Hi,
Am completely stuck with a QGIS project in Python and tried everything but
nothing seems to work. The python script does work as such BUT the canvas never
shows the map and therefor the exported maps are empty….
What I’m trying to achieve:
* Create a Python script that iterates through a series of ca. 2500
polygons based on attribute value, zoom to layer extend and save the canvas for
each attribute as an image file.
* I then use the image files in other documents
The issue is that while manually I get the canvas to reload and display the
map, this doesn’t happen when running the python script. Have tried couple of
ways:
1. Don’t load the project each time and just change the filter
2. Add sleep timers to give the canvas time to refresh etc.
3. Tried different QGIS versions (2.2, 2.4 & 2.6 on Win 64x)
But all to no avail…. Hope somebody’s got a great idea how to solve it.
Regards,
Frank
Python code:
# File location & specifications
PROJECTPATH = 'C:/Users/Frank/Documents /Targetting/Kaarten/'
PROJECTFILE = 'C:/Users/Frank/Documents /Targetting/TargettingkaartV26qgs.qgs'
EXTSNAPSHOTS = '.jpg'
EXTSNAPSHOTS2 = '.png'
SUFFIX = '65Plus_v1'
last_id = 1
while last_id < 5:
# Clear map canvas
QgsMapLayerRegistry.instance().removeAllMapLayers()
qgis.utils.iface.mapCanvas().refresh()
# Open QGIS project
QgsProject.instance().setFileName(PROJECTFILE)
QgsProject.instance().read()
qgis.utils.iface.mapCanvas().refresh()
time.sleep(30)
canvas = qgis.utils.iface.mapCanvas()
acl = canvas.layer(0)
qgis.utils.iface.mapCanvas().layer(0).selectAll()
selection = 'RijNo = ' + str(last_id)
acl.setSubsetString( selection )
acl.triggerRepaint
canvas.layer(1).triggerRepaint
time.sleep(5)
qgis.utils.iface.setActiveLayer(acl)
# Zoom in and out to refresh potential issues with OpenLayer
canvas.zoomByFactor(3)
canvas.zoomByFactor(0.5)
qgis.utils.iface.zoomToActiveLayer()
qgis.utils.iface.mapCanvas().refresh()
time.sleep(10)
# Save project
p=QgsProject.instance()
p.setFileName(PROJECTFILE)
p.write()
# Save content of map canvas as image
p = str(last_id) + 'kaart_'
qgis.utils.iface.mapCanvas().saveAsImage(PROJECTPATH+ p + SUFFIX +
EXTSNAPSHOTS)
last_id = last_id +1
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