------------------------------

*/

void CDCDithering::ConstructL()

{

    // This function is intentionally left blank.

}

/*

-----------------------------------------------------------------------------

    CDCDithering

    Destructor

    Return Values:  none

-----------------------------------------------------------------------------

*/

CDCDithering::~CDCDithering()

{

	// This function is intentionally left blank.

}

/*

-----------------------------------------------------------------------------

  ProcessL

  Process image referenced by aImage (modify aImage).

  May leave with KErrNoMemory if no memory available

  Return Values:  none

-----------------------------------------------------------------------------

*/

void CDCDithering::ProcessL(CFbsBitmap& aImage)

{

	TUint	r, g, b;	// Color components

	TUint8*	dataPtr;	// Pointer to data

	//Dithering variables, init to 0

	TInt	count=0;	

	TInt16	dither=0;

	//EColor16M image is needed

	if (aImage.DisplayMode() != EColor16M || aImage.DisplayMode() != EColor16M)

		return;

	// Line Buffer and pointer to the data

	TUint imageWidth = aImage.SizeInPixels().iWidth;

	TUint scanLineLengthInBytes = aImage.ScanLineLength(imageWidth, aImage.DisplayMode());

	//Allocate buffer for scanline

	iScanLineBuffer = HBufC8::NewMaxL(scanLineLengthInBytes);

	//Pointer to scanline

	TPtr8 linePtr = iScanLineBuffer->Des();

	//Step through image lines

	for (TInt lineNo=0; lineNo<aImage.SizeInPixels().iHeight; ++lineNo)

	{

		//Get line

		aImage.GetScanLine(linePtr, TPoint(0, lineNo), imageWidth, aImage.DisplayMode());

		//CHECK! CONST_CAST not used in every algorithm which way is better?

		dataPtr = CONST_CAST(TUint8*, linePtr.Ptr());

		//Step through image pixels

		for (TUint x=0; x < imageWidth; ++x)

		{

			// Get original values

			b = *dataPtr++;

			g = *dataPtr++;

			r = *dataPtr++;

			//Compute DCDithering factor from base count

			switch (count&1)

			{

			case 0:

				dither = (TInt16)(dither*0x7ffd);

				break;

			case 1:

				dither = (TInt16)(dither+0x7f21);

				break;

			}

			//Add DCDithering factor, adjust gain according to quantization factors.

			r = Limit255((TInt)r + (dither>>13));

			g = Limit255((TInt)g - (dither>>14));

			b = Limit255((TInt)b + (dither>>13));

			//Move to the previous pixel

			dataPtr -= 3;

			/* Set the result */

			*dataPtr++ = (TUint8)b;

			*dataPtr++ = (TUint8)g;

			*dataPtr++ = (TUint8)r;

			//Increase bae count

			count++;

		}

		//Set scan line

		aImage.SetScanLine(linePtr, lineNo);

	}

	//Free allocated memory

	delete(iScanLineBuffer);

	iScanLineBuffer = 0;

}

//  End of File  

//----IMAAMI----