13 KiB
title, tags, keywords, audience, last_updated, summary
| title | tags | keywords | audience | last_updated | summary |
|---|---|---|---|---|---|
| Generating PDF | publishing |
{% include linkrefs.html %}
Overview
This process for creating a PDF relies on Prince to transform the HTML content into PDF. Prince costs about $500 per license. That might seem like a lot, but if you're creating a PDF, you're probably working for a company that sells a product, so you likely have access to some resources.
The basic approach is to generate a list of all pages that need to be added to the PDF, and then add leverage Prince to package them up into a PDF.
It may seem like the setup is somewhat cumbersome, but it doesn't take long. Once you set it up, building a pdf is just a matter of running a couple of commands.
Also, creating a PDF this way gives you a lot more control and customization capabilities than with other methods for creating PDFs. If you know CSS, you can entirely customize the output.
Demo
You can see an example of the finished product here:
{% if site.audience == "designers" %} Designers PDF Download {% endif %}
{% if site.audience == "writers" %} Writers PDF Download {% endif %}
1. Set up Prince
Download and install Prince.
You can install a fully functional trial version. The only difference is that the title page will have a small Prince PDF watermark.
2. Create a new configuration file for each of your PDF targets
The PDF configuration file will build on the settings in the regular configuration file but will some additional fields. Here's the configuration file for the config_designers.yml file for this theme:
destination: /Applications/XAMPP/xamppfiles/htdocs/jekyll-documentation-theme/designers
url: "http://127.0.0.1:4002"
baseurl: "/designers/"
port: 4002
print: true
print_title: Jekyll Documentation Theme for Writers
print_subtitle: version 3.0
defaults:
-
scope:
path: ""
type: "pages"
values:
layout: "page_print"
comments: true
search: true
{{note}} Although you're creating a PDF, you must still build a web target before running Prince. Prince will pull from the HTML files and from the file-list for the TOC. Prince won't be able to find files if they simply have relative paths, such as /sample.html. The must have full URLs it can access — hence the url and baseurl. {{end}}
Unlike the other configuration files, the PDF configuration files require a url and baseurl. This is because the Prince utility needs to access the pages in a specific place. While you could probably set up locations via file folders, it's easier just to provide the locations here as url and baseurl.
Also note that the default page layout is page_print. This layout strips out all the sections that shouldn't appear in the print PDF, such as the sidebar and top navigation bar.
Finally, note that there's a print: true toggle in case you want to make some of your content unique to PDF output. For example, you could add conditional logic that checks whether site.print is true or not. If it's true, then include information only for the PDF, and so on.
In the configuration file, customize the values for the print_title and print_subtitle that you want. These will appear on the title page of the PDF.
3. Make sure your sidebar_doc.yml file has a titlepage.html and tocpage.html
There are two template pages in the root directory that are critical to PDFs:
- titlepage.html
- tocpage.html
These pages should appear in your sidebar YML file (in this theme, sidebar_doc.yml):
entries:
- title: Sidebar
subcategories:
- title: Frontmatter
audience: writers, designers
platform: all
product: all
version: all
web: false
items:
- title: Title Page
url: /titlepage.html
audience: writers, designers
platform: all
product: all
version: all
web: false
- title: Table of Contents
url: /tocpage.html
audience: writers, designers
platform: all
product: all
version: all
web: false
Leave these pages here in your sidebar. (The web: false property means they won't appear in your online TOC because the conditional logic of the sidebar.html checks whether web is equal to false or not.)
The code in the tocpage.html is nearly identical to that of the sidebar.html page except that it includes the baseurl for the URLs. This is essential for Prince to create the page numbers correctly with cross references.
There's another file (in the root directory of the theme) that is critical to the PDF generation process: prince-file-list.txt. This file simply iterates through the items in your sidebar and creates a list of links. Prince will consume the list of links from this file and create a running PDF that contains all of the pages listed, with appropriate cross references and styling for them all.
4. Customize your headers and footers
Open up the css/printstyles.css file and customize what you want for the headers and footers. At the very least, customize the email address that appears in the bottom left. {% if site.audience == "designers" %}e Exactly how the print styling works here is pretty cool. You don't need to understand the rest of the content in this section unless you want to customize your PDFs to look different from what I've configured.
This style creates a page reference for a link:
a[href]::after {
content: " (page " target-counter(attr(href), page) ")"
}
You don't want cross references for any link, so this style specifies that the content after should be blank:
a[href*="mailto"]::after, a[data-toggle="tooltip"]::after, a[href].noCrossRef::after {
content: "";
}
If you have a link to a file download, for example, add noCrossRef as a class to avoid having it say "page 0" in the cross reference.
This style specifies that after links to web resources, the URL should be inserted instead of the page number:
a[href^="http:"]::after, a[href^="https:"]::after {
content: " (" attr(href) ")";
}
This style sets your page margins:
@page {
margin: 60pt 90pt 60pt 90pt;
font-family: sans-serif;
font-style:none;
color: gray;
}
To set a specific style property for a particular page, you have to name the page. This allows Prince to identify the page.
First you add frontmatter to the page that specifies the type. For the titlepage.html, here's the frontmatter:
---
type: title
---
For the tocpage, here's the frontmatter:
---
type: frontmatter
---
For the index.html page, we have this type tag (among others):
---
type: first_page
---
The default_print.html layout will change the class of the body element based on the type value in the page's frontmatter:
<body class="{% if page.type == "title"%}title{% elsif page.type == "frontmatter" %}frontmatter{% elsif page.type == "first_page" %}first_page{% endif %} print">
Now in the css/printstyles.css file, you can assign a page name based on a specific class:
body.title { page: title }
This means that for content inside of body class="title", we can style this page in our stylesheet using @page title.
Here's how that title page is styled:
@page title {
@top-left {
content: " ";
}
@top-right {
content: " "
}
@bottom-right {
content: " ";
}
@bottom-left {
content: " ";
}
}
As you can see, we don't have any header or footer content, because it's the title page.
For the tocpage.html, which has the type: frontmatter, this is specified in the stylesheet:
body.frontmatter { page: frontmatter }
body.frontmatter {counter-reset: page 1}
@page frontmatter {
@top-left {
content: prince-script(guideName);
}
@top-right {
content: prince-script(datestamp);
}
@bottom-right {
content: counter(page, lower-roman);
}
@bottom-left {
content: "youremail@domain.com"; }
}
We reset the page count to 1 so that the title page doesn't start the count. Then we also add some header and footer info. The page numbers start counting in lower-roman numerals.
Finally, for the first page, we restart the counting to 1 again and this time use regular numbers.
body.first_page {counter-reset: page 1}
h1 { string-set: doctitle content() }
@page {
@top-left {
content: string(doctitle);
font-size: 11px;
font-style: italic;
}
@top-right {
content: prince-script(datestamp);
font-size: 11px;
}
@bottom-right {
content: "Page " counter(page);
font-size: 11px;
}
@bottom-left {
content: prince-script(guideName);
font-size: 11px;
}
}
You'll see some other items in there such as prince-script. This means we're using JavaScript to run some functions to dynamically generate that content. These JavaScript functions are located in the _includes/head_print.html:
<script>
Prince.addScriptFunc("datestamp", function() {
return "PDF last generated: {{ site.time | date: '%B %d, %Y' }}";
});
</script>
<script>
Prince.addScriptFunc("guideName", function() {
return "{{site.print_title}} User Guide";
});
</script>
There are a couple of Prince functions that are default functions from Prince. This gets the heading title of the page:
content: string(doctitle);
This gets the current page:
content: "Page " counter(page);
Because the theme uses JavaScript in the CSS, you have to add the --javascript tag in the Prince command (detailed later on this page).
{% endif %}
5. Customize the doc_multiserve_pdf.sh script
Open the doc_multiserve_pdf.sh file in the root directory and customize it for your specific configuration files.
echo 'Killing all Jekyll instances'
kill -9 $(ps aux | grep '[j]ekyll' | awk '{print $2}')
clear
# serve all di print deliverables
# Writers
echo "Serving Writers PDF"
jekyll serve --detach --config configs/config_writers.yml,configs/config_writers_pdf.yml
# Designers
echo "Serving Designers PDF"
jekyll serve --detach --config configs/config_designers.yml,configs/config_designers_pdf.yml
Note that the first part kills all Jekyll instances. This way you won't try to server Jekyll at a port that is already occupied.
6. Configure the Prince scripts
Open up doc_multibuild_pdf.sh and look at the Prince commands:
echo "Building the Writers PDF..."
prince --javascript --input-list=/Applications/XAMPP/xamppfiles/htdocs/documentation-theme-jekyll/writers-pdf/prince-file-list.txt -o /Users/tjohnson/projects/documentation-theme-jekyll/files/doc/documentation_theme_jekyll_writers_pdf.pdf;
This script issues a command to the Prince utility. JavaScript is enabled (--javascript), and we tell it exactly where to find the list of files (--input-list) — just point to the prince-file-list.txt file. Then we tell it what to output and where (-o).
Make sure that the path to the prince-file-list.txt is correct. For the output directory, I like to output the PDF file into my project's source. Then when I build the web output, the PDF is included.
7. Add a download button for the PDF
You can add a download button using some Bootstrap button code:
<a target="_blank" class="noCrossRef" href="doc_designers_pdf.pdf"><button type="button" class="btn btn-default" aria-label="Left Align"><span class="glyphicon glyphicon-download-alt" aria-hidden="true"></span> Designers PDF Download</button></a>
8. Run the scripts
To generate the PDF, you just run several scripts that have the commands packaged up:
- First run doc_multiserve_pdf.sh to serve up the PDF sites. The commands will detach the site from the preview server so that you can serve up multiple Jekyll sites in the same command terminal.
- Then run doc_multibuild_pdf.sh to build the PDF files.
- There are commands to kill all Jekyll preview servers before this runs.
{{note}} If you don't like the style of the PDFs, just adjust the styles in the printstyles.css file.{{end}}
JavaScript conflicts
I've noticed that when I have JavaScript in my pages, sometimes Prince doesn't like this, as it tries to process the JavaScript. It's better to conditionalize out any JavaScript from your PDF output before building your PDFs. If Prince encounters JavaScript on a page, it will give you this error:
prince: http://127.0.0.1:4002/designers/doc_shuffle.html:2: error: TypeError: value is not an object
However, the PDF will still build.