loader

Documentation

Overview

Package opentype provides the low level routines required to read Opentype font files, including collections.

This package is designed to provide an efficient, lazy, reading API.

For the parsing of the various tables, see package [tables]. For an higher level API, see the packages [XXX] TODO:

Index

• Variables
• type Loader
  • func NewLoader(file Resource) (*Loader, error)
  • func NewLoaders(file Resource) ([]*Loader, error)
  • func (pr *Loader) HasTable(table Tag) bool
  • func (pr *Loader) RawTable(tag Tag) ([]byte, error)
• type Resource
• type Tag
  • func MustNewTag(str string) Tag
  • func NewTag(a, b, c, d byte) Tag
  • func (t Tag) String() string

Variables

var (
	// TrueType is the first four bytes of an OpenType file containing a TrueType font
	TrueType = Tag(0x00010000)
	// AppleTrueType is the first four bytes of an OpenType file containing a TrueType font
	// (specifically one designed for Apple products, it's recommended to use TrueType instead)
	AppleTrueType = MustNewTag("true")
	// PostScript1 is the first four bytes of an OpenType file containing a PostScript 1 font
	PostScript1 = MustNewTag("typ1")
	// OpenType is the first four bytes of an OpenType file containing a PostScript Type 2 font
	// as specified by OpenType
	OpenType = MustNewTag("OTTO")
)

Types

type Loader

type Loader struct {

	// Type represents the kind of this font being loaded.
	// It is one of TrueType, TrueTypeApple, PostScript1, OpenType
	Type Tag
	// contains filtered or unexported fields
}

Loader is the low level font reader, providing full control over table loading.

func NewLoader

func NewLoader(file Resource) (*Loader, error)

NewLoader reads the `file` header and returns a new lazy loader. `file` will be used to parse tables, and should not be close.

func NewLoaders

func NewLoaders(file Resource) ([]*Loader, error)

NewLoaders is the same as `NewLoader`, but supports collections.

func (*Loader) HasTable

func (pr *Loader) HasTable(table Tag) bool

HasTable returns true if [table] is present.

func (*Loader) RawTable

func (pr *Loader) RawTable(tag Tag) ([]byte, error)

RawTable returns the binary content of the given table, or an error if not found.

type Resource

type Resource interface {
	Read([]byte) (int, error)
	ReadAt([]byte, int64) (int, error)
	Seek(int64, int) (int64, error)
}

Resource is a combination of io.Reader, io.Seeker and io.ReaderAt. This interface is satisfied by most things that you'd want to parse, for example *os.File, io.SectionReader or *bytes.Reader.

type Tag

type Tag uint32

Tag represents an open-type name. These are technically uint32's, but are usually displayed in ASCII as they are all acronyms. See https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6.html#Overview

func MustNewTag

func MustNewTag(str string) Tag

MustNewTag gives you the Tag corresponding to the acronym. This function will panic if the string passed in is not 4 bytes long.

func NewTag

func NewTag(a, b, c, d byte) Tag

NewTag returns the tag for <abcd>.

func (Tag) String

func (t Tag) String() string

String return the ASCII form of the tag.