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

[Matthias Kuhn]

http://www.qgis.org/api/classQgsFeatureRequest.html#ac7c734b9cab6939a706ea53040afe6b3

that might help

On January 12, 2017 5:20:07 PM GMT+01:00, Tom Chadwin <tom.chadwin at nnpa.org.uk> wrote:
>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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