[processing] Expose buffer settings (cap/join style/mitre limit)

Also make fixed distance buffer correctly handle null geometries (copy the row as a geometryless row)
qgis · Aug 11, 2016 · 5025c82 · 5025c82
1 parent 0a2b661
commit 5025c82
Show file tree

Hide file tree

Showing 15 changed files with 561 additions and 28 deletions.
diff --git a/python/plugins/processing/algs/help/qgis.yaml b/python/plugins/processing/algs/help/qgis.yaml
@@ -167,6 +167,14 @@ qgis:fieldcalculator: >
 qgis:fixeddistancebuffer: >
   This algorithm computes a buffer area for all the features in an input layer, using a fixed distance.
 
+  The segments parameter controls the number of line segments to use to approximate a quarter circle when creating rounded offsets.
+
+  The end cap style parameter controls how line endings are handled in the buffer.
+
+  The join style parameter specifies whether round, mitre or beveled joins should be used when offseting corners in a line.
+
+  The mitre limit parameter is only applicable for mitre join styles, and controls the maximum distance from the offset curve to use when creating a mitred join.
+
 qgis:frequencyanalysis: >
   This algorithms generates a table with frequency analysis of the values of a selected attribute from an input vector layer
 

diff --git a/python/plugins/processing/algs/qgis/Buffer.py b/python/plugins/processing/algs/qgis/Buffer.py
@@ -32,15 +32,12 @@
 
 
 def buffering(progress, writer, distance, field, useField, layer, dissolve,
-              segments):
+              segments, endCapStyle=1, joinStyle=1, mitreLimit=2):
 
     if useField:
         field = layer.fieldNameIndex(field)
 
     outFeat = QgsFeature()
-    inFeat = QgsFeature()
-    inGeom = QgsGeometry()
-    outGeom = QgsGeometry()
 
     current = 0
     features = vector.features(layer)
@@ -49,6 +46,7 @@ def buffering(progress, writer, distance, field, useField, layer, dissolve,
     # With dissolve
     if dissolve:
         first = True
+        buffered_geometries = []
         for inFeat in features:
             attrs = inFeat.attributes()
             if useField:
@@ -57,23 +55,19 @@ def buffering(progress, writer, distance, field, useField, layer, dissolve,
                 value = distance
 
             inGeom = inFeat.geometry()
-            if inGeom.isEmpty() or inGeom.isGeosEmpty():
+            if not inGeom:
                 ProcessingLog.addToLog(ProcessingLog.LOG_WARNING, 'Feature {} has empty geometry. Skipping...'.format(inFeat.id()))
                 continue
             if not inGeom.isGeosValid():
                 ProcessingLog.addToLog(ProcessingLog.LOG_WARNING, 'Feature {} has invalid geometry. Skipping...'.format(inFeat.id()))
                 continue
-            outGeom = inGeom.buffer(float(value), segments)
-            if first:
-                tempGeom = QgsGeometry(outGeom)
-                first = False
-            else:
-                tempGeom = tempGeom.combine(outGeom)
+            buffered_geometries.append(inGeom.buffer(float(value), segments, endCapStyle, joinStyle, mitreLimit))
 
             current += 1
             progress.setPercentage(int(current * total))
 
-        outFeat.setGeometry(tempGeom)
+        final_geometry = QgsGeometry.unaryUnion(buffered_geometries)
+        outFeat.setGeometry(final_geometry)
         outFeat.setAttributes(attrs)
         writer.addFeature(outFeat)
     else:
@@ -85,15 +79,15 @@ def buffering(progress, writer, distance, field, useField, layer, dissolve,
             else:
                 value = distance
             inGeom = inFeat.geometry()
+            outFeat = QgsFeature()
             if inGeom.isEmpty() or inGeom.isGeosEmpty():
-                ProcessingLog.addToLog(ProcessingLog.LOG_WARNING, 'Feature {} has empty geometry. Skipping...'.format(inFeat.id()))
-                continue
-            if not inGeom.isGeosValid():
+                pass
+            elif not inGeom.isGeosValid():
                 ProcessingLog.addToLog(ProcessingLog.LOG_WARNING, 'Feature {} has invalid geometry. Skipping...'.format(inFeat.id()))
                 continue
-
-            outGeom = inGeom.buffer(float(value), segments)
-            outFeat.setGeometry(outGeom)
+            else:
+                outGeom = inGeom.buffer(float(value), segments, endCapStyle, joinStyle, mitreLimit)
+                outFeat.setGeometry(outGeom)
             outFeat.setAttributes(attrs)
             writer.addFeature(outFeat)
             current += 1

diff --git a/python/plugins/processing/algs/qgis/FixedDistanceBuffer.py b/python/plugins/processing/algs/qgis/FixedDistanceBuffer.py
@@ -35,6 +35,8 @@
 from processing.core.parameters import ParameterVector
 from processing.core.parameters import ParameterBoolean
 from processing.core.parameters import ParameterNumber
+from processing.core.parameters import ParameterSelection
+
 from processing.core.outputs import OutputVector
 from . import Buffer as buff
 from processing.tools import dataobjects
@@ -50,6 +52,9 @@ class FixedDistanceBuffer(GeoAlgorithm):
     DISTANCE = 'DISTANCE'
     SEGMENTS = 'SEGMENTS'
     DISSOLVE = 'DISSOLVE'
+    END_CAP_STYLE = 'END_CAP_STYLE'
+    JOIN_STYLE = 'JOIN_STYLE'
+    MITRE_LIMIT = 'MITRE_LIMIT'
 
     def getIcon(self):
         return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'buffer.png'))
@@ -65,6 +70,22 @@ def defineCharacteristics(self):
                                           self.tr('Segments'), 1, default=5))
         self.addParameter(ParameterBoolean(self.DISSOLVE,
                                            self.tr('Dissolve result'), False))
+        self.end_cap_styles = [self.tr('Round'),
+                               'Flat',
+                               'Square']
+        self.addParameter(ParameterSelection(
+            self.END_CAP_STYLE,
+            self.tr('End cap style'),
+            self.end_cap_styles, default=0))
+        self.join_styles = [self.tr('Round'),
+                            'Mitre',
+                            'Bevel']
+        self.addParameter(ParameterSelection(
+            self.JOIN_STYLE,
+            self.tr('Join style'),
+            self.join_styles, default=0))
+        self.addParameter(ParameterNumber(self.MITRE_LIMIT,
+                                          self.tr('Mitre limit'), 1, default=2))
 
         self.addOutput(OutputVector(self.OUTPUT, self.tr('Buffer')))
 
@@ -73,10 +94,13 @@ def processAlgorithm(self, progress):
         distance = self.getParameterValue(self.DISTANCE)
         dissolve = self.getParameterValue(self.DISSOLVE)
         segments = int(self.getParameterValue(self.SEGMENTS))
+        end_cap_style = self.getParameterValue(self.END_CAP_STYLE) + 1
+        join_style = self.getParameterValue(self.JOIN_STYLE) + 1
+        miter_limit = self.getParameterValue(self.MITRE_LIMIT)
 
         writer = self.getOutputFromName(
             self.OUTPUT).getVectorWriter(layer.fields().toList(),
                                          QgsWkbTypes.Polygon, layer.crs())
 
         buff.buffering(progress, writer, distance, None, False, layer,
-                       dissolve, segments)
+                       dissolve, segments, end_cap_style, join_style, miter_limit)
diff --git a/python/plugins/processing/tests/testdata/expected/buffer_lines.gml b/python/plugins/processing/tests/testdata/expected/buffer_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="http://ogr.maptools.org/ buffer_lines.xsd"
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-2</gml:X><gml:Y>-4</gml:Y></gml:coord>
+      <gml:coord><gml:X>11.98768834059514</gml:X><gml:Y>5.987688340595138</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:buffer_lines fid="lines.0">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>8,3 8.034074173710932,3.258819045102521 8.133974596215561,3.5 8.292893218813452,3.707106781186547 10.292893218813452,5.707106781186548 10.546009500260457,5.891006524188368 10.843565534959772,5.987688340595138 11.156434465040231,5.987688340595137 11.453990499739549,5.891006524188367 11.707106781186548,5.707106781186548 11.891006524188368,5.453990499739547 11.987688340595138,5.156434465040232 11.987688340595138,4.843565534959771 11.891006524188368,4.546009500260455 11.70710678118655,4.292893218813454 10.0,2.585786437626905 10,2 9.951056516295154,1.690983005625053 9.809016994374948,1.412214747707527 9.587785252292472,1.190983005625053 9.309016994374948,1.048943483704846 9,1 6,1 5.690983005625051,1.048943483704847 5.412214747707526,1.190983005625053 5.190983005625052,1.412214747707528 5.048943483704846,1.690983005625053 5,2 5.048943483704846,2.309016994374947 5.190983005625052,2.587785252292472 5.412214747707526,2.809016994374947 5.690983005625051,2.951056516295153 6,3 8,3</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines fid="lines.1">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>1,0 1.309016994374949,-0.048943483704847 1.587785252292474,-0.190983005625053 1.809016994374948,-0.412214747707527 1.951056516295154,-0.690983005625053 2,-1 1.951056516295154,-1.309016994374947 1.809016994374948,-1.587785252292472 1.587785252292474,-1.809016994374947 1.309016994374949,-1.951056516295153 1,-2 -1,-2 -1.309016994374949,-1.951056516295153 -1.587785252292474,-1.809016994374947 -1.809016994374948,-1.587785252292472 -1.951056516295154,-1.309016994374947 -2,-1 -1.951056516295154,-0.690983005625053 -1.809016994374948,-0.412214747707528 -1.587785252292474,-0.190983005625053 -1.309016994374949,-0.048943483704847 -1,0 1,0</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines fid="lines.2">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>1,2 1.048943483704846,2.309016994374947 1.190983005625053,2.587785252292473 1.412214747707527,2.809016994374947 1.690983005625053,2.951056516295154 2,3 2.048943483704847,3.309016994374949 2.190983005625053,3.587785252292474 2.412214747707528,3.809016994374948 2.690983005625053,3.951056516295154 3,4 3.309016994374947,3.951056516295154 3.587785252292472,3.809016994374948 3.809016994374947,3.587785252292474 3.951056516295153,3.309016994374949 4,3 4,2 3.951056516295154,1.690983005625053 3.809016994374947,1.412214747707527 3.587785252292473,1.190983005625053 3.309016994374947,1.048943483704846 3,1 3,0 2.951056516295153,-0.309016994374949 2.809016994374947,-0.587785252292474 2.587785252292472,-0.809016994374948 2.309016994374947,-0.951056516295154 2,-1 1.690983005625053,-0.951056516295154 1.412214747707528,-0.809016994374948 1.190983005625054,-0.587785252292475 1.048943483704847,-0.309016994374949 1,0 1,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines fid="lines.3">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5,2 5.309016994374948,1.951056516295153 5.587785252292474,1.809016994374947 5.809016994374947,1.587785252292473 5.951056516295154,1.309016994374947 6,1 5.951056516295154,0.690983005625053 5.809016994374948,0.412214747707528 5.587785252292474,0.190983005625054 5.309016994374949,0.048943483704847 5,0 3,0 2.690983005625051,0.048943483704847 2.412214747707526,0.190983005625053 2.190983005625052,0.412214747707528 2.048943483704846,0.690983005625053 2,1 2.048943483704846,1.309016994374947 2.190983005625052,1.587785252292472 2.412214747707526,1.809016994374947 2.690983005625051,1.951056516295153 3,2 5,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines fid="lines.4">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>10,-2 10.309016994374948,-2.048943483704847 10.587785252292472,-2.190983005625053 10.809016994374948,-2.412214747707528 10.951056516295154,-2.690983005625053 11,-3 10.951056516295154,-3.309016994374947 10.809016994374948,-3.587785252292472 10.587785252292475,-3.809016994374947 10.30901699437495,-3.951056516295153 10,-4 7,-4 6.690983005625051,-3.951056516295153 6.412214747707526,-3.809016994374947 6.190983005625052,-3.587785252292472 6.048943483704846,-3.309016994374947 6,-3 6.048943483704846,-2.690983005625053 6.190983005625052,-2.412214747707528 6.412214747707526,-2.190983005625053 6.690983005625051,-2.048943483704847 7,-2 10,-2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines fid="lines.5">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>9.292893218813452,1.707106781186547 9.546009500260457,1.891006524188368 9.843565534959772,1.987688340595138 10.156434465040231,1.987688340595138 10.453990499739549,1.891006524188368 10.707106781186548,1.707106781186547 10.891006524188368,1.453990499739547 10.987688340595138,1.156434465040232 10.987688340595138,0.84356553495977 10.891006524188368,0.546009500260455 10.70710678118655,0.292893218813454 6.707106781186548,-3.707106781186547 6.453990499739546,-3.891006524188368 6.15643446504023,-3.987688340595138 5.843565534959769,-3.987688340595138 5.546009500260453,-3.891006524188368 5.292893218813452,-3.707106781186547 5.108993475811633,-3.453990499739548 5.012311659404863,-3.156434465040232 5.012311659404862,-2.843565534959771 5.108993475811631,-2.546009500260455 5.29289321881345,-2.292893218813454 9.292893218813452,1.707106781186547</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines fid="lines.6">
+    </ogr:buffer_lines>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/expected/buffer_lines.xsd b/python/plugins/processing/tests/testdata/expected/buffer_lines.xsd
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema targetNamespace="http://ogr.maptools.org/" xmlns:ogr="http://ogr.maptools.org/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:gml="http://www.opengis.net/gml" elementFormDefault="qualified" version="1.0">
+<xs:import namespace="http://www.opengis.net/gml" schemaLocation="http://schemas.opengis.net/gml/2.1.2/feature.xsd"/>
+<xs:element name="FeatureCollection" type="ogr:FeatureCollectionType" substitutionGroup="gml:_FeatureCollection"/>
+<xs:complexType name="FeatureCollectionType">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureCollectionType">
+      <xs:attribute name="lockId" type="xs:string" use="optional"/>
+      <xs:attribute name="scope" type="xs:string" use="optional"/>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+<xs:element name="buffer_lines" type="ogr:buffer_lines_Type" substitutionGroup="gml:_Feature"/>
+<xs:complexType name="buffer_lines_Type">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureType">
+      <xs:sequence>
+        <xs:element name="geometryProperty" type="gml:PolygonPropertyType" nillable="true" minOccurs="0" maxOccurs="1"/>
+      </xs:sequence>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+</xs:schema>
diff --git a/python/plugins/processing/tests/testdata/expected/buffer_lines_flat.gml b/python/plugins/processing/tests/testdata/expected/buffer_lines_flat.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="http://ogr.maptools.org/ buffer_lines_flat.xsd"
+     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>-4</gml:Y></gml:coord>
+      <gml:coord><gml:X>11.70710678118655</gml:X><gml:Y>5.707106781186548</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:buffer_lines_flat fid="lines.0">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>8,3 8.034074173710932,3.258819045102521 8.133974596215561,3.5 8.292893218813452,3.707106781186547 10.292893218813452,5.707106781186548 11.707106781186548,4.292893218813452 10.0,2.585786437626905 10,2 9.951056516295154,1.690983005625053 9.809016994374948,1.412214747707527 9.587785252292472,1.190983005625053 9.309016994374948,1.048943483704846 9,1 6,1 6,3 8,3</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines_flat>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines_flat fid="lines.1">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>1,0 1,-2 -1,-2 -1,0 1,0</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines_flat>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines_flat fid="lines.2">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>1,2 1.048943483704846,2.309016994374947 1.190983005625053,2.587785252292473 1.412214747707527,2.809016994374947 1.690983005625053,2.951056516295154 2,3 4,3 4,2 3.951056516295154,1.690983005625053 3.809016994374947,1.412214747707527 3.587785252292473,1.190983005625053 3.309016994374947,1.048943483704846 3,1 3,0 1,0 1,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines_flat>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines_flat fid="lines.3">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5,2 5,0 3,0 3,2 5,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines_flat>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines_flat fid="lines.4">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>10,-2 10,-4 7,-4 7,-2 10,-2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines_flat>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines_flat fid="lines.5">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>9.292893218813452,1.707106781186547 10.707106781186548,0.292893218813453 6.707106781186548,-3.707106781186547 5.292893218813452,-2.292893218813453 9.292893218813452,1.707106781186547</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+    </ogr:buffer_lines_flat>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:buffer_lines_flat fid="lines.6">
+    </ogr:buffer_lines_flat>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/expected/buffer_lines_flat.xsd b/python/plugins/processing/tests/testdata/expected/buffer_lines_flat.xsd
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema targetNamespace="http://ogr.maptools.org/" xmlns:ogr="http://ogr.maptools.org/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:gml="http://www.opengis.net/gml" elementFormDefault="qualified" version="1.0">
+<xs:import namespace="http://www.opengis.net/gml" schemaLocation="http://schemas.opengis.net/gml/2.1.2/feature.xsd"/>
+<xs:element name="FeatureCollection" type="ogr:FeatureCollectionType" substitutionGroup="gml:_FeatureCollection"/>
+<xs:complexType name="FeatureCollectionType">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureCollectionType">
+      <xs:attribute name="lockId" type="xs:string" use="optional"/>
+      <xs:attribute name="scope" type="xs:string" use="optional"/>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+<xs:element name="buffer_lines_flat" type="ogr:buffer_lines_flat_Type" substitutionGroup="gml:_Feature"/>
+<xs:complexType name="buffer_lines_flat_Type">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureType">
+      <xs:sequence>
+        <xs:element name="geometryProperty" type="gml:PolygonPropertyType" nillable="true" minOccurs="0" maxOccurs="1"/>
+      </xs:sequence>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+</xs:schema>