Update ci.yml, Dockerfile, install instructions

.github/workflows/ci.yml

@@ -20,7 +20,6 @@ env:
   COVERALLS_PARALLEL: true
   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
-
 jobs:
   main:
     runs-on: ubuntu-20.04
@@ -61,10 +60,10 @@ jobs:
             python-version: 3.8
             omp: n
             mpi: y
-    name: 'Python ${{ matrix.python-version }} (omp=${{ matrix.omp }},
+    name: "Python ${{ matrix.python-version }} (omp=${{ matrix.omp }},
       mpi=${{ matrix.mpi }}, dagmc=${{ matrix.dagmc }},
       libmesh=${{ matrix.libmesh }}, event=${{ matrix.event }}
-      vectfit=${{ matrix.vectfit }})'
+      vectfit=${{ matrix.vectfit }})"
 
     env:
       MPI: ${{ matrix.mpi }}
@@ -78,24 +77,23 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      -
-        name: Set up Python ${{ matrix.python-version }}
+      - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python-version }}
-      -
-        name: Environment Variables
+
+      - name: Environment Variables
         run: |
           echo "DAGMC_ROOT=$HOME/DAGMC"
           echo "OPENMC_CROSS_SECTIONS=$HOME/nndc_hdf5/cross_sections.xml" >> $GITHUB_ENV
           echo "OPENMC_ENDF_DATA=$HOME/endf-b-vii.1" >> $GITHUB_ENV
 
-      -
-        name: Apt dependencies
+      - name: Apt dependencies
         shell: bash
         run: |
           sudo apt -y update
-          sudo apt install -y libmpich-dev \
+          sudo apt install -y libpng-dev \
+                              libmpich-dev \
                               libnetcdf-dev \
                               libpnetcdf-dev \
                               libhdf5-serial-dev \
@@ -105,23 +103,21 @@ jobs:
           sudo update-alternatives --set mpirun /usr/bin/mpirun.mpich
           sudo update-alternatives --set mpi-x86_64-linux-gnu /usr/include/x86_64-linux-gnu/mpich
 
-      -
-        name: install
+      - name: install
         shell: bash
         run: |
           echo "$HOME/NJOY2016/build" >> $GITHUB_PATH
           $GITHUB_WORKSPACE/tools/ci/gha-install.sh
-      -
-        name: before
+
+      - name: before
         shell: bash
         run: $GITHUB_WORKSPACE/tools/ci/gha-before-script.sh
-      -
-        name: test
+
+      - name: test
         shell: bash
         run: $GITHUB_WORKSPACE/tools/ci/gha-script.sh
 
-      -
-        name: after_success
+      - name: after_success
         shell: bash
         run: |
           cpp-coveralls -i src -i include --exclude-pattern "/usr/*" --dump cpp_cov.json
@@ -131,8 +127,8 @@ jobs:
     needs: main
     runs-on: ubuntu-latest
     steps:
-    - name: Coveralls Finished
-      uses: coverallsapp/github-action@master
-      with:
-        github-token: ${{ secrets.github_token }}
-        parallel-finished: true
+      - name: Coveralls Finished
+        uses: coverallsapp/github-action@master
+        with:
+          github-token: ${{ secrets.github_token }}
+          parallel-finished: true

Dockerfile

@@ -29,7 +29,7 @@ RUN apt-get update -y && \
     apt-get install -y \
         python3-pip python-is-python3 wget git gfortran g++ cmake \
         mpich libmpich-dev libhdf5-serial-dev libhdf5-mpich-dev \
-        imagemagick && \
+        libpng-dev && \
     apt-get autoremove
 
 # Update system-provided pip

docs/source/quickinstall.rst

@@ -100,7 +100,7 @@ directly from the package manager:
 
 .. code-block:: sh
 
-    sudo apt install g++ cmake libhdf5-dev
+    sudo apt install g++ cmake libhdf5-dev libpng-dev
 
 After the packages have been installed, follow the instructions below for
 building and installing OpenMC from source.

docs/source/usersguide/install.rst

@@ -219,6 +219,15 @@ Prerequisites
 .. admonition:: Optional
    :class: note
 
+    * libpng_ official reference PNG library
+
+      OpenMC's built-in plotting capabilities use the libpng library to produce
+      compressed PNG files. In the absence of this library, OpenMC will fallback
+      to writing PPM files, which are uncompressed and only supported by select
+      image viewers. libpng can be installed on Ddebian derivates with::
+
+          sudo apt install libpng-dev
+
     * An MPI implementation for distributed-memory parallel runs
 
       To compile with support for parallel runs on a distributed-memory

docs/source/usersguide/plots.rst

@@ -80,26 +80,13 @@ assign them to a :class:`openmc.Plots` collection and export it to XML::
   plots += [plot2, plot3]
   plots.export_to_xml()
 
-To actually generate the plots, run the :func:`openmc.plot_geometry`
-function. Alternatively, run the :ref:`scripts_openmc` executable with the
-``--plot`` command-line flag. When that has finished, you will have one or more
-``.ppm`` files, i.e., `portable pixmap
-<http://netpbm.sourceforge.net/doc/ppm.html>`_ files. On some Linux
-distributions, these ``.ppm`` files are natively viewable. If you find that
-you're unable to open them on your system (or you don't like the fact that they
-are not compressed), you may want to consider converting them to another format.
-This is easily accomplished with the ``convert`` command available on most Linux
-distributions as part of the `ImageMagick
-<http://www.imagemagick.org/script/convert.php>`_ package. (On Debian
-derivatives: ``sudo apt install imagemagick``).  Images are then converted like:
-
-.. code-block:: sh
-
-    convert myplot.ppm myplot.png
-
-Alternatively, if you're working within a `Jupyter <https://jupyter.org/>`_
-Notebook or QtConsole, you can use the :func:`openmc.plot_inline` to run OpenMC
-in plotting mode and display the resulting plot within the notebook.
+To actually generate the plots, run the :func:`openmc.plot_geometry` function.
+Alternatively, run the :ref:`scripts_openmc` executable with the ``--plot``
+command-line flag. When that has finished, you will have one or more ``.png``
+files. Alternatively, if you're working within a `Jupyter
+<https://jupyter.org/>`_ Notebook or QtConsole, you can use the
+:func:`openmc.plot_inline` to run OpenMC in plotting mode and display the
+resulting plot within the notebook.
 
 .. _usersguide_voxel: