/*
 *  Copyright (c) 2002 Patrick Julien  <freak@codepimps.org>
 *  Copyright (c) 2004 Cyrille Berger
 *  Copyright (c) 2004 Boudewijn Rempt <boud@valdyas.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <limits.h>
#include <stdlib.h>

#include <config.h>
#include LCMS_HEADER

#include <tqimage.h>

#include <tdelocale.h>
#include <kdebug.h>
#include <tdeglobal.h>

#include "kis_abstract_colorspace.h"
#include "kis_u8_base_colorspace.h"
#include "kis_gray_colorspace.h"
#include "kis_integer_maths.h"

#define downscale(quantum)  (quantum) //((unsigned char) ((quantum)/257UL))
#define upscale(value)  (value) // ((TQ_UINT8) (257UL*(value)))

namespace {
    const TQ_INT32 MAX_CHANNEL_GRAYSCALE = 1;
    const TQ_INT32 MAX_CHANNEL_GRAYSCALEA = 2;
}

KisGrayColorSpace::KisGrayColorSpace(KisColorSpaceFactoryRegistry * parent, KisProfile *p) :
    KisU8BaseColorSpace(KisID("GRAYA", i18n("Grayscale")), TYPE_GRAYA_8, icSigGrayData, parent, p)
{
    m_channels.push_back(new KisChannelInfo(i18n("Gray"), i18n("G"), 0, KisChannelInfo::COLOR, KisChannelInfo::UINT8));
    m_channels.push_back(new KisChannelInfo(i18n("Alpha"), i18n("A"), 1, KisChannelInfo::ALPHA, KisChannelInfo::UINT8));

    m_alphaPos = PIXEL_GRAY_ALPHA;

    init();
}


KisGrayColorSpace::~KisGrayColorSpace()
{
}

void KisGrayColorSpace::setPixel(TQ_UINT8 *pixel, TQ_UINT8 gray, TQ_UINT8 alpha) const
{
    pixel[PIXEL_GRAY] = gray;
    pixel[PIXEL_GRAY_ALPHA] = alpha;
}

void KisGrayColorSpace::getPixel(const TQ_UINT8 *pixel, TQ_UINT8 *gray, TQ_UINT8 *alpha) const
{
    *gray = pixel[PIXEL_GRAY];
    *alpha = pixel[PIXEL_GRAY_ALPHA];
}

void KisGrayColorSpace::getAlpha(const TQ_UINT8 *pixel, TQ_UINT8 *alpha) const
{
    *alpha = pixel[PIXEL_GRAY_ALPHA];
}

void KisGrayColorSpace::setAlpha(TQ_UINT8 *pixels, TQ_UINT8 alpha, TQ_INT32 nPixels) const
{
    while (nPixels > 0) {
        pixels[PIXEL_GRAY_ALPHA] = alpha;
        --nPixels;
        pixels += MAX_CHANNEL_GRAYSCALEA;
    }
}

void KisGrayColorSpace::mixColors(const TQ_UINT8 **colors, const TQ_UINT8 *weights, TQ_UINT32 nColors, TQ_UINT8 *dst) const
{
    TQ_UINT32 totalGray = 0, newAlpha = 0;

    while (nColors--)
    {
        TQ_UINT32 alpha = (*colors)[PIXEL_GRAY_ALPHA];
        TQ_UINT32 alphaTimesWeight = UINT8_MULT(alpha, *weights);

        totalGray += (*colors)[PIXEL_GRAY] * alphaTimesWeight;
        newAlpha += alphaTimesWeight;

        weights++;
        colors++;
    }

    Q_ASSERT(newAlpha <= 255);

    dst[PIXEL_GRAY_ALPHA] = newAlpha;

    if (newAlpha > 0) {
        totalGray = UINT8_DIVIDE(totalGray, newAlpha);
    }

    // Divide by 255.
    totalGray += 0x80;
    TQ_UINT32 dstGray = ((totalGray >> 8) + totalGray) >> 8;
    Q_ASSERT(dstGray <= 255);
    dst[PIXEL_GRAY] = dstGray;
}

void KisGrayColorSpace::convolveColors(TQ_UINT8** colors, TQ_INT32* kernelValues, KisChannelInfo::enumChannelFlags channelFlags, TQ_UINT8 *dst, TQ_INT32 factor, TQ_INT32 offset, TQ_INT32 nColors) const
{
    TQ_INT32 totalGray = 0, totalAlpha = 0;

    while (nColors--)
    {
        TQ_INT32 weight = *kernelValues;

        if (weight != 0) {
            totalGray += (*colors)[PIXEL_GRAY] * weight;
            totalAlpha += (*colors)[PIXEL_GRAY_ALPHA] * weight;
        }
        colors++;
        kernelValues++;
    }


    if (channelFlags & KisChannelInfo::FLAG_COLOR) {
        dst[PIXEL_GRAY] = CLAMP((totalGray / factor) + offset, 0, TQ_UINT8_MAX);
    }
    if (channelFlags & KisChannelInfo::FLAG_ALPHA) {
        dst[PIXEL_GRAY_ALPHA] = CLAMP((totalAlpha/ factor) + offset, 0, TQ_UINT8_MAX);
    }

}


void KisGrayColorSpace::invertColor(TQ_UINT8 * src, TQ_INT32 nPixels)
{
    TQ_UINT32 psize = pixelSize();

    while (nPixels--)
    {
        src[PIXEL_GRAY] = TQ_UINT8_MAX - src[PIXEL_GRAY];
        src += psize;
    }
}

void KisGrayColorSpace::darken(const TQ_UINT8 * src, TQ_UINT8 * dst, TQ_INT32 shade, bool compensate, double compensation, TQ_INT32 nPixels) const
{
    TQ_UINT32 pSize = pixelSize();

    while (nPixels--) {
        if (compensate) {
            dst[PIXEL_GRAY]  = (TQ_INT8) TQMIN(255,((src[PIXEL_GRAY] * shade) / (compensation * 255)));
        }
        else {
            dst[PIXEL_GRAY]  = (TQ_INT8) TQMIN(255, (src[PIXEL_GRAY] * shade / 255));
        }
        dst += pSize;
        src += pSize;
    }
}

TQ_UINT8 KisGrayColorSpace::intensity8(const TQ_UINT8 * src) const
{
    return src[PIXEL_GRAY];
}

TQValueVector<KisChannelInfo *> KisGrayColorSpace::channels() const
{
    return m_channels;
}

TQ_UINT32 KisGrayColorSpace::nChannels() const
{
    return MAX_CHANNEL_GRAYSCALEA;
}

TQ_UINT32 KisGrayColorSpace::nColorChannels() const
{
    return MAX_CHANNEL_GRAYSCALE;
}

TQ_UINT32 KisGrayColorSpace::pixelSize() const
{
    return MAX_CHANNEL_GRAYSCALEA;
}

void KisGrayColorSpace::bitBlt(TQ_UINT8 *dst,
                      TQ_INT32 dstRowStride,
                      const TQ_UINT8 *src,
                      TQ_INT32 srcRowStride,
                      const TQ_UINT8 *mask,
                      TQ_INT32 maskRowStride,
                      TQ_UINT8 opacity,
                      TQ_INT32 rows,
                      TQ_INT32 cols,
                      const KisCompositeOp& op)
{
    switch (op.op()) {
    case COMPOSITE_OVER:
        compositeOver(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_MULT:
        compositeMultiply(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_DIVIDE:
        compositeDivide(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_DARKEN:
        compositeDarken(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_LIGHTEN:
        compositeLighten(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_SCREEN:
        compositeScreen(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_OVERLAY:
        compositeOverlay(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_DODGE:
        compositeDodge(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_BURN:
        compositeBurn(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_ERASE:
        compositeErase(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_COPY:
        compositeCopy(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;
    case COMPOSITE_CLEAR: {
        TQ_UINT8 *d;
        TQ_INT32 linesize;

        linesize = MAX_CHANNEL_GRAYSCALEA*sizeof(TQ_UINT8) * cols;
        d = dst;
        while (rows-- > 0) {
            memset(d, 0, linesize);
            d += dstRowStride;
        }
    }
        break;
    case COMPOSITE_ALPHA_DARKEN:
        compositeAlphaDarken(dst, dstRowStride, src, srcRowStride, mask, maskRowStride, rows, cols, opacity);
        break;

    default:
        break;
    }
}

KisCompositeOpList KisGrayColorSpace::userVisiblecompositeOps() const
{
    KisCompositeOpList list;

    list.append(KisCompositeOp(COMPOSITE_OVER));
    list.append(KisCompositeOp(COMPOSITE_MULT));
    list.append(KisCompositeOp(COMPOSITE_BURN));
    list.append(KisCompositeOp(COMPOSITE_DODGE));
    list.append(KisCompositeOp(COMPOSITE_DIVIDE));
    list.append(KisCompositeOp(COMPOSITE_SCREEN));
    list.append(KisCompositeOp(COMPOSITE_OVERLAY));
    list.append(KisCompositeOp(COMPOSITE_DARKEN));
    list.append(KisCompositeOp(COMPOSITE_LIGHTEN));

    return list;
}

void KisGrayColorSpace::compositeOver(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(srcAlpha, opacity);
                }

                if (srcAlpha == OPACITY_OPAQUE) {
                    memcpy(dst, src, MAX_CHANNEL_GRAYSCALEA * sizeof(TQ_UINT8));
                } else {
                    TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

                    TQ_UINT8 srcBlend;

                    if (dstAlpha == OPACITY_OPAQUE) {
                        srcBlend = srcAlpha;
                    } else {
                        TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                        dst[PIXEL_GRAY_ALPHA] = newAlpha;

                        if (newAlpha != 0) {
                            srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                        } else {
                            srcBlend = srcAlpha;
                        }
                    }

                    if (srcBlend == OPACITY_OPAQUE) {
                        memcpy(dst, src, MAX_CHANNEL_GRAYSCALE * sizeof(TQ_UINT8));
                    } else {
                        dst[PIXEL_GRAY] = UINT8_BLEND(src[PIXEL_GRAY], dst[PIXEL_GRAY], srcBlend);
                    }
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeMultiply(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                TQ_UINT8 srcColor = src[PIXEL_GRAY];
                TQ_UINT8 dstColor = dst[PIXEL_GRAY];

                srcColor = UINT8_MULT(srcColor, dstColor);

                dst[PIXEL_GRAY] = UINT8_BLEND(srcColor, dstColor, srcBlend);
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeDivide(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                for (int channel = 0; channel < MAX_CHANNEL_GRAYSCALE; channel++) {

                    TQ_UINT8 srcColor = src[channel];
                    TQ_UINT8 dstColor = dst[channel];

                    srcColor = TQMIN((dstColor * (UINT8_MAX + 1)) / (1 + srcColor), UINT8_MAX);

                    TQ_UINT8 newColor = UINT8_BLEND(srcColor, dstColor, srcBlend);

                    dst[channel] = newColor;
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeScreen(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                for (int channel = 0; channel < MAX_CHANNEL_GRAYSCALE; channel++) {

                    TQ_UINT8 srcColor = src[channel];
                    TQ_UINT8 dstColor = dst[channel];

                    srcColor = UINT8_MAX - UINT8_MULT(UINT8_MAX - dstColor, UINT8_MAX - srcColor);

                    TQ_UINT8 newColor = UINT8_BLEND(srcColor, dstColor, srcBlend);

                    dst[channel] = newColor;
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeOverlay(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                for (int channel = 0; channel < MAX_CHANNEL_GRAYSCALE; channel++) {

                    TQ_UINT8 srcColor = src[channel];
                    TQ_UINT8 dstColor = dst[channel];

                    srcColor = UINT8_MULT(dstColor, dstColor + UINT8_MULT(2 * srcColor, UINT8_MAX - dstColor));

                    TQ_UINT8 newColor = UINT8_BLEND(srcColor, dstColor, srcBlend);

                    dst[channel] = newColor;
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeDodge(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                for (int channel = 0; channel < MAX_CHANNEL_GRAYSCALE; channel++) {

                    TQ_UINT8 srcColor = src[channel];
                    TQ_UINT8 dstColor = dst[channel];

                    srcColor = TQMIN((dstColor * (UINT8_MAX + 1)) / (UINT8_MAX + 1 - srcColor), UINT8_MAX);

                    TQ_UINT8 newColor = UINT8_BLEND(srcColor, dstColor, srcBlend);

                    dst[channel] = newColor;
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeBurn(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                for (int channel = 0; channel < MAX_CHANNEL_GRAYSCALE; channel++) {

                    TQ_UINT8 srcColor = src[channel];
                    TQ_UINT8 dstColor = dst[channel];

                    srcColor = kMin(((UINT8_MAX - dstColor) * (UINT8_MAX + 1)) / (srcColor + 1), UINT8_MAX);
                    srcColor = kClamp(UINT8_MAX - srcColor, 0u, UINT8_MAX);

                    TQ_UINT8 newColor = UINT8_BLEND(srcColor, dstColor, srcBlend);

                    dst[channel] = newColor;
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeDarken(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                for (int channel = 0; channel < MAX_CHANNEL_GRAYSCALE; channel++) {

                    TQ_UINT8 srcColor = src[channel];
                    TQ_UINT8 dstColor = dst[channel];

                    srcColor = TQMIN(srcColor, dstColor);

                    TQ_UINT8 newColor = UINT8_BLEND(srcColor, dstColor, srcBlend);

                    dst[channel] = newColor;
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeLighten(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride, const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride, const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride, TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        TQ_INT32 columns = numColumns;
        const TQ_UINT8 *mask = maskRowStart;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            srcAlpha = TQMIN(srcAlpha, dstAlpha);

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (srcAlpha != OPACITY_TRANSPARENT) {

                if (opacity != OPACITY_OPAQUE) {
                    srcAlpha = UINT8_MULT(src[PIXEL_GRAY_ALPHA], opacity);
                }

                TQ_UINT8 srcBlend;

                if (dstAlpha == OPACITY_OPAQUE) {
                    srcBlend = srcAlpha;
                } else {
                    TQ_UINT8 newAlpha = dstAlpha + UINT8_MULT(OPACITY_OPAQUE - dstAlpha, srcAlpha);
                    dst[PIXEL_GRAY_ALPHA] = newAlpha;

                    if (newAlpha != 0) {
                        srcBlend = UINT8_DIVIDE(srcAlpha, newAlpha);
                    } else {
                        srcBlend = srcAlpha;
                    }
                }

                for (int channel = 0; channel < MAX_CHANNEL_GRAYSCALE; channel++) {

                    TQ_UINT8 srcColor = src[channel];
                    TQ_UINT8 dstColor = dst[channel];

                    srcColor = TQMAX(srcColor, dstColor);

                    TQ_UINT8 newColor = UINT8_BLEND(srcColor, dstColor, srcBlend);

                    dst[channel] = newColor;
                }
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}

void KisGrayColorSpace::compositeErase(TQ_UINT8 *dst,
            TQ_INT32 dstRowSize,
            const TQ_UINT8 *src,
            TQ_INT32 srcRowSize,
            const TQ_UINT8 *srcAlphaMask,
            TQ_INT32 maskRowStride,
            TQ_INT32 rows,
            TQ_INT32 cols,
            TQ_UINT8 /*opacity*/)
{
    TQ_INT32 i;
    TQ_UINT8 srcAlpha;

    while (rows-- > 0)
    {
        const TQ_UINT8 *s = src;
        TQ_UINT8 *d = dst;
        const TQ_UINT8 *mask = srcAlphaMask;

        for (i = cols; i > 0; i--, s+=MAX_CHANNEL_GRAYSCALEA, d+=MAX_CHANNEL_GRAYSCALEA)
        {
            srcAlpha = s[PIXEL_GRAY_ALPHA];
            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_BLEND(srcAlpha, OPACITY_OPAQUE, *mask);
                mask++;
            }
            d[PIXEL_GRAY_ALPHA] = UINT8_MULT(srcAlpha, d[PIXEL_GRAY_ALPHA]);
        }

        dst += dstRowSize;
        if(srcAlphaMask)
            srcAlphaMask += maskRowStride;
        src += srcRowSize;
    }
}

void KisGrayColorSpace::compositeAlphaDarken(TQ_UINT8 *dstRowStart, TQ_INT32 dstRowStride,
                                     const TQ_UINT8 *srcRowStart, TQ_INT32 srcRowStride,
                                     const TQ_UINT8 *maskRowStart, TQ_INT32 maskRowStride,
                                     TQ_INT32 rows, TQ_INT32 numColumns, TQ_UINT8 opacity)
{
    while (rows > 0) {

        const TQ_UINT8 *src = srcRowStart;
        TQ_UINT8 *dst = dstRowStart;
        const TQ_UINT8 *mask = maskRowStart;
        TQ_INT32 columns = numColumns;

        while (columns > 0) {

            TQ_UINT8 srcAlpha = src[PIXEL_GRAY_ALPHA];
            TQ_UINT8 dstAlpha = dst[PIXEL_GRAY_ALPHA];

            // apply the alphamask
            if(mask != 0)
            {
                if(*mask != OPACITY_OPAQUE)
                    srcAlpha = UINT8_MULT(srcAlpha, *mask);
                mask++;
            }

            if (opacity != OPACITY_OPAQUE) {
                srcAlpha = UINT8_MULT(srcAlpha, opacity);
            }

            if (srcAlpha != OPACITY_TRANSPARENT && srcAlpha >= dstAlpha) {
                dst[PIXEL_GRAY_ALPHA] = srcAlpha;
                memcpy(dst, src, MAX_CHANNEL_GRAYSCALE * sizeof(TQ_UINT8));
            }

            columns--;
            src += MAX_CHANNEL_GRAYSCALEA;
            dst += MAX_CHANNEL_GRAYSCALEA;
        }

        rows--;
        srcRowStart += srcRowStride;
        dstRowStart += dstRowStride;
        if(maskRowStart)
            maskRowStart += maskRowStride;
    }
}