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Sample Driver: jdemdataset.cpp
/******************************************************************************
* $Id: jdemdataset.cpp 33720 2016-03-15 00:39:53Z goatbar $
*
* Project: JDEM Reader
* Purpose: All code for Japanese DEM Reader
* Author: Frank Warmerdam, warmerdam@pobox.com
*
******************************************************************************
* Copyright (c) 2000, Frank Warmerdam <warmerdam@pobox.com>
* Copyright (c) 2009-2012, Even Rouault <even dot rouault at mines-paris dot org>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
****************************************************************************/
#include "gdal_frmts.h"
#include "gdal_pam.h"
CPL_CVSID("$Id: jdemdataset.cpp 33720 2016-03-15 00:39:53Z goatbar $");
/************************************************************************/
/* JDEMGetField() */
/************************************************************************/
static int JDEMGetField( char *pszField, int nWidth )
{
char szWork[32];
CPLAssert( nWidth < (int) sizeof(szWork) );
strncpy( szWork, pszField, nWidth );
szWork[nWidth] = '\0';
return atoi(szWork);
}
/************************************************************************/
/* JDEMGetAngle() */
/************************************************************************/
static double JDEMGetAngle( char *pszField )
{
int nAngle = JDEMGetField( pszField, 7 );
// Note, this isn't very general purpose, but it would appear
// from the field widths that angles are never negative. Nice
// to be a country in the "first quadrant".
const int nDegree = nAngle / 10000;
const int nMin = (nAngle / 100) % 100;
const int nSec = nAngle % 100;
return nDegree + nMin / 60.0 + nSec / 3600.0;
}
/************************************************************************/
/* ==================================================================== */
/* JDEMDataset */
/* ==================================================================== */
/************************************************************************/
class JDEMRasterBand;
class JDEMDataset : public GDALPamDataset
{
friend class JDEMRasterBand;
VSILFILE *fp;
GByte abyHeader[1012];
public:
JDEMDataset();
~JDEMDataset();
static GDALDataset *Open( GDALOpenInfo * );
static int Identify( GDALOpenInfo * );
CPLErr GetGeoTransform( double * padfTransform );
const char *GetProjectionRef();
};
/************************************************************************/
/* ==================================================================== */
/* JDEMRasterBand */
/* ==================================================================== */
/************************************************************************/
class JDEMRasterBand : public GDALPamRasterBand
{
friend class JDEMDataset;
int nRecordSize;
char* pszRecord;
int bBufferAllocFailed;
public:
JDEMRasterBand( JDEMDataset *, int );
~JDEMRasterBand();
virtual CPLErr IReadBlock( int, int, void * );
};
/************************************************************************/
/* JDEMRasterBand() */
/************************************************************************/
JDEMRasterBand::JDEMRasterBand( JDEMDataset *poDSIn, int nBandIn ) :
pszRecord(NULL),
bBufferAllocFailed(FALSE)
{
this->poDS = poDSIn;
this->nBand = nBandIn;
eDataType = GDT_Float32;
nBlockXSize = poDS->GetRasterXSize();
nBlockYSize = 1;
/* Cannot overflow as nBlockXSize <= 999 */
nRecordSize = nBlockXSize*5 + 9 + 2;
}
/************************************************************************/
/* ~JDEMRasterBand() */
/************************************************************************/
JDEMRasterBand::~JDEMRasterBand()
{
VSIFree(pszRecord);
}
/************************************************************************/
/* IReadBlock() */
/************************************************************************/
CPLErr JDEMRasterBand::IReadBlock( CPL_UNUSED int nBlockXOff,
int nBlockYOff,
void * pImage )
{
JDEMDataset *poGDS = (JDEMDataset *) poDS;
if (pszRecord == NULL)
{
if (bBufferAllocFailed)
return CE_Failure;
pszRecord = (char *) VSI_MALLOC_VERBOSE(nRecordSize);
if (pszRecord == NULL)
{
bBufferAllocFailed = TRUE;
return CE_Failure;
}
}
CPL_IGNORE_RET_VAL(VSIFSeekL( poGDS->fp, 1011 + nRecordSize*nBlockYOff, SEEK_SET ));
CPL_IGNORE_RET_VAL(VSIFReadL( pszRecord, 1, nRecordSize, poGDS->fp ));
if( !EQUALN((char *) poGDS->abyHeader,pszRecord,6) )
{
CPLError( CE_Failure, CPLE_AppDefined,
"JDEM Scanline corrupt. Perhaps file was not transferred\n"
"in binary mode?" );
return CE_Failure;
}
if( JDEMGetField( pszRecord + 6, 3 ) != nBlockYOff + 1 )
{
CPLError( CE_Failure, CPLE_AppDefined,
"JDEM scanline out of order, JDEM driver does not\n"
"currently support partial datasets." );
return CE_Failure;
}
for( int i = 0; i < nBlockXSize; i++ )
((float *) pImage)[i] = (float)
(JDEMGetField( pszRecord + 9 + 5 * i, 5) * 0.1);
return CE_None;
}
/************************************************************************/
/* ==================================================================== */
/* JDEMDataset */
/* ==================================================================== */
/************************************************************************/
/************************************************************************/
/* JDEMDataset() */
/************************************************************************/
JDEMDataset::JDEMDataset() :
fp(NULL)
{ }
/************************************************************************/
/* ~JDEMDataset() */
/************************************************************************/
JDEMDataset::~JDEMDataset()
{
FlushCache();
if( fp != NULL )
CPL_IGNORE_RET_VAL(VSIFCloseL( fp ));
}
/************************************************************************/
/* GetGeoTransform() */
/************************************************************************/
CPLErr JDEMDataset::GetGeoTransform( double * padfTransform )
{
const double dfLLLat = JDEMGetAngle( (char *) abyHeader + 29 );
const double dfLLLong = JDEMGetAngle( (char *) abyHeader + 36 );
const double dfURLat = JDEMGetAngle( (char *) abyHeader + 43 );
const double dfURLong = JDEMGetAngle( (char *) abyHeader + 50 );
padfTransform[0] = dfLLLong;
padfTransform[3] = dfURLat;
padfTransform[1] = (dfURLong - dfLLLong) / GetRasterXSize();
padfTransform[2] = 0.0;
padfTransform[4] = 0.0;
padfTransform[5] = -1 * (dfURLat - dfLLLat) / GetRasterYSize();
return CE_None;
}
/************************************************************************/
/* GetProjectionRef() */
/************************************************************************/
const char *JDEMDataset::GetProjectionRef()
{
return( "GEOGCS[\"Tokyo\",DATUM[\"Tokyo\",SPHEROID[\"Bessel 1841\",6377397.155,299.1528128,AUTHORITY[\"EPSG\",7004]],TOWGS84[-148,507,685,0,0,0,0],AUTHORITY[\"EPSG\",6301]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",8901]],UNIT[\"DMSH\",0.0174532925199433,AUTHORITY[\"EPSG\",9108]],AUTHORITY[\"EPSG\",4301]]" );
}
/************************************************************************/
/* Identify() */
/************************************************************************/
int JDEMDataset::Identify( GDALOpenInfo * poOpenInfo )
{
/* -------------------------------------------------------------------- */
/* Confirm that the header has what appears to be dates in the */
/* expected locations. Sadly this is a relatively weak test. */
/* -------------------------------------------------------------------- */
if( poOpenInfo->nHeaderBytes < 50 )
return FALSE;
/* check if century values seem reasonable */
if( (!STARTS_WITH_CI((char *)poOpenInfo->pabyHeader+11, "19")
&& !STARTS_WITH_CI((char *)poOpenInfo->pabyHeader+11, "20"))
|| (!STARTS_WITH_CI((char *)poOpenInfo->pabyHeader+15, "19")
&& !STARTS_WITH_CI((char *)poOpenInfo->pabyHeader+15, "20"))
|| (!STARTS_WITH_CI((char *)poOpenInfo->pabyHeader+19, "19")
&& !STARTS_WITH_CI((char *)poOpenInfo->pabyHeader+19, "20")) )
{
return FALSE;
}
return TRUE;
}
/************************************************************************/
/* Open() */
/************************************************************************/
GDALDataset *JDEMDataset::Open( GDALOpenInfo * poOpenInfo )
{
/* -------------------------------------------------------------------- */
/* Confirm that the header is compatible with a JDEM dataset. */
/* -------------------------------------------------------------------- */
if (!Identify(poOpenInfo))
return NULL;
/* -------------------------------------------------------------------- */
/* Confirm the requested access is supported. */
/* -------------------------------------------------------------------- */
if( poOpenInfo->eAccess == GA_Update )
{
CPLError( CE_Failure, CPLE_NotSupported,
"The JDEM driver does not support update access to existing"
" datasets.\n" );
return NULL;
}
/* Check that the file pointer from GDALOpenInfo* is available */
if( poOpenInfo->fpL == NULL )
{
return NULL;
}
/* -------------------------------------------------------------------- */
/* Create a corresponding GDALDataset. */
/* -------------------------------------------------------------------- */
JDEMDataset *poDS = new JDEMDataset();
/* Borrow the file pointer from GDALOpenInfo* */
poDS->fp = poOpenInfo->fpL;
poOpenInfo->fpL = NULL;
/* -------------------------------------------------------------------- */
/* Read the header. */
/* -------------------------------------------------------------------- */
CPL_IGNORE_RET_VAL(VSIFReadL( poDS->abyHeader, 1, 1012, poDS->fp ));
poDS->nRasterXSize = JDEMGetField( (char *) poDS->abyHeader + 23, 3 );
poDS->nRasterYSize = JDEMGetField( (char *) poDS->abyHeader + 26, 3 );
if (poDS->nRasterXSize <= 0 || poDS->nRasterYSize <= 0 )
{
CPLError( CE_Failure, CPLE_AppDefined,
"Invalid dimensions : %d x %d",
poDS->nRasterXSize, poDS->nRasterYSize);
delete poDS;
return NULL;
}
/* -------------------------------------------------------------------- */
/* Create band information objects. */
/* -------------------------------------------------------------------- */
poDS->SetBand( 1, new JDEMRasterBand( poDS, 1 ));
/* -------------------------------------------------------------------- */
/* Initialize any PAM information. */
/* -------------------------------------------------------------------- */
poDS->SetDescription( poOpenInfo->pszFilename );
poDS->TryLoadXML();
/* -------------------------------------------------------------------- */
/* Check for overviews. */
/* -------------------------------------------------------------------- */
poDS->oOvManager.Initialize( poDS, poOpenInfo->pszFilename );
return( poDS );
}
/************************************************************************/
/* GDALRegister_JDEM() */
/************************************************************************/
void GDALRegister_JDEM()
{
if( GDALGetDriverByName( "JDEM" ) != NULL )
return;
GDALDriver *poDriver = new GDALDriver();
poDriver->SetDescription( "JDEM" );
poDriver->SetMetadataItem( GDAL_DCAP_RASTER, "YES" );
poDriver->SetMetadataItem( GDAL_DMD_LONGNAME, "Japanese DEM (.mem)" );
poDriver->SetMetadataItem( GDAL_DMD_HELPTOPIC, "frmt_various.html#JDEM" );
poDriver->SetMetadataItem( GDAL_DMD_EXTENSION, "mem" );
poDriver->SetMetadataItem( GDAL_DCAP_VIRTUALIO, "YES" );
poDriver->pfnOpen = JDEMDataset::Open;
poDriver->pfnIdentify = JDEMDataset::Identify;
GetGDALDriverManager()->RegisterDriver( poDriver );
}

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