mitab_mapheaderblock.cpp

mitab,读取MapInfo的地图文件

     */
    if (m_nMAPVersionNumber <= 100)
    {
        m_XScale = m_YScale = pow(10.0, m_nCoordPrecision);
        m_XDispl = m_YDispl = 0.0;
    }

    for(i=0; i<6; i++)
        m_sProj.adProjParams[i] = ReadDouble();

    m_sProj.dDatumShiftX = ReadDouble();
    m_sProj.dDatumShiftY = ReadDouble();
    m_sProj.dDatumShiftZ = ReadDouble();
    for(i=0; i<5; i++)
    {
        /* In V.200 files, the next 5 datum params are unused and they
         * sometimes contain junk bytes... in this case we set adDatumParams[]
         * to 0 for the rest of the lib to be happy.
         */
        m_sProj.adDatumParams[i] = ReadDouble();
        if (m_nMAPVersionNumber <= 200)
            m_sProj.adDatumParams[i] = 0.0;
    }

    m_sProj.nAffineFlag = 0;
    if (m_nMAPVersionNumber >= 500 && m_nSizeUsed > 512)
    {
        // Read Affine parameters A,B,C,D,E,F 
        // only if version 500+ and block is larger than 512 bytes
        int nInUse = ReadByte();
        if (nInUse)
        {
            m_sProj.nAffineFlag = 1;
            m_sProj.nAffineUnits = ReadByte();
            GotoByteInBlock(0x0208); // Skip unused bytes
            m_sProj.dAffineParamA = ReadDouble();
            m_sProj.dAffineParamB = ReadDouble();
            m_sProj.dAffineParamC = ReadDouble();
            m_sProj.dAffineParamD = ReadDouble();
            m_sProj.dAffineParamE = ReadDouble();
            m_sProj.dAffineParamF = ReadDouble();
        }
    }

    return 0;
}


/**********************************************************************
 *                   TABMAPHeaderBlock::Int2Coordsys()
 *
 * Convert from long integer (internal) to coordinates system units
 * as defined in the file's coordsys clause.
 *
 * Note that the false easting/northing and the conversion factor from
 * datum to coordsys units are not included in the calculation.
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABMAPHeaderBlock::Int2Coordsys(GInt32 nX, GInt32 nY, 
                                    double &dX, double &dY)
{
    if (m_pabyBuf == NULL)
        return -1;

    // For some obscure reason, some guy decided that it would be 
    // more fun to be able to define our own origin quadrant!
    //
    // In version 100 .tab files (version 400 .map), it is possible to have 
    // a quadrant 0 and it should be treated the same way as quadrant 3

    if (m_nCoordOriginQuadrant==2 || m_nCoordOriginQuadrant==3 ||
        m_nCoordOriginQuadrant==0 )
        dX = -1.0 * (nX + m_XDispl) / m_XScale;
    else
        dX = (nX - m_XDispl) / m_XScale;

    if (m_nCoordOriginQuadrant==3 || m_nCoordOriginQuadrant==4||
        m_nCoordOriginQuadrant==0)
        dY = -1.0 * (nY + m_YDispl) / m_YScale;
    else
        dY = (nY - m_YDispl) / m_YScale;

//printf("Int2Coordsys: (%d, %d) -> (%.10g, %.10g)\n", nX, nY, dX, dY);

    return 0;
}

/**********************************************************************
 *                   TABMAPHeaderBlock::Coordsys2Int()
 *
 * Convert from coordinates system units as defined in the file's 
 * coordsys clause to long integer (internal) coordinates.
 *
 * Note that the false easting/northing and the conversion factor from
 * datum to coordsys units are not included in the calculation.
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABMAPHeaderBlock::Coordsys2Int(double dX, double dY, 
                                    GInt32 &nX, GInt32 &nY,
                                    GBool bIgnoreOverflow /*=FALSE*/)
{
    if (m_pabyBuf == NULL)
        return -1;

    // For some obscure reason, some guy decided that it would be 
    // more fun to be able to define our own origin quadrant!
    //
    // In version 100 .tab files (version 400 .map), it is possible to have 
    // a quadrant 0 and it should be treated the same way as quadrant 3

    /*-----------------------------------------------------------------
     * NOTE: double values must be used here, the limit of integer value 
     * have been reached some times due to the very big numbers used here.
     *----------------------------------------------------------------*/
    double dTempX, dTempY;

    if (m_nCoordOriginQuadrant==2 || m_nCoordOriginQuadrant==3 ||
        m_nCoordOriginQuadrant==0 )
        dTempX = (double)(-1.0*dX*m_XScale - m_XDispl);
    else
        dTempX = (double)(dX*m_XScale + m_XDispl);

    if (m_nCoordOriginQuadrant==3 || m_nCoordOriginQuadrant==4 ||
        m_nCoordOriginQuadrant==0 )
        dTempY = (double)(-1.0*dY*m_YScale - m_YDispl);
    else
        dTempY = (double)(dY*m_YScale + m_YDispl);

    /*-----------------------------------------------------------------
     * Make sure we'll never output coordinates outside of the valid
     * integer coordinates range: (-1e9, -1e9) - (1e9, 1e9)
     * Integer coordinates outside of that range will confuse MapInfo.
     *----------------------------------------------------------------*/
    GBool bIntBoundsOverflow = FALSE;
    if (dTempX < -1000000000)
    {
        dTempX = -1000000000;
        bIntBoundsOverflow = TRUE;
    }
    if (dTempX > 1000000000)
    {
        dTempX = 1000000000;
        bIntBoundsOverflow = TRUE;
    }
    if (dTempY < -1000000000)
    {
        dTempY = -1000000000;
        bIntBoundsOverflow = TRUE;
    }
    if (dTempY > 1000000000)
    {
        dTempY = 1000000000;
        bIntBoundsOverflow = TRUE;
    }

    nX = (GInt32) ROUND_INT(dTempX);
    nY = (GInt32) ROUND_INT(dTempY);

    if (bIntBoundsOverflow && !bIgnoreOverflow)
    {
        m_bIntBoundsOverflow = TRUE;
#ifdef DEBUG
        CPLError(CE_Warning, TAB_WarningBoundsOverflow, 
                 "Integer bounds overflow: (%f, %f) -> (%d, %d)\n",
                 dX, dY, nX, nY);
#endif
    }

    return 0;
}

/**********************************************************************
 *                   TABMAPHeaderBlock::ComprInt2Coordsys()
 *
 * Convert from compressed integer (internal) to coordinates system units
 * as defined in the file's coordsys clause.
 * The difference between long integer and compressed integer coords is
 * that compressed coordinates are scaled displacement relative to an 
 * object centroid.
 *
 * Note that the false easting/northing and the conversion factor from
 * datum to coordsys units are not included in the calculation.
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABMAPHeaderBlock::ComprInt2Coordsys(GInt32 nCenterX, GInt32 nCenterY, 
                                         int nDeltaX, int nDeltaY, 
                                         double &dX, double &dY)
{
    if (m_pabyBuf == NULL)
        return -1;

    return Int2Coordsys(nCenterX+nDeltaX, nCenterY+nDeltaY, dX, dY);
}


/**********************************************************************
 *                   TABMAPHeaderBlock::Int2CoordsysDist()
 *
 * Convert a pair of X and Y size (or distance) value from long integer
 * (internal) to coordinates system units as defined in the file's 
 * coordsys clause.
 *
 * The difference with Int2Coordsys() is that this function only applies
 * the scaling factor: it does not apply the displacement.
 *
 * Since the calculations on the X and Y values are independent, either
 * one can be omitted (i.e. passed as 0)
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABMAPHeaderBlock::Int2CoordsysDist(GInt32 nX, GInt32 nY, 
                                    double &dX, double &dY)
{
    if (m_pabyBuf == NULL)
        return -1;

    dX = nX / m_XScale;
    dY = nY / m_YScale;

    return 0;
}

/**********************************************************************
 *                   TABMAPHeaderBlock::Coordsys2IntDist()
 *
 * Convert a pair of X and Y size (or distance) values from coordinates
 * system units as defined in the file's coordsys clause to long integer
 * (internal) coordinates.
 *
 * The difference with Coordsys2Int() is that this function only applies
 * the scaling factor: it does not apply the displacement.
 *
 * Since the calculations on the X and Y values are independent, either
 * one can be omitted (i.e. passed as 0)
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABMAPHeaderBlock::Coordsys2IntDist(double dX, double dY, 
                                        GInt32 &nX, GInt32 &nY)
{
    if (m_pabyBuf == NULL)
        return -1;

    nX = (GInt32)(dX*m_XScale);
    nY = (GInt32)(dY*m_YScale);

    return 0;
}


/**********************************************************************
 *                   TABMAPHeaderBlock::SetCoordsysBounds()
 *
 * Take projection coordinates bounds of the newly created dataset and
 * compute new values for the X/Y Scales and X/Y displacement.
 *
 * This function must be called after creating a new dataset and before any
 * of the coordinates conversion functions can be used.
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABMAPHeaderBlock::SetCoordsysBounds(double dXMin, double dYMin, 
                                         double dXMax, double dYMax)
{
//printf("SetCoordsysBounds(%10g, %10g, %10g, %10g)\n", dXMin, dYMin, dXMax, dYMax);
    /*-----------------------------------------------------------------
     * Check for 0-width or 0-height bounds
     *----------------------------------------------------------------*/
    if (dXMax == dXMin)
    {
        dXMin -= 1.0;
        dXMax += 1.0;
    }

    if (dYMax == dYMin)
    {
        dYMin -= 1.0;
        dYMax += 1.0;
    }

    /*-----------------------------------------------------------------
     * X and Y scales are used to map coordsys coordinates to integer
     * internal coordinates.  We want to find the scale and displacement
     * values that will result in an integer coordinate range of
     * (-1e9, -1e9) - (1e9, 1e9)
     *
     * Note that we ALWAYS generate datasets with the OriginQuadrant = 1
     * so that we avoid reverted X/Y axis complications, etc.
     *----------------------------------------------------------------*/
    m_XScale = 2e9 / (dXMax - dXMin);
    m_YScale = 2e9 / (dYMax - dYMin);

    m_XDispl = -1.0 * m_XScale * (dXMax + dXMin) / 2;
    m_YDispl = -1.0 * m_YScale * (dYMax + dYMin) / 2;

    m_nXMin = -1000000000;
    m_nYMin = -1000000000;
    m_nXMax = 1000000000;
    m_nYMax = 1000000000;

    return 0;
}

/**********************************************************************
 *                   TABMAPHeaderBlock::GetMapObjectSize()
 *
 * Return the size of the object body for the specified object type.
 * The value is looked up in the first 256 bytes of the header.
 **********************************************************************/
int TABMAPHeaderBlock::GetMapObjectSize(int nObjType)
{
    if (m_pabyBuf == NULL)
    {
        CPLError(CE_Failure, CPLE_AssertionFailed,
                 "Block has not been initialized yet!");
        return -1;
    }

    if (nObjType < 0 || nObjType > 255)
    {
        CPLError(CE_Failure, CPLE_IllegalArg,
                 "Invalid object type %d", nObjType);
        return -1;
    }

    // Byte 0x80 is set for objects that have coordinates inside type 3 blocks
    return (m_pabyBuf[nObjType] & 0x7f);
}

/**********************************************************************
 *                   TABMAPHeaderBlock::MapObjectUsesCoordBlock()
 *
 * Return TRUE if the specified map object type has coordinates stored
 * inside type 3 coordinate blocks.
 * The info is looked up in the first 256 bytes of the header.
 **********************************************************************/
GBool TABMAPHeaderBlock::MapObjectUsesCoordBlock(int nObjType)
{
    if (m_pabyBuf == NULL)
    {
        CPLError(CE_Failure, CPLE_AssertionFailed,
                 "Block has not been initialized yet!");
        return FALSE;
    }

    if (nObjType < 0 || nObjType > 255)
    {
        CPLError(CE_Failure, CPLE_IllegalArg,
                 "Invalid object type %d", nObjType);
        return FALSE;
    }

    // Byte 0x80 is set for objects that have coordinates inside type 3 blocks

    return ((m_pabyBuf[nObjType] & 0x80) != 0) ? TRUE: FALSE;
}


/**********************************************************************
 *                   TABMAPHeaderBlock::GetProjInfo()