epoc32/include/graphics/blendingalgorithms.inl
author William Roberts <williamr@symbian.org>
Tue, 16 Mar 2010 16:12:26 +0000 (2010-03-16)
branchSymbian2
changeset 2 2fe1408b6811
parent 0 061f57f2323e
permissions -rw-r--r--
Final list of Symbian^2 public API header files
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// Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
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// All rights reserved.
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// This component and the accompanying materials are made available
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// under the terms of the License "Symbian Foundation License v1.0" to Symbian Foundation members and "Symbian Foundation End User License Agreement v1.0" to non-members
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// which accompanies this distribution, and is available
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// at the URL "http://www.symbianfoundation.org/legal/licencesv10.html".
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//
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// Initial Contributors:
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// Nokia Corporation - initial contribution.
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//
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// Contributors:
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//
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// Description:
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//
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const TUint32 KRBMask = 0x00ff00ff;
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const TUint32 KAGMask = 0xff00ff00;
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const TUint32 KGMask  = 0x0000ff00;
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//Algoriths for Premultiplied alpha screenmode/pixel format.
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inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask)
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	{
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	if(aMask)
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		{
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		if(aMask == 0xff) // opaque, so unchanged
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			{
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			return aSrcPixel;
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			}
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		else
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			{
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			return PMABlend_noChecks(aDestPixel, aSrcPixel, aMask);
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			}
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		}
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	 else // completely transparent
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		{
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		return aDestPixel;
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 		}
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	}
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inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel)
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	{
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	TUint8 mask = (TUint8)(aSrcPixel >> 24);
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	return PMAPixelBlend(aDestPixel, aSrcPixel, mask);
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	}
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inline TUint32 PMABlend_noChecks(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMaskingFactor)
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	{
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	TUint32 src_c = aSrcPixel & KRBMask;
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	TUint32 dst_c = aDestPixel  & KRBMask;
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	const TUint32 mask = 0x0100 - aMaskingFactor;
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	dst_c = (src_c +  ((mask * dst_c)>>8)) & KRBMask;
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	src_c = (aSrcPixel & KAGMask)>>8;
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	TUint32 dst_ag = (aDestPixel & KAGMask)>>8;
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	dst_c |= ((src_c +  ((mask * dst_ag)>>8)) & KRBMask)<<8;
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	return dst_c;
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	}
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inline void PMABlend_noChecksInplace(TUint32& aDest_io, TUint32& aSrcPixel,TUint8& aMaskingFactor)
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	{
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	TUint32 src_c = aSrcPixel & KRBMask;
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	TUint32 dst_ag = (aDest_io & KAGMask) >> 8;
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	aDest_io = aDest_io  & KRBMask;
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	const TUint32 mask = 0x0100 - aMaskingFactor;
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	aDest_io = (src_c +  ((mask * aDest_io) >> 8)) & KRBMask;
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	src_c = (aSrcPixel & KAGMask) >> 8;
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	aDest_io |= ((src_c +  ((mask * dst_ag) >> 8)) & KRBMask)<<8;
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	}
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inline void PMAInplaceBlend(TUint32& aDest_io, TUint32& aSrc_in)
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	{
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	TUint8 mask = (TUint8)(aSrc_in >> 24);
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	if(mask)
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		{
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		if(mask == 0xff) // opaque, so dst = src.
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			{
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			aDest_io = aSrc_in;
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			}
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		else
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			{
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			PMABlend_noChecksInplace(aDest_io, aSrc_in, mask);
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			}
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		}
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	//else src completely transparent, so dst unchanged.
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	}
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inline TUint32 NonPMA2PMAPixel(TUint32 aPixel)
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	{
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	TUint8 tA = (TUint8)(aPixel >> 24);
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	if (tA==0)
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		{ 
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		return 0;
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		}
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	if (tA==0xff) 
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		{
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		return aPixel;
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		}
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	// Use a bias value of 128 rather than 255, but also add 1/256 of the numerator 
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	// before dividing the sum by 256.
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	TUint32 tap1=tA+1;
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	TUint32 scaledRB = (aPixel & KRBMask) * tap1;
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	TUint32 scaledG = (aPixel & KGMask ) * tap1;
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	return (aPixel & 0xff000000) | ((scaledRB>>8) & KRBMask) | ((scaledG>>8)& KGMask);
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	}
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inline TUint32 PMA2NonPMAPixel(TUint32 aPixel, const TUint16* aNormTable)
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	{
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	TUint8 alpha = (TUint8)(aPixel >> 24);
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	if (alpha==0)
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		{ 
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		return 0;
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		}
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	if (alpha==0xff) 
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		{
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		return aPixel;
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		}
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	TUint16 norm = aNormTable[alpha];
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	TUint32 norm_rb = (((aPixel & KRBMask) * norm) >> 8) & KRBMask;
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	TUint32 norm_g =  (((aPixel & KGMask ) * norm) >> 8) & KGMask;
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	return ((aPixel & 0xff000000) | norm_rb | norm_g);
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	}
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inline void Convert2PMA(TUint32& aInOutValue)
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	{
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	aInOutValue = NonPMA2PMAPixel(aInOutValue);
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	}
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inline void Convert2NonPMA(TUint32& aInOutValue, const TUint16* aNormTable)
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	{
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	aInOutValue = PMA2NonPMAPixel(aInOutValue, aNormTable);
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	}