subfont

Documentation

Overview

Package subfont defines a font as a collection of subfonts. One subfont holds the character data for a specific size, style, weight and specific range of unicode codepoints.

Index

• type Data
• type Face
  • func (f *Face) Advance(r rune) int
  • func (f *Face) Glyph(r rune) (img image.Image, origin image.Point, advance int)
  • func (f *Face) Size() (height, ascent int)
• type Loader
• type Subfont

Types

type Data

type Data interface {
	// Advance returns the advance for the i-th glyph.
	Advance(i int) int

	// Glyph returns the data of the i-th glyph. The returned image is valid
	// until the next Glyph call.
	Glyph(i int) (img image.Image, origin image.Point, advance int)
}

Data represents a glyph storage.

type Face

type Face struct {
	Height   int16      // interline spacing (sumarizes all subfonts)
	Ascent   int16      // height above the baseline (sumarizes all subfonts)
	Subfonts []*Subfont // ordered subfonts that make up the face
	Loader   Loader     // used to load missing subfonts
}

Face is a collection of subfonts from one font with the same size, style and weight.

func (*Face) Advance

func (f *Face) Advance(r rune) int

Advance implements font.Face interface.

func (*Face) Glyph

func (f *Face) Glyph(r rune) (img image.Image, origin image.Point, advance int)

Glyph implements font.Face interface.

func (*Face) Size

func (f *Face) Size() (height, ascent int)

Size implements font.Face interface.

type Loader

type Loader interface {
	Load(r rune, current []*Subfont) (containing *Subfont, updated []*Subfont)
}

Loader is the interface that wraps the Load method.

Load loads a subfont containing the given rune. A successful call returns the pointer to the loaded subfont. Load may also add and/or remove any subfonts from the current list and return the updated version.

type Subfont

type Subfont struct {
	First  rune // first character in the subfont
	Last   rune // last character in the subfont
	Offset int  // offset in Data to the first character
	Data   Data // character data
}

Subfont provides Last-First+1 font glyphs for runes form First to Last. The glyphs are stored in Data starting from Offset.