psd.cpp

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/* This file is part of the KDE project
   Copyright (C) 2003 Ignacio Castaño <castano@ludicon.com>

   This program is free software; you can redistribute it and/or
   modify it under the terms of the Lesser 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 code is based on Thacher Ulrich PSD loading code released
   on public domain. See: http://tulrich.com/geekstuff/
*/

/* this code supports:
 * reading:
 *     rle and raw psd files
 * writing:
 *     not supported
 */

#include "psd.h"

#include <QtGui/QImage>
#include <QtCore/QDataStream>

#include <kdebug.h>

typedef quint32 uint;
typedef quint16 ushort;
typedef quint8 uchar;

namespace { // Private.

    enum ColorMode {
        CM_BITMAP = 0,
        CM_GRAYSCALE = 1,
        CM_INDEXED = 2,
        CM_RGB = 3,
        CM_CMYK = 4,
        CM_MULTICHANNEL = 7,
        CM_DUOTONE = 8,
        CM_LABCOLOR = 9
    };

    struct PSDHeader {
        uint signature;
        ushort version;
        uchar reserved[6];
        ushort channel_count;
        uint height;
        uint width;
        ushort depth;
        ushort color_mode;
    };

    static QDataStream & operator>> ( QDataStream & s, PSDHeader & header )
    {
        s >> header.signature;
        s >> header.version;
        for( int i = 0; i < 6; i++ ) {
            s >> header.reserved[i];
        }
        s >> header.channel_count;
        s >> header.height;
        s >> header.width;
        s >> header.depth;
        s >> header.color_mode;
        return s;
    }
        static bool seekBy(QDataStream& s, unsigned int bytes)
        {
                char buf[4096];
                while (bytes) {
                        unsigned int num= qMin(bytes,( unsigned int )sizeof(buf));
                        unsigned int l = num;
                        s.readRawData(buf, l);
                        if(l != num)
                          return false;
                        bytes -= num;
                }
                return true;
        }

    // Check that the header is a valid PSD.
    static bool IsValid( const PSDHeader & header )
    {
        if( header.signature != 0x38425053 ) {  // '8BPS'
            return false;
        }
        return true;
    }

    // Check that the header is supported.
    static bool IsSupported( const PSDHeader & header )
    {
        if( header.version != 1 ) {
            return false;
        }
        if( header.channel_count > 16 ) {
            return false;
        }
        if( header.depth != 8 ) {
            return false;
        }
        if( header.color_mode != CM_RGB ) {
            return false;
        }
        return true;
    }

    // Load the PSD image.
    static bool LoadPSD( QDataStream & s, const PSDHeader & header, QImage & img )
    {
        // Create dst image.
        img = QImage( header.width, header.height, QImage::Format_RGB32 );

        uint tmp;

        // Skip mode data.
        s >> tmp;
        s.device()->seek( s.device()->pos() + tmp );

        // Skip image resources.
        s >> tmp;
        s.device()->seek( s.device()->pos() + tmp );

        // Skip the reserved data.
        s >> tmp;
        s.device()->seek( s.device()->pos() + tmp );

        // Find out if the data is compressed.
        // Known values:
        //   0: no compression
        //   1: RLE compressed
        ushort compression;
        s >> compression;

        if( compression > 1 ) {
            // Unknown compression type.
            return false;
        }

        uint channel_num = header.channel_count;

        // Clear the image.
        if( channel_num < 4 ) {
            img.fill(qRgba(0, 0, 0, 0xFF));
        }
        else {
            // Enable alpha.
            img = img.convertToFormat(QImage::Format_ARGB32);

            // Ignore the other channels.
            channel_num = 4;
        }

        const uint pixel_count = header.height * header.width;

        static const uint components[4] = {2, 1, 0, 3}; // @@ Is this endian dependant?

        if( compression ) {

            // Skip row lengths.
                        if(!seekBy(s, header.height*header.channel_count*sizeof(ushort)))
                                return false;

            // Read RLE data.
            for(uint channel = 0; channel < channel_num; channel++) {

                uchar * ptr = img.bits() + components[channel];

                uint count = 0;
                while( count < pixel_count ) {
                    uchar c;
                                        if(s.atEnd())
                                                return false;
                    s >> c;
                    uint len = c;

                    if( len < 128 ) {
                        // Copy next len+1 bytes literally.
                        len++;
                        count += len;
                                                if ( count > pixel_count )
                                                        return false;

                        while( len != 0 ) {
                            s >> *ptr;
                            ptr += 4;
                            len--;
                        }
                    }
                    else if( len > 128 ) {
                        // Next -len+1 bytes in the dest are replicated from next source byte.
                        // (Interpret len as a negative 8-bit int.)
                        len ^= 0xFF;
                        len += 2;
                        count += len;
                                                if(s.atEnd() || count > pixel_count)
                                                        return false;
                        uchar val;
                        s >> val;
                        while( len != 0 ) {
                            *ptr = val;
                            ptr += 4;
                            len--;
                        }
                    }
                    else if( len == 128 ) {
                        // No-op.
                    }
                }
            }
        }
        else {
            // We're at the raw image data.  It's each channel in order (Red, Green, Blue, Alpha, ...)
            // where each channel consists of an 8-bit value for each pixel in the image.

            // Read the data by channel.
            for(uint channel = 0; channel < channel_num; channel++) {

                uchar * ptr = img.bits() + components[channel];

                // Read the data.
                uint count = pixel_count;
                while( count != 0 ) {
                    s >> *ptr;
                    ptr += 4;
                    count--;
                }
            }
        }

        return true;
    }

} // Private


PSDHandler::PSDHandler()
{
}

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

bool PSDHandler::read(QImage *image)
{
    QDataStream s( device() );
    s.setByteOrder( QDataStream::BigEndian );

    PSDHeader header;
    s >> header;

    // Check image file format.
    if( s.atEnd() || !IsValid( header ) ) {
        kDebug(399) << "This PSD file is not valid.";
        return false;
    }

    // Check if it's a supported format.
    if( !IsSupported( header ) ) {
        kDebug(399) << "This PSD file is not supported.";
        return false;
    }

    QImage img;
    if( !LoadPSD(s, header, img) ) {
        kDebug(399) << "Error loading PSD file.";
        return false;
    }

    *image = img;
    return true;
}

bool PSDHandler::write(const QImage &)
{
    // TODO Stub!
    return false;
}

QByteArray PSDHandler::name() const
{
    return "psd";
}

bool PSDHandler::canRead(QIODevice *device)
{
       if (!device) {
        qWarning("PSDHandler::canRead() called with no device");
        return false;
    }

    qint64 oldPos = device->pos();

    char head[4];
    qint64 readBytes = device->read(head, sizeof(head));
    if (readBytes != sizeof(head)) {
        if (device->isSequential()) {
            while (readBytes > 0)
                device->ungetChar(head[readBytes-- - 1]);
        } else {
            device->seek(oldPos);
        }
        return false;
    }

    if (device->isSequential()) {
        while (readBytes > 0)
            device->ungetChar(head[readBytes-- - 1]);
    } else {
        device->seek(oldPos);
    }

    return qstrncmp(head, "8BPS", 4) == 0;
}


class PSDPlugin : public QImageIOPlugin
{
public:
    QStringList keys() const;
    Capabilities capabilities(QIODevice *device, const QByteArray &format) const;
    QImageIOHandler *create(QIODevice *device, const QByteArray &format = QByteArray()) const;
};

QStringList PSDPlugin::keys() const
{
    return QStringList() << "psd" << "PSD";
}

QImageIOPlugin::Capabilities PSDPlugin::capabilities(QIODevice *device, const QByteArray &format) const
{
    if (format == "psd" || format == "PSD")
        return Capabilities(CanRead);
    if (!format.isEmpty())
        return 0;
    if (!device->isOpen())
        return 0;

    Capabilities cap;
    if (device->isReadable() && PSDHandler::canRead(device))
        cap |= CanRead;
    return cap;
}

QImageIOHandler *PSDPlugin::create(QIODevice *device, const QByteArray &format) const
{
    QImageIOHandler *handler = new PSDHandler;
    handler->setDevice(device);
    handler->setFormat(format);
    return handler;
}

Q_EXPORT_STATIC_PLUGIN(PSDPlugin)
Q_EXPORT_PLUGIN2(psd, PSDPlugin)