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/******************************************************************************
*
* Project: GDAL
* Purpose: Raster Polygon Enumerator
* Author: Frank Warmerdam, warmerdam@pobox.com
*
******************************************************************************
* Copyright (c) 2008, Frank Warmerdam
* Copyright (c) 2015, Even Rouault <even.rouault at spatialys.com>
*
* SPDX-License-Identifier: MIT
****************************************************************************/
#include "cpl_port.h"
#include "gdal_alg_priv.h"
#include <cstddef>
#include <limits>
#include "cpl_conv.h"
#include "cpl_error.h"
/*! @cond Doxygen_Suppress */
/************************************************************************/
/* GDALRasterPolygonEnumeratorT() */
/************************************************************************/
template <class DataType, class EqualityTest>
GDALRasterPolygonEnumeratorT<
DataType, EqualityTest>::GDALRasterPolygonEnumeratorT(int nConnectednessIn)
: nConnectedness(nConnectednessIn)
{
CPLAssert(nConnectedness == 4 || nConnectedness == 8);
}
/************************************************************************/
/* ~GDALRasterPolygonEnumeratorT() */
/************************************************************************/
template <class DataType, class EqualityTest>
GDALRasterPolygonEnumeratorT<DataType,
EqualityTest>::~GDALRasterPolygonEnumeratorT()
{
Clear();
}
/************************************************************************/
/* Clear() */
/************************************************************************/
template <class DataType, class EqualityTest>
void GDALRasterPolygonEnumeratorT<DataType, EqualityTest>::Clear()
{
CPLFree(panPolyIdMap);
CPLFree(panPolyValue);
panPolyIdMap = nullptr;
panPolyValue = nullptr;
nNextPolygonId = 0;
nPolyAlloc = 0;
}
/************************************************************************/
/* MergePolygon() */
/* */
/* Update the polygon map to indicate the merger of two polygons. */
/************************************************************************/
template <class DataType, class EqualityTest>
void GDALRasterPolygonEnumeratorT<DataType, EqualityTest>::MergePolygon(
int nSrcId, int nDstIdInit)
{
// Figure out the final dest id.
int nDstIdFinal = nDstIdInit;
while (panPolyIdMap[nDstIdFinal] != nDstIdFinal)
nDstIdFinal = panPolyIdMap[nDstIdFinal];
// Map the whole intermediate chain to it.
int nDstIdCur = nDstIdInit;
while (panPolyIdMap[nDstIdCur] != nDstIdCur)
{
int nNextDstId = panPolyIdMap[nDstIdCur];
panPolyIdMap[nDstIdCur] = nDstIdFinal;
nDstIdCur = nNextDstId;
}
// And map the whole source chain to it too (can be done in one pass).
while (panPolyIdMap[nSrcId] != nSrcId)
{
int nNextSrcId = panPolyIdMap[nSrcId];
panPolyIdMap[nSrcId] = nDstIdFinal;
nSrcId = nNextSrcId;
}
panPolyIdMap[nSrcId] = nDstIdFinal;
}
/************************************************************************/
/* NewPolygon() */
/* */
/* Allocate a new polygon id, and reallocate the polygon maps */
/* if needed. */
/************************************************************************/
template <class DataType, class EqualityTest>
int GDALRasterPolygonEnumeratorT<DataType, EqualityTest>::NewPolygon(
DataType nValue)
{
if (nNextPolygonId == std::numeric_limits<int>::max())
{
CPLError(CE_Failure, CPLE_AppDefined,
"GDALRasterPolygonEnumeratorT::NewPolygon(): maximum number "
"of polygons reached");
return -1;
}
if (nNextPolygonId >= nPolyAlloc)
{
int nPolyAllocNew;
if (nPolyAlloc < (std::numeric_limits<int>::max() - 20) / 2)
nPolyAllocNew = nPolyAlloc * 2 + 20;
else
nPolyAllocNew = std::numeric_limits<int>::max();
#if SIZEOF_VOIDP == 4
if (nPolyAllocNew >
static_cast<int>(std::numeric_limits<size_t>::max() /
sizeof(GInt32)) ||
nPolyAllocNew >
static_cast<int>(std::numeric_limits<size_t>::max() /
sizeof(DataType)))
{
CPLError(CE_Failure, CPLE_OutOfMemory,
"GDALRasterPolygonEnumeratorT::NewPolygon(): too many "
"polygons");
return -1;
}
#endif
auto panPolyIdMapNew = static_cast<GInt32 *>(
VSI_REALLOC_VERBOSE(panPolyIdMap, nPolyAllocNew * sizeof(GInt32)));
auto panPolyValueNew = static_cast<DataType *>(VSI_REALLOC_VERBOSE(
panPolyValue, nPolyAllocNew * sizeof(DataType)));
if (panPolyIdMapNew == nullptr || panPolyValueNew == nullptr)
{
VSIFree(panPolyIdMapNew);
VSIFree(panPolyValueNew);
return -1;
}
panPolyIdMap = panPolyIdMapNew;
panPolyValue = panPolyValueNew;
nPolyAlloc = nPolyAllocNew;
}
const int nPolyId = nNextPolygonId;
panPolyIdMap[nPolyId] = nPolyId;
panPolyValue[nPolyId] = nValue;
nNextPolygonId++;
return nPolyId;
}
/************************************************************************/
/* CompleteMerges() */
/* */
/* Make a pass through the maps, ensuring every polygon id */
/* points to the final id it should use, not an intermediate */
/* value. */
/************************************************************************/
template <class DataType, class EqualityTest>
void GDALRasterPolygonEnumeratorT<DataType, EqualityTest>::CompleteMerges()
{
int nFinalPolyCount = 0;
for (int iPoly = 0; iPoly < nNextPolygonId; iPoly++)
{
// Figure out the final id.
int nId = panPolyIdMap[iPoly];
while (nId != panPolyIdMap[nId])
{
nId = panPolyIdMap[nId];
}
// Then map the whole intermediate chain to it.
int nIdCur = panPolyIdMap[iPoly];
panPolyIdMap[iPoly] = nId;
while (nIdCur != panPolyIdMap[nIdCur])
{
int nNextId = panPolyIdMap[nIdCur];
panPolyIdMap[nIdCur] = nId;
nIdCur = nNextId;
}
if (panPolyIdMap[iPoly] == iPoly)
nFinalPolyCount++;
}
CPLDebug("GDALRasterPolygonEnumerator",
"Counted %d polygon fragments forming %d final polygons.",
nNextPolygonId, nFinalPolyCount);
}
/************************************************************************/
/* ProcessLine() */
/* */
/* Assign ids to polygons, one line at a time. */
/************************************************************************/
template <class DataType, class EqualityTest>
bool GDALRasterPolygonEnumeratorT<DataType, EqualityTest>::ProcessLine(
DataType *panLastLineVal, DataType *panThisLineVal, GInt32 *panLastLineId,
GInt32 *panThisLineId, int nXSize)
{
EqualityTest eq;
/* -------------------------------------------------------------------- */
/* Special case for the first line. */
/* -------------------------------------------------------------------- */
if (panLastLineVal == nullptr)
{
for (int i = 0; i < nXSize; i++)
{
if (panThisLineVal[i] == GP_NODATA_MARKER)
{
panThisLineId[i] = -1;
}
else if (i == 0 ||
!(eq.operator()(panThisLineVal[i], panThisLineVal[i - 1])))
{
panThisLineId[i] = NewPolygon(panThisLineVal[i]);
if (panThisLineId[i] < 0)
return false;
}
else
{
panThisLineId[i] = panThisLineId[i - 1];
}
}
return true;
}
/* -------------------------------------------------------------------- */
/* Process each pixel comparing to the previous pixel, and to */
/* the last line. */
/* -------------------------------------------------------------------- */
for (int i = 0; i < nXSize; i++)
{
if (panThisLineVal[i] == GP_NODATA_MARKER)
{
panThisLineId[i] = -1;
}
else if (i > 0 &&
eq.operator()(panThisLineVal[i], panThisLineVal[i - 1]))
{
panThisLineId[i] = panThisLineId[i - 1];
if (eq.operator()(panLastLineVal[i], panThisLineVal[i]) &&
(panPolyIdMap[panLastLineId[i]] !=
panPolyIdMap[panThisLineId[i]]))
{
MergePolygon(panLastLineId[i], panThisLineId[i]);
}
if (nConnectedness == 8 &&
eq.operator()(panLastLineVal[i - 1], panThisLineVal[i]) &&
(panPolyIdMap[panLastLineId[i - 1]] !=
panPolyIdMap[panThisLineId[i]]))
{
MergePolygon(panLastLineId[i - 1], panThisLineId[i]);
}
if (nConnectedness == 8 && i < nXSize - 1 &&
eq.operator()(panLastLineVal[i + 1], panThisLineVal[i]) &&
(panPolyIdMap[panLastLineId[i + 1]] !=
panPolyIdMap[panThisLineId[i]]))
{
MergePolygon(panLastLineId[i + 1], panThisLineId[i]);
}
}
else if (eq.operator()(panLastLineVal[i], panThisLineVal[i]))
{
panThisLineId[i] = panLastLineId[i];
}
else if (i > 0 && nConnectedness == 8 &&
eq.operator()(panLastLineVal[i - 1], panThisLineVal[i]))
{
panThisLineId[i] = panLastLineId[i - 1];
if (i < nXSize - 1 &&
eq.operator()(panLastLineVal[i + 1], panThisLineVal[i]) &&
(panPolyIdMap[panLastLineId[i + 1]] !=
panPolyIdMap[panThisLineId[i]]))
{
MergePolygon(panLastLineId[i + 1], panThisLineId[i]);
}
}
else if (i < nXSize - 1 && nConnectedness == 8 &&
eq.operator()(panLastLineVal[i + 1], panThisLineVal[i]))
{
panThisLineId[i] = panLastLineId[i + 1];
}
else
{
panThisLineId[i] = NewPolygon(panThisLineVal[i]);
if (panThisLineId[i] < 0)
return false;
}
}
return true;
}
template class GDALRasterPolygonEnumeratorT<std::int64_t, IntEqualityTest>;
template class GDALRasterPolygonEnumeratorT<float, FloatEqualityTest>;
template class GDALRasterPolygonEnumeratorT<double, DoubleEqualityTest>;
/*! @endcond */
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