[FEATURE][processing] Snap geometries to layer algorithm

Port the Geometry Snapper plugin across to the analysis lib, and expose to python bindings Add a new algorithm which performs the snapping to layers
qgis · Nov 7, 2016 · c3a978b · c3a978b
1 parent b4bca5b
commit c3a978b
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diff --git a/python/analysis/analysis.sip b/python/analysis/analysis.sip
@@ -9,6 +9,7 @@
 %Import core/core.sip
 
 %Include vector/qgsgeometryanalyzer.sip
+%Include vector/qgsgeometrysnapper.sip
 %Include vector/qgsoverlayanalyzer.sip
 %Include vector/qgspointsample.sip
 %Include vector/qgstransectsample.sip

diff --git a/python/analysis/vector/qgsgeometrysnapper.sip b/python/analysis/vector/qgsgeometrysnapper.sip
@@ -0,0 +1,43 @@
+/**
+ * \class QgsGeometrySnapper
+ * \ingroup analysis
+ * QgsGeometrySnapper allows a geometry to be snapped to the geometries within a
+ * different refence layer. Vertices in the geometries will be modified to
+ * match the reference layer features within a specified snap tolerance.
+ * \note added in QGIS 3.0
+ */
+
+class QgsGeometrySnapper : QObject
+{
+%TypeHeaderCode
+#include <qgsgeometrysnapper.h>
+%End
+
+  public:
+
+    /**
+     * Constructor for QgsGeometrySnapper. A reference layer which contains geometries to snap to must be
+     * set. The snap tolerance is specified in the layer units for the
+     * reference layer, and it is assumed that all geometries snapped using this object will have the
+     * same CRS as the reference layer (ie, no reprojection is performed).
+     */
+    QgsGeometrySnapper( QgsVectorLayer* referenceLayer, double snapTolerance );
+
+    /**
+     * Snaps a geometry to the reference layer and returns the result. The geometry must be in the same
+     * CRS as the reference layer.
+     */
+    QgsGeometry snapGeometry( const QgsGeometry& geometry ) const;
+
+    /**
+     * Snaps a set of features to the reference layer and returns the result. This operation is
+     * multithreaded for performance. The featureSnapped() signal will be emitted each time a feature
+     * is processed. This method is not safe to call from multiple threads concurrently.
+     */
+    QgsFeatureList snapFeatures( const QgsFeatureList& features );
+
+  signals:
+
+    //! Emitted each time a feature has been processed when calling snapFeatures()
+    void featureSnapped();
+};
diff --git a/python/plugins/processing/algs/help/qgis.yaml b/python/plugins/processing/algs/help/qgis.yaml
@@ -481,6 +481,9 @@ qgis:smoothgeometry: >
 
   The maximum angle parameter can be used to prevent smoothing of nodes with large angles. Any node where the angle of the segments to either side is larger then this will not be smoothed. Eg setting the maximum angle to 90 degrees or lower would preserve right angles in the geometry.
 
+qgis:snapgeometriestolayer: >
+  This algorithm snaps the geometries in a layer to the geometries in another layer. A tolerance is specified in layer units to control how close vertices need to be to the reference layer geometries before they are snapped. Snapping occurs to both vertices and edges, but snapping to a vertex is preferred. Vertices will be inserted or removed as required to make the geometries match the reference geometries.
+
 qgis:snappointstogrid: >
   This algorithm modifies the position of points in a vector layer, so they fall in the coordinates of a grid.
 

diff --git a/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py b/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py
@@ -175,6 +175,7 @@
 from .ExtendLines import ExtendLines
 from .ExtractSpecificNodes import ExtractSpecificNodes
 from .GeometryByExpression import GeometryByExpression
+from .SnapGeometries import SnapGeometriesToLayer
 
 pluginPath = os.path.normpath(os.path.join(
     os.path.split(os.path.dirname(__file__))[0], os.pardir))
@@ -237,7 +238,7 @@ def __init__(self):
                         IdwInterpolationZValue(), IdwInterpolationAttribute(),
                         TinInterpolationZValue(), TinInterpolationAttribute(),
                         RemoveNullGeometry(), ExtractByExpression(), ExtendLines(),
-                        ExtractSpecificNodes(), GeometryByExpression()
+                        ExtractSpecificNodes(), GeometryByExpression(), SnapGeometriesToLayer()
                         ]
 
         if hasMatplotlib:

diff --git a/python/plugins/processing/algs/qgis/SnapGeometries.py b/python/plugins/processing/algs/qgis/SnapGeometries.py
@@ -0,0 +1,83 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    SnapGeometries.py
+    -----------------
+    Date                 : October 2016
+    Copyright            : (C) 2016 by Nyall Dawson
+    Email                : nyall dot dawson at gmail dot com
+***************************************************************************
+*                                                                         *
+*   This program is free software; you can redistribute it and/or modify  *
+*   it under the terms of the GNU General Public License as published by  *
+*   the Free Software Foundation; either version 2 of the License, or     *
+*   (at your option) any later version.                                   *
+*                                                                         *
+***************************************************************************
+"""
+from builtins import str
+
+__author__ = 'Nyall Dawson'
+__date__ = 'October 2016'
+__copyright__ = '(C) 2016, Nyall Dawson'
+
+# This will get replaced with a git SHA1 when you do a git archive
+
+__revision__ = '$Format:%H$'
+
+from qgis.analysis import QgsGeometrySnapper
+from qgis.core import QgsFeature
+
+from processing.core.GeoAlgorithm import GeoAlgorithm
+from processing.core.parameters import ParameterVector, ParameterNumber
+from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
+from processing.core.outputs import OutputVector
+from processing.tools import dataobjects, vector
+
+
+class SnapGeometriesToLayer(GeoAlgorithm):
+
+    INPUT = 'INPUT'
+    REFERENCE_LAYER = 'REFERENCE_LAYER'
+    TOLERANCE = 'TOLERANCE'
+    OUTPUT = 'OUTPUT'
+
+    def defineCharacteristics(self):
+        self.name, self.i18n_name = self.trAlgorithm('Snap geometries to layer')
+        self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
+
+        self.addParameter(ParameterVector(self.INPUT, self.tr('Input layer')))
+        self.addParameter(ParameterVector(self.REFERENCE_LAYER, self.tr('Reference layer')))
+        self.addParameter(ParameterNumber(self.TOLERANCE, self.tr('Tolerance (layer units)'), 0.00000001, 9999999999, default=10.0))
+        self.addOutput(OutputVector(self.OUTPUT, self.tr('Snapped geometries')))
+
+    def processAlgorithm(self, progress):
+        layer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT))
+        reference_layer = dataobjects.getObjectFromUri(self.getParameterValue(self.REFERENCE_LAYER))
+        tolerance = self.getParameterValue(self.TOLERANCE)
+
+        if not layer.geometryType() == reference_layer.geometryType():
+            raise GeoAlgorithmExecutionException(
+                self.tr('Input layer and reference layer must have the same geometry type (eg both are line layers)'))
+
+        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(
+            layer.fields(), layer.wkbType(), layer.crs())
+
+        features = vector.features(layer)
+
+        self.processed = 0
+        self.progress = progress
+        self.total = 100.0 / len(features)
+
+        snapper = QgsGeometrySnapper(reference_layer, tolerance)
+        snapper.featureSnapped.connect(self.featureSnapped)
+        snapped_features = snapper.snapFeatures(features)
+        for f in snapped_features:
+            writer.addFeature(QgsFeature(f))
+
+        del writer
+
+    def featureSnapped(self):
+        self.processed += 1
+        self.progress.setPercentage(int(self.processed * self.total))
diff --git a/python/plugins/processing/tests/testdata/expected/snap_lines_to_lines.gfs b/python/plugins/processing/tests/testdata/expected/snap_lines_to_lines.gfs
@@ -0,0 +1,14 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>snap_lines_to_lines</Name>
+    <ElementPath>snap_lines_to_lines</ElementPath>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>7</FeatureCount>
+      <ExtentXMin>-1.00000</ExtentXMin>
+      <ExtentXMax>11.34679</ExtentXMax>
+      <ExtentYMin>-5.00000</ExtentYMin>
+      <ExtentYMax>5.28899</ExtentYMax>
+    </DatasetSpecificInfo>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/expected/snap_lines_to_lines.gml b/python/plugins/processing/tests/testdata/expected/snap_lines_to_lines.gml
@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-1</gml:X><gml:Y>-5</gml:Y></gml:coord>
+      <gml:coord><gml:X>11.34678899082569</gml:X><gml:Y>5.288990825688074</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:snap_lines_to_lines fid="lines.0">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>6,2 9,2 9,3 11,5 11.346788990825686,5.288990825688074</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:snap_lines_to_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_lines_to_lines fid="lines.1">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>-1,-1 1,-1</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:snap_lines_to_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_lines_to_lines fid="lines.2">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>2,0 2,2 2,2 3,2 3,2</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:snap_lines_to_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_lines_to_lines fid="lines.3">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>3,-3 3,-5</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:snap_lines_to_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_lines_to_lines fid="lines.4">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>7,-3 10,-3</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:snap_lines_to_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_lines_to_lines fid="lines.5">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>6,-3 10,1 10.208073394495411,0.849724770642202</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:snap_lines_to_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_lines_to_lines fid="lines.6">
+    </ogr:snap_lines_to_lines>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/expected/snap_polys_to_polys.gfs b/python/plugins/processing/tests/testdata/expected/snap_polys_to_polys.gfs
@@ -0,0 +1,32 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>snap_polys_to_polys</Name>
+    <ElementPath>snap_polys_to_polys</ElementPath>
+    <!--POLYGON-->
+    <GeometryType>3</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>4</FeatureCount>
+      <ExtentXMin>-1.00000</ExtentXMin>
+      <ExtentXMax>10.00000</ExtentXMax>
+      <ExtentYMin>-3.00000</ExtentYMin>
+      <ExtentYMax>5.00000</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>name</Name>
+      <ElementPath>name</ElementPath>
+      <Type>String</Type>
+      <Width>5</Width>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>intval</Name>
+      <ElementPath>intval</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>floatval</Name>
+      <ElementPath>floatval</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/expected/snap_polys_to_polys.gml b/python/plugins/processing/tests/testdata/expected/snap_polys_to_polys.gml
@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-1</gml:X><gml:Y>-3</gml:Y></gml:coord>
+      <gml:coord><gml:X>10</gml:X><gml:Y>5</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:snap_polys_to_polys fid="polys.0">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>-1,-1 -1,3 3,3 3,2 2,2 2,2 2,2 2,-1 -1,-1</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>aaaaa</ogr:name>
+      <ogr:intval>33</ogr:intval>
+      <ogr:floatval>44.123456</ogr:floatval>
+    </ogr:snap_polys_to_polys>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_polys_to_polys fid="polys.1">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5,5 6,4 4,4 5,5</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>Aaaaa</ogr:name>
+      <ogr:intval>-33</ogr:intval>
+      <ogr:floatval>0</ogr:floatval>
+    </ogr:snap_polys_to_polys>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_polys_to_polys fid="polys.3">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>6,1 10,1 10,-3 6,-3 6,1</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs><gml:innerBoundaryIs><gml:LinearRing><gml:coordinates>7,0 7,-2 9,0 7,0</gml:coordinates></gml:LinearRing></gml:innerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>ASDF</ogr:name>
+      <ogr:intval>0</ogr:intval>
+    </ogr:snap_polys_to_polys>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:snap_polys_to_polys fid="polys.4">
+      <ogr:intval>120</ogr:intval>
+      <ogr:floatval>-100291.43213</ogr:floatval>
+    </ogr:snap_polys_to_polys>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml b/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml
@@ -1387,3 +1387,33 @@ tests:
       OUTPUT_LAYER:
         name: expected/geometry_by_expression_line.gml
         type: vector
+
+  - algorithm: qgis:snapgeometriestolayer
+    name: Snap lines to lines
+    params:
+      INPUT:
+        name: snap_lines.gml
+        type: vector
+      REFERENCE_LAYER:
+        name: lines.gml
+        type: vector
+      TOLERANCE: 1.0
+    results:
+      OUTPUT:
+        name: expected/snap_lines_to_lines.gml
+        type: vector
+
+  - algorithm: qgis:snapgeometriestolayer
+    name: Snap polygons to polygons
+    params:
+      INPUT:
+        name: snap_polys.gml
+        type: vector
+      REFERENCE_LAYER:
+        name: polys.gml
+        type: vector
+      TOLERANCE: 1.0
+    results:
+      OUTPUT:
+        name: expected/snap_polys_to_polys.gml
+        type: vector
diff --git a/python/plugins/processing/tests/testdata/snap_lines.gfs b/python/plugins/processing/tests/testdata/snap_lines.gfs
@@ -0,0 +1,16 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>snap_lines</Name>
+    <ElementPath>snap_lines</ElementPath>
+    <!--LINESTRING-->
+    <GeometryType>2</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>7</FeatureCount>
+      <ExtentXMin>-1.00000</ExtentXMin>
+      <ExtentXMax>11.34679</ExtentXMax>
+      <ExtentYMin>-5.00000</ExtentYMin>
+      <ExtentYMax>5.28899</ExtentYMax>
+    </DatasetSpecificInfo>
+  </GMLFeatureClass>
+</GMLFeatureClassList>