mitab_mapcoordblock.cpp

用于读取TAB、MIF、SHP文件的类

}

/**********************************************************************
 *                   TABMAPObjectBlock::SetNextCoordBlock()
 *
 * Set the address (offset from beginning of file) of the coord. block
 * that follows the current one.
 **********************************************************************/
void     TABMAPCoordBlock::SetNextCoordBlock(GInt32 nNextCoordBlockAddress)
{
    m_nNextCoordBlock = nNextCoordBlockAddress;
}


/**********************************************************************
 *                   TABMAPObjectBlock::SetComprCoordOrigin()
 *
 * Set the Compressed integer coordinates space origin to be used when
 * reading compressed coordinates using ReadIntCoord().
 **********************************************************************/
void     TABMAPCoordBlock::SetComprCoordOrigin(GInt32 nX, GInt32 nY)
{
    m_nComprOrgX = nX;
    m_nComprOrgY = nY;
}

/**********************************************************************
 *                   TABMAPObjectBlock::ReadIntCoord()
 *
 * Read the next pair of integer coordinates value from the block, and
 * apply the translation relative to the origin of the coord. space
 * previously set using SetComprCoordOrigin() if bCompressed=TRUE.
 *
 * This means that the returned coordinates are always absolute integer
 * coordinates, even when the source coords are in compressed form.
 *
 * Returns 0 if succesful or -1 if an error happened, in which case 
 * CPLError() will have been called.
 **********************************************************************/
int     TABMAPCoordBlock::ReadIntCoord(GBool bCompressed, 
                                        GInt32 &nX, GInt32 &nY)
{
    if (bCompressed)
    {   
        nX = m_nComprOrgX + ReadInt16();
        nY = m_nComprOrgY + ReadInt16();
    }
    else
    {
        nX = ReadInt32();
        nY = ReadInt32();
    }

    if (CPLGetLastErrorType() == CE_Failure)
        return -1;

    return 0;
}

/**********************************************************************
 *                   TABMAPObjectBlock::ReadIntCoords()
 *
 * Read the specified number of pairs of X,Y integer coordinates values
 * from the block, and apply the translation relative to the origin of
 * the coord. space previously set using SetComprCoordOrigin() if 
 * bCompressed=TRUE.
 *
 * This means that the returned coordinates are always absolute integer
 * coordinates, even when the source coords are in compressed form.
 *
 * panXY should point to an array big enough to receive the specified
 * number of coordinates.
 *
 * Returns 0 if succesful or -1 if an error happened, in which case 
 * CPLError() will have been called.
 **********************************************************************/
int     TABMAPCoordBlock::ReadIntCoords(GBool bCompressed, int numCoordPairs, 
                                        GInt32 *panXY)
{
    int i, numValues = numCoordPairs*2;

    if (bCompressed)
    {   
        for(i=0; i<numValues; i+=2)
        {
            panXY[i]   = m_nComprOrgX + ReadInt16();
            panXY[i+1] = m_nComprOrgY + ReadInt16();
            if (CPLGetLastErrorType() != 0)
                return -1;
        }
    }
    else
    {
        for(i=0; i<numValues; i+=2)
        {
            panXY[i]   = ReadInt32();
            panXY[i+1] = ReadInt32();
            if (CPLGetLastErrorType() != 0)
                return -1;
        }
    }

    return 0;
}

/**********************************************************************
 *                   TABMAPObjectBlock::ReadCoordSecHdrs()
 *
 * Read a set of coordinate section headers for PLINE MULTIPLE or REGIONs
 * and store the result in the array of structures pasHdrs[].  It is assumed
 * that pasHdrs points to an allocated array of at least numSections 
 * TABMAPCoordSecHdr structures.
 *
 * The function will also set the values of numVerticesTotal to the 
 * total number of coordinates in the object (the sum of all sections 
 * headers read).
 *
 * At the end of the call, this TABMAPCoordBlock object will be located
 * at the beginning of the coordinate data.
 *
 * In V450 the numVertices is stored on an int32 instead of an int16
 *
 * IMPORTANT: This function makes the assumption that coordinates for all
 *            the sections are grouped together immediately after the
 *            last section header block (i.e. that the coord. data is not
 *            located all over the place).  If it is not the case then
 *            an error will be produced and the code to read region and
 *            multipline objects will have to be updated. 
 *
 * Returns 0 if succesful or -1 if an error happened, in which case 
 * CPLError() will have been called.
 **********************************************************************/
int     TABMAPCoordBlock::ReadCoordSecHdrs(GBool bCompressed, 
                                           GBool bV450Hdr,
                                           int numSections,
                                           TABMAPCoordSecHdr *pasHdrs,
                                           GInt32    &numVerticesTotal)
{
    int i, nTotalHdrSizeUncompressed;

    CPLErrorReset();

    /*-------------------------------------------------------------
     * Note about header+vertices size vs compressed coordinates:
     * The uncompressed header sections are actually 16 bytes, but the
     * offset calculations are based on prior decompression of the 
     * coordinates.  Our coordinate offset calculations have
     * to take this fact into account.
     * Also, V450 header section uses int32 instead of int16 for numVertices
     * and we add another 2 bytes to align with a 4 bytes boundary.
     *------------------------------------------------------------*/
    if (bV450Hdr)
        nTotalHdrSizeUncompressed = 28 * numSections;
    else
        nTotalHdrSizeUncompressed = 24 * numSections;

    numVerticesTotal = 0;

    for(i=0; i<numSections; i++)
    {
        /*-------------------------------------------------------------
         * Read the coord. section header blocks
         *------------------------------------------------------------*/
#ifdef TABDUMP
        int nHdrAddress = GetCurAddress();
#endif
        if (bV450Hdr)
            pasHdrs[i].numVertices = ReadInt32();
        else
            pasHdrs[i].numVertices = ReadInt16();
        pasHdrs[i].numHoles = ReadInt16();
        ReadIntCoord(bCompressed, pasHdrs[i].nXMin, pasHdrs[i].nYMin);
        ReadIntCoord(bCompressed, pasHdrs[i].nXMax, pasHdrs[i].nYMax);
        pasHdrs[i].nDataOffset = ReadInt32();

        if (CPLGetLastErrorType() != 0)
            return -1;

        numVerticesTotal += pasHdrs[i].numVertices;


        pasHdrs[i].nVertexOffset = (pasHdrs[i].nDataOffset - 
                                    nTotalHdrSizeUncompressed ) / 8;
#ifdef TABDUMP
        printf("READING pasHdrs[%d] @ %d = \n"
               "              { numVertices = %d, numHoles = %d, \n"
               "                nXMin=%d, nYMin=%d, nXMax=%d, nYMax=%d,\n"
               "                nDataOffset=%d, nVertexOffset=%d }\n",
               i, nHdrAddress, pasHdrs[i].numVertices, pasHdrs[i].numHoles, 
               pasHdrs[i].nXMin, pasHdrs[i].nYMin, pasHdrs[i].nXMax, 
               pasHdrs[i].nYMax, pasHdrs[i].nDataOffset, 
               pasHdrs[i].nVertexOffset);
        printf("                dX = %d, dY = %d  (center = %d , %d)\n",
               pasHdrs[i].nXMax - pasHdrs[i].nXMin,
               pasHdrs[i].nYMax - pasHdrs[i].nYMin,
               m_nComprOrgX, m_nComprOrgY);
#endif
    }

    for(i=0; i<numSections; i++)
    {
        /*-------------------------------------------------------------
         * Make sure all coordinates are grouped together
         * (Well... at least check that all the vertex indices are enclosed
         * inside the [0..numVerticesTotal] range.)
         *------------------------------------------------------------*/
        if ( pasHdrs[i].nVertexOffset < 0 || 
             (pasHdrs[i].nVertexOffset +
                           pasHdrs[i].numVertices ) > numVerticesTotal)
        {
            CPLError(CE_Failure, CPLE_AssertionFailed,
                     "Unsupported case or corrupt file: MULTIPLINE/REGION "
                     "object vertices do not appear to be grouped together.");
            return -1;
        }
    }

    return 0;
}

/**********************************************************************
 *                   TABMAPObjectBlock::WriteCoordSecHdrs()
 *
 * Write a set of coordinate section headers for PLINE MULTIPLE or REGIONs.
 * pasHdrs should point to an array of numSections TABMAPCoordSecHdr 
 * structures that have been properly initialized.
 *
 * In V450 the numVertices is stored on an int32 instead of an int16
 *
 * At the end of the call, this TABMAPCoordBlock object will be ready to
 * receive the coordinate data.
 *
 * Returns 0 if succesful or -1 if an error happened, in which case 
 * CPLError() will have been called.
 **********************************************************************/
int     TABMAPCoordBlock::WriteCoordSecHdrs(GBool bV450Hdr,
                                            int numSections,
                                            TABMAPCoordSecHdr *pasHdrs,
                                            GBool bCompressed /*=FALSE*/)
{
    int i;

    CPLErrorReset();

    for(i=0; i<numSections; i++)
    {
        /*-------------------------------------------------------------
         * Write the coord. section header blocks
         *------------------------------------------------------------*/
#ifdef TABDUMP
        printf("WRITING pasHdrs[%d] @ %d = \n"
               "              { numVertices = %d, numHoles = %d, \n"
               "                nXMin=%d, nYMin=%d, nXMax=%d, nYMax=%d,\n"
               "                nDataOffset=%d, nVertexOffset=%d }\n",
               i, GetCurAddress(), pasHdrs[i].numVertices, pasHdrs[i].numHoles, 
               pasHdrs[i].nXMin, pasHdrs[i].nYMin, pasHdrs[i].nXMax, 
               pasHdrs[i].nYMax, pasHdrs[i].nDataOffset, 
               pasHdrs[i].nVertexOffset);
        printf("                dX = %d, dY = %d  (center = %d , %d)\n",
               pasHdrs[i].nXMax - pasHdrs[i].nXMin,
               pasHdrs[i].nYMax - pasHdrs[i].nYMin,
               m_nComprOrgX, m_nComprOrgY);
#endif

        if (bV450Hdr)
            WriteInt32(pasHdrs[i].numVertices);
        else
            WriteInt16(pasHdrs[i].numVertices);
        WriteInt16(pasHdrs[i].numHoles);
        WriteIntCoord(pasHdrs[i].nXMin, pasHdrs[i].nYMin, bCompressed);
        WriteIntCoord(pasHdrs[i].nXMax, pasHdrs[i].nYMax, bCompressed);
        WriteInt32(pasHdrs[i].nDataOffset);

        if (CPLGetLastErrorType() == CE_Failure )
            return -1;
    }

    return 0;
}


/**********************************************************************