📄 libmng_filter.c
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/* ************************************************************************** */
/* * For conditions of distribution and use, * */
/* * see copyright notice in libmng.h * */
/* ************************************************************************** */
/* * * */
/* * project : libmng * */
/* * file : libmng_filter.c copyright (c) 2000-2003 G.Juyn * */
/* * version : 1.0.6 * */
/* * * */
/* * purpose : Filtering routines (implementation) * */
/* * * */
/* * author : G.Juyn * */
/* * * */
/* * comment : implementation of the filtering routines * */
/* * * */
/* * changes : 0.5.1 - 05/08/2000 - G.Juyn * */
/* * - changed strict-ANSI stuff * */
/* * 0.5.1 - 05/12/2000 - G.Juyn * */
/* * - changed trace to macro for callback error-reporting * */
/* * * */
/* * 0.9.2 - 08/05/2000 - G.Juyn * */
/* * - changed file-prefixes * */
/* * * */
/* * 0.9.3 - 09/07/2000 - G.Juyn * */
/* * - added support for new filter_types * */
/* * * */
/* * 1.0.5 - 08/07/2002 - G.Juyn * */
/* * - added test-option for PNG filter method 193 (=no filter) * */
/* * 1.0.5 - 08/19/2002 - G.Juyn * */
/* * - B597134 - libmng pollutes the linker namespace * */
/* * * */
/* * 1.0.6 - 07/07/2003 - G.R-P * */
/* * - reversed some loops to use decrementing counter * */
/* * * */
/* ************************************************************************** */
#include "libmng.h"
#include "libmng_data.h"
#include "libmng_error.h"
#include "libmng_trace.h"
#ifdef __BORLANDC__
#pragma hdrstop
#endif
#include "libmng_filter.h"
#if defined(__BORLANDC__) && defined(MNG_STRICT_ANSI)
#pragma option -A /* force ANSI-C */
#endif
/* ************************************************************************** */
#ifdef MNG_INCLUDE_FILTERS
/* ************************************************************************** */
MNG_LOCAL mng_retcode filter_sub (mng_datap pData)
{
mng_uint32 iBpp;
mng_uint8p pRawx;
mng_uint8p pRawx_prev;
mng_int32 iX;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_SUB, MNG_LC_START)
#endif
iBpp = pData->iFilterbpp;
pRawx = pData->pWorkrow + pData->iPixelofs + iBpp;
pRawx_prev = pData->pWorkrow + pData->iPixelofs;
for (iX = iBpp; iX < pData->iRowsize; iX++)
{
*pRawx = (mng_uint8)(*pRawx + *pRawx_prev);
pRawx++;
pRawx_prev++;
}
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_SUB, MNG_LC_END)
#endif
return MNG_NOERROR;
}
/* ************************************************************************** */
MNG_LOCAL mng_retcode filter_up (mng_datap pData)
{
mng_uint8p pRawx;
mng_uint8p pPriorx;
mng_int32 iX;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_UP, MNG_LC_START)
#endif
pRawx = pData->pWorkrow + pData->iPixelofs;
pPriorx = pData->pPrevrow + pData->iPixelofs;
#ifdef MNG_DECREMENT_LOOPS
for (iX = pData->iRowsize - 1; iX >= 0; iX--)
#else
for (iX = 0; iX < pData->iRowsize; iX++)
#endif
{
*pRawx = (mng_uint8)(*pRawx + *pPriorx);
pRawx++;
pPriorx++;
}
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_UP, MNG_LC_END)
#endif
return MNG_NOERROR;
}
/* ************************************************************************** */
MNG_LOCAL mng_retcode filter_average (mng_datap pData)
{
mng_int32 iBpp;
mng_uint8p pRawx;
mng_uint8p pRawx_prev;
mng_uint8p pPriorx;
mng_int32 iX;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_AVERAGE, MNG_LC_START)
#endif
iBpp = pData->iFilterbpp;
pRawx = pData->pWorkrow + pData->iPixelofs;
pPriorx = pData->pPrevrow + pData->iPixelofs;
pRawx_prev = pData->pWorkrow + pData->iPixelofs;
#ifdef MNG_DECREMENT_LOOPS
for (iX = iBpp - 1; iX >= 0; iX--)
#else
for (iX = 0; iX < iBpp; iX++)
#endif
{
*pRawx = (mng_uint8)(*pRawx + ((*pPriorx) >> 1));
pRawx++;
pPriorx++;
}
for (iX = iBpp; iX < pData->iRowsize; iX++)
{
*pRawx = (mng_uint8)(*pRawx + ((*pRawx_prev + *pPriorx) >> 1));
pRawx++;
pPriorx++;
pRawx_prev++;
}
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_AVERAGE, MNG_LC_END)
#endif
return MNG_NOERROR;
}
/* ************************************************************************** */
MNG_LOCAL mng_retcode filter_paeth (mng_datap pData)
{
mng_int32 iBpp;
mng_uint8p pRawx;
mng_uint8p pRawx_prev;
mng_uint8p pPriorx;
mng_uint8p pPriorx_prev;
mng_int32 iX;
mng_uint32 iA, iB, iC;
mng_uint32 iP;
mng_uint32 iPa, iPb, iPc;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_PAETH, MNG_LC_START)
#endif
iBpp = pData->iFilterbpp;
pRawx = pData->pWorkrow + pData->iPixelofs;
pPriorx = pData->pPrevrow + pData->iPixelofs;
pRawx_prev = pData->pWorkrow + pData->iPixelofs;
pPriorx_prev = pData->pPrevrow + pData->iPixelofs;
#ifdef MNG_DECREMENT_LOOPS
for (iX = iBpp - 1; iX >= 0; iX--)
#else
for (iX = 0; iX < iBpp; iX++)
#endif
{
*pRawx = (mng_uint8)(*pRawx + *pPriorx);
pRawx++;
pPriorx++;
}
for (iX = iBpp; iX < pData->iRowsize; iX++)
{
iA = (mng_uint32)*pRawx_prev;
iB = (mng_uint32)*pPriorx;
iC = (mng_uint32)*pPriorx_prev;
iP = iA + iB - iC;
iPa = abs (iP - iA);
iPb = abs (iP - iB);
iPc = abs (iP - iC);
if ((iPa <= iPb) && (iPa <= iPc))
*pRawx = (mng_uint8)(*pRawx + iA);
else
if (iPb <= iPc)
*pRawx = (mng_uint8)(*pRawx + iB);
else
*pRawx = (mng_uint8)(*pRawx + iC);
pRawx++;
pPriorx++;
pRawx_prev++;
pPriorx_prev++;
}
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_PAETH, MNG_LC_END)
#endif
return MNG_NOERROR;
}
/* ************************************************************************** */
mng_retcode mng_filter_a_row (mng_datap pData)
{
mng_retcode iRetcode;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_A_ROW, MNG_LC_START)
#endif
switch (*(pData->pWorkrow + pData->iFilterofs))
{
case 1 : {
iRetcode = filter_sub (pData);
break;
}
case 2 : {
iRetcode = filter_up (pData);
break;
}
case 3 : {
iRetcode = filter_average (pData);
break;
}
case 4 : {
iRetcode = filter_paeth (pData);
break;
}
default : iRetcode = MNG_INVALIDFILTER;
}
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_FILTER_A_ROW, MNG_LC_END)
#endif
return iRetcode;
}
/* ************************************************************************** */
/* ************************************************************************** */
#ifdef FILTER192
mng_retcode mng_init_rowdiffering (mng_datap pData)
{
mng_uint8p pRawi, pRawo;
mng_int32 iX;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_INIT_ROWDIFFERING, MNG_LC_START)
#endif
if (pData->iFilter == 0xC0) /* has leveling parameters ? */
{
switch (pData->iColortype) /* salvage leveling parameters */
{
case 0 : { /* gray */
if (pData->iBitdepth <= 8)
pData->iLevel0 = (mng_uint16)*pData->pWorkrow;
else
pData->iLevel0 = mng_get_uint16 (pData->pWorkrow);
break;
}
case 2 : { /* rgb */
if (pData->iBitdepth <= 8)
{
pData->iLevel0 = (mng_uint16)*pData->pWorkrow;
pData->iLevel1 = (mng_uint16)*(pData->pWorkrow+1);
pData->iLevel2 = (mng_uint16)*(pData->pWorkrow+2);
}
else
{
pData->iLevel0 = mng_get_uint16 (pData->pWorkrow);
pData->iLevel1 = mng_get_uint16 (pData->pWorkrow+2);
pData->iLevel2 = mng_get_uint16 (pData->pWorkrow+4);
}
break;
}
case 3 : { /* indexed */
pData->iLevel0 = (mng_uint16)*pData->pWorkrow;
break;
}
case 4 : { /* gray+alpha */
if (pData->iBitdepth <= 8)
{
pData->iLevel0 = (mng_uint16)*pData->pWorkrow;
pData->iLevel1 = (mng_uint16)*(pData->pWorkrow+1);
}
else
{
pData->iLevel0 = mng_get_uint16 (pData->pWorkrow);
pData->iLevel1 = mng_get_uint16 (pData->pWorkrow+2);
}
break;
}
case 6 : { /* rgb+alpha */
if (pData->iBitdepth <= 8)
{
pData->iLevel0 = (mng_uint16)*pData->pWorkrow;
pData->iLevel1 = (mng_uint16)*(pData->pWorkrow+1);
pData->iLevel2 = (mng_uint16)*(pData->pWorkrow+2);
pData->iLevel3 = (mng_uint16)*(pData->pWorkrow+3);
}
else
{
pData->iLevel0 = mng_get_uint16 (pData->pWorkrow);
pData->iLevel1 = mng_get_uint16 (pData->pWorkrow+2);
pData->iLevel2 = mng_get_uint16 (pData->pWorkrow+4);
pData->iLevel3 = mng_get_uint16 (pData->pWorkrow+6);
}
break;
}
}
}
/* shift the entire row back in place */
pRawi = pData->pWorkrow + pData->iFilterofs;
pRawo = pData->pWorkrow;
for (iX = 0; iX < pData->iRowsize + pData->iPixelofs - pData->iFilterofs; iX++)
*pRawo++ = *pRawi++;
pData->iFilterofs = 0; /* indicate so ! */
#ifdef FILTER193
if (pData->iFilter == 0xC1) /* no adaptive filtering ? */
pData->iPixelofs = pData->iFilterofs;
else
#endif
pData->iPixelofs = pData->iFilterofs + 1;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_INIT_ROWDIFFERING, MNG_LC_END)
#endif
return MNG_NOERROR;
}
/* ************************************************************************** */
mng_retcode mng_differ_g1 (mng_datap pData)
{
mng_uint8p pRawi, pRawo;
mng_int32 iX;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_DIFFER_G1, MNG_LC_START)
#endif
if (pData->iLevel0 & 0x01) /* is it uneven level ? */
{
pRawi = pData->pWorkrow + pData->iPixelofs;
pRawo = pData->pPrevrow + pData->iPixelofs;
/* just invert every bit */
#ifdef MNG_DECREMENT_LOOPS
for (iX = pData->iRowsize - 1; iX >= 0; iX--)
#else
for (iX = 0; iX < pData->iRowsize; iX++)
#endif
*pRawo++ = (mng_uint8)(~(*pRawi++));
}
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_DIFFER_G1, MNG_LC_END)
#endif
return MNG_NOERROR;
}
/* ************************************************************************** */
mng_retcode mng_differ_g2 (mng_datap pData)
{
mng_uint8p pRawi, pRawo;
mng_int32 iX;
mng_int32 iC, iS;
mng_uint8 iB, iN, iQ;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_DIFFER_G2, MNG_LC_START)
#endif
pRawi = pData->pWorkrow + pData->iPixelofs;
pRawo = pData->pPrevrow + pData->iPixelofs;
iC = 0;
iB = 0;
iN = 0;
iS = 0;
#ifdef MNG_DECREMENT_LOOPS
for (iX = pData->iRowsamples - 1; iX >= 0; iX--)
#else
for (iX = 0; iX < pData->iRowsamples; iX++)
#endif
{
if (!iC)
{
iC = 4;
iB = *pRawi++;
iN = 0;
iS = 8;
}
iS -= 2;
iQ = (mng_uint8)(((iB >> iS) + pData->iLevel0) & 0x03);
iN = (mng_uint8)((iN << 2) + iQ);
iC--;
if (!iC)
*pRawo++ = iN;
}
if (iC)
*pRawo = (mng_uint8)(iN << iS);
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_DIFFER_G2, MNG_LC_END)
#endif
return MNG_NOERROR;
}
/* ************************************************************************** */
mng_retcode mng_differ_g4 (mng_datap pData)
{
mng_uint8p pRawi, pRawo;
mng_int32 iX;
mng_int32 iC, iS;
mng_uint8 iB, iN, iQ;
#ifdef MNG_SUPPORT_TRACE
MNG_TRACE (pData, MNG_FN_DIFFER_G4, MNG_LC_START)
#endif
pRawi = pData->pWorkrow + pData->iPixelofs;
pRawo = pData->pPrevrow + pData->iPixelofs;
iC = 0;
iB = 0;
iN = 0;
iS = 0;
#ifdef MNG_DECREMENT_LOOPS
for (iX = pData->iRowsamples - 1; iX >= 0; iX--)
#else
for (iX = 0; iX < pData->iRowsamples; iX++)
#endif
{
if (!iC)
{
iC = 2;
iB = *pRawi++;
iN = 0;
iS = 8;
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