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[feature][expressions] Add new shared_paths function

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Returns a collection containing paths shared by the two
input geometries. Those going in the same direction are
in the first element of the collection, those going in
the opposite direction are in the second element. The
paths themselves are given in the direction of the first
geometry.

(Exposes the GEOS shared paths functionality for use
in expressions.)
This commit is contained in:
Nyall Dawson 2022-09-04 08:00:11 +10:00
parent b9413ed7b9
commit dcdb4cd054
3 changed files with 54 additions and 0 deletions
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23
resources/function_help/json/shared_paths Normal file
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@ -0,0 +1,23 @@
{
"name": "shared_paths",
"type": "function",
"groups": ["GeometryGroup"],
"description": "Returns a collection containing paths shared by the two input geometries. Those going in the same direction are in the first element of the collection, those going in the opposite direction are in the second element. The paths themselves are given in the direction of the first geometry.",
"arguments": [{
"arg": "geometry1",
"description": "a LineString/MultiLineString geometry"
},
{
"arg": "geometry2",
"description": "a LineString/MultiLineString geometry"
}
],
"examples": [{
"expression": "geom_to_wkt(shared_paths(geom_from_wkt('MULTILINESTRING((26 125,26 200,126 200,126 125,26 125),(51 150,101 150,76 175,51 150)))'),geom_from_wkt('LINESTRING(151 100,126 156.25,126 125,90 161, 76 175)')))",
"returns": "'GeometryCollection (MultiLineString ((126 156.25, 126 125),(101 150, 90 161),(90 161, 76 175)),MultiLineString EMPTY)'"
}, {
"expression": "geom_to_wkt(shared_paths(geom_from_wkt('LINESTRING(76 175,90 161,126 125,126 156.25,151 100)'),geom_from_wkt('MULTILINESTRING((26 125,26 200,126 200,126 125,26 125),(51 150,101 150,76 175,51 150))')))",
"returns": "'GeometryCollection (MultiLineString EMPTY,MultiLineString ((76 175, 90 161),(90 161, 101 150),(126 125, 126 156.25)))'"
}],
"tags": ["linestrings", "paths", "overlapping", "shared", "linestring", "multilinestring"]
}

23
src/core/expression/qgsexpressionfunction.cpp
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@ -2926,6 +2926,24 @@ static QVariant fcnLineMerge( const QVariantList &values, const QgsExpressionCon
return QVariant::fromValue( merged );
}
static QVariant fcnSharedPaths( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
{
const QgsGeometry geom = QgsExpressionUtils::getGeometry( values.at( 0 ), parent );
if ( geom.isNull() )
return QVariant();
const QgsGeometry geom2 = QgsExpressionUtils::getGeometry( values.at( 1 ), parent );
if ( geom2.isNull() )
return QVariant();
const QgsGeometry sharedPaths = geom.sharedPaths( geom2 );
if ( sharedPaths.isNull() )
return QVariant();
return QVariant::fromValue( sharedPaths );
}
static QVariant fcnSimplify( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
{
QgsGeometry geom = QgsExpressionUtils::getGeometry( values.at( 0 ), parent );
@ -7984,6 +8002,11 @@ const QList<QgsExpressionFunction *> &QgsExpression::Functions()
fcnGeometryN, QStringLiteral( "GeometryGroup" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "boundary" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ), fcnBoundary, QStringLiteral( "GeometryGroup" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "line_merge" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ), fcnLineMerge, QStringLiteral( "GeometryGroup" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "shared_paths" ), QgsExpressionFunction::ParameterList
{
QgsExpressionFunction::Parameter( QStringLiteral( "geometry1" ) ),
QgsExpressionFunction::Parameter( QStringLiteral( "geometry2" ) )
}, fcnSharedPaths, QStringLiteral( "GeometryGroup" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "bounds" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ), fcnBounds, QStringLiteral( "GeometryGroup" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "simplify" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "tolerance" ) ), fcnSimplify, QStringLiteral( "GeometryGroup" ) )
<< new QgsStaticExpressionFunction( QStringLiteral( "simplify_vw" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "tolerance" ) ), fcnSimplifyVW, QStringLiteral( "GeometryGroup" ) )

8
tests/src/core/testqgsexpression.cpp
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@ -1138,6 +1138,14 @@ class TestQgsExpression: public QObject
QTest::newRow( "line_merge point" ) << "line_merge(geom_from_wkt('POINT(1 2)'))" << false << QVariant();
QTest::newRow( "line_merge line" ) << "geom_to_wkt(line_merge(geometry:=geom_from_wkt('LineString(0 0, 10 10)')))" << false << QVariant( "LineString (0 0, 10 10)" );
QTest::newRow( "line_merge multiline" ) << "geom_to_wkt(line_merge(geom_from_wkt('MultiLineString((0 0, 10 10),(10 10, 20 20))')))" << false << QVariant( "LineString (0 0, 10 10, 20 20)" );
QTest::newRow( "shared_paths not geom 1" ) << "shared_paths('g', geom_from_wkt('LineString(0 0, 10 10)'))" << true << QVariant();
QTest::newRow( "shared_paths not geom 2" ) << "shared_paths(geom_from_wkt('LineString(0 0, 10 10)'), 'g')" << true << QVariant();
QTest::newRow( "shared_paths null 1" ) << "shared_paths(NULL, geom_from_wkt('LineString(0 0, 10 10)'))" << false << QVariant();
QTest::newRow( "shared_paths null 2" ) << "shared_paths(geom_from_wkt('LineString(0 0, 10 10)'), NULL)" << false << QVariant();
QTest::newRow( "shared_paths point 1" ) << "shared_paths(make_point(1,2), geom_from_wkt('LineString(0 0, 10 10)'))" << false << QVariant();
QTest::newRow( "shared_paths point 2" ) << "shared_paths(geom_from_wkt('LineString(0 0, 10 10)'), make_point(1,2))" << false << QVariant();
QTest::newRow( "shared_paths lines 1" ) << "geom_to_wkt(shared_paths(geometry1:=geom_from_wkt('MULTILINESTRING((26 125,26 200,126 200,126 125,26 125),(51 150,101 150,76 175,51 150))'), geometry2:=geom_from_wkt('LINESTRING(151 100,126 156.25,126 125,90 161, 76 175)')))" << false << QVariant( "GeometryCollection (MultiLineString ((126 156.25, 126 125),(101 150, 90 161),(90 161, 76 175)),MultiLineString EMPTY)" );
QTest::newRow( "shared_paths lines 2" ) << "geom_to_wkt(shared_paths(geometry1:=geom_from_wkt('MULTILINESTRING((26 125,26 200,126 200,126 125,26 125),(51 150,101 150,76 175,51 150))'), geometry2:=reverse(geom_from_wkt('LINESTRING(151 100,126 156.25,126 125,90 161, 76 175)'))))" << false << QVariant( "GeometryCollection (MultiLineString EMPTY,MultiLineString ((126 156.25, 126 125),(101 150, 90 161),(90 161, 76 175)))" );
QTest::newRow( "offset_curve not geom" ) << "offset_curve('g', 5)" << true << QVariant();
QTest::newRow( "offset_curve null" ) << "offset_curve(NULL, 5)" << false << QVariant();
QTest::newRow( "offset_curve point" ) << "offset_curve(geom_from_wkt('POINT(1 2)'),5)" << false << QVariant();