QGIS/python/plugins/processing/core/LayerExporter.py
2013-08-20 09:22:03 +02:00

138 lines
6.1 KiB
Python

# -*- coding: utf-8 -*-
"""
***************************************************************************
LayerExporter.py
---------------------
Date : August 2012
Copyright : (C) 2012 by Victor Olaya
Email : volayaf at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************
"""
import os.path
__author__ = 'Victor Olaya'
__date__ = 'August 2012'
__copyright__ = '(C) 2012, Victor Olaya'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'
from processing.core.ProcessingConfig import ProcessingConfig
from processing.core.ProcessingUtils import ProcessingUtils
from qgis.core import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from processing.gdal.GdalUtils import GdalUtils
class LayerExporter():
'''This class provides method to export layers so they can be used by third party applications.
These method are used by the GeoAlgorithm class and allow the developer to use transparently
any layer that is loaded into QGIS, without having to worry about its origin'''
@staticmethod
def exportVectorLayer(layer):
'''Takes a QgsVectorLayer and returns the filename to refer to it, which allows external
apps which support only file-based layers to use it. It performs the necessary export
in case the input layer is not in a standard format suitable for most applications, it is
a remote one or db-based (non-file based) one, or if there is a selection and it should be
used, exporting just the selected features.
Currently, the output is restricted to shapefiles, so anything that is not in a shapefile
will get exported.
It also export to a new file if the original one contains non-ascii characters'''
settings = QSettings()
systemEncoding = settings.value( "/UI/encoding", "System" )
filename = os.path.basename(unicode(layer.source()))
idx = filename.rfind(".")
if idx != -1:
filename = filename[:idx]
filename = str(layer.name())
validChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:"
filename = ''.join(c for c in filename if c in validChars)
if len(filename) == 0:
filename = "layer"
output = ProcessingUtils.getTempFilenameInTempFolder(filename + ".shp")
provider = layer.dataProvider()
useSelection = ProcessingConfig.getSetting(ProcessingConfig.USE_SELECTED)
if useSelection and layer.selectedFeatureCount() != 0:
writer = QgsVectorFileWriter(output, systemEncoding, layer.pendingFields(), provider.geometryType(), layer.crs())
selection = layer.selectedFeatures()
for feat in selection:
writer.addFeature(feat)
del writer
return output
else:
isASCII=True
try:
unicode(layer.source()).decode("ascii")
except UnicodeEncodeError:
isASCII=False
if (not unicode(layer.source()).endswith("shp") or not isASCII):
writer = QgsVectorFileWriter( output, systemEncoding, layer.pendingFields(), provider.geometryType(), layer.crs() )
for feat in layer.getFeatures():
writer.addFeature(feat)
del writer
return output
else:
return unicode(layer.source())
@staticmethod
def exportRasterLayer(layer):
'''Takes a QgsRasterLayer and returns the filename to refer to it, which allows external
apps which support only file-based layers to use it. It performs the necessary export
in case the input layer is not in a standard format suitable for most applications, it is
a remote one or db-based (non-file based) one
Currently, the output is restricted to geotiff, but not all other formats are exported.
Only those formats not supported by GDAL are exported, so it is assumed that the external
app uses GDAL to read the layer'''
#TODO:Do the conversion here
return unicode(layer.source())
@staticmethod
def exportTable( table):
'''Takes a QgsVectorLayer and returns the filename to refer to its attributes table,
which allows external apps which support only file-based layers to use it.
It performs the necessary export in case the input layer is not in a standard format
suitable for most applications, it isa remote one or db-based (non-file based) one
Currently, the output is restricted to dbf.
It also export to a new file if the original one contains non-ascii characters'''
settings = QSettings()
systemEncoding = settings.value( "/UI/encoding", "System" )
output = ProcessingUtils.getTempFilename("dbf")
provider = table.dataProvider()
isASCII=True
try:
unicode(table.source()).decode("ascii")
except UnicodeEncodeError:
isASCII=False
isDbf = unicode(table.source()).endswith("dbf") or unicode(table.source()).endswith("shp")
if (not isDbf or not isASCII):
writer = QgsVectorFileWriter( output, systemEncoding, provider.fields(), QGis.WKBNoGeometry, layer.crs() )
for feat in table.getFeatures():
writer.addFeature(feat)
del writer
return output
else:
filename = unicode(table.source())
if unicode(table.source()).endswith("shp"):
return filename[:-3] + "dbf"
else:
return filename