I am writing a stand-alone application in Python/QGIS that simply creates maps.
I want to load vector/raster layers, set symbology, set extent
At the moment, that is all!
Currently I am just using the simple rendering technique outlined here: http://www.qgis.org/pyqgis-cookbook/composer.html#simple-rendering
I have failed, however, at adapting this code to define a specific extent. I provide the code below.
The only examples that I can find that show how to change extent involve creating a MapCanvas. ...But I am not certain that this is something I want to do considering I am just making very simple maps...and it seems to introduce a whole new set of complications. Surely there is an easy way to define extent via the 'simple rendering' technique?
Becky
from qgis.core import *
from qgis.utils import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtCore import QFileInfo, QSettings
QgsApplication.setPrefixPath('/Applications/QGIS-1.9.app/Contents/MacOS', True)
QgsApplication.initQgis()
province = QgsVectorLayer('/filepath/Province_studyUTM36S.shp' , 'layer', 'ogr')
town = QgsVectorLayer('/filepath/TownPolygons_UTM36S.shp' , 'layer', 'ogr')
road = QgsVectorLayer('/filepath/Roads_UTM36S.shp' , 'layer', 'ogr')
QgsMapLayerRegistry.instance().addMapLayer(province)
QgsMapLayerRegistry.instance().addMapLayer(road)
QgsMapLayerRegistry.instance().addMapLayer(town)
rasterFile = '/filepath/Landsat.tif'
fileInfo = QFileInfo(rasterFile)
baseName = fileInfo.baseName()
rlayer = QgsRasterLayer(rasterFile, baseName)
QgsMapLayerRegistry.instance().addMapLayer(rlayer)
img = QImage(QSize(800,600), QImage.Format_ARGB32_Premultiplied)
color = QColor(255,255,255)
img.fill(color.rgb())
p = QPainter()
p.begin(img)
p.setRenderHint(QPainter.Antialiasing)
render = QgsMapRenderer()
ID = [ rlayer.getLayerID(), town.getLayerID(), road.getLayerID(), province.getLayerID()]
render.setLayerSet(ID)
rect = QgsRectangle(render.fullExtent())
rect.scale(1.1)
render.setExtent(rect)
render.setOutputSize(img.size(), img.logicalDpiX())
render.render(p)
p.end()
img.save("/filepath/first_render.png","png")