sl@0: // Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: //
sl@0: 
sl@0: #ifndef __BLENDINGALGORITHMS_H__
sl@0: #define __BLENDINGALGORITHMS_H__
sl@0: 
sl@0: #include <e32def.h>
sl@0: /**
sl@0: @file
sl@0: @internalTechnology
sl@0: */
sl@0: 
sl@0: /** Premultiplied Alpha (PMA) Blending algorithm.
sl@0: Assumes src and target pixels are in PMA format (i.e., the color channels are already multiplied
sl@0: with the alpha channel.
sl@0: Blending Equations:
sl@0: Cd' = Cs + ((255 - As) * Cd)/255
sl@0: Ad' = As + ((255 - As) * Ad)/255
sl@0: where Cd' and Ad' are destination values for color and alpha channels respectively, after blending,
sl@0: Cd and Ad are destination values before blending, and Cs and As are source values (color and
sl@0: alpha values respectively).
sl@0: Optimisations:
sl@0: Use of 256 instead of 255 converts the division to shift (faster).
sl@0: Red and Blue channels are calculated together in one 32 bit operation.
sl@0: Alpha and Green channels are calculated in the same way. However, due the
sl@0: position of these channels within the pixel format, an extra shift is required.
sl@0: The equations used are:
sl@0: Cd' = Cs + (((0x100 - As) * Cd)>>8)
sl@0: Ad' = As + (((0x100 - As) * Ad)>>8)
sl@0: For the results to not overflow, it is required that the value of any of the color channels
sl@0: is no greater than the alpha channel, which is what is exepected of pma format.
sl@0: It is also assumed that the aMask is equal to source alpha.
sl@0: @param 	aDestPixel	The destination pixel value.
sl@0: @param	aSrcPixel	The source pixel value.
sl@0: @param	aMask		The source alpha. It is assumed to be same as source alpha.
sl@0: @return the alpha-blended pixel (within the PMA space).
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask);
sl@0: 
sl@0: /** Same as inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask)
sl@0: Calls inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask), with aMask
sl@0: extracted from the source pixel.
sl@0: @see PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask)
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel);
sl@0: 
sl@0: /**
sl@0: Does the premultiplied alpha blend, but does not check for any pre/post conditions.
sl@0: Please DO NOT Add any optimisations to check for these conditions in this code!
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline TUint32 PMABlend_noChecks(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMaskingFactor);
sl@0: 
sl@0: /**
sl@0: The version of PMABlend_noChecks which does the blending in place.
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline void PMABlend_noChecksInplace(TUint32& aDest_io, const TUint32& aSrcPixel, TUint8 aMaskingFactor);
sl@0: 
sl@0: /**
sl@0: The in-place version of the PMAPixelBlend algorithm
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline void PMAInplaceBlend(TUint32& aDest_io, TUint32& aSrc_in);
sl@0: /**
sl@0: Premultiplies the color channel values with the Alpha channel value.
sl@0: Alpha value remains unchanged. An approximation is used in the operation where the division
sl@0: by 255 is approximated by a shift-by-8-bits operation (i.e. division by 256).
sl@0: @param	aPixel	The 32 bit pixel value to be pre-multiplied.
sl@0: @return	The PMA value.
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline TUint32 NonPMA2PMAPixel(TUint32 aPixel);
sl@0: 
sl@0: /**
sl@0: Divives the PMA pixel color channels with the Alpha value, to convert them to non-PMA format.
sl@0: Alpha value remains unchanged.
sl@0: @param	aPixel	the premultiplied 32 bit pixel value.
sl@0: @param	aNormTable	The lookup table used to do the normalisation (the table converts the division
sl@0: 					to multiplication operation).
sl@0: 					The table is usually obtainable by a call to the method:
sl@0: 					PtrTo16BitNormalisationTable, which is defined in lookuptable.dll(.lib).
sl@0: 					The lookup table for normalised alpha is compluted using this equation: 
sl@0: 					Table[index] = (255*256) / index (where index is an 8 bit value).
sl@0: @return The NON-PMA 32 bit pixel value.
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline TUint32 PMA2NonPMAPixel(TUint32 aPixel, const TUint16* aNormTable);
sl@0: 
sl@0: /**
sl@0: In-place version of NonPMA2PMAPixel.
sl@0: @see NonPMA2PMAPixel
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline void Convert2PMA(TUint32& aInOutValue);
sl@0: 
sl@0: /**
sl@0: In-place version of PMA2NonPMAPixel
sl@0: @see PMA2NonPMAPixel
sl@0: @internalTechnology
sl@0: @released
sl@0: */
sl@0: inline void Convert2NonPMA(TUint32& aInOutValue, const TUint16* aNormTable);
sl@0: 
sl@0: #include <graphics/blendingalgorithms.inl>
sl@0: 
sl@0: #endif //__BLENDINGALGORITHMS_H__