lefevre

package module
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 Go to latest Published: Apr 22, 2026 License: BSD-3-Clause Imports: 3 Imported by: 0

README

lefevre

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This is a Go rewrite of kb_text_shape.h (v2.14, by Jimmy Lefevre), a 28K-line single-header C library for Unicode text segmentation and OpenType shaping.

It also now includes text rasterizing in raster package.

Scope/Roadmap

The scope of this package is fulfilled. A pure go, no dependency package to do text shaping and rastering.

What remains is reducing heap allocations and improving APIs to be more comfy and performant.

Examples

Below is the result of running

echo "مرحبا hello, office résumé?" | go run ./examples/visual/ testdata/DejaVuSans.ttf > lefevre.svg

Visualization example.

A CPU rasterization demo is also available:

go run ./examples/raster/ -font testdata/DejaVuSans.ttf

Rasterization example.

LLM policy

This project is in great part assisted by LLMs.

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func FontCount 

func FontCount(data []byte) int

FontCount returns the number of fonts in a TTC/OTF/TTF byte slice. Returns 0 for invalid or empty data.

func GuessTextProperties 

func GuessTextProperties(text string) (Direction, Script)

GuessTextProperties scans text for the first strong directional character and first identifiable script. Useful for mono-script, mono-direction text.

Types

type Break 

type Break struct {
	Position           int
	Flags              BreakFlags
	Direction          Direction
	ParagraphDirection Direction
	Script             Script
}

Break describes a segmentation break point in the input text.

type BreakConfigFlags 

type BreakConfigFlags uint8

BreakConfigFlags controls break generation behavior. 

const (
	BreakConfigNone                        BreakConfigFlags = 0
	BreakConfigEndOfTextGeneratesHardBreak BreakConfigFlags = 1
)

type BreakFlags 

type BreakFlags uint8

BreakFlags is a bitfield indicating what type of break occurred at a position. 

const (
	BreakFlagDirection          BreakFlags = 1 << iota // Direction change (LTR <-> RTL)
	BreakFlagScript                                    // Script change
	BreakFlagGrapheme                                  // Grapheme cluster boundary
	BreakFlagWord                                      // Word boundary
	BreakFlagLineSoft                                  // Optional line break point
	BreakFlagLineHard                                  // Mandatory line break (newline/paragraph)
	BreakFlagManual                                    // User-requested break
	BreakFlagParagraphDirection                        // Paragraph direction change

	BreakFlagLine = BreakFlagLineSoft | BreakFlagLineHard
	BreakFlagAny  = BreakFlagDirection | BreakFlagScript | BreakFlagGrapheme | BreakFlagWord | BreakFlagLineSoft | BreakFlagLineHard
)

func (BreakFlags) HasAll 

func (f BreakFlags) HasAll(flagsQuery BreakFlags) bool

HasAll returns true if f contains all bits in flag.

func (BreakFlags) IsHardBreak 

func (f BreakFlags) IsHardBreak() bool

IsHardBreak returns true if the hard line break flag is set.

func (BreakFlags) IsLineBreak 

func (f BreakFlags) IsLineBreak() bool

IsLineBreak returns true if either soft or hard line break flag is set.

type BreakState 

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

BreakState is a streaming text segmentation state machine. Zero value is valid; call Begin before feeding codepoints.

func (*BreakState) AddCodepoint 

func (bs *BreakState) AddCodepoint(codepoint rune, positionIncrement int, endOfText bool)

AddCodepoint feeds one codepoint to the segmenter.

func (*BreakState) Begin 

func (bs *BreakState) Begin(paragraphDirection Direction, style JapaneseLineBreakStyle, flags BreakConfigFlags)

Begin initializes or resets the break state for a new text run.

func (*BreakState) End 

func (bs *BreakState) End()

End flushes any remaining breaks after all codepoints have been added.

func (*BreakState) Next 

func (bs *BreakState) Next() (Break, bool)

Next returns the next pending break, or false if none remain.

type Breaker 

type Breaker struct {
	Direction Direction
	JStyle    JapaneseLineBreakStyle
	Flags     BreakConfigFlags
	// contains filtered or unexported fields
}

Breaker is a high-level streaming text segmenter. Feed text via AppendBreak, then call End to flush remaining breaks. The zero value is ready to use with default settings.

func (*Breaker) AppendBreak 

func (b *Breaker) AppendBreak(dst []Break, text []byte) ([]Break, int)

AppendBreak processes all complete runes in text, appending breaks to dst. Returns the extended slice and the number of bytes consumed. Incomplete trailing UTF-8 sequences are not consumed. Never sets end-of-text; call End after the last chunk.

func (*Breaker) End 

func (b *Breaker) End(dst []Break) []Break

End signals end-of-text and flushes remaining breaks to dst. After End, the Breaker can be reused for new text.

type Direction 

type Direction uint8

Direction represents the directionality of text. 

const (
	DirectionUnknown Direction = iota
	DirectionLTR
	DirectionRTL
)

func (Direction) Reverse 

func (d Direction) Reverse() Direction

Reverse returns the opposite direction. Unknown stays Unknown.

func (Direction) String 

func (d Direction) String() string

String returns "LTR", "RTL", or "Unknown".

type FeatureOverride 

type FeatureOverride struct {
	Tag   FeatureTag
	Value int
}

FeatureOverride controls a specific OpenType feature's value.

type FeatureTag 

type FeatureTag uint32

FeatureTag is an OpenType feature tag stored as a little-endian uint32 (e.g., "liga", "kern"). 

const (
	FeatureTagUnregistered FeatureTag = 0
	FeatureTagIsol         FeatureTag = 'i' | 's'<<8 | 'o'<<16 | 'l'<<24
	FeatureTagFina         FeatureTag = 'f' | 'i'<<8 | 'n'<<16 | 'a'<<24
	FeatureTagFin2         FeatureTag = 'f' | 'i'<<8 | 'n'<<16 | '2'<<24
	FeatureTagFin3         FeatureTag = 'f' | 'i'<<8 | 'n'<<16 | '3'<<24
	FeatureTagMedi         FeatureTag = 'm' | 'e'<<8 | 'd'<<16 | 'i'<<24
	FeatureTagMed2         FeatureTag = 'm' | 'e'<<8 | 'd'<<16 | '2'<<24
	FeatureTagInit         FeatureTag = 'i' | 'n'<<8 | 'i'<<16 | 't'<<24
	FeatureTagLjmo         FeatureTag = 'l' | 'j'<<8 | 'm'<<16 | 'o'<<24
	FeatureTagVjmo         FeatureTag = 'v' | 'j'<<8 | 'm'<<16 | 'o'<<24
	FeatureTagTjmo         FeatureTag = 't' | 'j'<<8 | 'm'<<16 | 'o'<<24
	FeatureTagRphf         FeatureTag = 'r' | 'p'<<8 | 'h'<<16 | 'f'<<24
	FeatureTagBlwf         FeatureTag = 'b' | 'l'<<8 | 'w'<<16 | 'f'<<24
	FeatureTagHalf         FeatureTag = 'h' | 'a'<<8 | 'l'<<16 | 'f'<<24
	FeatureTagPstf         FeatureTag = 'p' | 's'<<8 | 't'<<16 | 'f'<<24
	FeatureTagAbvf         FeatureTag = 'a' | 'b'<<8 | 'v'<<16 | 'f'<<24
	FeatureTagPref         FeatureTag = 'p' | 'r'<<8 | 'e'<<16 | 'f'<<24
	FeatureTagNumr         FeatureTag = 'n' | 'u'<<8 | 'm'<<16 | 'r'<<24
	FeatureTagFrac         FeatureTag = 'f' | 'r'<<8 | 'a'<<16 | 'c'<<24
	FeatureTagDnom         FeatureTag = 'd' | 'n'<<8 | 'o'<<16 | 'm'<<24
	FeatureTagCfar         FeatureTag = 'c' | 'f'<<8 | 'a'<<16 | 'r'<<24
	FeatureTagAalt         FeatureTag = 'a' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagAbvm         FeatureTag = 'a' | 'b'<<8 | 'v'<<16 | 'm'<<24
	FeatureTagAbvs         FeatureTag = 'a' | 'b'<<8 | 'v'<<16 | 's'<<24
	FeatureTagAfrc         FeatureTag = 'a' | 'f'<<8 | 'r'<<16 | 'c'<<24
	FeatureTagAkhn         FeatureTag = 'a' | 'k'<<8 | 'h'<<16 | 'n'<<24
	FeatureTagApkn         FeatureTag = 'a' | 'p'<<8 | 'k'<<16 | 'n'<<24
	FeatureTagBlwm         FeatureTag = 'b' | 'l'<<8 | 'w'<<16 | 'm'<<24
	FeatureTagBlws         FeatureTag = 'b' | 'l'<<8 | 'w'<<16 | 's'<<24
	FeatureTagCalt         FeatureTag = 'c' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagCase         FeatureTag = 'c' | 'a'<<8 | 's'<<16 | 'e'<<24
	FeatureTagCcmp         FeatureTag = 'c' | 'c'<<8 | 'm'<<16 | 'p'<<24
	FeatureTagChws         FeatureTag = 'c' | 'h'<<8 | 'w'<<16 | 's'<<24
	FeatureTagCjct         FeatureTag = 'c' | 'j'<<8 | 'c'<<16 | 't'<<24
	FeatureTagClig         FeatureTag = 'c' | 'l'<<8 | 'i'<<16 | 'g'<<24
	FeatureTagCpct         FeatureTag = 'c' | 'p'<<8 | 'c'<<16 | 't'<<24
	FeatureTagCpsp         FeatureTag = 'c' | 'p'<<8 | 's'<<16 | 'p'<<24
	FeatureTagCswh         FeatureTag = 'c' | 's'<<8 | 'w'<<16 | 'h'<<24
	FeatureTagCurs         FeatureTag = 'c' | 'u'<<8 | 'r'<<16 | 's'<<24
	FeatureTagCv01         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '1'<<24
	FeatureTagCv02         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '2'<<24
	FeatureTagCv03         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '3'<<24
	FeatureTagCv04         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '4'<<24
	FeatureTagCv05         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '5'<<24
	FeatureTagCv06         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '6'<<24
	FeatureTagCv07         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '7'<<24
	FeatureTagCv08         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '8'<<24
	FeatureTagCv09         FeatureTag = 'c' | 'v'<<8 | '0'<<16 | '9'<<24
	FeatureTagCv10         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '0'<<24
	FeatureTagCv11         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '1'<<24
	FeatureTagCv12         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '2'<<24
	FeatureTagCv13         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '3'<<24
	FeatureTagCv14         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '4'<<24
	FeatureTagCv15         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '5'<<24
	FeatureTagCv16         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '6'<<24
	FeatureTagCv17         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '7'<<24
	FeatureTagCv18         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '8'<<24
	FeatureTagCv19         FeatureTag = 'c' | 'v'<<8 | '1'<<16 | '9'<<24
	FeatureTagCv20         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '0'<<24
	FeatureTagCv21         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '1'<<24
	FeatureTagCv22         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '2'<<24
	FeatureTagCv23         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '3'<<24
	FeatureTagCv24         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '4'<<24
	FeatureTagCv25         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '5'<<24
	FeatureTagCv26         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '6'<<24
	FeatureTagCv27         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '7'<<24
	FeatureTagCv28         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '8'<<24
	FeatureTagCv29         FeatureTag = 'c' | 'v'<<8 | '2'<<16 | '9'<<24
	FeatureTagCv30         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '0'<<24
	FeatureTagCv31         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '1'<<24
	FeatureTagCv32         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '2'<<24
	FeatureTagCv33         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '3'<<24
	FeatureTagCv34         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '4'<<24
	FeatureTagCv35         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '5'<<24
	FeatureTagCv36         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '6'<<24
	FeatureTagCv37         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '7'<<24
	FeatureTagCv38         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '8'<<24
	FeatureTagCv39         FeatureTag = 'c' | 'v'<<8 | '3'<<16 | '9'<<24
	FeatureTagCv40         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '0'<<24
	FeatureTagCv41         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '1'<<24
	FeatureTagCv42         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '2'<<24
	FeatureTagCv43         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '3'<<24
	FeatureTagCv44         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '4'<<24
	FeatureTagCv45         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '5'<<24
	FeatureTagCv46         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '6'<<24
	FeatureTagCv47         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '7'<<24
	FeatureTagCv48         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '8'<<24
	FeatureTagCv49         FeatureTag = 'c' | 'v'<<8 | '4'<<16 | '9'<<24
	FeatureTagCv50         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '0'<<24
	FeatureTagCv51         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '1'<<24
	FeatureTagCv52         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '2'<<24
	FeatureTagCv53         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '3'<<24
	FeatureTagCv54         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '4'<<24
	FeatureTagCv55         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '5'<<24
	FeatureTagCv56         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '6'<<24
	FeatureTagCv57         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '7'<<24
	FeatureTagCv58         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '8'<<24
	FeatureTagCv59         FeatureTag = 'c' | 'v'<<8 | '5'<<16 | '9'<<24
	FeatureTagCv60         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '0'<<24
	FeatureTagCv61         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '1'<<24
	FeatureTagCv62         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '2'<<24
	FeatureTagCv63         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '3'<<24
	FeatureTagCv64         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '4'<<24
	FeatureTagCv65         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '5'<<24
	FeatureTagCv66         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '6'<<24
	FeatureTagCv67         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '7'<<24
	FeatureTagCv68         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '8'<<24
	FeatureTagCv69         FeatureTag = 'c' | 'v'<<8 | '6'<<16 | '9'<<24
	FeatureTagCv70         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '0'<<24
	FeatureTagCv71         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '1'<<24
	FeatureTagCv72         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '2'<<24
	FeatureTagCv73         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '3'<<24
	FeatureTagCv74         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '4'<<24
	FeatureTagCv75         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '5'<<24
	FeatureTagCv76         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '6'<<24
	FeatureTagCv77         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '7'<<24
	FeatureTagCv78         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '8'<<24
	FeatureTagCv79         FeatureTag = 'c' | 'v'<<8 | '7'<<16 | '9'<<24
	FeatureTagCv80         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '0'<<24
	FeatureTagCv81         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '1'<<24
	FeatureTagCv82         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '2'<<24
	FeatureTagCv83         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '3'<<24
	FeatureTagCv84         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '4'<<24
	FeatureTagCv85         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '5'<<24
	FeatureTagCv86         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '6'<<24
	FeatureTagCv87         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '7'<<24
	FeatureTagCv88         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '8'<<24
	FeatureTagCv89         FeatureTag = 'c' | 'v'<<8 | '8'<<16 | '9'<<24
	FeatureTagCv90         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '0'<<24
	FeatureTagCv91         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '1'<<24
	FeatureTagCv92         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '2'<<24
	FeatureTagCv93         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '3'<<24
	FeatureTagCv94         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '4'<<24
	FeatureTagCv95         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '5'<<24
	FeatureTagCv96         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '6'<<24
	FeatureTagCv97         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '7'<<24
	FeatureTagCv98         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '8'<<24
	FeatureTagCv99         FeatureTag = 'c' | 'v'<<8 | '9'<<16 | '9'<<24
	FeatureTagC2pc         FeatureTag = 'c' | '2'<<8 | 'p'<<16 | 'c'<<24
	FeatureTagC2sc         FeatureTag = 'c' | '2'<<8 | 's'<<16 | 'c'<<24
	FeatureTagDist         FeatureTag = 'd' | 'i'<<8 | 's'<<16 | 't'<<24
	FeatureTagDlig         FeatureTag = 'd' | 'l'<<8 | 'i'<<16 | 'g'<<24
	FeatureTagDtls         FeatureTag = 'd' | 't'<<8 | 'l'<<16 | 's'<<24
	FeatureTagExpt         FeatureTag = 'e' | 'x'<<8 | 'p'<<16 | 't'<<24
	FeatureTagFalt         FeatureTag = 'f' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagFlac         FeatureTag = 'f' | 'l'<<8 | 'a'<<16 | 'c'<<24
	FeatureTagFwid         FeatureTag = 'f' | 'w'<<8 | 'i'<<16 | 'd'<<24
	FeatureTagHaln         FeatureTag = 'h' | 'a'<<8 | 'l'<<16 | 'n'<<24
	FeatureTagHalt         FeatureTag = 'h' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagHist         FeatureTag = 'h' | 'i'<<8 | 's'<<16 | 't'<<24
	FeatureTagHkna         FeatureTag = 'h' | 'k'<<8 | 'n'<<16 | 'a'<<24
	FeatureTagHlig         FeatureTag = 'h' | 'l'<<8 | 'i'<<16 | 'g'<<24
	FeatureTagHngl         FeatureTag = 'h' | 'n'<<8 | 'g'<<16 | 'l'<<24
	FeatureTagHojo         FeatureTag = 'h' | 'o'<<8 | 'j'<<16 | 'o'<<24
	FeatureTagHwid         FeatureTag = 'h' | 'w'<<8 | 'i'<<16 | 'd'<<24
	FeatureTagItal         FeatureTag = 'i' | 't'<<8 | 'a'<<16 | 'l'<<24
	FeatureTagJalt         FeatureTag = 'j' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagJp78         FeatureTag = 'j' | 'p'<<8 | '7'<<16 | '8'<<24
	FeatureTagJp83         FeatureTag = 'j' | 'p'<<8 | '8'<<16 | '3'<<24
	FeatureTagJp90         FeatureTag = 'j' | 'p'<<8 | '9'<<16 | '0'<<24
	FeatureTagJp04         FeatureTag = 'j' | 'p'<<8 | '0'<<16 | '4'<<24
	FeatureTagKern         FeatureTag = 'k' | 'e'<<8 | 'r'<<16 | 'n'<<24
	FeatureTagLfbd         FeatureTag = 'l' | 'f'<<8 | 'b'<<16 | 'd'<<24
	FeatureTagLiga         FeatureTag = 'l' | 'i'<<8 | 'g'<<16 | 'a'<<24
	FeatureTagLnum         FeatureTag = 'l' | 'n'<<8 | 'u'<<16 | 'm'<<24
	FeatureTagLocl         FeatureTag = 'l' | 'o'<<8 | 'c'<<16 | 'l'<<24
	FeatureTagLtra         FeatureTag = 'l' | 't'<<8 | 'r'<<16 | 'a'<<24
	FeatureTagLtrm         FeatureTag = 'l' | 't'<<8 | 'r'<<16 | 'm'<<24
	FeatureTagMark         FeatureTag = 'm' | 'a'<<8 | 'r'<<16 | 'k'<<24
	FeatureTagMgrk         FeatureTag = 'm' | 'g'<<8 | 'r'<<16 | 'k'<<24
	FeatureTagMkmk         FeatureTag = 'm' | 'k'<<8 | 'm'<<16 | 'k'<<24
	FeatureTagMset         FeatureTag = 'm' | 's'<<8 | 'e'<<16 | 't'<<24
	FeatureTagNalt         FeatureTag = 'n' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagNlck         FeatureTag = 'n' | 'l'<<8 | 'c'<<16 | 'k'<<24
	FeatureTagNukt         FeatureTag = 'n' | 'u'<<8 | 'k'<<16 | 't'<<24
	FeatureTagOnum         FeatureTag = 'o' | 'n'<<8 | 'u'<<16 | 'm'<<24
	FeatureTagOpbd         FeatureTag = 'o' | 'p'<<8 | 'b'<<16 | 'd'<<24
	FeatureTagOrdn         FeatureTag = 'o' | 'r'<<8 | 'd'<<16 | 'n'<<24
	FeatureTagOrnm         FeatureTag = 'o' | 'r'<<8 | 'n'<<16 | 'm'<<24
	FeatureTagPalt         FeatureTag = 'p' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagPcap         FeatureTag = 'p' | 'c'<<8 | 'a'<<16 | 'p'<<24
	FeatureTagPkna         FeatureTag = 'p' | 'k'<<8 | 'n'<<16 | 'a'<<24
	FeatureTagPnum         FeatureTag = 'p' | 'n'<<8 | 'u'<<16 | 'm'<<24
	FeatureTagPres         FeatureTag = 'p' | 'r'<<8 | 'e'<<16 | 's'<<24
	FeatureTagPsts         FeatureTag = 'p' | 's'<<8 | 't'<<16 | 's'<<24
	FeatureTagPwid         FeatureTag = 'p' | 'w'<<8 | 'i'<<16 | 'd'<<24
	FeatureTagQwid         FeatureTag = 'q' | 'w'<<8 | 'i'<<16 | 'd'<<24
	FeatureTagRand         FeatureTag = 'r' | 'a'<<8 | 'n'<<16 | 'd'<<24
	FeatureTagRclt         FeatureTag = 'r' | 'c'<<8 | 'l'<<16 | 't'<<24
	FeatureTagRkrf         FeatureTag = 'r' | 'k'<<8 | 'r'<<16 | 'f'<<24
	FeatureTagRlig         FeatureTag = 'r' | 'l'<<8 | 'i'<<16 | 'g'<<24
	FeatureTagRtbd         FeatureTag = 'r' | 't'<<8 | 'b'<<16 | 'd'<<24
	FeatureTagRtla         FeatureTag = 'r' | 't'<<8 | 'l'<<16 | 'a'<<24
	FeatureTagRtlm         FeatureTag = 'r' | 't'<<8 | 'l'<<16 | 'm'<<24
	FeatureTagRuby         FeatureTag = 'r' | 'u'<<8 | 'b'<<16 | 'y'<<24
	FeatureTagRvrn         FeatureTag = 'r' | 'v'<<8 | 'r'<<16 | 'n'<<24
	FeatureTagSalt         FeatureTag = 's' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagSinf         FeatureTag = 's' | 'i'<<8 | 'n'<<16 | 'f'<<24
	FeatureTagSize         FeatureTag = 's' | 'i'<<8 | 'z'<<16 | 'e'<<24
	FeatureTagSmcp         FeatureTag = 's' | 'm'<<8 | 'c'<<16 | 'p'<<24
	FeatureTagSmpl         FeatureTag = 's' | 'm'<<8 | 'p'<<16 | 'l'<<24
	FeatureTagSs01         FeatureTag = 's' | 's'<<8 | '0'<<16 | '1'<<24
	FeatureTagSs02         FeatureTag = 's' | 's'<<8 | '0'<<16 | '2'<<24
	FeatureTagSs03         FeatureTag = 's' | 's'<<8 | '0'<<16 | '3'<<24
	FeatureTagSs04         FeatureTag = 's' | 's'<<8 | '0'<<16 | '4'<<24
	FeatureTagSs05         FeatureTag = 's' | 's'<<8 | '0'<<16 | '5'<<24
	FeatureTagSs06         FeatureTag = 's' | 's'<<8 | '0'<<16 | '6'<<24
	FeatureTagSs07         FeatureTag = 's' | 's'<<8 | '0'<<16 | '7'<<24
	FeatureTagSs08         FeatureTag = 's' | 's'<<8 | '0'<<16 | '8'<<24
	FeatureTagSs09         FeatureTag = 's' | 's'<<8 | '0'<<16 | '9'<<24
	FeatureTagSs10         FeatureTag = 's' | 's'<<8 | '1'<<16 | '0'<<24
	FeatureTagSs11         FeatureTag = 's' | 's'<<8 | '1'<<16 | '1'<<24
	FeatureTagSs12         FeatureTag = 's' | 's'<<8 | '1'<<16 | '2'<<24
	FeatureTagSs13         FeatureTag = 's' | 's'<<8 | '1'<<16 | '3'<<24
	FeatureTagSs14         FeatureTag = 's' | 's'<<8 | '1'<<16 | '4'<<24
	FeatureTagSs15         FeatureTag = 's' | 's'<<8 | '1'<<16 | '5'<<24
	FeatureTagSs16         FeatureTag = 's' | 's'<<8 | '1'<<16 | '6'<<24
	FeatureTagSs17         FeatureTag = 's' | 's'<<8 | '1'<<16 | '7'<<24
	FeatureTagSs18         FeatureTag = 's' | 's'<<8 | '1'<<16 | '8'<<24
	FeatureTagSs19         FeatureTag = 's' | 's'<<8 | '1'<<16 | '9'<<24
	FeatureTagSs20         FeatureTag = 's' | 's'<<8 | '2'<<16 | '0'<<24
	FeatureTagSsty         FeatureTag = 's' | 's'<<8 | 't'<<16 | 'y'<<24
	FeatureTagStch         FeatureTag = 's' | 't'<<8 | 'c'<<16 | 'h'<<24
	FeatureTagSubs         FeatureTag = 's' | 'u'<<8 | 'b'<<16 | 's'<<24
	FeatureTagSups         FeatureTag = 's' | 'u'<<8 | 'p'<<16 | 's'<<24
	FeatureTagSwsh         FeatureTag = 's' | 'w'<<8 | 's'<<16 | 'h'<<24
	FeatureTagTest         FeatureTag = 't' | 'e'<<8 | 's'<<16 | 't'<<24
	FeatureTagTitl         FeatureTag = 't' | 'i'<<8 | 't'<<16 | 'l'<<24
	FeatureTagTnam         FeatureTag = 't' | 'n'<<8 | 'a'<<16 | 'm'<<24
	FeatureTagTnum         FeatureTag = 't' | 'n'<<8 | 'u'<<16 | 'm'<<24
	FeatureTagTrad         FeatureTag = 't' | 'r'<<8 | 'a'<<16 | 'd'<<24
	FeatureTagTwid         FeatureTag = 't' | 'w'<<8 | 'i'<<16 | 'd'<<24
	FeatureTagUnic         FeatureTag = 'u' | 'n'<<8 | 'i'<<16 | 'c'<<24
	FeatureTagValt         FeatureTag = 'v' | 'a'<<8 | 'l'<<16 | 't'<<24
	FeatureTagVapk         FeatureTag = 'v' | 'a'<<8 | 'p'<<16 | 'k'<<24
	FeatureTagVatu         FeatureTag = 'v' | 'a'<<8 | 't'<<16 | 'u'<<24
	FeatureTagVchw         FeatureTag = 'v' | 'c'<<8 | 'h'<<16 | 'w'<<24
	FeatureTagVert         FeatureTag = 'v' | 'e'<<8 | 'r'<<16 | 't'<<24
	FeatureTagVhal         FeatureTag = 'v' | 'h'<<8 | 'a'<<16 | 'l'<<24
	FeatureTagVkna         FeatureTag = 'v' | 'k'<<8 | 'n'<<16 | 'a'<<24
	FeatureTagVkrn         FeatureTag = 'v' | 'k'<<8 | 'r'<<16 | 'n'<<24
	FeatureTagVpal         FeatureTag = 'v' | 'p'<<8 | 'a'<<16 | 'l'<<24
	FeatureTagVrt2         FeatureTag = 'v' | 'r'<<8 | 't'<<16 | '2'<<24
	FeatureTagVrtr         FeatureTag = 'v' | 'r'<<8 | 't'<<16 | 'r'<<24
	FeatureTagZero         FeatureTag = 'z' | 'e'<<8 | 'r'<<16 | 'o'<<24
)

type Font 

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

Font is a parsed font resource. Create with FontFromMemory.

func FontFromMemory 

func FontFromMemory(data []byte, fontIndex int) (*Font, error)

FontFromMemory parses a font from raw TTF/OTF/TTC bytes. fontIndex selects which font in a TTC/OTC collection (0-based). For single .ttf/.otf files, use 0.

func (*Font) GlyphAdvance 

func (f *Font) GlyphAdvance(glyphID uint16) int32

GlyphAdvance returns the horizontal advance width for a glyph ID in font units. Returns 0 if the glyph ID is invalid or the font lacks horizontal metrics.

func (*Font) GlyphBounds 

func (f *Font) GlyphBounds(glyphID uint16) (xMin, yMin, xMax, yMax int16)

GlyphBounds returns the bounding box of a glyph in font units. Returns zeros if the glyph has no outline (e.g., space) or the glyph ID is invalid.

func (*Font) GlyphID 

func (f *Font) GlyphID(codepoint rune) uint16

GlyphID returns the glyph index for a codepoint via the font's cmap table. Returns 0 (.notdef) if the codepoint is not mapped or the font is invalid.

func (*Font) GlyphOutline 

func (f *Font) GlyphOutline(dst []Segment, glyphID uint16) []Segment

GlyphOutline appends the outline path segments for glyphID to dst. Coordinates are in font units with Y-up convention. For composite glyphs, components are recursively flattened. Returns dst unchanged if the glyph has no outline (e.g., space).

func (*Font) Info 

func (f *Font) Info() FontInfo

Info returns metadata about the font. Returns zero FontInfo if the font is invalid.

func (*Font) IsValid 

func (f *Font) IsValid() bool

IsValid reports whether the font was successfully parsed.

type FontInfo 

type FontInfo struct {
	Family, Subfamily    string
	FullName             string
	PostScriptName       string
	Copyright, Version   string
	Manufacturer         string
	TypographicFamily    string
	TypographicSubfamily string
	StyleFlags           FontStyleFlags
	Weight               FontWeight
	Width                FontWidth
	// Font metrics (from head, hhea, OS/2 tables).
	UnitsPerEm             uint16
	XMin, YMin, XMax, YMax int16
	Ascent, Descent        int16
	LineGap                int16
	CapHeight              int16
}

FontInfo holds metadata about a loaded font.

type FontStyleFlags 

type FontStyleFlags uint8

FontStyleFlags is a bitfield for font style information. 

const (
	FontStyleRegular FontStyleFlags = 0
	FontStyleBold    FontStyleFlags = 1 << iota
	FontStyleItalic
)

type FontWeight 

type FontWeight uint8

FontWeight represents the weight of a font. 

const (
	FontWeightUnknown FontWeight = iota
	FontWeightThin
	FontWeightExtraLight
	FontWeightLight
	FontWeightNormal
	FontWeightMedium
	FontWeightSemiBold
	FontWeightBold
	FontWeightExtraBold
	FontWeightBlack
)

type FontWidth 

type FontWidth uint8

FontWidth represents the width/stretch of a font. 

const (
	FontWidthUnknown FontWidth = iota
	FontWidthUltraCondensed
	FontWidthExtraCondensed
	FontWidthCondensed
	FontWidthSemiCondensed
	FontWidthNormal
	FontWidthSemiExpanded
	FontWidthExpanded
	FontWidthExtraExpanded
	FontWidthUltraExpanded
)

type Glyph 

type Glyph struct {
	Codepoint rune
	ID        uint16 // Glyph index in font
	UserID    int    // User-assigned or auto-assigned tracking index

	OffsetX, OffsetY   int32 // GPOS positioning offset
	AdvanceX, AdvanceY int32 // Advance to next glyph

	Flags GlyphFlags
	// contains filtered or unexported fields
}

Glyph is the output of text shaping: a positioned glyph ready for rasterization.

type GlyphFlags 

type GlyphFlags uint32

GlyphFlags is a bitfield for glyph shaping properties. 

const (
	GlyphFlagIsol                 GlyphFlags = 1 << iota // Isolated form (Arabic)
	GlyphFlagFina                                        // Final form (Arabic)
	GlyphFlagFin2                                        // Terminal form #2
	GlyphFlagFin3                                        // Terminal form #3
	GlyphFlagMedi                                        // Medial form (Arabic)
	GlyphFlagMed2                                        // Medial form #2
	GlyphFlagInit                                        // Initial form (Arabic)
	GlyphFlagLJMO                                        // Leading Jamo (Hangul)
	GlyphFlagVJMO                                        // Vowel Jamo (Hangul)
	GlyphFlagTJMO                                        // Trailing Jamo (Hangul)
	GlyphFlagRPHF                                        // Reph form (Indic)
	GlyphFlagBLWF                                        // Below-base form (Indic)
	GlyphFlagHALF                                        // Half form (Indic)
	GlyphFlagPSTF                                        // Post-base form (Indic)
	GlyphFlagABVF                                        // Above-base form (Indic)
	GlyphFlagPREF                                        // Pre-base form (Indic)
	GlyphFlagNUMR                                        // Numerator (fraction)
	GlyphFlagFRAC                                        // Fraction
	GlyphFlagDNOM                                        // Denominator (fraction)
	GlyphFlagCFAR                                        // Conjunct form after Ro
	GlyphFlagDoNotDecompose                              // Glyph should not be decomposed
	GlyphFlagFirstInMultiple                             // First glyph in multiple substitution
	GlyphFlagNoBreak                                     // Do not break at this glyph
	GlyphFlagCursive                                     // Cursive attachment
	GlyphFlagGeneratedByGSUB                             // Generated by GSUB substitution
	GlyphFlagUsedInGPOS                                  // Used in GPOS positioning
	GlyphFlagSTCHEndpoint                                // Stretch endpoint
	GlyphFlagSTCHExtension                               // Stretch extension
	GlyphFlagLigature                                    // Ligature glyph
	GlyphFlagMultipleSubstitution                        // Result of multiple substitution
)

func (GlyphFlags) Has 

func (f GlyphFlags) Has(flag GlyphFlags) bool

Has returns true if f contains all bits in flag.

type JapaneseLineBreakStyle 

type JapaneseLineBreakStyle uint8

JapaneseLineBreakStyle controls kinsoku rules for Japanese text. 

const (
	JapaneseLineBreakStrict JapaneseLineBreakStyle = iota
	JapaneseLineBreakNormal
	JapaneseLineBreakLoose
)

type Run 

type Run struct {
	Font               *Font
	Script             Script
	Direction          Direction
	ParagraphDirection Direction
	Flags              BreakFlags
	Glyphs             []Glyph
}

Run is a contiguous sequence of shaped glyphs with uniform properties.

type Script 

type Script uint8

Script identifies a Unicode script (e.g., Latin, Arabic, Devanagari). 

const (
	ScriptUnknown Script = iota
	ScriptAdlam
	ScriptAhom
	ScriptAnatolianHieroglyphs
	ScriptArabic
	ScriptArmenian
	ScriptAvestan
	ScriptBalinese
	ScriptBamum
	ScriptBassaVah
	ScriptBatak
	ScriptBengali
	ScriptBhaiksuki
	ScriptBopomofo
	ScriptBrahmi
	ScriptBuginese
	ScriptBuhid
	ScriptCanadianSyllabics
	ScriptCarian
	ScriptCaucasianAlbanian
	ScriptChakma
	ScriptCham
	ScriptCherokee
	ScriptChorasmian
	ScriptCJKIdeographic
	ScriptCoptic
	ScriptCypriotSyllabary
	ScriptCyproMinoan
	ScriptCyrillic
	ScriptDefault
	ScriptDefault2
	ScriptDeseret
	ScriptDevanagari
	ScriptDivesAkuru
	ScriptDogra
	ScriptDuployan
	ScriptEgyptianHieroglyphs
	ScriptElbasan
	ScriptElymaic
	ScriptEthiopic
	ScriptGaray
	ScriptGeorgian
	ScriptGlagolitic
	ScriptGothic
	ScriptGrantha
	ScriptGreek
	ScriptGujarati
	ScriptGunjalaGondi
	ScriptGurmukhi
	ScriptGurungKhema
	ScriptHangul
	ScriptHanifiRohingya
	ScriptHanunoo
	ScriptHatran
	ScriptHebrew
	ScriptHiragana
	ScriptImperialAramaic
	ScriptInscriptionalPahlavi
	ScriptInscriptionalParthian
	ScriptJavanese
	ScriptKaithi
	ScriptKannada
	ScriptKatakana
	ScriptKawi
	ScriptKayahLi
	ScriptKharoshthi
	ScriptKhitanSmallScript
	ScriptKhmer
	ScriptKhojki
	ScriptKhudawadi
	ScriptKiratRai
	ScriptLao
	ScriptLatin
	ScriptLepcha
	ScriptLimbu
	ScriptLinearA
	ScriptLinearB
	ScriptLisu
	ScriptLycian
	ScriptLydian
	ScriptMahajani
	ScriptMakasar
	ScriptMalayalam
	ScriptMandaic
	ScriptManichaean
	ScriptMarchen
	ScriptMasaramGondi
	ScriptMedefaidrin
	ScriptMeeteiMayek
	ScriptMendeKikakui
	ScriptMeroiticCursive
	ScriptMeroiticHieroglyphs
	ScriptMiao
	ScriptModi
	ScriptMongolian
	ScriptMro
	ScriptMultani
	ScriptMyanmar
	ScriptNabataean
	ScriptNagMundari
	ScriptNandinagari
	ScriptNewa
	ScriptNewTaiLue
	ScriptNKo
	ScriptNushu
	ScriptNyiakengPuachueHmong
	ScriptOgham
	ScriptOlChiki
	ScriptOlOnal
	ScriptOldItalic
	ScriptOldHungarian
	ScriptOldNorthArabian
	ScriptOldPermic
	ScriptOldPersianCuneiform
	ScriptOldSogdian
	ScriptOldSouthArabian
	ScriptOldTurkic
	ScriptOldUyghur
	ScriptOdia
	ScriptOsage
	ScriptOsmanya
	ScriptPahawhHmong
	ScriptPalmyrene
	ScriptPauCinHau
	ScriptPhagsPa
	ScriptPhoenician
	ScriptPsalterPahlavi
	ScriptRejang
	ScriptRunic
	ScriptSamaritan
	ScriptSaurashtra
	ScriptSharada
	ScriptShavian
	ScriptSiddham
	ScriptSignWriting
	ScriptSogdian
	ScriptSinhala
	ScriptSoraSompeng
	ScriptSoyombo
	ScriptSumeroAkkadianCuneiform
	ScriptSundanese
	ScriptSunuwar
	ScriptSylotiNagri
	ScriptSyriac
	ScriptTagalog
	ScriptTagbanwa
	ScriptTaiLe
	ScriptTaiTham
	ScriptTaiViet
	ScriptTakri
	ScriptTamil
	ScriptTangsa
	ScriptTangut
	ScriptTelugu
	ScriptThaana
	ScriptThai
	ScriptTibetan
	ScriptTifinagh
	ScriptTirhuta
	ScriptTodhri
	ScriptToto
	ScriptTuluTigalari
	ScriptUgariticCuneiform
	ScriptVai
	ScriptVithkuqi
	ScriptWancho
	ScriptWarangCiti
	ScriptYezidi
	ScriptYi
	ScriptZanabazarSquare
)

func (Script) Direction 

func (s Script) Direction() Direction

Direction returns the natural text direction for this script (LTR or RTL).

func (Script) IsComplex 

func (s Script) IsComplex() bool

IsComplex reports whether this script requires a complex shaping engine.

func (Script) Shaper 

func (s Script) Shaper() Shaper

Shaper returns the shaping engine required for this script.

func (Script) String 

func (s Script) String() string

String returns the four-character ISO 15924 script tag (e.g., "latn", "arab").

func (Script) Tag 

func (s Script) Tag() ScriptTag

Tag returns the ISO 15924 four-character tag for this script.

type ScriptTag 

type ScriptTag uint32

ScriptTag is a four-character ISO 15924 script identifier stored as a little-endian uint32. 

const (
	ScriptTagUnknown                 ScriptTag = ' ' | ' '<<8 | ' '<<16 | ' '<<24
	ScriptTagAdlam                   ScriptTag = 'a' | 'd'<<8 | 'l'<<16 | 'm'<<24
	ScriptTagAhom                    ScriptTag = 'a' | 'h'<<8 | 'o'<<16 | 'm'<<24
	ScriptTagAnatolianHieroglyphs    ScriptTag = 'h' | 'l'<<8 | 'u'<<16 | 'w'<<24
	ScriptTagArabic                  ScriptTag = 'a' | 'r'<<8 | 'a'<<16 | 'b'<<24
	ScriptTagArmenian                ScriptTag = 'a' | 'r'<<8 | 'm'<<16 | 'n'<<24
	ScriptTagAvestan                 ScriptTag = 'a' | 'v'<<8 | 's'<<16 | 't'<<24
	ScriptTagBalinese                ScriptTag = 'b' | 'a'<<8 | 'l'<<16 | 'i'<<24
	ScriptTagBamum                   ScriptTag = 'b' | 'a'<<8 | 'm'<<16 | 'u'<<24
	ScriptTagBassaVah                ScriptTag = 'b' | 'a'<<8 | 's'<<16 | 's'<<24
	ScriptTagBatak                   ScriptTag = 'b' | 'a'<<8 | 't'<<16 | 'k'<<24
	ScriptTagBengali                 ScriptTag = 'b' | 'n'<<8 | 'g'<<16 | '2'<<24
	ScriptTagBhaiksuki               ScriptTag = 'b' | 'h'<<8 | 'k'<<16 | 's'<<24
	ScriptTagBopomofo                ScriptTag = 'b' | 'o'<<8 | 'p'<<16 | 'o'<<24
	ScriptTagBrahmi                  ScriptTag = 'b' | 'r'<<8 | 'a'<<16 | 'h'<<24
	ScriptTagBuginese                ScriptTag = 'b' | 'u'<<8 | 'g'<<16 | 'i'<<24
	ScriptTagBuhid                   ScriptTag = 'b' | 'u'<<8 | 'h'<<16 | 'd'<<24
	ScriptTagCanadianSyllabics       ScriptTag = 'c' | 'a'<<8 | 'n'<<16 | 's'<<24
	ScriptTagCarian                  ScriptTag = 'c' | 'a'<<8 | 'r'<<16 | 'i'<<24
	ScriptTagCaucasianAlbanian       ScriptTag = 'a' | 'g'<<8 | 'h'<<16 | 'b'<<24
	ScriptTagChakma                  ScriptTag = 'c' | 'a'<<8 | 'k'<<16 | 'm'<<24
	ScriptTagCham                    ScriptTag = 'c' | 'h'<<8 | 'a'<<16 | 'm'<<24
	ScriptTagCherokee                ScriptTag = 'c' | 'h'<<8 | 'e'<<16 | 'r'<<24
	ScriptTagChorasmian              ScriptTag = 'c' | 'h'<<8 | 'r'<<16 | 's'<<24
	ScriptTagCJKIdeographic          ScriptTag = 'h' | 'a'<<8 | 'n'<<16 | 'i'<<24
	ScriptTagCoptic                  ScriptTag = 'c' | 'o'<<8 | 'p'<<16 | 't'<<24
	ScriptTagCypriotSyllabary        ScriptTag = 'c' | 'p'<<8 | 'r'<<16 | 't'<<24
	ScriptTagCyproMinoan             ScriptTag = 'c' | 'p'<<8 | 'm'<<16 | 'n'<<24
	ScriptTagCyrillic                ScriptTag = 'c' | 'y'<<8 | 'r'<<16 | 'l'<<24
	ScriptTagDefault                 ScriptTag = 'D' | 'F'<<8 | 'L'<<16 | 'T'<<24
	ScriptTagDefault2                ScriptTag = 'D' | 'F'<<8 | 'L'<<16 | 'T'<<24
	ScriptTagDeseret                 ScriptTag = 'd' | 's'<<8 | 'r'<<16 | 't'<<24
	ScriptTagDevanagari              ScriptTag = 'd' | 'e'<<8 | 'v'<<16 | '2'<<24
	ScriptTagDivesAkuru              ScriptTag = 'd' | 'i'<<8 | 'a'<<16 | 'k'<<24
	ScriptTagDogra                   ScriptTag = 'd' | 'o'<<8 | 'g'<<16 | 'r'<<24
	ScriptTagDuployan                ScriptTag = 'd' | 'u'<<8 | 'p'<<16 | 'l'<<24
	ScriptTagEgyptianHieroglyphs     ScriptTag = 'e' | 'g'<<8 | 'y'<<16 | 'p'<<24
	ScriptTagElbasan                 ScriptTag = 'e' | 'l'<<8 | 'b'<<16 | 'a'<<24
	ScriptTagElymaic                 ScriptTag = 'e' | 'l'<<8 | 'y'<<16 | 'm'<<24
	ScriptTagEthiopic                ScriptTag = 'e' | 't'<<8 | 'h'<<16 | 'i'<<24
	ScriptTagGaray                   ScriptTag = 'g' | 'a'<<8 | 'r'<<16 | 'a'<<24
	ScriptTagGeorgian                ScriptTag = 'g' | 'e'<<8 | 'o'<<16 | 'r'<<24
	ScriptTagGlagolitic              ScriptTag = 'g' | 'l'<<8 | 'a'<<16 | 'g'<<24
	ScriptTagGothic                  ScriptTag = 'g' | 'o'<<8 | 't'<<16 | 'h'<<24
	ScriptTagGrantha                 ScriptTag = 'g' | 'r'<<8 | 'a'<<16 | 'n'<<24
	ScriptTagGreek                   ScriptTag = 'g' | 'r'<<8 | 'e'<<16 | 'k'<<24
	ScriptTagGujarati                ScriptTag = 'g' | 'j'<<8 | 'r'<<16 | '2'<<24
	ScriptTagGunjalaGondi            ScriptTag = 'g' | 'o'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagGurmukhi                ScriptTag = 'g' | 'u'<<8 | 'r'<<16 | '2'<<24
	ScriptTagGurungKhema             ScriptTag = 'g' | 'u'<<8 | 'k'<<16 | 'h'<<24
	ScriptTagHangul                  ScriptTag = 'h' | 'a'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagHanifiRohingya          ScriptTag = 'r' | 'o'<<8 | 'h'<<16 | 'g'<<24
	ScriptTagHanunoo                 ScriptTag = 'h' | 'a'<<8 | 'n'<<16 | 'o'<<24
	ScriptTagHatran                  ScriptTag = 'h' | 'a'<<8 | 't'<<16 | 'r'<<24
	ScriptTagHebrew                  ScriptTag = 'h' | 'e'<<8 | 'b'<<16 | 'r'<<24
	ScriptTagHiragana                ScriptTag = 'k' | 'a'<<8 | 'n'<<16 | 'a'<<24
	ScriptTagImperialAramaic         ScriptTag = 'a' | 'r'<<8 | 'm'<<16 | 'i'<<24
	ScriptTagInscriptionalPahlavi    ScriptTag = 'p' | 'h'<<8 | 'l'<<16 | 'i'<<24
	ScriptTagInscriptionalParthian   ScriptTag = 'p' | 'r'<<8 | 't'<<16 | 'i'<<24
	ScriptTagJavanese                ScriptTag = 'j' | 'a'<<8 | 'v'<<16 | 'a'<<24
	ScriptTagKaithi                  ScriptTag = 'k' | 't'<<8 | 'h'<<16 | 'i'<<24
	ScriptTagKannada                 ScriptTag = 'k' | 'n'<<8 | 'd'<<16 | '2'<<24
	ScriptTagKatakana                ScriptTag = 'k' | 'a'<<8 | 'n'<<16 | 'a'<<24
	ScriptTagKawi                    ScriptTag = 'k' | 'a'<<8 | 'w'<<16 | 'i'<<24
	ScriptTagKayahLi                 ScriptTag = 'k' | 'a'<<8 | 'l'<<16 | 'i'<<24
	ScriptTagKharoshthi              ScriptTag = 'k' | 'h'<<8 | 'a'<<16 | 'r'<<24
	ScriptTagKhitanSmallScript       ScriptTag = 'k' | 'i'<<8 | 't'<<16 | 's'<<24
	ScriptTagKhmer                   ScriptTag = 'k' | 'h'<<8 | 'm'<<16 | 'r'<<24
	ScriptTagKhojki                  ScriptTag = 'k' | 'h'<<8 | 'o'<<16 | 'j'<<24
	ScriptTagKhudawadi               ScriptTag = 's' | 'i'<<8 | 'n'<<16 | 'd'<<24
	ScriptTagKiratRai                ScriptTag = 'k' | 'r'<<8 | 'a'<<16 | 'i'<<24
	ScriptTagLao                     ScriptTag = 'l' | 'a'<<8 | 'o'<<16 | ' '<<24
	ScriptTagLatin                   ScriptTag = 'l' | 'a'<<8 | 't'<<16 | 'n'<<24
	ScriptTagLepcha                  ScriptTag = 'l' | 'e'<<8 | 'p'<<16 | 'c'<<24
	ScriptTagLimbu                   ScriptTag = 'l' | 'i'<<8 | 'm'<<16 | 'b'<<24
	ScriptTagLinearA                 ScriptTag = 'l' | 'i'<<8 | 'n'<<16 | 'a'<<24
	ScriptTagLinearB                 ScriptTag = 'l' | 'i'<<8 | 'n'<<16 | 'b'<<24
	ScriptTagLisu                    ScriptTag = 'l' | 'i'<<8 | 's'<<16 | 'u'<<24
	ScriptTagLycian                  ScriptTag = 'l' | 'y'<<8 | 'c'<<16 | 'i'<<24
	ScriptTagLydian                  ScriptTag = 'l' | 'y'<<8 | 'd'<<16 | 'i'<<24
	ScriptTagMahajani                ScriptTag = 'm' | 'a'<<8 | 'h'<<16 | 'j'<<24
	ScriptTagMakasar                 ScriptTag = 'm' | 'a'<<8 | 'k'<<16 | 'a'<<24
	ScriptTagMalayalam               ScriptTag = 'm' | 'l'<<8 | 'm'<<16 | '2'<<24
	ScriptTagMandaic                 ScriptTag = 'm' | 'a'<<8 | 'n'<<16 | 'd'<<24
	ScriptTagManichaean              ScriptTag = 'm' | 'a'<<8 | 'n'<<16 | 'i'<<24
	ScriptTagMarchen                 ScriptTag = 'm' | 'a'<<8 | 'r'<<16 | 'c'<<24
	ScriptTagMasaramGondi            ScriptTag = 'g' | 'o'<<8 | 'n'<<16 | 'm'<<24
	ScriptTagMedefaidrin             ScriptTag = 'm' | 'e'<<8 | 'd'<<16 | 'f'<<24
	ScriptTagMeeteiMayek             ScriptTag = 'm' | 't'<<8 | 'e'<<16 | 'i'<<24
	ScriptTagMendeKikakui            ScriptTag = 'm' | 'e'<<8 | 'n'<<16 | 'd'<<24
	ScriptTagMeroiticCursive         ScriptTag = 'm' | 'e'<<8 | 'r'<<16 | 'c'<<24
	ScriptTagMeroiticHieroglyphs     ScriptTag = 'm' | 'e'<<8 | 'r'<<16 | 'o'<<24
	ScriptTagMiao                    ScriptTag = 'p' | 'l'<<8 | 'r'<<16 | 'd'<<24
	ScriptTagModi                    ScriptTag = 'm' | 'o'<<8 | 'd'<<16 | 'i'<<24
	ScriptTagMongolian               ScriptTag = 'm' | 'o'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagMro                     ScriptTag = 'm' | 'r'<<8 | 'o'<<16 | 'o'<<24
	ScriptTagMultani                 ScriptTag = 'm' | 'u'<<8 | 'l'<<16 | 't'<<24
	ScriptTagMyanmar                 ScriptTag = 'm' | 'y'<<8 | 'm'<<16 | '2'<<24
	ScriptTagNabataean               ScriptTag = 'n' | 'b'<<8 | 'a'<<16 | 't'<<24
	ScriptTagNagMundari              ScriptTag = 'n' | 'a'<<8 | 'g'<<16 | 'm'<<24
	ScriptTagNandinagari             ScriptTag = 'n' | 'a'<<8 | 'n'<<16 | 'd'<<24
	ScriptTagNewa                    ScriptTag = 'n' | 'e'<<8 | 'w'<<16 | 'a'<<24
	ScriptTagNewTaiLue               ScriptTag = 't' | 'a'<<8 | 'l'<<16 | 'u'<<24
	ScriptTagNKo                     ScriptTag = 'n' | 'k'<<8 | 'o'<<16 | ' '<<24
	ScriptTagNushu                   ScriptTag = 'n' | 's'<<8 | 'h'<<16 | 'u'<<24
	ScriptTagNyiakengPuachueHmong    ScriptTag = 'h' | 'm'<<8 | 'n'<<16 | 'p'<<24
	ScriptTagOgham                   ScriptTag = 'o' | 'g'<<8 | 'a'<<16 | 'm'<<24
	ScriptTagOlChiki                 ScriptTag = 'o' | 'l'<<8 | 'c'<<16 | 'k'<<24
	ScriptTagOlOnal                  ScriptTag = 'o' | 'n'<<8 | 'a'<<16 | 'o'<<24
	ScriptTagOldItalic               ScriptTag = 'i' | 't'<<8 | 'a'<<16 | 'l'<<24
	ScriptTagOldHungarian            ScriptTag = 'h' | 'u'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagOldNorthArabian         ScriptTag = 'n' | 'a'<<8 | 'r'<<16 | 'b'<<24
	ScriptTagOldPermic               ScriptTag = 'p' | 'e'<<8 | 'r'<<16 | 'm'<<24
	ScriptTagOldPersianCuneiform     ScriptTag = 'x' | 'p'<<8 | 'e'<<16 | 'o'<<24
	ScriptTagOldSogdian              ScriptTag = 's' | 'o'<<8 | 'g'<<16 | 'o'<<24
	ScriptTagOldSouthArabian         ScriptTag = 's' | 'a'<<8 | 'r'<<16 | 'b'<<24
	ScriptTagOldTurkic               ScriptTag = 'o' | 'r'<<8 | 'k'<<16 | 'h'<<24
	ScriptTagOldUyghur               ScriptTag = 'o' | 'u'<<8 | 'g'<<16 | 'r'<<24
	ScriptTagOdia                    ScriptTag = 'o' | 'r'<<8 | 'y'<<16 | '2'<<24
	ScriptTagOsage                   ScriptTag = 'o' | 's'<<8 | 'g'<<16 | 'e'<<24
	ScriptTagOsmanya                 ScriptTag = 'o' | 's'<<8 | 'm'<<16 | 'a'<<24
	ScriptTagPahawhHmong             ScriptTag = 'h' | 'm'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagPalmyrene               ScriptTag = 'p' | 'a'<<8 | 'l'<<16 | 'm'<<24
	ScriptTagPauCinHau               ScriptTag = 'p' | 'a'<<8 | 'u'<<16 | 'c'<<24
	ScriptTagPhagsPa                 ScriptTag = 'p' | 'h'<<8 | 'a'<<16 | 'g'<<24
	ScriptTagPhoenician              ScriptTag = 'p' | 'h'<<8 | 'n'<<16 | 'x'<<24
	ScriptTagPsalterPahlavi          ScriptTag = 'p' | 'h'<<8 | 'l'<<16 | 'p'<<24
	ScriptTagRejang                  ScriptTag = 'r' | 'j'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagRunic                   ScriptTag = 'r' | 'u'<<8 | 'n'<<16 | 'r'<<24
	ScriptTagSamaritan               ScriptTag = 's' | 'a'<<8 | 'm'<<16 | 'r'<<24
	ScriptTagSaurashtra              ScriptTag = 's' | 'a'<<8 | 'u'<<16 | 'r'<<24
	ScriptTagSharada                 ScriptTag = 's' | 'h'<<8 | 'r'<<16 | 'd'<<24
	ScriptTagShavian                 ScriptTag = 's' | 'h'<<8 | 'a'<<16 | 'w'<<24
	ScriptTagSiddham                 ScriptTag = 's' | 'i'<<8 | 'd'<<16 | 'd'<<24
	ScriptTagSignWriting             ScriptTag = 's' | 'g'<<8 | 'n'<<16 | 'w'<<24
	ScriptTagSogdian                 ScriptTag = 's' | 'o'<<8 | 'g'<<16 | 'd'<<24
	ScriptTagSinhala                 ScriptTag = 's' | 'i'<<8 | 'n'<<16 | 'h'<<24
	ScriptTagSoraSompeng             ScriptTag = 's' | 'o'<<8 | 'r'<<16 | 'a'<<24
	ScriptTagSoyombo                 ScriptTag = 's' | 'o'<<8 | 'y'<<16 | 'o'<<24
	ScriptTagSumeroAkkadianCuneiform ScriptTag = 'x' | 's'<<8 | 'u'<<16 | 'x'<<24
	ScriptTagSundanese               ScriptTag = 's' | 'u'<<8 | 'n'<<16 | 'd'<<24
	ScriptTagSunuwar                 ScriptTag = 's' | 'u'<<8 | 'n'<<16 | 'u'<<24
	ScriptTagSylotiNagri             ScriptTag = 's' | 'y'<<8 | 'l'<<16 | 'o'<<24
	ScriptTagSyriac                  ScriptTag = 's' | 'y'<<8 | 'r'<<16 | 'c'<<24
	ScriptTagTagalog                 ScriptTag = 't' | 'g'<<8 | 'l'<<16 | 'g'<<24
	ScriptTagTagbanwa                ScriptTag = 't' | 'a'<<8 | 'g'<<16 | 'b'<<24
	ScriptTagTaiLe                   ScriptTag = 't' | 'a'<<8 | 'l'<<16 | 'e'<<24
	ScriptTagTaiTham                 ScriptTag = 'l' | 'a'<<8 | 'n'<<16 | 'a'<<24
	ScriptTagTaiViet                 ScriptTag = 't' | 'a'<<8 | 'v'<<16 | 't'<<24
	ScriptTagTakri                   ScriptTag = 't' | 'a'<<8 | 'k'<<16 | 'r'<<24
	ScriptTagTamil                   ScriptTag = 't' | 'm'<<8 | 'l'<<16 | '2'<<24
	ScriptTagTangsa                  ScriptTag = 't' | 'n'<<8 | 's'<<16 | 'a'<<24
	ScriptTagTangut                  ScriptTag = 't' | 'a'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagTelugu                  ScriptTag = 't' | 'e'<<8 | 'l'<<16 | '2'<<24
	ScriptTagThaana                  ScriptTag = 't' | 'h'<<8 | 'a'<<16 | 'a'<<24
	ScriptTagThai                    ScriptTag = 't' | 'h'<<8 | 'a'<<16 | 'i'<<24
	ScriptTagTibetan                 ScriptTag = 't' | 'i'<<8 | 'b'<<16 | 't'<<24
	ScriptTagTifinagh                ScriptTag = 't' | 'f'<<8 | 'n'<<16 | 'g'<<24
	ScriptTagTirhuta                 ScriptTag = 't' | 'i'<<8 | 'r'<<16 | 'h'<<24
	ScriptTagTodhri                  ScriptTag = 't' | 'o'<<8 | 'd'<<16 | 'r'<<24
	ScriptTagToto                    ScriptTag = 't' | 'o'<<8 | 't'<<16 | 'o'<<24
	ScriptTagTuluTigalari            ScriptTag = 't' | 'u'<<8 | 't'<<16 | 'g'<<24
	ScriptTagUgariticCuneiform       ScriptTag = 'u' | 'g'<<8 | 'a'<<16 | 'r'<<24
	ScriptTagVai                     ScriptTag = 'v' | 'a'<<8 | 'i'<<16 | ' '<<24
	ScriptTagVithkuqi                ScriptTag = 'v' | 'i'<<8 | 't'<<16 | 'h'<<24
	ScriptTagWancho                  ScriptTag = 'w' | 'c'<<8 | 'h'<<16 | 'o'<<24
	ScriptTagWarangCiti              ScriptTag = 'w' | 'a'<<8 | 'r'<<16 | 'a'<<24
	ScriptTagYezidi                  ScriptTag = 'y' | 'e'<<8 | 'z'<<16 | 'i'<<24
	ScriptTagYi                      ScriptTag = 'y' | 'i'<<8 | ' '<<16 | ' '<<24
	ScriptTagZanabazarSquare         ScriptTag = 'z' | 'a'<<8 | 'n'<<16 | 'b'<<24
)

type Segment 

type Segment struct {
	Op     SegmentOp
	X, Y   int16 // Endpoint (font units)
	Cx, Cy int16 // Control point for QuadTo (unused for other ops)
}

Segment is one element of a glyph outline path. Coordinates are in font units with Y-up convention.

type SegmentOp 

type SegmentOp uint8

SegmentOp identifies a glyph outline path operation. 

const (
	SegmentMoveTo SegmentOp = iota // Start new contour at (X, Y)
	SegmentLineTo                  // Line to (X, Y)
	SegmentQuadTo                  // Quadratic bezier: control (Cx, Cy), endpoint (X, Y)
	SegmentClose                   // Close contour
)

type ShapeConfig 

type ShapeConfig struct {
	Font     *Font             // Font to shape with (required)
	Size     int32             // Font size in font units; 0 means use UnitsPerEm from font
	Features []FeatureOverride // OpenType feature overrides (e.g., disable ligatures)
}

ShapeConfig configures text shaping. The zero value uses default settings.

func (*ShapeConfig) Shape 

func (cfg *ShapeConfig) Shape(dst []Run, text string, breaks []Break) []Run

Shape shapes text into positioned glyph runs, appending results to dst. breaks is the segmentation output from a Breaker for the same text. Each run in the output corresponds to a segment of uniform script/direction. Returns dst unchanged if Font is nil or invalid.

func (*ShapeConfig) ShapeSimple 

func (cfg *ShapeConfig) ShapeSimple(dst []Run, text string, dir Direction) []Run

ShapeSimple segments and shapes text in one call. Equivalent to running a Breaker then calling Shape.

type ShapeError 

type ShapeError uint8

ShapeError represents errors during shaping. 

const (
	ShapeErrorNone ShapeError = iota
	ShapeErrorInvalidFont
	ShapeErrorTextBeforeBegin
	ShapeErrorOutOfMemory
)

func (ShapeError) Error 

func (e ShapeError) Error() string

Error implements the error interface.

type Shaper 

type Shaper uint8

Shaper identifies the script-specific shaping engine. 

const (
	ShaperDefault Shaper = iota
	ShaperArabic
	ShaperHangul
	ShaperHebrew
	ShaperIndic
	ShaperKhmer
	ShaperMyanmar
	ShaperTibetan
	ShaperUSE
)

func (Shaper) IsComplex 

func (s Shaper) IsComplex() bool

IsComplex returns true if this shaper requires complex shaping support.

func (Shaper) String 

func (s Shaper) String() string

String returns the shaper name.

Source Files

View all Source files

Directories

Path Synopsis
cmd
gentables command
Command gentables extracts Unicode property tables from kb_text_shape.h and generates Go source files.
 Command gentables extracts Unicode property tables from kb_text_shape.h and generates Go source files.
examples
font command
Example font demonstrates the kbts font parsing APIs.
 Example font demonstrates the kbts font parsing APIs.
raster command
Example raster demonstrates CPU glyph rasterization with and without antialiasing, writing the result to a PNG image.
 Example raster demonstrates CPU glyph rasterization with and without antialiasing, writing the result to a PNG image.
segmentation command
Example segmentation demonstrates the kbts text segmentation APIs.
 Example segmentation demonstrates the kbts text segmentation APIs.
visual command
Example visual renders shaped text as an SVG with glyph outlines.
 Example visual renders shaped text as an SVG with glyph outlines.

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