/*
 *  Copyright (c) 2002 Patrick Julien <freak@codepimps.org>
 *  Copyright (c) 2004 Boudewijn Rempt <boud@valdyas.org>
 *  Copyright (c) 2004 Clarence Dang <dang@kde.org>
 *  Copyright (c) 2004 Adrian Page <adrian@pagenet.plus.com>
 *  Copyright (c) 2004 Cyrille Berger <cberger@cberger.net>
 *
 *  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 <qrect.h>

#include <kdebug.h>

#include "kis_brush.h"
#include "kis_global.h"
#include "kis_paint_device.h"
#include "kis_layer.h"
#include "kis_painter.h"
#include "kis_types.h"
#include "kis_paintop.h"
#include "kis_iterators_pixel.h"
#include "kis_colorspace.h"
#include "kis_selection.h"
#include "kis_eraseop.h"

KisPaintOp * KisEraseOpFactory::createOp(const KisPaintOpSettings */*settings*/, KisPainter * painter)
{
    KisPaintOp * op = new KisEraseOp(painter);
    Q_CHECK_PTR(op);
    return op;
}


KisEraseOp::KisEraseOp(KisPainter * painter)
    : super(painter)
{
}

KisEraseOp::~KisEraseOp()
{
}

void KisEraseOp::paintAt(const KisPoint &pos, const KisPaintInformation& info)
{
// Erasing is traditionally in paint applications one of two things:
// either it is painting in the 'background' color, or it is replacing
// all pixels with transparent (black?) pixels.
//
// That's what this paint op does for now; however, anyone who has
// ever worked with paper and soft pencils knows that a sharp piece of
// eraser rubber is a pretty useful too for making sharp to fuzzy lines
// in the graphite layer, or equally useful: for smudging skin tones.
//
// A smudge tool for Krita is in the making, but when working with
// a tablet, the eraser tip should be at least as functional as a rubber eraser.
// That means that only after repeated or forceful application should all the
// 'paint' or 'graphite' be removed from the surface -- a kind of pressure
// sensitive, incremental smudge.
//
// And there should be an option to not have the eraser work on certain
// kinds of material. Layers are just a hack for this; putting your ink work
// in one layer and your pencil in another is not the same as really working
// with the combination.

    if (!m_painter) return;

    KisPaintDeviceSP device = m_painter->device();
    if (!device) return;

    KisBrush *brush = m_painter->brush();
    if (! brush->canPaintFor(info) )
        return;
    KisPoint hotSpot = brush->hotSpot(info);
    KisPoint pt = pos - hotSpot;

    Q_INT32 destX;
    double xFraction;
    Q_INT32 destY;
    double yFraction;

    splitCoordinate(pt.x(), &destX, &xFraction);
    splitCoordinate(pt.y(), &destY, &yFraction);

    KisAlphaMaskSP mask = brush->mask(info, xFraction, yFraction);

    KisPaintDeviceSP dab = new KisPaintDevice(device->colorSpace(), "erase op dab");
    Q_CHECK_PTR(dab);

    Q_INT32 maskWidth = mask->width();
    Q_INT32 maskHeight = mask->height();

    QRect dstRect;

    KisRectIteratorPixel it = dab->createRectIterator(0, 0, maskWidth, maskHeight, true);
    KisColorSpace* cs = dab->colorSpace();
    while (!it.isDone()) {
        cs->setAlpha(it.rawData(), Q_UINT8_MAX - mask->alphaAt(it.x(), it.y()), 1);
        ++it;
    }

    QRect dabRect = QRect(0, 0, maskWidth, maskHeight);
    dstRect = QRect(destX, destY, dabRect.width(), dabRect.height());

    KisImage * image = device->image();

    if (image != 0) {
        dstRect &= image->bounds();
    }

    if (dstRect.isNull() || dstRect.isEmpty() || !dstRect.isValid()) return;

    Q_INT32 sx = dstRect.x() - destX;
    Q_INT32 sy = dstRect.y() - destY;
    Q_INT32 sw = dstRect.width();
    Q_INT32 sh = dstRect.height();

    if (m_source->hasSelection()) {
        m_painter->bltSelection(dstRect.x(), dstRect.y(), COMPOSITE_ERASE, dab.data(),
                                m_source->selection(), m_painter->opacity(), sx, sy, sw, sh);
    }
    else {
        m_painter->bitBlt(dstRect.x(), dstRect.y(), COMPOSITE_ERASE, dab.data(), m_painter->opacity(), sx, sy, sw, sh);
    }

    m_painter->addDirtyRect(dstRect);
}