README
¶
Font 
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
- Variables
- func Extension(b []byte) string
- func MediaType(b []byte) (string, error)
- func NewSFNTReader(r io.Reader) (*bytes.Reader, error)
- func ParseEOT(b []byte) ([]byte, error)
- func ParseWOFF(b []byte) ([]byte, error)
- func ParseWOFF2(b []byte) ([]byte, error)
- func ToSFNT(b []byte) ([]byte, error)
- type Font
- type SFNT
Constants ¶
const MaxCmapSegments = 20000
Variables ¶
var ErrExceedsMemory = fmt.Errorf("memory limit exceded")
ErrExceedsMemory is returned if the font is malformed.
var ErrInvalidFontData = fmt.Errorf("invalid font data")
ErrInvalidFontData is returned if the font is malformed.
var MaxMemory uint32 = 30 * 1024 * 1024
MaxMemory is the maximum memory that can be allocated by a font.
Functions ¶
func Extension ¶
Extension returns the file extension for a given font. An empty string is returned when the font is not recognized.
func NewSFNTReader ¶
NewReader 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 ¶
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 ¶
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 ¶
ParseWOFF2 parses the WOFF2 font format and returns its contained SFNT font format (TTF or OTF). See https://www.w3.org/TR/WOFF2/
Types ¶
type SFNT ¶
type SFNT struct {
Data []byte
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
// optional
Kern *kernTable
}
Source Files