Photos: A Plugin for Pelican

Use Photos to add a photo or a gallery of photos to an article, or to include photos in the body text. Photos are kept separately, as an organized library of high resolution photos, and resized as needed.

Installation

This plugin can be installed via:

python -m pip install pelican-photos

The plug-in requires Pillow: the Python Imaging Library and optionally Piexif, whose installation are outside the scope of this document.

Usage

The plug-in resizes the referred photos, and generates thumbnails for galleries and associated photos, based on the following configuration and default values:

PHOTO_LIBRARY = "~/Pictures" : Absolute path to the folder where the original photos are kept, organized in sub-folders.

PHOTO_GALLERY = (1024, 768, 80) : For photos in galleries, maximum width and height, plus JPEG quality as a percentage. This would typically be the size of the photo displayed when the reader clicks a thumbnail.

PHOTO_ARTICLE = (760, 506, 80) : For photos associated with articles, maximum width, height, and quality. The maximum size would typically depend on the needs of the theme. 760px is suitable for the theme notmyidea.

PHOTO_THUMB = (192, 144, 60) : For thumbnails, maximum width, height, and quality.

PHOTO_SQUARE_THUMB = False : Crops thumbnails to make them square.

PHOTO_RESIZE_JOBS = 5 : Number of parallel resize jobs to be run. Defaults to 1.

• -1 = Do not use the Python multiprocessing module and enable additional debugging
• 0 = Try to detect cpu count and start CPU_COUNT + 1 processes
• 1 = Use 1 process
• 2 = Use 2 processes
• 3 = Use 3 processes
• ...

PHOTO_WATERMARK = True : Adds a watermark to all photos in articles and pages. Defaults to using your site name.

PHOTO_WATERMARK_TEXT' = SITENAME : Allow the user to change the watermark text or remove it completely. By default it uses SourceCodePro-Bold as the font.

PHOTO_WATERMARK_IMG = '' : Allows the user to add an image in addition to or as the only watermark. Set the variable to the location.

The following features require the piexif library PHOTO_EXIF_KEEP = True : Keeps the exif of the input photo.

PHOTO_EXIF_REMOVE_GPS = True : Removes any GPS information from the files exif data.

PHOTO_EXIF_COPYRIGHT = 'COPYRIGHT' : Attaches an author and a license to the file. Choices include: - COPYRIGHT: Copyright - CC0: Public Domain - CC-BY-NC-ND: Creative Commons Attribution-NonCommercial-NoDerivatives - CC-BY-NC-SA: Creative Commons Attribution-NonCommercial-ShareAlike - CC-BY: Creative Commons Attribution - CC-BY-SA: Creative Commons Attribution-ShareAlike - CC-BY-NC: Creative Commons Attribution-NonCommercial - CC-BY-ND: Creative Commons Attribution-NoDerivatives

PHOTO_EXIF_COPYRIGHT_AUTHOR = 'Your Name Here' : Adds an author name to the photo's exif and copyright statement. Defaults to AUTHOR value from the pelicanconf.py

PHOTO_INLINE_GALLERY_ENABLED : Enable inline gallery processing. (Default: False)

PHOTO_INLINE_GALLERY_PATTERN : The pattern to look for. The gallery_name is used to find the right gallery.

Defaults:

r"gallery::(?P<gallery_name>[/{}\w_-]+)"

PHOTO_INLINE_GALLERY_TEMPLATE : Template to render the inline gallery.

Default: "inline_gallery"

PHOTO_DEFAULT_IMAGE_OPTIONS : Default keyword options to pass to the PIL.Image.save() function. You can find all available options in the Pillow: Image file formats section.

Defaults:

{
	"jpeg": {
		"optimize": True
	}
}

PHOTO_RESULT_IMAGE_AVERAGE_COLOR = False : Calculate the average color for an result image. This can be used to provide a default background color while using lazy loading.

PHOTO_PROFILING_ENABLED = False : Enable profiling of function calls and measure the time. You have to run pelican in debug mode to see the results.

The plug-in automatically resizes the photos and publishes them to the following output folder:

./output/photos

WARNING: The plug-in can take hours to resize 40,000 photos, therefore, photos and thumbnails are only generated once. Clean the output folders to regenerate the resized photos again.

How to use

Maintain an organized library of high resolution photos somewhere on disk, using folders to group related images. The default path ~/Pictures is convenient for Mac OS X users.

• To create a gallery of photos, add the metadata field gallery: {photo}folder to an article. To simplify the transition from the plug-in Gallery, the syntax gallery: {filename}folder is also accepted.
• You can now have multiple galleries. The galleries need to be seperated by a comma in the metadata field. The syntax is gallery: {photo}folder, {photo}folder2. You can also add titles to your galleries. The syntax is: {photo}folder, {photo}folder2{This is a title}. Using the following example the first gallery would have the title of the folder location and the second would have the title This is a tile.
• To use an image in the body of the text, just use the syntax {photo}folder/image.jpg instead of the usual {filename}/images/image.jpg.
• To use an image in the body of the text, which can be used with Lightbox just use the syntax {lightbox}folder/image.jpg. For use with other implementations, the gallery and caption attribute names can be set with PHOTO_LIGHTBOX_GALLERY_ATTR and PHOTO_LIGHTBOX_CAPTION_ATTR.
• To associate an image with an article, add the metadata field image: {photo}folder/image.jpg to an article. Use associated images to improve navigation. For compatibility, the syntax image: {filename}/images/image.jpg is also accepted.

Exif, Captions, and Blacklists

Folders of photos may optionally have three text files, where each line describes one photo. You can use the # to comment out a line. Generating these optional files is left as an exercise for the reader (but consider using Phil Harvey's exiftool). See below for one method of extracting exif data.

exif.txt : Associates compact technical information with photos, typically the camera settings. For example:

best.jpg: Canon EOS 5D Mark II - 20mm f/8 1/250s ISO 100
night.jpg: Canon EOS 5D Mark II - 47mm f/8 5s ISO 100
# new.jpg: Canon EOS 5D Mark II - 47mm f/8 5s ISO 100

captions.txt : Associates comments with photos. For example:

best.jpg: My best photo ever! How lucky of me!
night.jpg: Twilight over the dam.
# new.jpg: My new photo blog entry is not quite ready.

blacklist.txt : Skips photos the user does not want to include. For example:

this-file-will-be-skipped.jpg
this-one-will-be-skipped-too.jpg
# but-this-file-will-NOT-be-skipped.jpg
this-one-will-be-also-skipped.jpg

Here is an example Markdown article that shows the four use cases:

title: My Article
gallery: {photo}favorite
image: {photo}favorite/best.jpg

Here are my best photos, taken with my favorite camera:
![]({photo}mybag/camera.jpg).
![]({lightbox}mybag/flash.jpg).

The default behavior of the Photos plugin removes the exif information from the file. If you would like to keep the exif information, you can install the piexif library for python and add the following settings to keep some or all of the exif information. This feature is not a replacement for the exif.txt feature but in addition to that feature. This feature currently only works with jpeg input files.

How to change the Jinja templates

The plugin provides the following variables to your templates:

article.photo_image : For articles with an associated photo, a tuple with the following information:

• The filename of the original photo.
• The output path to the generated photo.
• The output path to the generated thumbnail.

For example, modify the template article.html as shown below to display the associated image before the article content:

<div class="entry-content">
	{% if article.photo_image %}<img src="{{ SITEURL }}/{{ article.photo_image[1] }}" />{% endif %}
	{% include 'article_infos.html' %}
	{{ article.content }}
</div><!-- /.entry-content -->

article.photo_gallery : For articles with a gallery, a list of the photos in the gallery. Each item in the list is a tuple with five elements:

• The title of the gallery
• The filename of the original photo.
• The output path to the generated photo.
• The output path to the generated thumbnail.
• The EXIF information of the photo, as read from the file exif.txt.
• The caption of the photo, as read from captions.txt.

For example, add the following to the template article.html to add the gallery as the end of the article:

{% if article.photo_gallery %}
<div class="gallery">
		{% for title, gallery in article.photo_gallery %}
			<h1>{{ title }}</h1>
				{% for name, photo, thumb, exif, caption in gallery %}
						<a href="{{ SITEURL }}/{{ photo }}" title="{{ name }}" exif="{{ exif }}" caption="{{ caption }}"><img src="{{ SITEURL }}/{{ thumb }}"></a>
				{% endfor %}
		{% endfor %}
</div>
{% endif %}

For example, add the following to the template index.html, inside the entry-content, to display the thumbnail with a link to the article:

{% if article.photo_image %}<a href="{{ SITEURL }}/{{ article.url }}"><img src="{{ SITEURL }}/{{ article.photo_image[2] }}"
	style="display: inline; float: right; margin: 2px 0 2ex 4ex;" /></a>
{% endif %}

How to make the gallery lightbox

There are several JavaScript libraries that display a list of images as a lightbox. The example below uses Magnific Popup, which allows the more complex initialization needed to display both the filename, the compact technical information, and the caption. The solution would be simpler if photos did not show any extra information.

Copy the files magnific-popup.css and magnific-popup.js to the root of your Pelican template.

Add the following to the template base.html, inside the HTML head tags:

{% if (article and article.photo_gallery) or (articles_page and articles_page.object_list[0].photo_gallery) %}
	<link rel="stylesheet" href="{{ SITEURL }}/{{ THEME_STATIC_DIR }}/magnific-popup.css">
{% endif %}

Add the following to the template base.html, before the closing HTML </body> tag:

{% if (article and article.photo_gallery) or (articles_page and articles_page.object_list[0].photo_gallery) %}
<!-- jQuery 1.7.2+ or Zepto.js 1.0+ -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>

<!-- Magnific Popup core JS file -->
<script src="{{ SITEURL }}/{{ THEME_STATIC_DIR }}/magnific-popup.js"></script>
<script>
$('.gallery').magnificPopup({
	delegate: 'a',
	type: 'image',
	gallery: {
		enabled: true,
		navigateByImgClick: true,
		preload: [1,2]
	},
	image: {
		titleSrc: function(item) {
			if (item.el.attr('caption') && item.el.attr('exif')) {
				return (item.el.attr('caption').replace(/\\n/g, '<br />') +
					'<small>' + item.el.attr('title') + ' - ' + item.el.attr('exif') + '</small>');
			}
		return item.el.attr('title') + '<small>' + item.el.attr('exif') + '</small>';
	} }
});
</script>
{% endif %}

How to make a Bootstrap Carousel

If you are using bootstrap, the following code is an example of how one could create a carousel.

{% if article.photo_gallery %}
  {% for title, gallery in article.photo_gallery %}
    <h1>{{ title }}</h1>
    <div id="carousel-{{ loop.index }}" class="carousel slide">
      <ol class="carousel-indicators">
          {% for i in range(0, gallery|length) %}
          <li data-target="#carousel-{{ loop.index }}" data-slide-to="{{ i }}" {% if i==0 %} class="active" {% endif %}></li>
          {% endfor %}
      </ol>
      <div class="carousel-inner">
        {% for name, photo, thumb, exif, caption in gallery %}
          {% if loop.first %}
            <div class="item active">
          {% else %}
            <div class="item">
          {% endif %}
          <img src="{{ SITEURL }}/{{ photo }}" exif="{{ exif }}" alt="{{ caption }}">
          <div class="carousel-caption">
              <h5>{{ caption }}</h5>
          </div> <!-- carousel-caption -->
        </div> <!-- item -->
        {% endfor %}
      </div> <!-- carousel-inner -->
      <a class="left carousel-control" href="#carousel-{{ loop.index }}" data-slide="prev">
        <span class="glyphicon glyphicon-chevron-left"></span>
      </a>
      <a class="right carousel-control" href="#carousel-{{ loop.index }}" data-slide="next">
        <span class="glyphicon glyphicon-chevron-right"></span>
      </a>
    </div> <!-- closes carousel-{{ loop.index }} -->
    {% endfor %}
{% endif %}

Exiftool example

You can add the following stanza to your fab file if you are using fabric to generate the appropriate text files for your galleries. You need to set the location of Exiftool control files.

def photo_gallery_gen(location):
    """Create gallery metadata files."""
    local_path = os.getcwd() + 'LOCATION OF YOUR EXIF CONTROL FILES'
    with lcd(location):
        local("exiftool -p {fmt_path}/exif.fmt . > exif.txt".format(
            fmt_path=local_path))
        local("exiftool -p {fmt_path}/captions.fmt . > captions.txt".format(
            fmt_path=local_path))

captions.fmt example file

$FileName: $Description

exif.fmt example file

$FileName: $CreateDate - $Make $Model Stats:(f/$Aperture, ${ShutterSpeed}s, ISO $ISO Flash: $Flash) GPS:($GPSPosition $GPSAltitude)

Known use cases

pxquim.pt uses Photos and the plug-in Sub-parts to publish 600 photo galleries with 40,000 photos. Photos keeps the high-resolution photos separate from the site articles.

pxquim.com uses sub-parts to cover conferences, where it makes sense to have a sub-part for each speaker.

Alternatives

Gallery : Galleries are distinct entities, without the organizational capabilities of articles. Photos must be resized separately, and must be kept with the source of the blog. Gallery was the initial inspiration for Photos.

Image_process : Resize and process images in the article body in a more flexible way (based on the CSS class of the image), but without the ability to create galleries. The source photos must be kept with the source of the blog.

Contributing

Contributions are welcome and much appreciated. Every little bit helps. You can contribute by improving the documentation, adding missing features, and fixing bugs. You can also help out by reviewing and commenting on existing issues.

To start contributing to this plugin, review the Contributing to Pelican documentation, beginning with the Contributing Code section.

License

This project is licensed under the AGPL-3.0 license.