// vim: set tabstop=4 shiftwidth=4 noexpandtab:
/*
Gwenview: an image viewer
Copyright 2008 Aurélien Gâteau <aurelien.gateau@free.fr>

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, Cambridge, MA 02110-1301, USA.

--

The content of this file is based on qjpeghandler.cpp
Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.

*/
// Self
#include "jpeghandler.h"

// Qt
#include <QImage>
#include <QSize>
#include <QVariant>

// KDE
#include <kdebug.h>

// libjpeg
#include <setjmp.h>
#define XMD_H
extern "C" {
#include <jpeglib.h>
}

// Local
#include "../iodevicejpegsourcemanager.h"

namespace Gwenview {

#undef ENABLE_LOG
#undef LOG
//#define ENABLE_LOG
#ifdef ENABLE_LOG
#define LOG(x) kDebug() << x
#else
#define LOG(x) ;
#endif


struct JpegFatalError : public jpeg_error_mgr {
	jmp_buf mJmpBuffer;

	static void handler(j_common_ptr cinfo) {
		JpegFatalError* error=static_cast<JpegFatalError*>(cinfo->err);
		(error->output_message)(cinfo);
		longjmp(error->mJmpBuffer,1);
	}
};


static void expand24to32bpp(QImage* image) {
	for (int j=0; j<image->height(); j++) {
		uchar *in = image->scanLine(j) + (image->width() - 1)*3;
		QRgb *out = (QRgb*)( image->scanLine(j) ) + image->width() - 1;

		for (int i=image->width() - 1; i>=0; --i, --out, in -= 3) {
			*out = qRgb(in[0], in[1], in[2]);
		}
	}
}


static QSize getJpegSize(QIODevice* ioDevice) {
	struct jpeg_decompress_struct cinfo;
	QSize size;

	// Error handling
	struct JpegFatalError jerr;
	cinfo.err = jpeg_std_error(&jerr);
	cinfo.err->error_exit = JpegFatalError::handler;
	if (setjmp(jerr.mJmpBuffer)) {
		jpeg_destroy_decompress(&cinfo);
		return size;
	}

	// Init decompression
	jpeg_create_decompress(&cinfo);
	Gwenview::IODeviceJpegSourceManager::setup(&cinfo, ioDevice);
	jpeg_read_header(&cinfo, true);

	size = QSize(cinfo.image_width, cinfo.image_height);
	jpeg_destroy_decompress(&cinfo);
	return size;
}


static bool loadJpeg(QImage* image, QIODevice* ioDevice, QSize scaledSize) {
	struct jpeg_decompress_struct cinfo;

	// Error handling
	struct JpegFatalError jerr;
	cinfo.err = jpeg_std_error(&jerr);
	cinfo.err->error_exit = JpegFatalError::handler;
	if (setjmp(jerr.mJmpBuffer)) {
		jpeg_destroy_decompress(&cinfo);
		return false;
	}

	// Init decompression
	jpeg_create_decompress(&cinfo);
	Gwenview::IODeviceJpegSourceManager::setup(&cinfo, ioDevice);
	jpeg_read_header(&cinfo, true);

	// Compute scale value
	cinfo.scale_num=1;
	if (scaledSize.isValid()) {
		cinfo.scale_denom = qMin(cinfo.image_width / scaledSize.width(),
								 cinfo.image_height / scaledSize.height());
		if (cinfo.scale_denom < 2) {
			cinfo.scale_denom = 1;
		} else if (cinfo.scale_denom < 4) {
			cinfo.scale_denom = 2;
		} else if (cinfo.scale_denom < 8) {
			cinfo.scale_denom = 4;
		} else {
			cinfo.scale_denom = 8;
		}
	} else {
		cinfo.scale_denom = 1;
	}
	LOG("cinfo.scale_denom=" << cinfo.scale_denom);

	// Init image
	jpeg_start_decompress(&cinfo);
	switch(cinfo.output_components) {
	case 3:
	case 4:
		*image = QImage(cinfo.output_width, cinfo.output_height, QImage::Format_RGB32);
		break;
	case 1: // B&W image
		*image = QImage(cinfo.output_width, cinfo.output_height, QImage::Format_Indexed8);
		image->setNumColors(256);
		for (int i=0; i<256; i++) {
			image->setColor(i, qRgba(i, i, i, 255));
		}
		break;
	default:
		jpeg_destroy_decompress(&cinfo);
		return false;
	}

	while (cinfo.output_scanline < cinfo.output_height) {
		uchar *line = image->scanLine(cinfo.output_scanline);
		jpeg_read_scanlines(&cinfo, &line, 1);
	}

	jpeg_finish_decompress(&cinfo);

	// Expand 24->32 bpp
	if ( cinfo.output_components == 3 ) {
		expand24to32bpp(image);
	}

	if (scaledSize.isValid()) {
		*image = image->scaled(scaledSize, Qt::KeepAspectRatio, Qt::SmoothTransformation);
	}

	jpeg_destroy_decompress(&cinfo);

	return true;
}


/****************************************************************************
This code is a copy of qjpeghandler.cpp because I can't find a way to fallback
to it for image writing.
BEGIN_COPY
****************************************************************************/
struct my_error_mgr : public jpeg_error_mgr {
    jmp_buf setjmp_buffer;
};

#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

static void my_error_exit (j_common_ptr cinfo)
{
    my_error_mgr* myerr = (my_error_mgr*) cinfo->err;
    char buffer[JMSG_LENGTH_MAX];
    (*cinfo->err->format_message)(cinfo, buffer);
    qWarning("%s", buffer);
    longjmp(myerr->setjmp_buffer, 1);
}

#if defined(Q_C_CALLBACKS)
}
#endif


static const int max_buf = 4096;

struct my_jpeg_destination_mgr : public jpeg_destination_mgr {
    // Nothing dynamic - cannot rely on destruction over longjump
    QIODevice *device;
    JOCTET buffer[max_buf];

public:
    my_jpeg_destination_mgr(QIODevice *);
};


#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

static void qt_init_destination(j_compress_ptr)
{
}

static boolean qt_empty_output_buffer(j_compress_ptr cinfo)
{
    my_jpeg_destination_mgr* dest = (my_jpeg_destination_mgr*)cinfo->dest;

    int written = dest->device->write((char*)dest->buffer, max_buf);
    if (written == -1)
        (*cinfo->err->error_exit)((j_common_ptr)cinfo);

    dest->next_output_byte = dest->buffer;
    dest->free_in_buffer = max_buf;

#if defined(Q_OS_UNIXWARE)
    return B_TRUE;
#else
    return true;
#endif
}

static void qt_term_destination(j_compress_ptr cinfo)
{
    my_jpeg_destination_mgr* dest = (my_jpeg_destination_mgr*)cinfo->dest;
    qint64 n = max_buf - dest->free_in_buffer;

    qint64 written = dest->device->write((char*)dest->buffer, n);
    if (written == -1)
        (*cinfo->err->error_exit)((j_common_ptr)cinfo);
}

#if defined(Q_C_CALLBACKS)
}
#endif

inline my_jpeg_destination_mgr::my_jpeg_destination_mgr(QIODevice *device)
{
    jpeg_destination_mgr::init_destination = qt_init_destination;
    jpeg_destination_mgr::empty_output_buffer = qt_empty_output_buffer;
    jpeg_destination_mgr::term_destination = qt_term_destination;
    this->device = device;
    next_output_byte = buffer;
    free_in_buffer = max_buf;
}


static bool write_jpeg_image(const QImage &sourceImage, QIODevice *device, int sourceQuality)
{
    bool success = false;
    const QImage image = sourceImage;
    const QVector<QRgb> cmap = image.colorTable();

    struct jpeg_compress_struct cinfo;
    JSAMPROW row_pointer[1];
    row_pointer[0] = 0;

    struct my_jpeg_destination_mgr *iod_dest = new my_jpeg_destination_mgr(device);
    struct my_error_mgr jerr;

    cinfo.err = jpeg_std_error(&jerr);
    jerr.error_exit = my_error_exit;

    if (!setjmp(jerr.setjmp_buffer)) {
        // WARNING:
        // this if loop is inside a setjmp/longjmp branch
        // do not create C++ temporaries here because the destructor may never be called
        // if you allocate memory, make sure that you can free it (row_pointer[0])
        jpeg_create_compress(&cinfo);

        cinfo.dest = iod_dest;

        cinfo.image_width = image.width();
        cinfo.image_height = image.height();

        bool gray=false;
        switch (image.depth()) {
        case 1:
        case 8:
            gray = true;
            for (int i = image.numColors(); gray && i--;) {
                gray = gray & (qRed(cmap[i]) == qGreen(cmap[i]) &&
                               qRed(cmap[i]) == qBlue(cmap[i]));
            }
            cinfo.input_components = gray ? 1 : 3;
            cinfo.in_color_space = gray ? JCS_GRAYSCALE : JCS_RGB;
            break;
        case 32:
            cinfo.input_components = 3;
            cinfo.in_color_space = JCS_RGB;
        }

        jpeg_set_defaults(&cinfo);

        qreal diffInch = qAbs(image.dotsPerMeterX()*2.54/100. - qRound(image.dotsPerMeterX()*2.54/100.))
                         + qAbs(image.dotsPerMeterY()*2.54/100. - qRound(image.dotsPerMeterY()*2.54/100.));
        qreal diffCm = (qAbs(image.dotsPerMeterX()/100. - qRound(image.dotsPerMeterX()/100.))
                        + qAbs(image.dotsPerMeterY()/100. - qRound(image.dotsPerMeterY()/100.)))*2.54;
        if (diffInch < diffCm) {
            cinfo.density_unit = 1; // dots/inch
            cinfo.X_density = qRound(image.dotsPerMeterX()*2.54/100.);
            cinfo.Y_density = qRound(image.dotsPerMeterY()*2.54/100.);
        } else {
            cinfo.density_unit = 2; // dots/cm
            cinfo.X_density = (image.dotsPerMeterX()+50) / 100;
            cinfo.Y_density = (image.dotsPerMeterY()+50) / 100;
        }


        int quality = sourceQuality >= 0 ? qMin(sourceQuality,100) : 75;
#if defined(Q_OS_UNIXWARE)
        jpeg_set_quality(&cinfo, quality, B_TRUE /* limit to baseline-JPEG values */);
        jpeg_start_compress(&cinfo, B_TRUE);
#else
        jpeg_set_quality(&cinfo, quality, true /* limit to baseline-JPEG values */);
        jpeg_start_compress(&cinfo, true);
#endif

        row_pointer[0] = new uchar[cinfo.image_width*cinfo.input_components];
        int w = cinfo.image_width;
        while (cinfo.next_scanline < cinfo.image_height) {
            uchar *row = row_pointer[0];
            switch (image.depth()) {
            case 1:
                if (gray) {
                    const uchar* data = image.scanLine(cinfo.next_scanline);
                    if (image.format() == QImage::Format_MonoLSB) {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (i & 7)));
                            row[i] = qRed(cmap[bit]);
                        }
                    } else {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (7 -(i & 7))));
                            row[i] = qRed(cmap[bit]);
                        }
                    }
                } else {
                    const uchar* data = image.scanLine(cinfo.next_scanline);
                    if (image.format() == QImage::Format_MonoLSB) {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (i & 7)));
                            *row++ = qRed(cmap[bit]);
                            *row++ = qGreen(cmap[bit]);
                            *row++ = qBlue(cmap[bit]);
                        }
                    } else {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (7 -(i & 7))));
                            *row++ = qRed(cmap[bit]);
                            *row++ = qGreen(cmap[bit]);
                            *row++ = qBlue(cmap[bit]);
                        }
                    }
                }
                break;
            case 8:
                if (gray) {
                    const uchar* pix = image.scanLine(cinfo.next_scanline);
                    for (int i=0; i<w; i++) {
                        *row = qRed(cmap[*pix]);
                        ++row; ++pix;
                    }
                } else {
                    const uchar* pix = image.scanLine(cinfo.next_scanline);
                    for (int i=0; i<w; i++) {
                        *row++ = qRed(cmap[*pix]);
                        *row++ = qGreen(cmap[*pix]);
                        *row++ = qBlue(cmap[*pix]);
                        ++pix;
                    }
                }
                break;
            case 32: {
                QRgb* rgb = (QRgb*)image.scanLine(cinfo.next_scanline);
                for (int i=0; i<w; i++) {
                    *row++ = qRed(*rgb);
                    *row++ = qGreen(*rgb);
                    *row++ = qBlue(*rgb);
                    ++rgb;
                }
            }
            }
            jpeg_write_scanlines(&cinfo, row_pointer, 1);
        }

        jpeg_finish_compress(&cinfo);
        jpeg_destroy_compress(&cinfo);
        success = true;
    } else {
        jpeg_destroy_compress(&cinfo);
        success = false;
    }

    delete iod_dest;
    delete [] row_pointer[0];
    return success;
}
/****************************************************************************
END_COPY
****************************************************************************/



struct JpegHandlerPrivate {
	QSize mScaledSize;
	int mQuality;
};


JpegHandler::JpegHandler()
: d(new JpegHandlerPrivate) {
	d->mQuality = 75;
}


JpegHandler::~JpegHandler() {
	delete d;
}


bool JpegHandler::canRead() const {
	if (canRead(device())) {
		setFormat("jpeg");
		return true;
	}
	return false;
}


bool JpegHandler::canRead(QIODevice* device) {
	if (!device) {
		kWarning() << "called with no device";
		return false;
	}

	return device->peek(2) == "\xFF\xD8";
}


bool JpegHandler::read(QImage* image) {
	LOG("");
	if (!canRead()) {
		return false;
	}
	return loadJpeg(image, device(), d->mScaledSize);
}


bool JpegHandler::write(const QImage& image) {
	LOG("");
	return write_jpeg_image(image, device(), d->mQuality);
}


bool JpegHandler::supportsOption(ImageOption option) const {
    return option == ScaledSize || option == Size || option == Quality;
}


QVariant JpegHandler::option(ImageOption option) const {
	if (option == ScaledSize) {
		return d->mScaledSize;
	} else if (option == Size) {
		if (canRead() && !device()->isSequential()) {
			qint64 pos = device()->pos();
			QSize size = getJpegSize(device());
			device()->seek(pos);
			return size;
		}
	} else if (option == Quality) {
		return d->mQuality;
	}
	return QVariant();
}


void JpegHandler::setOption(ImageOption option, const QVariant &value) {
	if (option == ScaledSize) {
		d->mScaledSize = value.toSize();
	} else if (option == Quality) {
		d->mQuality = value.toInt();
	}
}


} // namespace
