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Better clip for very separate features

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This commit is contained in:
Nyall Dawson 2016-08-03 13:41:22 +10:00
parent 71ebdb8f69
commit d1aa03a09b
1 changed files with 61 additions and 43 deletions
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50
python/plugins/processing/algs/qgis/Clip.py
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@ -60,40 +60,53 @@ class Clip(GeoAlgorithm):
self.addOutput(OutputVector(Clip.OUTPUT, self.tr('Clipped'))) self.addOutput(OutputVector(Clip.OUTPUT, self.tr('Clipped')))
def processAlgorithm(self, progress): def processAlgorithm(self, progress):
sourceLayer = dataobjects.getObjectFromUri( source_layer = dataobjects.getObjectFromUri(
self.getParameterValue(Clip.INPUT)) self.getParameterValue(Clip.INPUT))
maskLayer = dataobjects.getObjectFromUri( mask_layer = dataobjects.getObjectFromUri(
self.getParameterValue(Clip.OVERLAY)) self.getParameterValue(Clip.OVERLAY))
writer = self.getOutputFromName(self.OUTPUT).getVectorWriter( writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(
sourceLayer.pendingFields(), source_layer.fields(),
sourceLayer.dataProvider().geometryType(), source_layer.dataProvider().geometryType(),
sourceLayer.dataProvider().crs()) source_layer.crs())
inFeatA = QgsFeature()
inFeatB = QgsFeature()
outFeat = QgsFeature()
# first build up a list of clip geometries # first build up a list of clip geometries
clip_geoms = [] clip_geoms = []
for maskFeat in vector.features(maskLayer, QgsFeatureRequest().setSubsetOfAttributes([])): for maskFeat in vector.features(mask_layer, QgsFeatureRequest().setSubsetOfAttributes([])):
clip_geoms.append(maskFeat.geometry()) clip_geoms.append(maskFeat.geometry())
# are we clipping against a single feature? if so, we can show finer progress reports
if len(clip_geoms) > 1: if len(clip_geoms) > 1:
combined_clip_geom = QgsGeometry.unaryUnion(clip_geoms) combined_clip_geom = QgsGeometry.unaryUnion(clip_geoms)
single_clip_feature = False
else: else:
combined_clip_geom = clip_geoms[0] combined_clip_geom = clip_geoms[0]
single_clip_feature = True
# use prepared geometries for faster insection tests # use prepared geometries for faster intersection tests
engine = QgsGeometry.createGeometryEngine(combined_clip_geom.geometry()) engine = QgsGeometry.createGeometryEngine(combined_clip_geom.geometry())
engine.prepareGeometry() engine.prepareGeometry()
input_features = [f for f in vector.features(sourceLayer, QgsFeatureRequest().setFilterRect(combined_clip_geom.boundingBox()))] tested_feature_ids = set()
for i, clip_geom in enumerate(clip_geoms):
input_features = [f for f in vector.features(source_layer, QgsFeatureRequest().setFilterRect(clip_geom.boundingBox()))]
if single_clip_feature:
total = 100.0 / len(input_features) total = 100.0 / len(input_features)
else:
total = 0
for current, in_feat in enumerate(input_features): for current, in_feat in enumerate(input_features):
if not in_feat.geometry(): if not in_feat.geometry():
continue continue
if in_feat.id() in tested_feature_ids:
# don't retest a feature we have already checked
continue
tested_feature_ids.add(in_feat.id())
if not engine.intersects(in_feat.geometry().geometry()): if not engine.intersects(in_feat.geometry().geometry()):
continue continue
@ -113,10 +126,10 @@ class Clip(GeoAlgorithm):
new_geom = in_feat.geometry() new_geom = in_feat.geometry()
try: try:
outFeat = QgsFeature() out_feat = QgsFeature()
outFeat.setGeometry(new_geom) out_feat.setGeometry(new_geom)
outFeat.setAttributes(in_feat.attributes()) out_feat.setAttributes(in_feat.attributes())
writer.addFeature(outFeat) writer.addFeature(out_feat)
except: except:
ProcessingLog.addToLog(ProcessingLog.LOG_ERROR, ProcessingLog.addToLog(ProcessingLog.LOG_ERROR,
self.tr('Feature geometry error: One or more ' self.tr('Feature geometry error: One or more '
@ -124,6 +137,11 @@ class Clip(GeoAlgorithm):
'invalid geometry.')) 'invalid geometry.'))
continue continue
if single_clip_feature:
progress.setPercentage(int(current * total)) progress.setPercentage(int(current * total))
if not single_clip_feature:
# coarse progress report for multiple clip geometries
progress.setPercentage(100.0 * i / len(clip_geoms))
del writer del writer