shpopen.c

用于读取TAB、MIF、SHP文件的类

    ByteCopy( &i32, abyHeader+24, 4 );
    if( !bBigEndian ) SwapWord( 4, abyHeader+24 );
    
    if( fseek( psSHP->fpSHX, 0, 0 ) != 0 
        || fwrite( abyHeader, 100, 1, psSHP->fpSHX ) != 1 )
    {
#ifdef USE_CPL
        CPLError( CE_Failure, CPLE_OpenFailed, 
                  "Failure writing .shx header." );
#endif
        return;
    }

/* -------------------------------------------------------------------- */
/*      Write out the .shx contents.                                    */
/* -------------------------------------------------------------------- */
    panSHX = (int32 *) malloc(sizeof(int32) * 2 * psSHP->nRecords);

    for( i = 0; i < psSHP->nRecords; i++ )
    {
	panSHX[i*2  ] = psSHP->panRecOffset[i]/2;
	panSHX[i*2+1] = psSHP->panRecSize[i]/2;
	if( !bBigEndian ) SwapWord( 4, panSHX+i*2 );
	if( !bBigEndian ) SwapWord( 4, panSHX+i*2+1 );
    }

    if( (int)fwrite( panSHX, sizeof(int32)*2, psSHP->nRecords, psSHP->fpSHX ) 
        != psSHP->nRecords )
    {
#ifdef USE_CPL
        CPLError( CE_Failure, CPLE_OpenFailed, 
                  "Failure writing .shx contents." );
#endif
    }

    free( panSHX );

/* -------------------------------------------------------------------- */
/*      Flush to disk.                                                  */
/* -------------------------------------------------------------------- */
    fflush( psSHP->fpSHP );
    fflush( psSHP->fpSHX );
}

/************************************************************************/
/*                              shpopen()                               */
/*                                                                      */
/*      Open the .shp and .shx files based on the basename of the       */
/*      files or either file name.                                      */
/************************************************************************/
   
SHPHandle SHPAPI_CALL
SHPOpen( const char * pszLayer, const char * pszAccess )

{
    char		*pszFullname, *pszBasename;
    SHPHandle		psSHP;
    
    uchar		*pabyBuf;
    int			i;
    double		dValue;
    
/* -------------------------------------------------------------------- */
/*      Ensure the access string is one of the legal ones.  We          */
/*      ensure the result string indicates binary to avoid common       */
/*      problems on Windows.                                            */
/* -------------------------------------------------------------------- */
    if( strcmp(pszAccess,"rb+") == 0 || strcmp(pszAccess,"r+b") == 0
        || strcmp(pszAccess,"r+") == 0 )
        pszAccess = "r+b";
    else
        pszAccess = "rb";
    
/* -------------------------------------------------------------------- */
/*	Establish the byte order on this machine.			*/
/* -------------------------------------------------------------------- */
    i = 1;
    if( *((uchar *) &i) == 1 )
        bBigEndian = FALSE;
    else
        bBigEndian = TRUE;

/* -------------------------------------------------------------------- */
/*	Initialize the info structure.					*/
/* -------------------------------------------------------------------- */
    psSHP = (SHPHandle) calloc(sizeof(SHPInfo),1);

    psSHP->bUpdated = FALSE;

/* -------------------------------------------------------------------- */
/*	Compute the base (layer) name.  If there is any extension	*/
/*	on the passed in filename we will strip it off.			*/
/* -------------------------------------------------------------------- */
    pszBasename = (char *) malloc(strlen(pszLayer)+5);
    strcpy( pszBasename, pszLayer );
    for( i = strlen(pszBasename)-1; 
	 i > 0 && pszBasename[i] != '.' && pszBasename[i] != '/'
	       && pszBasename[i] != '\\';
	 i-- ) {}

    if( pszBasename[i] == '.' )
        pszBasename[i] = '\0';

/* -------------------------------------------------------------------- */
/*	Open the .shp and .shx files.  Note that files pulled from	*/
/*	a PC to Unix with upper case filenames won't work!		*/
/* -------------------------------------------------------------------- */
    pszFullname = (char *) malloc(strlen(pszBasename) + 5);
    sprintf( pszFullname, "%s.shp", pszBasename );
    psSHP->fpSHP = fopen(pszFullname, pszAccess );
    if( psSHP->fpSHP == NULL )
    {
        sprintf( pszFullname, "%s.SHP", pszBasename );
        psSHP->fpSHP = fopen(pszFullname, pszAccess );
    }
    
    if( psSHP->fpSHP == NULL )
    {
#ifdef USE_CPL
        CPLError( CE_Failure, CPLE_OpenFailed, 
                  "Unable to open %s.shp or %s.SHP.", 
                  pszBasename, pszBasename );
#endif
        free( psSHP );
        free( pszBasename );
        free( pszFullname );
        return( NULL );
    }

    sprintf( pszFullname, "%s.shx", pszBasename );
    psSHP->fpSHX = fopen(pszFullname, pszAccess );
    if( psSHP->fpSHX == NULL )
    {
        sprintf( pszFullname, "%s.SHX", pszBasename );
        psSHP->fpSHX = fopen(pszFullname, pszAccess );
    }
    
    if( psSHP->fpSHX == NULL )
    {
#ifdef USE_CPL
        CPLError( CE_Failure, CPLE_OpenFailed, 
                  "Unable to open %s.shx or %s.SHX.", 
                  pszBasename, pszBasename );
#endif
        fclose( psSHP->fpSHP );
        free( psSHP );
        free( pszBasename );
        free( pszFullname );
        return( NULL );
    }

    free( pszFullname );
    free( pszBasename );

/* -------------------------------------------------------------------- */
/*  Read the file size from the SHP file.				*/
/* -------------------------------------------------------------------- */
    pabyBuf = (uchar *) malloc(100);
    fread( pabyBuf, 100, 1, psSHP->fpSHP );

    psSHP->nFileSize = (pabyBuf[24] * 256 * 256 * 256
			+ pabyBuf[25] * 256 * 256
			+ pabyBuf[26] * 256
			+ pabyBuf[27]) * 2;

/* -------------------------------------------------------------------- */
/*  Read SHX file Header info                                           */
/* -------------------------------------------------------------------- */
    if( fread( pabyBuf, 100, 1, psSHP->fpSHX ) != 1 
        || pabyBuf[0] != 0 
        || pabyBuf[1] != 0 
        || pabyBuf[2] != 0x27 
        || (pabyBuf[3] != 0x0a && pabyBuf[3] != 0x0d) )
    {
#ifdef USE_CPL
        CPLError( CE_Failure, CPLE_AppDefined, 
                  ".shx file is unreadable, or corrupt." );
#endif
	fclose( psSHP->fpSHP );
	fclose( psSHP->fpSHX );
	free( psSHP );

	return( NULL );
    }

    psSHP->nRecords = pabyBuf[27] + pabyBuf[26] * 256
      + pabyBuf[25] * 256 * 256 + pabyBuf[24] * 256 * 256 * 256;
    psSHP->nRecords = (psSHP->nRecords*2 - 100) / 8;

    psSHP->nShapeType = pabyBuf[32];

    if( psSHP->nRecords < 0 || psSHP->nRecords > 256000000 )
    {
#ifdef USE_CPL
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Record count in .shp header is %d, which seems\n"
                  "unreasonable.  Assuming header is corrupt.",
                  psSHP->nRecords );
#endif
	fclose( psSHP->fpSHP );
	fclose( psSHP->fpSHX );
	free( psSHP );

	return( NULL );
    }

/* -------------------------------------------------------------------- */
/*      Read the bounds.                                                */
/* -------------------------------------------------------------------- */
    if( bBigEndian ) SwapWord( 8, pabyBuf+36 );
    memcpy( &dValue, pabyBuf+36, 8 );
    psSHP->adBoundsMin[0] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+44 );
    memcpy( &dValue, pabyBuf+44, 8 );
    psSHP->adBoundsMin[1] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+52 );
    memcpy( &dValue, pabyBuf+52, 8 );
    psSHP->adBoundsMax[0] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+60 );
    memcpy( &dValue, pabyBuf+60, 8 );
    psSHP->adBoundsMax[1] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+68 );		/* z */
    memcpy( &dValue, pabyBuf+68, 8 );
    psSHP->adBoundsMin[2] = dValue;
    
    if( bBigEndian ) SwapWord( 8, pabyBuf+76 );
    memcpy( &dValue, pabyBuf+76, 8 );
    psSHP->adBoundsMax[2] = dValue;
    
    if( bBigEndian ) SwapWord( 8, pabyBuf+84 );		/* z */
    memcpy( &dValue, pabyBuf+84, 8 );
    psSHP->adBoundsMin[3] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+92 );
    memcpy( &dValue, pabyBuf+92, 8 );
    psSHP->adBoundsMax[3] = dValue;

    free( pabyBuf );

/* -------------------------------------------------------------------- */
/*	Read the .shx file to get the offsets to each record in 	*/
/*	the .shp file.							*/
/* -------------------------------------------------------------------- */
    psSHP->nMaxRecords = psSHP->nRecords;

    psSHP->panRecOffset =
        (int *) malloc(sizeof(int) * MAX(1,psSHP->nMaxRecords) );
    psSHP->panRecSize =
        (int *) malloc(sizeof(int) * MAX(1,psSHP->nMaxRecords) );

    pabyBuf = (uchar *) malloc(8 * MAX(1,psSHP->nRecords) );
    if( (int) fread( pabyBuf, 8, psSHP->nRecords, psSHP->fpSHX ) 
			!= psSHP->nRecords )
    {
#ifdef USE_CPL
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Failed to read all values for %d records in .shx file.",
                  psSHP->nRecords );
#endif
        /* SHX is short or unreadable for some reason. */
	fclose( psSHP->fpSHP );
	fclose( psSHP->fpSHX );
        free( psSHP->panRecOffset );
        free( psSHP->panRecSize );
	free( psSHP );

	return( NULL );
    }

    for( i = 0; i < psSHP->nRecords; i++ )
    {
	int32		nOffset, nLength;

	memcpy( &nOffset, pabyBuf + i * 8, 4 );
	if( !bBigEndian ) SwapWord( 4, &nOffset );

	memcpy( &nLength, pabyBuf + i * 8 + 4, 4 );
	if( !bBigEndian ) SwapWord( 4, &nLength );

	psSHP->panRecOffset[i] = nOffset*2;
	psSHP->panRecSize[i] = nLength*2;
    }
    free( pabyBuf );

    return( psSHP );
}

/************************************************************************/
/*                              SHPClose()                              */
/*								       	*/
/*	Close the .shp and .shx files.					*/
/************************************************************************/

void SHPAPI_CALL
SHPClose(SHPHandle psSHP )

{
    if( psSHP == NULL )
        return;

/* -------------------------------------------------------------------- */
/*	Update the header if we have modified anything.			*/
/* -------------------------------------------------------------------- */
    if( psSHP->bUpdated )
	SHPWriteHeader( psSHP );

/* -------------------------------------------------------------------- */
/*      Free all resources, and close files.                            */
/* -------------------------------------------------------------------- */
    free( psSHP->panRecOffset );
    free( psSHP->panRecSize );

    fclose( psSHP->fpSHX );
    fclose( psSHP->fpSHP );

    if( psSHP->pabyRec != NULL )
    {
        free( psSHP->pabyRec );
    }
    
    free( psSHP );
}

/************************************************************************/
/*                             SHPGetInfo()                             */
/*                                                                      */
/*      Fetch general information about the shape file.                 */
/************************************************************************/

void SHPAPI_CALL
SHPGetInfo(SHPHandle psSHP, int * pnEntities, int * pnShapeType,
           double * padfMinBound, double * padfMaxBound )

{
    int		i;

    if( psSHP == NULL )
        return;
    
    if( pnEntities != NULL )
        *pnEntities = psSHP->nRecords;

    if( pnShapeType != NULL )
        *pnShapeType = psSHP->nShapeType;

    for( i = 0; i < 4; i++ )
    {
        if( padfMinBound != NULL )
            padfMinBound[i] = psSHP->adBoundsMin[i];
        if( padfMaxBound != NULL )