Fonts and Faces

The terms fonts and faces are borrowed from the Harfbuzz library: A face represents a font file like an OpenType font or a TrueType font and a font is a face in a specific size.

In order to put text into the PDF, you first load a face:

func (d *PDFDocument) LoadFace(filename string, index int) (*pdf.Face, error)

and from that face, you can create a font:

func NewFont(face *pdf.Face, size bag.ScaledPoint) *Font

Text shaping

Turning text into a series of glyph ids (code points) is the process of shaping. The harfbuzz.Feature slice is important. For example the text fish can be turned into different glyph ids depending on the liga feature.

func (f *Font) Shape(text string, features []harfbuzz.Feature) []Atom

The Shape() method returns a slice of Atoms which is the following type:

type Atom struct {
	Advance    bag.ScaledPoint
	Height     bag.ScaledPoint
	Depth      bag.ScaledPoint
	IsSpace    bool
	Components string
	Codepoint  int
	Hyphenate  bool
	Kernafter  bag.ScaledPoint
}