Last Update: 2020-08-12

Installation¶

Overview¶

If you like to develop an EnMAP-Box application, or more general, a QGIS and Qt application, we recommend to use a state-of-the-art Integrated Development Environment (IDE) like PyCharm. It offers run-time debugging, code completion, spell-checking, syntax highlighting, SCM support, unit-testing and many other helpful things.

1. Have Git installed¶

If not, download and install Git from https://git-scm.com/downloads

Check if git is installed to your local shell, e.g. as:

C:\Windows\System32>git --version
git version 2.26.0.windows.1

2. Clone this repository¶

Clone the EnMAP-Box repository (or a fork) to your local my_repositories folder and update its submodules by:

cd my_repositories
git clone --recurse-submodules git@github.com:EnMAP-Box/enmap-box.git
cd enmap-box
git config --local include.path ../.gitconfig

The last line ensures that pull requests will update submodules as well.

Now you can use git pull to update your local copy of the EnMAP-Box repository:

cd my_repositories/enmap-box
git pull

Tip

Replace the repo uri with that of your EnMAP-Box repo fork, if you like to provide code via pull requests.

3. Setup a QGIS environment¶

This section gives examples how you can setup a QGIS & EnMAP-Box development used by PyCharm on different platforms.

a) OSGeo4W (Windows)¶

1. Install or update packages¶

Install QGIS using the OSGeo4W Network installer https://qgis.org/en/site/forusers/download.html
Install the OSGeo4W environment to a folder of choice (preferably one you have permanent writing access to). In following this is called OSGeo4W.

Start the OSGeo4W Setup.
Go forward to these steps by clicking next. Usually the default settings should be fine
- ‘Advanced Install’
- ‘Install from Internet’
- ‘Root Directory’ (should be your OSGEO4W directory)
- Select Local Package Directory (default)
- Select Your Internet Connect (default Direct Connection)
- Choose A Download Site (default https://download.osgeo.org )
Select Packages to install / update

Package Note

qgis recent official QGIS version

python3-scikit-learn
Press Next to install packages / updates

2. Setup development environment¶

Copy the qgis-env.bat and start_pycharm.bat from https://github.com/EnMAP-Box/enmap-box/tree/main/scripts/OSGeo4W to a local folder, e.g. your windows desktop

Modify the qgis-env.bat config section to fit to your local environment, i.e. set the correct paths to your local OSGeoW installation and PyCharm executable

@echo off

:: ### CONFIG SECTION ###
:: root of local OSGEO4W installation
set OSGEO4W_ROOT=D:\OSGeo4W
:: PyCharm executable, adjust for version updates
set PYCHARM_EXE="C:\Program Files (x86)\JetBrains\PyCharm 2022.1.2\bin\pycharm64.exe"

:: git binaries and git lfs binaries
set BIN_GIT=C:\Program Files\Git\bin
set BIN_LFS=C:\Program Files\Git LFS

Call start_pycharm.bat to open PyCharm within the latest QGIS release. You can modify the start script to start a different QGIS build. E.g.

call "%~dp0\qgis-env.bat" qgis-ltr
start "PYCHARM" /B %PYCHARM_EXE%

will start the QGIS Long Term Release (if installed) instead of the latest QGIS release (qgis).

Possible QGIS versions provided by the OSGeo4W installer are:

Build	Description
qgis	QGIS Desktop (latest release)
qgis-ltr	QGIS Desktop (long term release)
qgis-dev	QGIS nightly build of the development branch
qgis-rel-dev	QGIS nightly build of the latest release branch

b) Linux¶

Install QGI as described in https://qgis.org/en/site/forusers/download.html

c) macOS¶

Install QGIS as described in https://qgis.org/en/site/forusers/download.html

d) Docker¶

tbd.

e) Setup Conda (all platforms)¶

Warning

Installing QGIS via conda is not officially supported by the QGIS core development team. The QGIS versions available in conda can therefore differ from the official QGIS versions.

At this date (2022-01-18) conda is stucked at QGIS 3.18, which the official QGIS is at 3.22

The installation of QGIS within a conda / anaconda environment is (almost) the same on macOS, windows or linux. Using conda it is often much easier to install additional python packages while admin rights are not required.`

Make sure conda is installed on your system.
Create a new conda environment named qgis_stable as specified in conda_environment.yml:

conda env create --name qgis_stable --file https://github.com/EnMAP-Box/enmap-box/raw/develop/conda_environment.yml

Tip

Depending on the components and applications you like to use, it might be required to install more packages. If you cloned the EnMAP-Box repository you can also point to the local conda_environment.yml. Edit the --name or the YAML file itself as you wish. For more information on creating and managing conda environments visit the conda documentation

Activate the new environment
```
conda activate qgis_stable
```
Now you can start `QGIS`_, the Qt Designer and Qt Assistant from your conda shell:
```
qgis
designer
assistant
```
To easily start applications like PyCharm in this environment, which have not been installed by conda, you might define an alias during the activation of the environment.
- Create an activation script and define an alias for PyCharm:
  
  Windows: <your conda installation>/envs/qgis_stable/etc/conda/activate.d/pycharm-activate.bat
  @echo off doskey pycharm="<path to pycharm executable>"
  MacOS: <your conda installation>/envs/qgis_stable/etc.conda/activate.d/pycharm-activate.sh
  alias pycharm='open -a PyCharm\ CE.app'
- For completeness, also create a deactivation script:
  
  Windows: <your conda installation>/envs/qgis_stable/etc/conda/deactivate.d/others-deactivate.bat
  @echo off doskey pycharm=
  MacOS/Linux: <your conda installation>/envs/qgis_stable/etc.conda/deactivate.d/pycharm-deactivate.sh
  alias pycharm=

4. Setup PyCharm¶

Start PyCharm and add my_repositories/enmap-box as new project via File > Open File or Project
If this is not already the case, tell PyCharm where to find your Git-executable. Open File > Settings > Version Control > Git to set Path to Git executable. Press Test to check the used Git version.

Set the Git executable used by PyCharm
Tip

Use where to return the path of a git-executable that is available in your DOS/Linux/macOS shell
```
(qgis_stable) C:\>where git
C:\Users\geo_beja\AppData\Local\Programs\Git\cmd\git.exe
```
Switch to Project: enmap-box > Project Interpreter and select the QGIS python as python interpreter.

Add the qgis_stable python to the list of python interpreters

Select the qgis_stable python as project interpreter

Switch to Project Structure and add the QGIS python folder as additional project content root.

OSGeo4W	`<your OSGeo4W folder>\bin\python`
Linux	`/usr/bin/python3`
macOS	`/Application/QGIS.app/Contents/MacOS/bin/python3`
conda (win)	`<your conda installation>/envs/qgis_stable/Library/python`
conda (linux)	`<your conda installation>/envs/qgis_stable/share/qgis/python`
conda (macOS)	`<your conda installation>/envs/qgis_stable/QGIS.app/Contents/MacOS/../Resources/python`

Right-click on the plugins subfolder and select Sources. This makes QGIS internal plugins like the “processing” plugin available to PyCharm.

Now the PyQGIS API is available to your Python installation.

Tip

The same way allows you to include other directories to your project’s PYTHONPATH, e.g. to make code available from other folder or repositories.

../_images/pycharm_project_content_roots.png

Use qgis_stable/Library/python as additional content root

PyCharm and PyQGIS may need the environmental variable QGIS_PREFIX_PATH. Typical paths are:

QGIS Installation	QGIS_PREFIX_PATH
OSGeo4W	<OSGeo4W>/apps/qgis
Linux
conda (Windows)	<conda installation>\envs\qgis_stable\Library
conda (Linux)	<conda installation>/envs/qgis_stable
conda (macOS)	<conda installation>/envs/qgis_stable/QGIS.app/Contents/Resources

If not already set in the environment from which you started PyCharm, you can set it explicitly. Open Run > Debug … > Edit Configurations and add the QGIS_PREFIX_PATH to the User environmental variables. This way PyCharm runs python files in a environment with QGIS_PREFIX_PATH defined.

Also define the Environment variables for the Python console. Go to File > Settings > Build, Execution, Deployment > Console > Python Console and add QGIS_PREFIX_PATH to the Environment variables.

You may also modify the shell used in your PyCharm terminal to use the QGIS environment. Open Tools > Terminal and set the shell path to, for example:

QGIS Installation	Terminal path
OSGeo4W	`cmd.exe "/K" qgis_env.bat` (see above how to create the `qgis_env.bat`)
conda (Windows)	`cmd.exe "/K" <conda installation>\Scripts\activate.bat qgis_stable`

How to use the conda terminal in PyCharm

Test the Python environment

To check if the QGIS API is available, open a Python Console and import the QgsApplication object.

from qgis.core import QgsApplication
QgsApplication.instance() is None

The output should return True, as we have not initialized any QgsApplication.

Now check if we can use the EnMAP-Box API to start the EnMAP-Box

import enmapbox
enmapbox.run()

This should initialize a new QgsApplication and start the EnMAP-Box. The outputs printed to the python shell should look like:

Application state:
QGIS_PREFIX_PATH env var:               D:\miniconda3\envs\qgis_stable\Library
Prefix:         D:\miniconda3\envs\qgis_stable\Library
Plugin Path:            D:\miniconda3\envs\qgis_stable\Library/plugins
Package Data Path:      D:\miniconda3\envs\qgis_stable\Library/.
Active Theme Name:
Active Theme Path:      D:\miniconda3\envs\qgis_stable\Library/./resources/themes\\icons/
Default Theme Path:     :/images/themes/default/
SVG Search Paths:       D:\miniconda3\envs\qgis_stable\Library/./svg/
        C:\Users\geo_beja\AppData\Local\Temp\QGIS-PythonTestConfigPathp1k7w_s_\profiles\default/svg/
User DB Path:   D:\miniconda3\envs\qgis_stable\Library/./resources/qgis.db
Auth DB Path:   C:\Users\geo_beja\AppData\Local\Temp\QGIS-PythonTestConfigPathp1k7w_s_\profiles\default/qgis-auth.db

If the terminal environment was setup well, you can start the EnMAP-Box from the Terminal window as well by

(qgis_stable) ..\enmap-box>python enmapbox

Other Tools¶

The Qt company provides several tools to that help to create Qt applications and are useful for PyQt and PyQGIS users as well.

Qt Assistant¶

The Qt Assistant allows you to browse fast and offline through Qt help files (*.qch). These files exists for all Qt classes and the QGIS API. They can be generated event with Sphinx, which allows you to provide your own source-code documentation as .qch file as well.

Start the Qt Assistant, e.g. from your PyCharm terminal:
```
(qgis_stable) $>assistant
```
Download the *.qch* files which contain:
- the Qt API documentation files: https://github.com/PierreRaybaut/PyQtdoc
- the QGIS API documentation qgis.qch
Go to Preferences > Add and add the following *.qch files

File Documentation

qgis.qch qgis.core, qgis.gui

qtcore.qch Qt5.QtCore

qtgui.qch Qt5.QtGui

qtwidgets.qch Qt5.QtWidgets

Now you can explore the Qt (Q...) and QGIS (Qgs...) classes

Qt Designer¶

The Qt Designer is a powerful tool to create GUI frontends by drawing, drag and drop. Created GUI form files are saved in a XML file ending with *.ui. These can be called from python to automatically create the entire GUI backend, e.g. windows and buttons defined with the Qt Designer.

You can start the Qt Designer from your PyCharm terminal by:

(qgis_stable) $>designer

Qt Designer showing the metadataeditor.ui for the Metadata editor.

Qt Creator¶

Qt Creator is the one-in-all IDE to develop Qt C++ applications. It includes the functionality covered by Qt Assistant (here called Help) and Qt Designer (here called form designer) and helps to browse C++ code. It is the preferred tool to explore the QGIS C++ source code, for example if you like to better understand what it does behind the QGIS python API.

Qt and the Qt Creator are available at https://www.qt.io/download. Ensure to install the code documentation for the same Qt version used by QGIS.

Qt Creator with opened metadataeditor.ui.

OSGeo4W for Devs¶

If you work on windows and want to test your code based on nightly builds of the upcoming QGIS version, or like to inspect/debug the QGIS C++ API at runtime, you might use the OSGeo4W installer to setup your development environment:

Setup Environment¶

Download the (new) OSGeo4W installer (osgeo4w-setup.exe from https://www.qgis.org/en/site/forusers/download.html )
Install the nightly build branch qgis-dev and related debug symbols qgis-dev-pdb.
Install other required packages, e.g. pip3 etc. Later on. In case of missing packages, search and install via OSGeo4W installer first. If not available there, use the OSGeo4W shell and call pip.

Create a qgis-dev-env.bat to setup your QGIS environment

set OSGEO4W_ROOT=D:\OSGeo4W
set QGISDISTR=qgis-dev
set DIR_GIT=C:\Program Files\Git\cmd
set DIR_LFS=C:\Program Files\Git LFS
:: add GIT and LFS to path

call "%OSGEO4W_ROOT%\bin\o4w_env.bat"
path %OSGEO4W_ROOT%\apps\%QGISDISTR%\bin;%DIR_GIT%;%DIR_LFS%;%PATH%

set QGIS_PREFIX_PATH=%OSGEO4W_ROOT:\=/%/apps/%QGISDISTR%
set GDAL_FILENAME_IS_UTF8=YES
rem Set VSI cache to be used as buffer, see #6448
set VSI_CACHE=TRUE
set VSI_CACHE_SIZE=1000000
set QT_PLUGIN_PATH=%OSGEO4W_ROOT%\apps\%QGISDISTR%\qtplugins;%OSGEO4W_ROOT%\apps\qt5\plugins
set PYTHONPATH=%OSGEO4W_ROOT%\apps\%QGISDISTR%\python;%OSGEO4W_ROOT%\apps\%QGISDISTR%\python\plugins;%PYTHONPATH%

Don’t forget to make git and git-lfs available in this environment.

Create a qgis-dev-pycharm.bat in the same folder as qgis-dev.bat that starts PyCharm

call "%~dp0\QGIS-dev.bat"
set PYCHARM_EXE="C:\Program Files (x86)\JetBrains\PyCharm 2020.3.4\bin\pycharm64.exe"

start "PYCHARM" /B %PYCHARM_EXE%

:: uncomment to start QGIS
:: start "QGIS" /B "%OSGEO4W_ROOT%\bin%QGISDISTR%-bin.exe" %*

Call qgis-dev-pycharm.bat to start PyCharm and set your project settings to:

Project Interpreter: <OSGEO4W>binpython.exe

Using the OSGeo4W python as project interpreter.
Terminal Shell Path: cmd.exe “/K” <your path to>qgis-dev.bat (this is why we created two batch files. qgis-dev.bat setups the environment, but does not start any app)

The qgis-dev.bat will be called when starting the terminal
add <OSGEO4W>appsqgis-devpython and <OSGEO4W>appsqgis-devpythonplugins as source folders

Adding the QGIS python and pythonplugins folder as content roots.

Debug QGIS with Visual Studio¶

Clone the QGIS repo and checkout the latest master
Install Visual Studio and open the QGIS repo
Start a QGIS desktop, e.g. with qgis-dev from the OSGeo4W shell
Attach the Visual Studio debugger to a QGIS desktop instance

Open Debug > Attach to Process (CTRL+ALT+P)
Filter available processes by ‘QGIS’ and, e.g., select qgis-dev-bin.exe
Press the Attach button

References¶

Git -the simple guide (no deep shit) https://rogerdudler.github.io/git-guide/
Qt5 C++ API https://doc.qt.io/qt-5/
QGIS C++ API https://api.qgis.org/api/
QGIS Python https://qgis.org/pyqgis
QGIS Python developer cookbook https://docs.qgis.org/3.4/en/docs/pyqgis_developer_cookbook

File	Documentation
qgis.qch	qgis.core, qgis.gui
qtcore.qch	Qt5.QtCore
qtgui.qch	Qt5.QtGui
qtwidgets.qch	Qt5.QtWidgets