QGIS/python/plugins/sextante/core/LayerExporter.py

68 lines
3.2 KiB
Python

from sextante.core.SextanteConfig import SextanteConfig
from sextante.core.SextanteUtils import SextanteUtils
from qgis.core import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from sextante.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'''
settings = QSettings()
systemEncoding = settings.value( "/UI/encoding", "System" ).toString()
output = SextanteUtils.getTempFilename("shp")
provider = layer.dataProvider()
allAttrs = provider.attributeIndexes()
provider.select( allAttrs )
useSelection = SextanteConfig.getSetting(SextanteConfig.USE_SELECTED)
if useSelection and layer.selectedFeatureCount() != 0:
writer = QgsVectorFileWriter( output, systemEncoding,provider.fields(), provider.geometryType(), provider.crs() )
selection = layer.selectedFeatures()
for feat in selection:
writer.addFeature(feat)
del writer
return output
else:
if (not unicode(layer.source()).endswith("shp")):
writer = QgsVectorFileWriter( output, systemEncoding,provider.fields(), provider.geometryType(), provider.crs() )
feat = QgsFeature()
while provider.nextFeature(feat):
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'''
exts = GdalUtils.getSupportedRasterExtensions()
for ext in exts:
if (unicode(layer.source()).endswith(ext)):
return unicode(layer.source())
#TODO:Do the conversion here
return unicode(layer.source())