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Package opentype

import "golang.org/x/image/font/opentype"
Overview
Index
Examples

Overview ▾

Package opentype implements a glyph rasterizer for TTF (TrueType Fonts) and OTF (OpenType Fonts).

This package provides a high-level API, centered on the NewFace function, implementing the golang.org/x/image/font.Face interface.

The sibling golang.org/x/image/font/sfnt package provides a low-level API.

func NewFace 

func NewFace(f *Font, opts *FaceOptions) (font.Face, error)

NewFace returns a new font.Face for the given Font.

If opts is nil, sensible defaults will be used.

▾ Example

Code:

const (
    width        = 72
    height       = 36
    startingDotX = 6
    startingDotY = 28
)

f, err := opentype.Parse(goitalic.TTF)
if err != nil {
    log.Fatalf("Parse: %v", err)
}
face, err := opentype.NewFace(f, &opentype.FaceOptions{
    Size:    32,
    DPI:     72,
    Hinting: font.HintingNone,
})
if err != nil {
    log.Fatalf("NewFace: %v", err)
}

dst := image.NewGray(image.Rect(0, 0, width, height))
d := font.Drawer{
    Dst:  dst,
    Src:  image.White,
    Face: face,
    Dot:  fixed.P(startingDotX, startingDotY),
}
fmt.Printf("The dot is at %v\n", d.Dot)
d.DrawString("jel")
fmt.Printf("The dot is at %v\n", d.Dot)
d.Src = image.NewUniform(color.Gray{0x7F})
d.DrawString("ly")
fmt.Printf("The dot is at %v\n", d.Dot)

const asciiArt = ".++8"
buf := make([]byte, 0, height*(width+1))
for y := 0; y < height; y++ {
    for x := 0; x < width; x++ {
        c := asciiArt[dst.GrayAt(x, y).Y>>6]
        if c != '.' {
            // No-op.
        } else if x == startingDotX-1 {
            c = ']'
        } else if y == startingDotY-1 {
            c = '_'
        }
        buf = append(buf, c)
    }
    buf = append(buf, '\n')
}
os.Stdout.Write(buf)

Output:

The dot is at {6:00 28:00}
The dot is at {41:32 28:00}
The dot is at {66:48 28:00}
.....]..................................................................
.....]..................................................................
.....]..................................................................
.....]..................................+++......+++....................
.....]........+++.......................888......+++....................
.....].......+88+......................+88+......+++....................
.....].......888+......................+88+.....+++.....................
.....].......888+......................+88+.....+++.....................
.....].................................888......+++.....................
.....].................................888......+++.....................
.....]....................++..........+88+......+++.....................
.....]......+88+.......+888888+.......+88+.....+++....+++..........++...
.....]......888......+888888888+......+88+.....+++....++++........+++...
.....]......888.....+888+...+888......888......+++.....+++........++....
.....].....+888....+888......+88+.....888......+++.....+++.......+++....
.....].....+88+....888.......+88+....+88+......+++.....+++......+++.....
.....].....+88+...+888.......+88+....+88+.....+++......+++......+++.....
.....].....888....888+++++++++88+....+88+.....+++......+++.....+++......
.....].....888....88888888888888+....888......+++......++++....++.......
.....]....+888...+88888888888888.....888......+++.......+++...+++.......
.....]....+88+...+888...............+888......+++.......+++..+++........
.....]....+88+...+888...............+88+.....+++........+++..+++........
.....]....888....+888...............+88+.....+++........+++.+++.........
.....]....888....+888...............888......+++........++++++..........
.....]...+888.....888+..............888......+++........++++++..........
.....]...+88+.....+8888+....++8.....888+.....++++........++++...........
.....]...+88+......+8888888888+.....+8888....+++++.......++++...........
_____]___888________+88888888++______+888_____++++_______+++____________
.....]...888...........+++.............++................+++............
.....]..+88+............................................+++.............
.....]..+88+...........................................+++..............
.....].+888............................................+++..............
....888888............................................+++...............
....88888............................................++++...............
....+++.................................................................
.....]..................................................................

type Collection

Collection is a collection of one or more fonts.

All of the Collection methods are safe to call concurrently. 

type Collection = sfnt.Collection

func ParseCollection 

func ParseCollection(src []byte) (*Collection, error)

ParseCollection parses an OpenType font collection, such as TTC or OTC data, from a []byte data source.

If passed data for a single font, a TTF or OTF instead of a TTC or OTC, it will return a collection containing 1 font.

func ParseCollectionReaderAt 

func ParseCollectionReaderAt(src io.ReaderAt) (*Collection, error)

ParseCollectionReaderAt parses an OpenType collection, such as TTC or OTC data, from an io.ReaderAt data source.

If passed data for a single font, a TTF or OTF instead of a TTC or OTC, it will return a collection containing 1 font.

type Face

Face implements the font.Face interface for Font values.

A Face is not safe to use concurrently. 

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

func (*Face) Close 

func (f *Face) Close() error

Close satisfies the font.Face interface.

func (*Face) Glyph 

func (f *Face) Glyph(dot fixed.Point26_6, r rune) (dr image.Rectangle, mask image.Image, maskp image.Point, advance fixed.Int26_6, ok bool)

Glyph satisfies the font.Face interface.

func (*Face) GlyphAdvance 

func (f *Face) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool)

GlyphAdvance satisfies the font.Face interface.

func (*Face) GlyphBounds 

func (f *Face) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool)

GlyphBounds satisfies the font.Face interface.

func (*Face) Kern 

func (f *Face) Kern(r0, r1 rune) fixed.Int26_6

Kern satisfies the font.Face interface.

func (*Face) Metrics 

func (f *Face) Metrics() font.Metrics

Metrics satisfies the font.Face interface.

type FaceOptions

FaceOptions describes the possible options given to NewFace when creating a new font.Face from a Font. 

type FaceOptions struct {
    Size    float64      // Size is the font size in points
    DPI     float64      // DPI is the dots per inch resolution
    Hinting font.Hinting // Hinting selects how to quantize a vector font's glyph nodes
}

type Font

Font is an OpenType font, also known as an SFNT font.

All of the Font methods are safe to call concurrently, as long as each call has a different *sfnt.Buffer (or nil).

The Font methods that don't take a *sfnt.Buffer argument are always safe to call concurrently. 

type Font = sfnt.Font

func Parse 

func Parse(src []byte) (*Font, error)

Parse parses an OpenType font, such as TTF or OTF data, from a []byte data source.

func ParseReaderAt 

func ParseReaderAt(src io.ReaderAt) (*Font, error)

ParseReaderAt parses an OpenType font, such as TTF or OTF data, from an io.ReaderAt data source.