font

package
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 Go to latest Published: Dec 30, 2023 License: MIT Imports: 24 Imported by: 0

README

Font API reference

This library contains font parsers for WOFF, WOFF2, and EOT. It takes a byte-slice as input and converts it to SFNT formats (either TTF or OTF). As font formats for the web, WOFF, WOFF2, and EOT are really just containers for SFNT fonts (such as TTF and OTF) that have better compression.

The WOFF and WOFF2 converters have been testing using the validation tests from the W3C. Font collections (such as TTC and OTC) are not yet supported, but will be in the near future. Compression in EOT files are also not yet supported.

Usage

Import using:

import "github.com/tdewolff/canvas/font"

Then we can parse any byte-slice that is in the WOFF/WOFF2/EOT file format and extract its TTF/OTF content.

font, err := ioutil.ReadFile("DejaVuSerif.woff")
if err != nil {
    panic(err)
}

sfnt, err := font.ToSFNT(font)
if err != nil {
    panic(err)
}

or using an io.Reader

font, err := os.Open("DejaVuSerif.woff")
if err != nil {
    panic(err)
}

font, err = font.NewSFNTReader(font)
if err != nil {
    panic(err)
}
WOFF
woff, err := ioutil.ReadFile("DejaVuSerif.woff")
if err != nil {
    panic(err)
}

sfnt, err := font.ParseWOFF(woff)
if err != nil {
    panic(err)
}

ext := font.Extension(sfnt)
if err = ioutil.WriteFile("DejaVuSerif"+ext, sfnt, 0644); err != nil {
    panic(err)
}

Tested using https://github.com/w3c/woff/tree/master/woff1/tests.

WOFF2
woff2, err := ioutil.ReadFile("DejaVuSerif.woff2")
if err != nil {
    panic(err)
}

sfnt, err := font.ParseWOFF2(woff2)
if err != nil {
    panic(err)
}

ext := font.Extension(sfnt)
if err = ioutil.WriteFile("DejaVuSerif"+ext, sfnt, 0644); err != nil {
    panic(err)
}

Tested using https://github.com/w3c/woff2-tests.

EOT
eof, err := ioutil.ReadFile("DejaVuSerif.eot")
if err != nil {
    panic(err)
}

sfnt, err = font.ParseEOT(eot)
if err != nil {
    panic(err)
}

ext := font.Extension(sfnt)
if err = ioutil.WriteFile("DejaVuSerif"+ext, sfnt, 0644); err != nil {
    panic(err)
}

License

Released under the MIT license.

Documentation

Index

Constants

View Source 
const (
	PlatformUnicode   = PlatformID(0)
	PlatformMacintosh = PlatformID(1)
	PlatformWindows   = PlatformID(3)
	PlatformCustom    = PlatformID(4)
)

see PlatformID

View Source 
const (
	EncodingUnicode2BMP                 = EncodingID(3)
	EncodingUnicode2FullRepertoir       = EncodingID(4)
	EncodingUnicodeVariationSequences   = EncodingID(5)
	EncodingUnicodeFullRepertoire       = EncodingID(6)
	EncodingMacintoshRoman              = EncodingID(0)
	EncodingMacintoshJapanese           = EncodingID(1)
	EncodingMacintoshChineseTraditional = EncodingID(2)
	EncodingMacintoshKorean             = EncodingID(3)
	EncodingMacintoshArabic             = EncodingID(4)
	EncodingMacintoshHebrew             = EncodingID(5)
	EncodingMacintoshGreek              = EncodingID(6)
	EncodingMacintoshRussian            = EncodingID(7)
	EncodingMacintoshRSymbol            = EncodingID(8)
	EncodingMacintoshDevanagari         = EncodingID(9)
	EncodingMacintoshGurmukhi           = EncodingID(10)
	EncodingMacintoshGujarati           = EncodingID(11)
	EncodingMacintoshOriya              = EncodingID(12)
	EncodingMacintoshBengali            = EncodingID(13)
	EncodingMacintoshTamil              = EncodingID(14)
	EncodingMacintoshTelugu             = EncodingID(15)
	EncodingMacintoshKannada            = EncodingID(16)
	EncodingMacintoshMalayalam          = EncodingID(17)
	EncodingMacintoshSinhalese          = EncodingID(18)
	EncodingMacintoshBurmese            = EncodingID(19)
	EncodingMacintoshKhmer              = EncodingID(20)
	EncodingMacintoshThai               = EncodingID(21)
	EncodingMacintoshLaotian            = EncodingID(22)
	EncodingMacintoshGeorgian           = EncodingID(23)
	EncodingMacintoshArmenian           = EncodingID(24)
	EncodingMacintoshChineseSimplified  = EncodingID(25)
	EncodingMacintoshTibetan            = EncodingID(26)
	EncodingMacintoshMongolian          = EncodingID(27)
	EncodingMacintoshGeez               = EncodingID(28)
	EncodingMacintoshSlavic             = EncodingID(29)
	EncodingMacintoshVietnamese         = EncodingID(30)
	EncodingMacintoshSindhi             = EncodingID(31)
	EncodingMacintoshUninterpreted      = EncodingID(32)
	EncodingWindowsSymbol               = EncodingID(0)
	EncodingWindowsUnicodeBMP           = EncodingID(1)
	EncodingWindowsShiftJIS             = EncodingID(2)
	EncodingWindowsPRC                  = EncodingID(3)
	EncodingWindowsBig5                 = EncodingID(4)
	EncodingWindowsWansung              = EncodingID(5)
	EncodingWindowsJohab                = EncodingID(6)
	EncodingWindowsUnicodeFullRepertoir = EncodingID(10)
)

see EncodingID

View Source 
const (
	NameCopyrightNotice            = NameID(0)
	NameFontFamily                 = NameID(1)
	NameFontSubfamily              = NameID(2)
	NameUniqueIdentifier           = NameID(3)
	NameFull                       = NameID(4)
	NameVersion                    = NameID(5)
	NamePostScript                 = NameID(6)
	NameTrademark                  = NameID(7)
	NameManufacturer               = NameID(8)
	NameDesigner                   = NameID(9)
	NameDescription                = NameID(10)
	NameVendorURL                  = NameID(11)
	NameDesignerURL                = NameID(12)
	NameLicense                    = NameID(13)
	NameLicenseURL                 = NameID(14)
	NamePreferredFamily            = NameID(16)
	NamePreferredSubfamily         = NameID(17)
	NameCompatibleFull             = NameID(18)
	NameSampleText                 = NameID(19)
	NamePostScriptCID              = NameID(20)
	NameWWSFamily                  = NameID(21)
	NameWWSSubfamily               = NameID(22)
	NameLightBackgroundPalette     = NameID(23)
	NameDarkBackgroundPalette      = NameID(24)
	NameVariationsPostScriptPrefix = NameID(25)
)

see NameID

View Source 
const (
	UnknownScript = ScriptTag("")
	DefaultScript = ScriptTag("DFLT")
)
View Source 
const (
	UnknownLanguage = LanguageTag("")
	DefaultLanguage = LanguageTag("DFLT") // permanently reserved and not used in font

)
View Source 
const MaxCmapSegments = 20000

MaxCmapSegments is the maximum number of cmap segments that will be accepted.

View Source 
const (
	UnknownFeature = FeatureTag("")
)

Variables

View Source 
var ErrExceedsMemory = fmt.Errorf("memory limit exceded")

ErrExceedsMemory is returned if the font is malformed.

View Source 
var ErrInvalidFontData = fmt.Errorf("invalid font data")

ErrInvalidFontData is returned if the font is malformed.

View Source 
var MaxMemory uint32 = 30 * 1024 * 1024

MaxMemory is the maximum memory that can be allocated by a font.

Functions

func DefaultFontDirs 

func DefaultFontDirs() []string

func DefaultGenericFonts 

func DefaultGenericFonts() map[string][]string

func Extension 

func Extension(b []byte) string

Extension returns the file extension for a given font. An empty string is returned when the font is not recognized.

func FromGoFreetype 

func FromGoFreetype(font *truetype.Font) []byte

FromGoFreetype parses a structure from truetype.Font to a valid SFNT byte slice.

func FromGoSFNT 

func FromGoSFNT(font *sfnt.Font) []byte

FromGoSFNT parses a structure from sfnt.Font to a valid SFNT byte slice.

func MediaType 

func MediaType(b []byte) (string, error)

MediaType returns the media type (MIME) for a given font.

func NewSFNTReader 

func NewSFNTReader(r io.Reader) (*bytes.Reader, error)

NewSFNTReader takes an io.Reader and transforms it into an SFNT reader. That is, given TTF/OTF/WOFF/WOFF2/EOT input, it will return TTF/OTF output.

func ParseEOT 

func ParseEOT(b []byte) ([]byte, error)

ParseEOT parses the EOT font format and returns its contained SFNT font format (TTF or OTF). See https://www.w3.org/Submission/EOT/

func ParseWOFF 

func ParseWOFF(b []byte) ([]byte, error)

ParseWOFF parses the WOFF font format and returns its contained SFNT font format (TTF or OTF). See https://www.w3.org/TR/WOFF/

func ParseWOFF2 

func ParseWOFF2(b []byte) ([]byte, error)

ParseWOFF2 parses the WOFF2 font format and returns its contained SFNT font format (TTF or OTF). See https://www.w3.org/TR/WOFF2/

func ToSFNT 

func ToSFNT(b []byte) ([]byte, error)

ToSFNT takes a byte slice and transforms it into an SFNT byte slice. That is, given TTF/OTF/WOFF/WOFF2/EOT input, it will return TTF/OTF output.

func Uint16ToFlags 

func Uint16ToFlags(v uint16) (flags [16]bool)

Uint16ToFlags converts a uint16 in 16 booleans from least to most significant.

func Uint8ToFlags 

func Uint8ToFlags(v uint8) (flags [8]bool)

Uint8ToFlags converts a uint8 in 8 booleans from least to most significant.

Types

type BinaryReader 

type BinaryReader struct {
	// contains filtered or unexported fields
}

BinaryReader is a binary big endian file format reader.

func NewBinaryReader 

func NewBinaryReader(buf []byte) *BinaryReader

NewBinaryReader returns a big endian binary file format reader.

func (*BinaryReader) EOF 

func (r *BinaryReader) EOF() bool

EOF returns true if we reached the end-of-file.

func (*BinaryReader) Len 

func (r *BinaryReader) Len() uint32

Len returns the remaining length of the buffer.

func (*BinaryReader) Pos 

func (r *BinaryReader) Pos() uint32

Pos returns the reader's position.

func (*BinaryReader) ReadByte 

func (r *BinaryReader) ReadByte() byte

ReadByte reads a single byte.

func (*BinaryReader) ReadBytes 

func (r *BinaryReader) ReadBytes(n uint32) []byte

ReadBytes reads n bytes.

func (*BinaryReader) ReadInt16 

func (r *BinaryReader) ReadInt16() int16

ReadInt16 reads a int16.

func (*BinaryReader) ReadInt16LE 

func (r *BinaryReader) ReadInt16LE() int16

ReadInt16LE reads a int16 little endian.

func (*BinaryReader) ReadInt32 

func (r *BinaryReader) ReadInt32() int32

ReadInt32 reads a int32.

func (*BinaryReader) ReadInt64 

func (r *BinaryReader) ReadInt64() int64

ReadInt64 reads a int64.

func (*BinaryReader) ReadInt8 

func (r *BinaryReader) ReadInt8() int8

ReadInt8 reads a int8.

func (*BinaryReader) ReadString 

func (r *BinaryReader) ReadString(n uint32) string

ReadString reads a string of length n.

func (*BinaryReader) ReadUint16 

func (r *BinaryReader) ReadUint16() uint16

ReadUint16 reads a uint16.

func (*BinaryReader) ReadUint16LE 

func (r *BinaryReader) ReadUint16LE() uint16

ReadUint16LE reads a uint16 little endian.

func (*BinaryReader) ReadUint32 

func (r *BinaryReader) ReadUint32() uint32

ReadUint32 reads a uint32.

func (*BinaryReader) ReadUint32LE 

func (r *BinaryReader) ReadUint32LE() uint32

ReadUint32LE reads a uint32 little endian.

func (*BinaryReader) ReadUint64 

func (r *BinaryReader) ReadUint64() uint64

ReadUint64 reads a uint64.

func (*BinaryReader) ReadUint8 

func (r *BinaryReader) ReadUint8() uint8

ReadUint8 reads a uint8.

func (*BinaryReader) Seek 

func (r *BinaryReader) Seek(pos uint32)

Seek set the reader position in the buffer.

type BinaryWriter 

type BinaryWriter struct {
	// contains filtered or unexported fields
}

BinaryWriter is a big endian binary file format writer.

func NewBinaryWriter 

func NewBinaryWriter(buf []byte) *BinaryWriter

NewBinaryWriter returns a big endian binary file format writer.

func (*BinaryWriter) Bytes 

func (w *BinaryWriter) Bytes() []byte

Bytes returns the buffer's bytes.

func (*BinaryWriter) Len 

func (w *BinaryWriter) Len() uint32

Len returns the buffer's length in bytes.

func (*BinaryWriter) WriteByte 

func (w *BinaryWriter) WriteByte(v byte)

WriteByte writes the given byte to the buffer.

func (*BinaryWriter) WriteBytes 

func (w *BinaryWriter) WriteBytes(v []byte)

WriteBytes writes the given bytes to the buffer.

func (*BinaryWriter) WriteInt16 

func (w *BinaryWriter) WriteInt16(v int16)

WriteInt16 writes the given int16 to the buffer.

func (*BinaryWriter) WriteInt32 

func (w *BinaryWriter) WriteInt32(v int32)

WriteInt32 writes the given int32 to the buffer.

func (*BinaryWriter) WriteInt64 

func (w *BinaryWriter) WriteInt64(v int64)

WriteInt64 writes the given int64 to the buffer.

func (*BinaryWriter) WriteInt8 

func (w *BinaryWriter) WriteInt8(v int8)

WriteInt8 writes the given int8 to the buffer.

func (*BinaryWriter) WriteString 

func (w *BinaryWriter) WriteString(v string)

WriteString writes the given string to the buffer.

func (*BinaryWriter) WriteUint16 

func (w *BinaryWriter) WriteUint16(v uint16)

WriteUint16 writes the given uint16 to the buffer.

func (*BinaryWriter) WriteUint32 

func (w *BinaryWriter) WriteUint32(v uint32)

WriteUint32 writes the given uint32 to the buffer.

func (*BinaryWriter) WriteUint64 

func (w *BinaryWriter) WriteUint64(v uint64)

WriteUint64 writes the given uint64 to the buffer.

func (*BinaryWriter) WriteUint8 

func (w *BinaryWriter) WriteUint8(v uint8)

WriteUint8 writes the given uint8 to the buffer.

type BitmapReader 

type BitmapReader struct {
	// contains filtered or unexported fields
}

BitmapReader is a binary bitmap reader.

func NewBitmapReader 

func NewBitmapReader(buf []byte) *BitmapReader

NewBitmapReader returns a binary bitmap reader.

func (*BitmapReader) EOF 

func (r *BitmapReader) EOF() bool

EOF returns if we reached the buffer's end-of-file.

func (*BitmapReader) Pos 

func (r *BitmapReader) Pos() uint32

Pos returns the current bit position.

func (*BitmapReader) Read 

func (r *BitmapReader) Read() bool

Read reads the next bit.

type EncodingID 

type EncodingID uint16

EncodingID is the encoding identifier for the name table

type FeatureTag 

type FeatureTag string

type FontMetadata 

type FontMetadata struct {
	Filename string
	Family   string
	Style
}

func (FontMetadata) String 

func (metadata FontMetadata) String() string

type Hinting 

type Hinting int

Hinting specifies the type of hinting to use (none supported yes). 

const (
	NoHinting Hinting = iota
	VerticalHinting
)

see Hinting

type LanguageTag 

type LanguageTag string

type NameID 

type NameID uint16

NameID is the name identifier for the name table

type Pather 

type Pather interface {
	MoveTo(float64, float64)
	LineTo(float64, float64)
	QuadTo(float64, float64, float64, float64)
	CubeTo(float64, float64, float64, float64, float64, float64)
	Close()
}

Pather is an interface to append a glyph's path to canvas.Path.

type PlatformID 

type PlatformID uint16

PlatformID is the platform identifier for the name table

type SFNT 

type SFNT struct {
	Data              []byte
	Version           string
	IsCFF, IsTrueType bool // only one can be true
	Tables            map[string][]byte

	// required
	Cmap *cmapTable
	Head *headTable
	Hhea *hheaTable
	Hmtx *hmtxTable
	Maxp *maxpTable
	Name *nameTable
	OS2  *os2Table
	Post *postTable

	// TrueType
	Glyf *glyfTable
	Loca *locaTable

	// CFF
	CFF *cffTable

	// optional
	Kern *kernTable
	Vhea *vheaTable
	//Hdmx *hdmxTable // TODO
	Vmtx *vmtxTable
	Gpos *gposgsubTable
	Gsub *gposgsubTable
	Jsft *jsftTable
}

SFNT is a parsed OpenType font.

func ParseEmbeddedSFNT 

func ParseEmbeddedSFNT(b []byte, index int) (*SFNT, error)

ParseEmbeddedSFNT is like ParseSFNT but for embedded font files in PDFs. It allows font files with fewer required tables.

func ParseFont 

func ParseFont(b []byte, index int) (*SFNT, error)

ParseFont parses a byte slice and of a TTF, OTF, WOFF, WOFF2, or EOT font format. It will return the parsed font and its mimetype.

func ParseSFNT 

func ParseSFNT(b []byte, index int) (*SFNT, error)

ParseSFNT parses an OpenType file format (TTF, OTF, TTC). The index is used for font collections to select a single font.

func (*SFNT) GlyphAdvance 

func (sfnt *SFNT) GlyphAdvance(glyphID uint16) uint16

GlyphAdvance returns the (horizontal) advance width of the glyph.

func (*SFNT) GlyphBounds 

func (sfnt *SFNT) GlyphBounds(glyphID uint16) (int16, int16, int16, int16, error)

GlyphBounds returns the bounding rectangle (xmin,ymin,xmax,ymax) of the glyph.

func (*SFNT) GlyphIndex 

func (sfnt *SFNT) GlyphIndex(r rune) uint16

GlyphIndex returns the glyphID for a given rune. When the rune is not defined it returns 0.

func (*SFNT) GlyphName 

func (sfnt *SFNT) GlyphName(glyphID uint16) string

GlyphName returns the name of the glyph.

func (*SFNT) GlyphPath 

func (sfnt *SFNT) GlyphPath(p Pather, glyphID, ppem uint16, x, y, scale float64, hinting Hinting) error

GlyphPath draws the glyph's contour as a path to the pather interface. It will use the specified ppem (pixels-per-EM) for hinting purposes. The path is draws to the (x,y) coordinate and scaled using the given scale factor.

func (*SFNT) GlyphVerticalAdvance 

func (sfnt *SFNT) GlyphVerticalAdvance(glyphID uint16) uint16

GlyphVerticalAdvance returns the vertical advance width of the glyph.

func (*SFNT) Kerning 

func (sfnt *SFNT) Kerning(left, right uint16) int16

Kerning returns the kerning between two glyphs, i.e. the advance correction for glyph pairs.

func (*SFNT) NumGlyphs 

func (sfnt *SFNT) NumGlyphs() uint16

NumGlyphs returns the number of glyphs the font contains.

func (*SFNT) Subset 

func (sfnt *SFNT) Subset(glyphIDs []uint16, writeTables WriteTables) ([]byte, []uint16)

Subset regenerates a font file containing only the passed glyphIDs, thereby resulting in a significant size reduction. The glyphIDs will apear in the specified order in the file, and their dependencies are added to the end. It returns the compressed font file and the glyphIDs in the order in which they appear.

func (*SFNT) VerticalMetrics 

func (sfnt *SFNT) VerticalMetrics() (uint16, uint16, uint16)

VerticalMetrics returns the ascender, descender, and line gap values. It returns the "win" values, or the "typo" values if OS/2.FsSelection.USE_TYPO_METRICS is set. If those are zero or not set, default to the "hhea" values.

func (*SFNT) Write 

func (sfnt *SFNT) Write() []byte

Write writes out the SFNT file.

type ScriptTag 

type ScriptTag string

type Style 

type Style int

Style defines the font style to be used for the font. It specifies a boldness with optionally italic, e.g. Black | Italic will specify a black boldness (a font-weight of 800 in CSS) and italic. 

const (
	UnknownStyle Style = -1
	Thin         Style = iota
	ExtraLight
	Light
	Regular
	Medium
	SemiBold
	Bold
	ExtraBold
	Black
	Italic Style = 1 << 8
)

see Style

func ParseStyle 

func ParseStyle(s string) Style

func ParseStyleCSS 

func ParseStyleCSS(weight int, italic bool) Style

func (Style) Italic 

func (style Style) Italic() bool

Italic returns true if italic.

func (Style) String 

func (style Style) String() string

func (Style) Weight 

func (style Style) Weight() Style

Weight returns the font weight (Regular, Bold, ...)

type SystemFonts 

type SystemFonts struct {
	Generics map[string][]string
	Fonts    map[string]map[Style]FontMetadata
}

func FindSystemFonts 

func FindSystemFonts(dirs []string) (*SystemFonts, error)

func LoadSystemFonts 

func LoadSystemFonts(filename string) (*SystemFonts, error)

func (*SystemFonts) Add 

func (s *SystemFonts) Add(metadata FontMetadata)

func (*SystemFonts) Match 

func (s *SystemFonts) Match(name string, style Style) (FontMetadata, bool)

func (*SystemFonts) Save 

func (s *SystemFonts) Save(filename string) error

func (*SystemFonts) String 

func (s *SystemFonts) String() string

type ValueRecord 

type ValueRecord struct {
	XPlacement       int16
	YPlacement       int16
	XAdvance         int16
	YAdvance         int16
	XPlaDeviceOffset uint16
	YPlaDeviceOffset uint16
	XAdvDeviceOffset uint16
	YAdvDeviceOffset uint16
}

type WriteTables 

type WriteTables int
const (
	WriteAllTables WriteTables = iota
	WriteMinTables
	WritePDFTables
)

Source Files

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