double QgsDistanceArea::measurePolygon( const QList<QgsPoint>& points ) const
{
try
{
if ( mEllipsoidalMode && ( mEllipsoid != GEO_NONE ) )
{
QList<QgsPoint> pts;
for ( QList<QgsPoint>::const_iterator i = points.begin(); i != points.end(); ++i )
{
pts.append( mCoordTransform->transform( *i ) );
}
return computePolygonArea( pts );
}
else
{
return computePolygonArea( points );
}
}
catch ( QgsCsException &cse )
{
Q_UNUSED( cse );
QgsMessageLog::logMessage( QObject::tr( "Caught a coordinate system exception while trying to transform a point. Unable to calculate polygon area." ) );
return 0.0;
}
}
double QgsDistanceArea::measurePolygon( const QgsCurveV2* curve ) const
{
if ( !curve )
{
return 0.0;
}
QList<QgsPointV2> linePointsV2;
curve->points( linePointsV2 );
QList<QgsPoint> linePoints;
QList<QgsPointV2>::const_iterator ptIt = linePointsV2.constBegin();
for ( ; ptIt != linePointsV2.constEnd(); ++ptIt )
{
linePoints.append( mCoordTransform->transform( QgsPoint( ptIt->x(), ptIt->y() ) ) );
}
return computePolygonArea( linePoints );
}
const unsigned char *QgsDistanceArea::measurePolygon( const unsigned char* feature, double* area, double* perimeter, bool hasZptr ) const
{
if ( !feature )
{
QgsDebugMsg( "no feature to measure" );
return nullptr;
}
QgsConstWkbPtr wkbPtr( feature + 1 + sizeof( int ) );
// get number of rings in the polygon
int numRings;
wkbPtr >> numRings;
if ( numRings == 0 )
{
QgsDebugMsg( "no rings to measure" );
return nullptr;
}
// Set pointer to the first ring
QList<QgsPoint> points;
QgsPoint pnt;
double x, y;
if ( area )
*area = 0;
if ( perimeter )
*perimeter = 0;
try
{
for ( int idx = 0; idx < numRings; idx++ )
{
int nPoints;
wkbPtr >> nPoints;
// Extract the points from the WKB and store in a pair of
// vectors.
for ( int jdx = 0; jdx < nPoints; jdx++ )
{
wkbPtr >> x >> y;
if ( hasZptr )
{
// totally ignore Z value
wkbPtr += sizeof( double );
}
pnt = QgsPoint( x, y );
if ( mEllipsoidalMode && ( mEllipsoid != GEO_NONE ) )
{
pnt = mCoordTransform->transform( pnt );
}
points.append( pnt );
}
if ( points.size() > 2 )
{
if ( area )
{
double areaTmp = computePolygonArea( points );
if ( idx == 0 )
{
// exterior ring
*area += areaTmp;
}
else
{
*area -= areaTmp; // interior rings
}
}
if ( perimeter )
{
if ( idx == 0 )
{
// exterior ring
*perimeter += computeDistance( points );
}
}
}
points.clear();
}
}
catch ( QgsCsException &cse )
{
Q_UNUSED( cse );
QgsMessageLog::logMessage( QObject::tr( "Caught a coordinate system exception while trying to transform a point. Unable to calculate polygon area or perimeter." ) );
}
return wkbPtr;
}
unsigned char* QgsDistanceArea::measurePolygon( unsigned char* feature, double* area, double* perimeter, bool hasZptr )
{
// get number of rings in the polygon
unsigned int numRings = *(( int* )( feature + 1 + sizeof( int ) ) );
if ( numRings == 0 )
return 0;
// Set pointer to the first ring
unsigned char* ptr = feature + 1 + 2 * sizeof( int );
QList<QgsPoint> points;
QgsPoint pnt;
double x, y;
if ( area )
*area = 0;
if ( perimeter )
*perimeter = 0;
try
{
for ( unsigned int idx = 0; idx < numRings; idx++ )
{
int nPoints = *(( int* )ptr );
ptr += 4;
// Extract the points from the WKB and store in a pair of
// vectors.
for ( int jdx = 0; jdx < nPoints; jdx++ )
{
x = *(( double * ) ptr );
ptr += sizeof( double );
y = *(( double * ) ptr );
ptr += sizeof( double );
if ( hasZptr )
{
// totally ignore Z value
ptr += sizeof( double );
}
pnt = QgsPoint( x, y );
if ( mProjectionsEnabled && ( mEllipsoid != "NONE" ) )
{
pnt = mCoordTransform->transform( pnt );
}
points.append( pnt );
}
if ( points.size() > 2 )
{
if ( area )
{
double areaTmp = computePolygonArea( points );
if ( idx == 0 )
{
// exterior ring
*area += areaTmp;
}
else
{
*area -= areaTmp; // interior rings
}
}
if ( perimeter )
{
*perimeter += measureLine( points );
}
}
points.clear();
if ( !area )
{
break;
}
}
}
catch ( QgsCsException &cse )
{
Q_UNUSED( cse );
QgsMessageLog::logMessage( QObject::tr( "Caught a coordinate system exception while trying to transform a point. Unable to calculate polygon area or perimeter." ) );
}
return ptr;
}
