Add guide to putting images in the corpus

source/meta/images-guide.txt

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+:orphan:
+
+=============
+Adding Images
+=============
+
+.. note::
+
+   This guide is advisory, and its suggestions do not necessarily apply
+   to every situation.
+
+Without Giza (Recommended)
+--------------------------
+
+Adding an SVG
+~~~~~~~~~~~~~
+
+Whenever possible, you should publish diagrams in SVG form. This
+provides a crisp image at any screen resolution with a small file
+size.
+
+First install `mut <https://github.com/mongodb/mut>`_,
+`Inkscape <http://inkscape.org/>`_, and
+`svgo <https://github.com/svg/svgo>`_.
+
+Place your SVG in ``source/images/``. If you named your SVG
+``foo.svg``, then run the following:
+
+.. code-block:: sh
+
+   mut-images foo.svg
+
+This will generate ``foo.bakedsvg.svg``. This *baked* SVG file
+contains no text: to prevent users from needing to download any fonts,
+``mut-images`` transforms all text elements into paths. It then uses
+``svgo`` to minify the resulting SVG file.
+
+Create a ``source/images/foo.rst`` file with contents such as the
+following:
+
+.. code-block:: rst
+
+   .. figure:: /images/foo.bakedsvg.svg
+      :alt: An example image.
+      :figwidth: 500px
+
+Check in and commit all three files.
+
+Adding a PNG
+~~~~~~~~~~~~
+
+Not all images start their life as an SVG. The process is less refined
+for adding these files, but in general keep the resolution under two times
+the display width.
+
+For example, if you want to display an image as 500px wide, the image
+itself should not be wider than 1000px.
+
+.. note::
+
+   The MongoDB Documentation Project does not currently have a best
+   practice for handling very large (>1080p) files or photographic
+   content.
+
+   It may make sense to use
+   `mozjpeg <https://github.com/mozilla/mozjpeg>`_ if you need lossy
+   compression; `imagemagick <http://imagemagick.org/>`_ to resize images;
+   and a `Ninja <http://ninja-build.org/>`_ file to put the pieces
+   together.
+
+The default ``libpng`` encoder does not create optimal PNG files, so
+install `zopflipng <https://github.com/google/zopfli>`_. To compress a
+PNG, use the following template:
+
+.. code-block:: sh
+
+   zopflipng -m <input.png> <output.png>
+
+This may take several minutes, as the ``-m`` option requests a
+brute-force search for optimal compression parameters.
+
+Place the output PNG in ``source/images/``, and create a
+``source/images/foo.rst`` file with contents such as the following:
+
+.. code-block:: rst
+
+   .. figure:: /images/foo.png
+      :alt: An example image.
+      :figwidth: 500px
+
+With Giza
+---------
+
+Some MongoDB documentation projects use Giza's image generation. This
+can be effective when you need images rendered at different sizes
+for different output formats.
+
+It has the following disadvantages:
+
+* Giza only accepts SVGs: you must embed raster files inside of an SVG,
+* Giza invokes inkscape for each input file, and
+* Reliability problems. There was one instance where giza generated
+  some images sans any text.
+
+Giza looks for the path listed in ``system.files.data.files`` within
+``config/build_conf.yaml`` for a manifest containing image metadata.
+
+The image metadata is a YAML list of documents such as the following:
+
+.. code-block:: yaml
+
+   name: opsmanager-large
+   alt: "A highly available deployment uses horizontal scaling of the application database and backup    blockstore database, as well as multiple backup daemons."
+   output:
+     - type: print
+       tag: 'print'
+       dpi: 300
+       width: 2100
+     - type: web
+       dpi: 72
+       width: 700
+
+From this example, Giza will generate the following files in the build
+directory:
+
+* ``/source/images/opsmanager-large.rst``
+* ``/source/images/opsmanager-large.png``
+* ``/source/images/opsmanager-large-print.png``