def create_memory_layer(layer, new_name=''):
"""Return a memory copy of a layer
:param layer: QgsVectorLayer that shall be copied to memory.
:type layer: QgsVectorLayer
:param new_name: The name of the copied layer.
:type new_name: str
:returns: An in-memory copy of a layer.
:rtype: QgsMapLayer
"""
if new_name is '':
new_name = layer.name() + ' TMP'
if layer.type() == QgsMapLayer.VectorLayer:
vector_type = layer.geometryType()
if vector_type == QGis.Point:
type_string = 'Point'
elif vector_type == QGis.Line:
type_string = 'Line'
elif vector_type == QGis.Polygon:
type_string = 'Polygon'
else:
raise MemoryLayerCreationError('Layer is whether Point nor '
'Line nor Polygon')
else:
raise MemoryLayerCreationError('Layer is not a VectorLayer')
crs = layer.crs().authid().lower()
uuid_string = str(uuid.uuid4())
uri = '%s?crs=%s&index=yes&uuid=%s' % (type_string, crs, uuid_string)
memory_layer = QgsVectorLayer(uri, new_name, 'memory')
memory_provider = memory_layer.dataProvider()
provider = layer.dataProvider()
vector_fields = provider.fields()
fields = []
for i in vector_fields:
fields.append(i)
memory_provider.addAttributes(fields)
for ft in provider.getFeatures():
memory_provider.addFeatures([ft])
return memory_layer
def create_memory_layer(layer_name,
geometry,
coordinate_reference_system=None,
fields=None):
"""Create a vector memory layer.
:param layer_name: The name of the layer.
:type layer_name: str
:param geometry: The geometry of the layer.
:rtype geometry: QgsWkbTypes (note:
from C++ QgsWkbTypes::GeometryType enum)
:param coordinate_reference_system: The CRS of the memory layer.
:type coordinate_reference_system: QgsCoordinateReferenceSystem
:param fields: Fields of the vector layer. Default to None.
:type fields: QgsFields
:return: The memory layer.
:rtype: QgsVectorLayer
"""
if geometry == QgsWkbTypes.PointGeometry:
wkb_type = QgsWkbTypes.MultiPoint
elif geometry == QgsWkbTypes.LineGeometry:
wkb_type = QgsWkbTypes.MultiLineString
elif geometry == QgsWkbTypes.PolygonGeometry:
wkb_type = QgsWkbTypes.MultiPolygon
elif geometry == QgsWkbTypes.NullGeometry:
wkb_type = QgsWkbTypes.NoGeometry
else:
raise MemoryLayerCreationError(
'Layer geometry must be one of: Point, Line, '
'Polygon or Null, I got %s' % geometry)
if coordinate_reference_system is None:
coordinate_reference_system = QgsCoordinateReferenceSystem()
if fields is None:
fields = QgsFields()
elif not isinstance(fields, QgsFields):
# fields is a list
new_fields = QgsFields()
for f in fields:
new_fields.append(f)
fields = new_fields
memory_layer = QgsMemoryProviderUtils. \
createMemoryLayer(name=layer_name,
fields=fields,
geometryType=wkb_type,
crs=coordinate_reference_system)
memory_layer.dataProvider().createSpatialIndex()
memory_layer.keywords = {'inasafe_fields': {}}
return memory_layer
def create_memory_layer(layer_name,
geometry,
coordinate_reference_system=None,
fields=None):
"""Create a vector memory layer.
:param layer_name: The name of the layer.
:type layer_name: str
:param geometry: The geometry of the layer.
:rtype geometry: QGis.WkbType
:param coordinate_reference_system: The CRS of the memory layer.
:type coordinate_reference_system: QgsCoordinateReferenceSystem
:param fields: Fields of the vector layer. Default to None.
:type fields: QgsFields
:return: The memory layer.
:rtype: QgsVectorLayer
"""
if geometry == QGis.Point:
type_string = 'MultiPoint'
elif geometry == QGis.Line:
type_string = 'MultiLineString'
elif geometry == QGis.Polygon:
type_string = 'MultiPolygon'
elif geometry == QGis.NoGeometry:
type_string = 'none'
else:
raise MemoryLayerCreationError(
'Layer is whether Point nor Line nor Polygon, I got %s' % geometry)
uri = '%s?index=yes&uuid=%s' % (type_string, str(uuid4()))
if coordinate_reference_system:
crs = coordinate_reference_system.authid().lower()
uri += '&crs=%s' % crs
memory_layer = QgsVectorLayer(uri, layer_name, 'memory')
memory_layer.keywords = {'inasafe_fields': {}}
if fields:
data_provider = memory_layer.dataProvider()
data_provider.addAttributes(fields)
memory_layer.updateFields()
return memory_layer