Port extend lines to new API

Author: nyalldawson

python/plugins/processing/algs/qgis/ExtendLines.py

@@ -25,20 +25,13 @@
 
 __revision__ = '$Format:%H$'
 
-from qgis.core import (QgsApplication,
-                       QgsFeatureSink,
-                       QgsProcessingUtils)
-from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
-from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
-from processing.core.parameters import ParameterVector, ParameterNumber
-from processing.core.outputs import OutputVector
-from processing.tools import dataobjects
+from qgis.core import (QgsProcessingParameterNumber,
+                       QgsProcessingException)
+from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
 
 
-class ExtendLines(QgisAlgorithm):
+class ExtendLines(QgisFeatureBasedAlgorithm):
 
-    INPUT_LAYER = 'INPUT_LAYER'
-    OUTPUT_LAYER = 'OUTPUT_LAYER'
     START_DISTANCE = 'START_DISTANCE'
     END_DISTANCE = 'END_DISTANCE'
 
@@ -47,47 +40,37 @@ def group(self):
 
     def __init__(self):
         super().__init__()
+        self.start_distance = None
+        self.end_distance = None
 
-    def initAlgorithm(self, config=None):
-        self.addParameter(ParameterVector(self.INPUT_LAYER,
-                                          self.tr('Input layer'), [dataobjects.TYPE_VECTOR_LINE]))
-        self.addParameter(ParameterNumber(self.START_DISTANCE,
-                                          self.tr('Start distance'), default=0.0))
-        self.addParameter(ParameterNumber(self.END_DISTANCE,
-                                          self.tr('End distance'), default=0.0))
-
-        self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Extended lines')))
+    def initParameters(self, config=None):
+        self.addParameter(QgsProcessingParameterNumber(self.START_DISTANCE,
+                                                       self.tr('Start distance'), defaultValue=0.0))
+        self.addParameter(QgsProcessingParameterNumber(self.END_DISTANCE,
+                                                       self.tr('End distance'), defaultValue=0.0))
 
     def name(self):
         return 'extendlines'
 
     def displayName(self):
         return self.tr('Extend lines')
 
-    def processAlgorithm(self, parameters, context, feedback):
-        layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_LAYER), context)
-
-        writer = self.getOutputFromName(
-            self.OUTPUT_LAYER).getVectorWriter(layer.fields(), layer.wkbType(), layer.crs(), context)
-
-        start_distance = self.getParameterValue(self.START_DISTANCE)
-        end_distance = self.getParameterValue(self.END_DISTANCE)
-
-        features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
+    def outputName(self):
+        return self.tr('Extended')
 
-        for current, input_feature in enumerate(features):
-            output_feature = input_feature
-            input_geometry = input_feature.geometry()
-            if input_geometry:
-                output_geometry = input_geometry.extendLine(start_distance, end_distance)
-                if not output_geometry:
-                    raise GeoAlgorithmExecutionException(
-                        self.tr('Error calculating extended line'))
+    def prepareAlgorithm(self, parameters, context, feedback):
+        self.start_distance = self.parameterAsDouble(parameters, self.START_DISTANCE, context)
+        self.end_distance = self.parameterAsDouble(parameters, self.END_DISTANCE, context)
+        return True
 
-                output_feature.setGeometry(output_geometry)
+    def processFeature(self, feature, feedback):
+        input_geometry = feature.geometry()
+        if input_geometry:
+            output_geometry = input_geometry.extendLine(self.start_distance, self.end_distance)
+            if not output_geometry:
+                raise QgsProcessingException(
+                    self.tr('Error calculating extended line'))
 
-            writer.addFeature(output_feature, QgsFeatureSink.FastInsert)
-            feedback.setProgress(int(current * total))
+            feature.setGeometry(output_geometry)
 
-        del writer
+        return feature

python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py

@@ -57,6 +57,7 @@
 from .Difference import Difference
 from .DropGeometry import DropGeometry
 from .DropMZValues import DropMZValues
+from .ExtendLines import ExtendLines
 from .ExtentFromLayer import ExtentFromLayer
 from .ExtractNodes import ExtractNodes
 from .FixGeometry import FixGeometry
@@ -162,7 +163,6 @@
 # from .Relief import Relief
 # from .IdwInterpolation import IdwInterpolation
 # from .TinInterpolation import TinInterpolation
-# from .ExtendLines import ExtendLines
 # from .ExtractSpecificNodes import ExtractSpecificNodes
 # from .GeometryByExpression import GeometryByExpression
 # from .RasterCalculator import RasterCalculator
@@ -217,11 +217,10 @@ def getAlgs(self):
         #         SpatialIndex(), DefineProjection(),
         #         RectanglesOvalsDiamondsVariable(),
         #         RectanglesOvalsDiamondsFixed(), MergeLines(),
-        #
         #         PointsAlongGeometry(),
         #         Relief(),
         #         IdwInterpolation(), TinInterpolation(),
-        #         ExtendLines(), ExtractSpecificNodes(),
+        #         ExtractSpecificNodes(),
         #         GeometryByExpression(),
         #         RasterCalculator(),
         #         ShortestPathPointToPoint(), ShortestPathPointToLayer(),
@@ -247,6 +246,7 @@ def getAlgs(self):
                 Difference(),
                 DropGeometry(),
                 DropMZValues(),
+                ExtendLines(),
                 ExtentFromLayer(),
                 ExtractNodes(),
                 FixGeometry(),

python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

@@ -1346,7 +1346,7 @@ tests:
       OUTPUT:
         name: expected/remove_null_polys.gml
         type: vector
-#
+
   - algorithm: native:extractbyexpression
     name: Extract by Expression
     params:
@@ -1359,34 +1359,34 @@ tests:
         name: expected/extract_expression.gml
         type: vector
 
-#  - algorithm: qgis:extendlines
-#    name: Extend lines
-#    params:
-#      END_DISTANCE: 0.2
-#      INPUT_LAYER:
-#        name: lines.gml
-#        type: vector
-#      START_DISTANCE: 0.1
-#    results:
-#      OUTPUT_LAYER:
-#        name: expected/extend_lines.gml
-#        type: vector
-#        compare:
-#          geometry:
-#            precision: 7
-#  - algorithm: qgis:extendlines
-#    name: Extend multilines
-#    params:
-#      END_DISTANCE: 0.4
-#      INPUT_LAYER:
-#        name: multilines.gml
-#        type: vector
-#      START_DISTANCE: 0.2
-#    results:
-#      OUTPUT_LAYER:
-#        name: expected/extend_multilines.gml
-#        type: vector
-#
+  - algorithm: qgis:extendlines
+    name: Extend lines
+    params:
+      END_DISTANCE: 0.2
+      INPUT:
+        name: lines.gml
+        type: vector
+      START_DISTANCE: 0.1
+    results:
+      OUTPUT:
+        name: expected/extend_lines.gml
+        type: vector
+        compare:
+          geometry:
+            precision: 7
+  - algorithm: qgis:extendlines
+    name: Extend multilines
+    params:
+      END_DISTANCE: 0.4
+      INPUT:
+        name: multilines.gml
+        type: vector
+      START_DISTANCE: 0.2
+    results:
+      OUTPUT:
+        name: expected/extend_multilines.gml
+        type: vector
+
 #  - algorithm: qgis:extractspecificnodes
 #    name: Extract specific nodes lines
 #    params: