grfmt_jpeg.cpp

OPENCV系列的

                lstrm.SetPos( pos + length );
            }
        }
parsing_end: ;
    }
    catch( int )
    {
    }

    result = is_jfif && is_sof && is_qt && is_ht && is_sos;
    if( !result )
    {
        m_width = m_height = -1;
        m_offset = -1;
        m_strm.Close();
    }
    return result;
}


bool GrFmtJpegReader::LoadQuantTables( int length )
{
    uchar buffer[128];
    int  i, tq_size;
    
    RMByteStream& lstrm = m_strm.m_low_strm;
    length -= 2;

    while( length > 0 )
    {
        int tq = lstrm.GetByte();
        int size = tq >> 4;
        tq &= 15;

        tq_size = (64<<size) + 1; 
        if( tq > 3 || size > 1 || length < tq_size ) return false;
        length -= tq_size;

        lstrm.GetBytes( buffer, tq_size - 1 );
        
        if( size == 0 ) // 8 bit quant factors
        {
            for( i = 0; i < 64; i++ )
            {
                int idx = zigzag[i];
                m_tq[tq][idx] = buffer[i] * 16 * idct_prescale[idx];
            }
        }
        else // 16 bit quant factors
        {
            for( i = 0; i < 64; i++ )
            {
                int idx = zigzag[i];
                m_tq[tq][idx] = ((unsigned short*)buffer)[i] * idct_prescale[idx];
            }
        }
        m_is_tq[tq] = true;
    }

    return true;
}


bool GrFmtJpegReader::LoadHuffmanTables( int length )
{
    const int max_bits = 16;
    uchar buffer[1024];
    int  buffer2[1024];

    int  i, ht_size;
    RMByteStream& lstrm = m_strm.m_low_strm;
    length -= 2;

    while( length > 0 )
    {
        int t = lstrm.GetByte();
        int hclass = t >> 4;
        t &= 15;

        if( t > 3 || hclass > 1 || length < 17 ) return false;
        length -= 17;

        lstrm.GetBytes( buffer, max_bits );
        for( i = 0, ht_size = 0; i < max_bits; i++ ) ht_size += buffer[i];

        if( length < ht_size ) return false;
        length -= ht_size;

        lstrm.GetBytes( buffer + max_bits, ht_size );
        
        if( !::bsCreateDecodeHuffmanTable( 
                  ::bsCreateSourceHuffmanTable( 
                        buffer, buffer2, max_bits, first_table_bits ),
                        hclass == 0 ? m_td[t] : m_ta[t], 
                        max_dec_htable_size )) return false;
        if( hclass == 0 )
            m_is_td[t] = true;
        else
            m_is_ta[t] = true;
    }
    return true;
}


bool GrFmtJpegReader::ReadData( uchar* data, int step, int color )
{
    if( m_offset < 0 || !m_strm.IsOpened())
        return false;

    try
    {
        RMByteStream& lstrm = m_strm.m_low_strm;
        lstrm.SetPos( m_offset );

        for(;;)
        {
            int marker = m_strm.FindMarker() & 255;

            if( marker == 0xD8 /* SOI */ || marker == 0xD9 /* EOI */ )
                goto decoding_end;

            // check for standalone markers
            if( marker != 0x01 /* TEM */ && !( 0xD0 <= marker && marker <= 0xD7 ))
            {
                int pos    = lstrm.GetPos();
                int length = lstrm.GetWord();
            
                switch( marker )
                {
                case 0xC4: // DHT
                    if( !LoadHuffmanTables( length )) goto decoding_end;
                    break;

                case 0xDA: // SOS
                    // read scan header
                    {
                        int idx[3] = { -1, -1, -1 };
                        int i, ns = lstrm.GetByte();
                        int sum = 0, a; // spectral selection & approximation

                        if( ns != m_planes ) goto decoding_end;
                        for( i = 0; i < ns; i++ )
                        {
                            int td, ta, c = lstrm.GetByte() - 1;
                            if( c < 0 || m_planes <= c )
                            {
                                c = i; // hack
                            }
                            
                            if( idx[c] != -1 ) goto decoding_end;
                            idx[i] = c;
                            td = lstrm.GetByte();
                            ta = td & 15;
                            td >>= 4;
                            if( !(ta <= 3 && m_is_ta[ta] && 
                                  td <= 3 && m_is_td[td] &&
                                  m_is_tq[m_ci[c].tq]) )
                                goto decoding_end;

                            m_ci[c].td = (char)td;
                            m_ci[c].ta = (char)ta;

                            sum += m_ci[c].h*m_ci[c].v;
                        }

                        if( sum > 10 ) goto decoding_end;

                        m_ss = lstrm.GetByte();
                        m_se = lstrm.GetByte();

                        a = lstrm.GetByte();
                        m_al = a & 15;
                        m_ah = a >> 4;

                        ProcessScan( idx, ns, data, step, color );
                        goto decoding_end; // only single scan case is supported now
                    }

                    //m_offset = pos - 2;
                    //break;

                case 0xDD: // DRI
                    m_MCUs = lstrm.GetWord();
                    break;
                }
                
                if( marker != 0xDA ) lstrm.SetPos( pos + length );
            }
        }
decoding_end: ;
    }
    catch( int )
    {
    }
    return true;
}


void  GrFmtJpegReader::ResetDecoder()
{
    m_ci[0].dc_pred = m_ci[1].dc_pred = m_ci[2].dc_pred = 0; 
}

void  GrFmtJpegReader::ProcessScan( int* idx, int ns, uchar* data, int step, int color )
{
    int   i, s = 0, mcu, x1 = 0, y1 = 0;
    int   temp[64];
    int   blocks[10][64];
    int   pos[3], h[3], v[3];
    int   x_shift = 0, y_shift = 0;
    int   nch = color ? 3 : 1;

    assert( ns == m_planes && m_ss == 0 && m_se == 63 &&
            m_al == 0 && m_ah == 0 ); // sequental & single scan

    assert( idx[0] == 0 && (ns ==1 || (idx[1] == 1 && idx[2] == 2)));

    for( i = 0; i < ns; i++ )
    {
        int c = idx[i];
        h[c] = m_ci[c].h*8;
        v[c] = m_ci[c].v*8;
        pos[c] = s >> 6;
        s += h[c]*v[c];
    }

    if( ns == 3 )
    {
        x_shift = h[0]/(h[1]*2);
        y_shift = v[0]/(v[1]*2);
    }

    m_strm.Flush();
    ResetDecoder();

    for( mcu = 0;; mcu++ )
    {
        int  x2, y2, x, y;
        int* cmp;
        uchar* data1;
        
        if( mcu == m_MCUs && m_MCUs != 0 )
        {
            ResetDecoder();
            m_strm.AlignOnByte();
            mcu = 0;
        }

        // Get mcu
        for( i = 0; i < ns; i++ )
        {
            int  c = idx[i];
            cmp = blocks[pos[c]];
            for( y = 0; y < v[c]; y += 8, cmp += h[c]*8 )
                for( x = 0; x < h[c]; x += 8 )
                {
                    GetBlock( temp, c );
                    if( i < (color ? 3 : 1))
                    {
                        aan_idct8x8( temp, cmp + x, h[c] );
                    }
                }
        }

        y2 = v[0];
        x2 = h[0];

        if( y1 + y2 > m_height ) y2 = m_height - y1;
        if( x1 + x2 > m_width ) x2 = m_width - x1;

        cmp = blocks[0];
        data1 = data + x1*nch;

        if( ns == 1 )
            for( y = 0; y < y2; y++, data1 += step, cmp += h[0] )
            {
                if( color )
                {
                    for( x = 0; x < x2; x++ )
                    {
                        int val = descale( cmp[x] + 128*4, 2 );
                        data1[x*3] = data1[x*3 + 1] = data1[x*3 + 2] = saturate( val );
                    }
                }
                else
                {
                    for( x = 0; x < x2; x++ )
                    {
                        int val = descale( cmp[x] + 128*4, 2 );
                        data1[x] = saturate( val );
                    }
                }
            }
        else
        {
            for( y = 0; y < y2; y++, data1 += step, cmp += h[0] )
            {
                if( color )
                {
                    int  shift = h[1]*(y >> y_shift);
                    int* cmpCb = blocks[pos[1]] + shift; 
                    int* cmpCr = blocks[pos[2]] + shift;
                    for( x = 0; x < x2; x++ )
                    {
                        int Y  = (cmp[x] + 128*4) << fixc;
                        int Cb = cmpCb[x >> x_shift];
                        int Cr = cmpCr[x >> x_shift];
                        int t = (Y + Cb*b_cb) >> (fixc + 2);
                        data1[x*3] = saturate(t);
                        t = (Y + Cb*g_cb + Cr*g_cr) >> (fixc + 2);
                        data1[x*3 + 1] = saturate(t);
                        t = (Y + Cr*r_cr) >> (fixc + 2);
                        data1[x*3 + 2] = saturate(t);
                    }
                }
                else
                {
                    for( x = 0; x < x2; x++ )
                    {
                        int val = descale( cmp[x] + 128*4, 2 );
                        data1[x] = saturate(val);
                    }
                }
            }
        }

        x1 += h[0];
        if( x1 >= m_width )
        {
            x1 = 0;
            y1 += v[0];
            data += v[0]*step;
            if( y1 >= m_height ) break;
        }
    }
}


void  GrFmtJpegReader::GetBlock( int* block, int c )
{
    memset( block, 0, 64*sizeof(block[0]) );

    assert( 0 <= c && c < 3 );
    const short* td = m_td[m_ci[c].td];
    const short* ta = m_ta[m_ci[c].ta];
    const int* tq = m_tq[m_ci[c].tq];

    // Get DC coefficient
    int i = 0, cat  = m_strm.GetHuff( td );
    int mask = bs_bit_mask[cat];
    int val  = m_strm.Get( cat );

    val -= (val*2 <= mask ? mask : 0);
    m_ci[c].dc_pred = val += m_ci[c].dc_pred;
    
    block[0] = descale(val * tq[0],16);

    // Get AC coeffs
    for(;;)
    {
        cat = m_strm.GetHuff( ta );
        if( cat == 0 ) break; // end of block

        i += (cat >> 4) + 1;
        cat &= 15;
        mask = bs_bit_mask[cat];
        val  = m_strm.Get( cat );
        cat  = zigzag[i];
        val -= (val*2 <= mask ? mask : 0);
        block[cat] = descale(val * tq[cat], 16);
        assert( i <= 63 );
        if( i >= 63 ) break;
    }
}

////////////////////// WJpegStream ///////////////////////

WJpegBitStream::WJpegBitStream()
{
}


WJpegBitStream::~WJpegBitStream()
{
    Close();
    m_is_opened = false;
}



bool  WJpegBitStream::Open( const char* filename )
{
    Close();
    Allocate();
    
    m_is_opened = m_low_strm.Open( filename );
    if( m_is_opened )
    {
        m_block_pos = 0;
        ResetBuffer();
    }
    return m_is_opened;
}


void  WJpegBitStream::Close()
{
    if( m_is_opened )
    {
        Flush();
        m_low_strm.Close();
        m_is_opened = false;
    }
}


void  WJpegBitStream::Flush()
{
    Put( -1, m_bit_idx & 31 );
    *((ulong*&)m_current)++ = m_val;
    WriteBlock();
    ResetBuffer();
}


void  WJpegBitStream::WriteBlock()
{
    uchar* ptr = m_start;
    bsBSwapBlock( m_start, m_current );

    while( ptr < m_current )
    {
        int val = *ptr++;
        m_low_strm.PutByte( val );
        if( val == 0xff )
        {
            m_low_strm.PutByte( 0 );
        }
    }
    
    m_current = m_start;
}


/////////////////////// GrFmtJpegWriter ///////////////////

GrFmtJpegWriter::GrFmtJpegWriter()
{
    m_description = fmtDescrJpeg;
}


GrFmtJpegWriter::~GrFmtJpegWriter()
{
}


//  Standard JPEG quantization tables
static const uchar jpegTableK1_T[] =
{
    16, 12, 14, 14,  18,  24,  49,  72,
    11, 12, 13, 17,  22,  35,  64,  92,