Matt, I don’t know if this was specific to OSX or of it might be relevant to your issue on Windows, but I had to set another Qt path. See this gist: https://gist.github.com/dmofot/94345126db10660053ccfb0d76a1e32a
DT On Thu, Jan 10, 2019 at 4:44 PM Matt Brauer <jbraue...@gmail.com> wrote: > I am implementing qgis 3.4.3 in a custom application, but when I > instantiate the QgsApplication() class, I receive the error "Could not find > the Qt platform plugin "Windows" in "". > > I've attempted using various installs of qgis 3.x+ including the > standalone installer and OSGeo4W web installer. I currently am sticking > with the OSGeo4W web installer installation. I am using a Python 3.7 > installation separate from what comes with OSGeo4W and attempting to > integrate qgis functionality. > > I have followed the instructions in the following QGIS help doc under the > section: "Using PyQGIS in Custom Applications" > https://docs.qgis.org/2.18/en/docs/pyqgis_developer_cookbook/intro.html#run-python-code-when-qgis-starts > > After attempting to run the script I realized a dll plugin was missing. > After some research, I found its the qwindows.dll that qt uses. The > qwindows.dll is included in the OSGeo4W installation under: > C:\OSGeo4W\apps\Qt5\plugins\platforms > > I changed the QT_PLUGIN_PATH variable on the local command prompt to > include the directory above, but the same error prevailed. I also changed > the QT_DEBUG_PLUGINS variable to 1 which printed out the locations Qt is > looking for plugins. Interestingly, it wasn't looking for plugins in the > path I specified in the QT_PLUGIN_PATH variable. > > Python Code: > > import sys#add qgis python libraries to instance python path in case not > added #at the environment variable %PYTHONPATH% level > sys.path.extend(['C:\\OSGeo4W\\apps\\qgis\\python', > 'C:\\OSGeo4W\\apps\\Python37\\Lib\\site-packages']) > from qgis.core import * > # supply path to qgis install > locationQgsApplication.setPrefixPath('C:\\OSGeo4W\\apps\\qgis', True) > # create a reference to the QgsApplication# setting the second argument to > True enables the GUI, which we need to do# since this is a custom application > qgs = QgsApplication([], True) > # load providers > qgs.initQgis() > # Write your code here to load some layers, use processing algorithms, etc. > # When your script is complete, call exitQgis() to remove the provider and# > layer registries from memory > qgs.exitQgis() > > Batch File Code to Start Cmd Prompt with Proper Variables: > > @echo off > SET OSGEO4W_ROOT=C:\OSGeo4W::Include environment variables set by qgis on > startup > call %OSGEO4W_ROOT%\bin\o4w_env.bat > call %OSGEO4W_ROOT%\bin\qt5_env.bat > call %OSGEO4W_ROOT%\bin\py3_env.bat@echo off > path %PATH%;%OSGEO4W_ROOT%\apps\qgis\bin > path %PATH%;C:\OSGeo4W\apps\Qt5\bin > path %PATH%;C:\OSGeo4W\apps\Python37\Scripts > path %PATH%;C:\OSGeo4W\apps\Python37 > > set PYTHONPATH=%PYTHONPATH%;%OSGEO4W_ROOT%\apps\qgis\python > set PYTHONHOME=%OSGEO4W_ROOT%\apps\Python37 > set > QT_PLUGIN_PATH=%OSGEO4W_ROOT%\apps\Qt5\plugins;%OSGEO4W_ROOT%\apps\qgis\qtplugins > set QT_DEBUG_PLUGINS=1 > > cmd.exe > > I expect to run the python script and receive no errors since I'm pointing > to the directory where the qwindows.dll missing plugin is stored. However, > I am still receiving the missing windows plugin error. > > Here is the actual message with QT_DEBUG_PLUGINS set to 1: > QFactoryLoader::QFactoryLoader() checking directory path > "C:/OSGeo4W/apps/qgis/qtplugins/platforms" ... > QFactoryLoader::QFactoryLoader() checking directory path > "C:/OSGeo4W/apps/Python37/platforms" ... qt.qpa.plugin: Could not find the > Qt platform plugin "windows" in "" This application failed to start because > no Qt platform plugin could be initialized. Reinstalling the application > may fix this problem. > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
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