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I'm trying map rendering with stand alone script, so I have small script which works fine in python console provided QGIS, however when I run same code in stand-alone script it executes without error, but output is not produced.

Here is my standalone script:

from qgis.core import *
from qgis.gui import *
from qgis.utils import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtXml import *

QgsApplication.setPrefixPathddd("C:\Program Files (x86)\QGIS Valmiera", True)

QgsApplication.initQgis()

mapinstance = QgsMapLayerRegistry.instance()
mapinstance.removeAllMapLayers()

layer = QgsVectorLayer("F:\scripts\map\wb.shp", "test", "ogr")

if layer.isValid():
    print "shplayer succesfully loaded - adding to mapinstance"
    mapinstance.addMapLayer(layer)
else:
    print "shplayer failed to load!"

print mapinstance.mapLayers()

# create image
img = QImage(QSize(800,600), QImage.Format_ARGB32_Premultiplied)
# set image background color
color = QColor(255,255,255)
img.fill(color.rgb())
# create painter
p = QPainter()
p.begin(img)
p.setRenderHint(QPainter.Antialiasing)
render = QgsMapRenderer()
# set layer set
lst = [ layer.id() ] # add ID of every layer
render.setLayerSet(lst)
# set extent
rect = QgsRectangle(render.fullExtent())
#rect.scale(1.39800703)
rect.scale(1.1)
render.setExtent(rect)
# set output size
render.setOutputSize(img.size(), img.logicalDpiX())
# do the rendering
render.render(p)
p.end()

# save image
img.save('F:\scripts\out.png',"png")    

QgsApplication.exitQgis()
raphael
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roony
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1 Answers1

2

You need to add in a variable for the QgsApplication. Try changing the beginning to this:

QgsApplication.initQgis()
app = QgsApplication([], True)

Adding the app variable should fix your problem.

Rendering and Labeling Shapefile with PyQGIS

How to use map composer in a stand-alone script?

Community
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midfield99
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  • Thanks for your reply. I have added those line to my code, however its giving me error "shape layer failed to load!". I did checked shape file path and its seems to be correct. Plz help. – roony Mar 12 '14 at 12:03
  • Is "test" a valid column attribute for that shapefile? – midfield99 Mar 12 '14 at 14:08
  • And this looks like there are some typos: QgsApplication.setPrefixPathddd You will have trouble http://osgeo-org.1560.x6.nabble.com/vector-layers-loaded-using-pyQGIS-not-isValid-td4104640.htmlloading layers if the prefix path is bad. – midfield99 Mar 12 '14 at 14:15
  • "test" is not attribute of shape file, I think its user defined name as given in PyQGIS developer cookbook. also I have removed typo error of setPrefixPath, still getting same error... – roony Mar 12 '14 at 15:16
  • Change \ to / in your file paths. – midfield99 Mar 12 '14 at 18:14
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    I made changes to path "C:/Program Files/QGIS Valmiera/apps/qgis" . It's working fine.. thanks :) – roony Mar 12 '14 at 19:00