Text in PDFKit

The basics

PDFKit makes adding text to documents quite simple, and includes many options to customize the display of the output. Adding text to a document is as simple as calling the text method.

doc.text 'Hello world!'

Internally, PDFKit keeps track of the current X and Y position of text as it is added to the document. This way, subsequent calls to the text method will automatically appear as new lines below the previous line. However, you can modify the position of text by passing X and Y coordinates to the text method after the text itself.

doc.text 'Hello world!', 100, 100

If you want to move down or up by lines, just call the moveDown or moveUp method with the number of lines you'd like to move (1 by default).

Line wrapping and justification

PDFKit includes support for line wrapping out of the box! If no options are given, text is automatically wrapped within the page margins and placed in the document flow below any previous text, or at the top of the page. PDFKit automatically inserts new pages as necessary so you don't have to worry about doing that for long pieces of text. PDFKit can also automatically wrap text into multiple columns.

If you pass a specific X and Y position for the text, it will not wrap unless you also pass the width option, setting the width the text should be wrapped to. If you set the height option, the text will be clipped to the number of lines that can fit in that height.

When line wrapping is enabled, you can choose a text justification. There are four options: left (the default), center, right, and justify. They work just as they do in your favorite word processor, but here is an example showing their use in a text box.

lorem = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam in suscipit purus.  Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Vivamus nec hendrerit felis. Morbi aliquam facilisis risus eu lacinia. Sed eu leo in turpis fringilla hendrerit. Ut nec accumsan nisl.'

doc.fontSize 8
doc.text 'This text is left aligned. ' + lorem,
  width: 410
  align: 'left'

doc.moveDown()
doc.text 'This text is centered. ' + lorem,
  width: 410
  align: 'center'

doc.moveDown()
doc.text 'This text is right aligned. ' + lorem, 
  width: 410
  align: 'right'

doc.moveDown()
doc.text 'This text is justified. ' + lorem, 
  width: 410
  align: 'justify'

# draw bounding rectangle
doc.rect(doc.x, 0, 410, doc.y).stroke()

The output of this example, looks like this:

Text styling

PDFKit has many options for controlling the look of text added to PDF documents, which can be passed to the text method. They are enumerated below.

Additionally, the fill and stroke color and opacity methods described in the vector graphics section are applied to text content as well.


Here is an example combining some of the options above, wrapping a piece of text into three columns, in a specified width and height.

lorem = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam in suscipit purus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Vivamus nec hendrerit felis. Morbi aliquam facilisis risus eu lacinia. Sed eu leo in turpis fringilla hendrerit. Ut nec accumsan nisl. Suspendisse rhoncus nisl posuere tortor tempus et dapibus elit porta. Cras leo neque, elementum a rhoncus ut, vestibulum non nibh. Phasellus pretium justo turpis. Etiam vulputate, odio vitae tincidunt ultricies, eros odio dapibus nisi, ut tincidunt lacus arcu eu elit. Aenean velit erat, vehicula eget lacinia ut, dignissim non tellus. Aliquam nec lacus mi, sed vestibulum nunc. Suspendisse potenti. Curabitur vitae sem turpis. Vestibulum sed neque eget dolor dapibus porttitor at sit amet sem. Fusce a turpis lorem. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae;'   

doc.text lorem,
  columns: 3
  columnGap: 15
  height: 100
  width: 465
  align: 'justify'

The output looks like this:

Rich Text

As mentioned above, PDFKit supports a simple form of rich text via the continued option. When set to true, PDFKit will retain the text wrapping state between text calls. This way, when you call text again after changing the text styles, the wrapping will continue right where it left off.

The options given to the first text call are also retained for subsequent calls after a continued one, but of course you can override them. In the following example, the width option from the first text call is retained by the second call.

doc.fillColor 'green'
   .text lorem.slice(0, 500),
     width: 465
     continued: yes
   .fillColor 'red'
   .text lorem.slice(500)

Here is the output:

Fonts

The PDF format defines 14 standard fonts that can be used in PDF documents (4 styles of Helvetica, Courier, and Times, as well as Symbol and Zapf Dingbats), but also allows fonts to be embedded right in the document. PDFKit supports embedding TrueType (.ttf), OpenType (.otf), WOFF, WOFF2, TrueType Collection (.ttc), and Datafork TrueType (.dfont) fonts.

To change the font used to render text, just call the font method. If you are using a standard PDF font, just pass the name to the font method. Otherwise, pass the path to the font file, or a Buffer containing the font data. If the font is a collection font (.ttc and .dfont files), meaning that it contains multiple styles in the same file, you should pass the name of the style to be extracted from the collection.

Here is an example showing how to set the font in each case.

# Set the font size
doc.fontSize(18)

# Using a standard PDF font
doc.font('Times-Roman')
   .text('Hello from Times Roman!')
   .moveDown(0.5)

# Using a TrueType font (.ttf)   
doc.font('fonts/GoodDog.ttf')
   .text('This is Good Dog!')
   .moveDown(0.5)

# Using a collection font (.ttc or .dfont)   
doc.font('fonts/Chalkboard.ttc', 'Chalkboard-Bold')
   .text('This is Chalkboard, not Comic Sans.')

The output of this example looks like this:

Another nice feature of the PDFKit font support, is the ability to register a font file under a name for use later rather than entering the path to the font every time you want to use it.

# Register a font
doc.registerFont('Heading Font', 'fonts/Chalkboard.ttc', 'Chalkboard-Bold')

# Use the font later
doc.font('Heading Font')
   .text('This is a heading.')

That's about all there is too it for text in PDFKit. Let's move on now to images.