1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/epoc32/include/graphics/blendingalgorithms.h Tue Mar 16 16:12:26 2010 +0000
1.3 @@ -0,0 +1,130 @@
1.4 +// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
1.5 +// All rights reserved.
1.6 +// This component and the accompanying materials are made available
1.7 +// 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
1.8 +// which accompanies this distribution, and is available
1.9 +// at the URL "http://www.symbianfoundation.org/legal/licencesv10.html".
1.10 +//
1.11 +// Initial Contributors:
1.12 +// Nokia Corporation - initial contribution.
1.13 +//
1.14 +// Contributors:
1.15 +//
1.16 +// Description:
1.17 +//
1.18 +
1.19 +#ifndef __BLENDINGALGORITHMS_H__
1.20 +#define __BLENDINGALGORITHMS_H__
1.21 +
1.22 +#include <e32def.h>
1.23 +/**
1.24 +@file
1.25 +@internalTechnology
1.26 +*/
1.27 +
1.28 +/** Premultiplied Alpha (PMA) Blending algorithm.
1.29 +Assumes src and target pixels are in PMA format (i.e., the color channels are already multiplied
1.30 +with the alpha channel.
1.31 +Blending Equations:
1.32 +Cd' = Cs + ((255 - As) * Cd)/255
1.33 +Ad' = As + ((255 - As) * Ad)/255
1.34 +where Cd' and Ad' are destination values for color and alpha channels respectively, after blending,
1.35 +Cd and Ad are destination values before blending, and Cs and As are source values (color and
1.36 +alpha values respectively).
1.37 +Optimisations:
1.38 +Use of 256 instead of 255 converts the division to shift (faster).
1.39 +Red and Blue channels are calculated together in one 32 bit operation.
1.40 +Alpha and Green channels are calculated in the same way. However, due the
1.41 +position of these channels within the pixel format, an extra shift is required.
1.42 +The equations used are:
1.43 +Cd' = Cs + (((0x100 - As) * Cd)>>8)
1.44 +Ad' = As + (((0x100 - As) * Ad)>>8)
1.45 +For the results to not overflow, it is required that the value of any of the color channels
1.46 +is no greater than the alpha channel, which is what is exepected of pma format.
1.47 +It is also assumed that the aMask is equal to source alpha.
1.48 +@param aDestPixel The destination pixel value.
1.49 +@param aSrcPixel The source pixel value.
1.50 +@param aMask The source alpha. It is assumed to be same as source alpha.
1.51 +@return the alpha-blended pixel (within the PMA space).
1.52 +@internalTechnology
1.53 +@released
1.54 +*/
1.55 +inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask);
1.56 +
1.57 +/** Same as inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask)
1.58 +Calls inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask), with aMask
1.59 +extracted from the source pixel.
1.60 +@see PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMask)
1.61 +@internalTechnology
1.62 +@released
1.63 +*/
1.64 +inline TUint32 PMAPixelBlend(TUint32 aDestPixel, TUint32 aSrcPixel);
1.65 +
1.66 +/**
1.67 +Does the premultiplied alpha blend, but does not check for any pre/post conditions.
1.68 +Please DO NOT Add any optimisations to check for these conditions in this code!
1.69 +@internalTechnology
1.70 +@released
1.71 +*/
1.72 +inline TUint32 PMABlend_noChecks(TUint32 aDestPixel, TUint32 aSrcPixel, TUint8 aMaskingFactor);
1.73 +
1.74 +/**
1.75 +The version of PMABlend_noChecks which does the blending in place.
1.76 +@internalTechnology
1.77 +@released
1.78 +*/
1.79 +inline void PMABlend_noChecksInplace(TUint32& aDest_io, TUint32& aSrcPixel,TUint8& aMaskingFactor);
1.80 +
1.81 +/**
1.82 +The in-place version of the PMAPixelBlend algorithm
1.83 +@internalTechnology
1.84 +@released
1.85 +*/
1.86 +inline void PMAInplaceBlend(TUint32& aDest_io, TUint32& aSrc_in);
1.87 +/**
1.88 +Premultiplies the color channel values with the Alpha channel value.
1.89 +Alpha value remains unchanged. An approximation is used in the operation where the division
1.90 +by 255 is approximated by a shift-by-8-bits operation (i.e. division by 256).
1.91 +@param aPixel The 32 bit pixel value to be pre-multiplied.
1.92 +@return The PMA value.
1.93 +@internalTechnology
1.94 +@released
1.95 +*/
1.96 +inline TUint32 NonPMA2PMAPixel(TUint32 aPixel);
1.97 +
1.98 +/**
1.99 +Divives the PMA pixel color channels with the Alpha value, to convert them to non-PMA format.
1.100 +Alpha value remains unchanged.
1.101 +@param aPixel the premultiplied 32 bit pixel value.
1.102 +@param aNormTable The lookup table used to do the normalisation (the table converts the division
1.103 + to multiplication operation).
1.104 + The table is usually obtainable by a call to the method:
1.105 + PtrTo16BitNormalisationTable, which is defined in lookuptable.dll(.lib).
1.106 + The lookup table for normalised alpha is compluted using this equation:
1.107 + Table[index] = (255*256) / index (where index is an 8 bit value).
1.108 +@return The NON-PMA 32 bit pixel value.
1.109 +@internalTechnology
1.110 +@released
1.111 +*/
1.112 +inline TUint32 PMA2NonPMAPixel(TUint32 aPixel, const TUint16* aNormTable);
1.113 +
1.114 +/**
1.115 +In-place version of NonPMA2PMAPixel.
1.116 +@see NonPMA2PMAPixel
1.117 +@internalTechnology
1.118 +@released
1.119 +*/
1.120 +inline void Convert2PMA(TUint32& aInOutValue);
1.121 +
1.122 +/**
1.123 +In-place version of PMA2NonPMAPixel
1.124 +@see PMA2NonPMAPixel
1.125 +@internalTechnology
1.126 +@released
1.127 +*/
1.128 +inline void Convert2NonPMA(TUint32& aInOutValue, const TUint16* aNormTable);
1.129 +
1.130 +
1.131 +#include <graphics/blendingalgorithms.inl>
1.132 +
1.133 +#endif //__BLENDINGALGORITHMS_H__