[Qgis-developer] Create memory layer containing only features visible in current canvas extent

[Tom Chadwin]

I've found this method:

viewportPolygon =
QgsGeometry().fromWkt(iface.mapCanvas().extent().asWktPolygon())
layer = iface.activeLayer()

resultlayer = QgsVectorLayer("Polygon", "result", "memory")
resultlayer.dataProvider().addAttributes(list(layer.dataProvider().fields()))

clippedFeatures = []
for feature in layer.dataProvider().getFeatures():
    clippedGeometry = feature.geometry().intersection(viewportPolygon)


>From http://gis.stackexchange.com/a/74471/36921

However, this loops through all features. I'm concerned that this will
struggle with large layers. Is there a more efficient method?



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