Sample Driver: jdemdataset.cpp

/******************************************************************************
 *
 * 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 "cpl_port.h"
#include "gdal_frmts.h"
#include "gdal_pam.h"

#include <algorithm>

CPL_CVSID("$Id: jdemdataset.cpp dbe2c476beb384094e80251a819e5b667886f754 2017-12-22 15:41:03Z Even Rouault $")

/************************************************************************/
/*                            JDEMGetField()                            */
/************************************************************************/

static int JDEMGetField( const char *pszField, int nWidth )

{
    char szWork[32] = {};
    CPLAssert(nWidth < static_cast<int>(sizeof(szWork)));

    strncpy(szWork, pszField, nWidth);
    szWork[nWidth] = '\0';

    return atoi(szWork);
}

/************************************************************************/
/*                            JDEMGetAngle()                            */
/************************************************************************/

static double JDEMGetAngle( const char *pszField )

{
    const 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 ) override;
    const char *GetProjectionRef() override;
};

/************************************************************************/
/* ==================================================================== */
/*                            JDEMRasterBand                             */
/* ==================================================================== */
/************************************************************************/

class JDEMRasterBand : public GDALPamRasterBand
{
    friend class JDEMDataset;

    int          nRecordSize;
    char        *pszRecord;
    bool         bBufferAllocFailed;

  public:
                JDEMRasterBand( JDEMDataset *, int );
    virtual ~JDEMRasterBand();

    virtual CPLErr IReadBlock( int, int, void * ) override;
};

/************************************************************************/
/*                           JDEMRasterBand()                            */
/************************************************************************/

JDEMRasterBand::JDEMRasterBand( JDEMDataset *poDSIn, int nBandIn ) :
    // Cannot overflow as nBlockXSize <= 999.
    nRecordSize(poDSIn->GetRasterXSize() * 5 + 9 + 2),
    pszRecord(nullptr),
    bBufferAllocFailed(false)
{
    poDS = poDSIn;
    nBand = nBandIn;

    eDataType = GDT_Float32;

    nBlockXSize = poDS->GetRasterXSize();
    nBlockYSize = 1;
}

/************************************************************************/
/*                          ~JDEMRasterBand()                            */
/************************************************************************/

JDEMRasterBand::~JDEMRasterBand() { VSIFree(pszRecord); }

/************************************************************************/
/*                             IReadBlock()                             */
/************************************************************************/

CPLErr JDEMRasterBand::IReadBlock( CPL_UNUSED int nBlockXOff,
                                   int nBlockYOff,
                                   void * pImage )

{
    JDEMDataset *poGDS = static_cast<JDEMDataset *>(poDS);

    if (pszRecord == nullptr)
    {
        if (bBufferAllocFailed)
            return CE_Failure;

        pszRecord = static_cast<char *>(VSI_MALLOC_VERBOSE(nRecordSize));
        if (pszRecord == nullptr)
        {
            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(reinterpret_cast<char *>(poGDS->abyHeader), pszRecord, 6) )
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "JDEM Scanline corrupt.  Perhaps file was not transferred "
                 "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 "
                 "currently support partial datasets.");
        return CE_Failure;
    }

    for( int i = 0; i < nBlockXSize; i++ )
        static_cast<float *>(pImage)[i] =
            JDEMGetField(pszRecord + 9 + 5 * i, 5) * 0.1f;

    return CE_None;
}

/************************************************************************/
/* ==================================================================== */
/*                              JDEMDataset                             */
/* ==================================================================== */
/************************************************************************/

/************************************************************************/
/*                            JDEMDataset()                             */
/************************************************************************/

JDEMDataset::JDEMDataset() :
    fp(nullptr)
{
    std::fill_n(abyHeader, CPL_ARRAYSIZE(abyHeader), static_cast<GByte>(0));
}

/************************************************************************/
/*                           ~JDEMDataset()                             */
/************************************************************************/

JDEMDataset::~JDEMDataset()

{
    FlushCache();
    if( fp != nullptr )
        CPL_IGNORE_RET_VAL(VSIFCloseL(fp));
}

/************************************************************************/
/*                          GetGeoTransform()                           */
/************************************************************************/

CPLErr JDEMDataset::GetGeoTransform( double *padfTransform )

{
    const char *psHeader = reinterpret_cast<char *>(abyHeader);

    const double dfLLLat = JDEMGetAngle(psHeader + 29);
    const double dfLLLong = JDEMGetAngle(psHeader + 36);
    const double dfURLat = JDEMGetAngle(psHeader + 43);
    const double dfURLong = JDEMGetAngle(psHeader + 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.
    const char *psHeader = reinterpret_cast<char *>(poOpenInfo->pabyHeader);
    if( (!STARTS_WITH_CI(psHeader + 11, "19") &&
         !STARTS_WITH_CI(psHeader + 11, "20")) ||
        (!STARTS_WITH_CI(psHeader + 15, "19") &&
         !STARTS_WITH_CI(psHeader + 15, "20")) ||
        (!STARTS_WITH_CI(psHeader + 19, "19") &&
         !STARTS_WITH_CI(psHeader + 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 nullptr;

    // 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.");
        return nullptr;
    }

    // Check that the file pointer from GDALOpenInfo* is available.
    if( poOpenInfo->fpL == nullptr )
    {
        return nullptr;
    }

    // Create a corresponding GDALDataset.
    JDEMDataset *poDS = new JDEMDataset();

    // Borrow the file pointer from GDALOpenInfo*.
    poDS->fp = poOpenInfo->fpL;
    poOpenInfo->fpL = nullptr;

    // Read the header.
    CPL_IGNORE_RET_VAL(VSIFReadL(poDS->abyHeader, 1, 1012, poDS->fp));

    const char *psHeader = reinterpret_cast<char *>(poDS->abyHeader);
    poDS->nRasterXSize = JDEMGetField(psHeader + 23, 3);
    poDS->nRasterYSize = JDEMGetField(psHeader + 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 nullptr;
    }

    // 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") != nullptr )
        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);
}