ActiveGo 1.8Package sfnt
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var (
// ErrColoredGlyph indicates that the requested glyph is not a monochrome
// vector glyph, such as a colored (bitmap or vector) emoji glyph.
ErrColoredGlyph = errors.New("sfnt: colored glyph")
// ErrNotFound indicates that the requested value was not found.
ErrNotFound = errors.New("sfnt: not found")
)
type Buffer ¶
Buffer holds re-usable buffers that can reduce the total memory allocation of repeated Font method calls.
See the Font type's documentation comment for more details.
type Buffer struct {
// contains filtered or unexported fields
}
type Collection ¶
Collection is a collection of one or more fonts.
All of the Collection methods are safe to call concurrently.
type Collection struct {
// contains filtered or unexported fields
}
func ParseCollection ¶
func ParseCollection(src []byte) (*Collection, error)
ParseCollection parses an SFNT 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 SFNT 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.
func (*Collection) Font ¶
func (c *Collection) Font(i int) (*Font, error)
Font returns the i'th font in the collection.
func (*Collection) NumFonts ¶
func (c *Collection) NumFonts() int
NumFonts returns the number of fonts in the collection.
type Font ¶
Font is an SFNT font.
Many of its methods take a *Buffer argument, as re-using buffers can reduce the total memory allocation of repeated Font method calls, such as measuring and rasterizing every unique glyph in a string of text. If efficiency is not a concern, passing a nil *Buffer is valid, and implies using a temporary buffer for a single call.
It is valid to re-use a *Buffer with multiple Font method calls, even with different *Font receivers, as long as they are not concurrent calls.
All of the Font methods are safe to call concurrently, as long as each call has a different *Buffer (or nil).
The Font methods that don't take a *Buffer argument are always safe to call concurrently.
Some methods provide lengths or coordinates, e.g. bounds, font metrics and control points. All of these methods take a ppem parameter, which is the number of pixels in 1 em, expressed as a 26.6 fixed point value. For example, if 1 em is 10 pixels then ppem is fixed.I(10), which equals fixed.Int26_6(10 << 6).
To get those lengths or coordinates in terms of font units instead of pixels, use ppem = fixed.Int26_6(f.UnitsPerEm()) and if those methods take a font.Hinting parameter, use font.HintingNone. The return values will have type fixed.Int26_6, but those numbers can be converted back to Units with no further scaling necessary.
type Font struct {
// contains filtered or unexported fields
}
func Parse ¶
func Parse(src []byte) (*Font, error)
Parse parses an SFNT font, such as TTF or OTF data, from a []byte data source.
func ParseReaderAt ¶
func ParseReaderAt(src io.ReaderAt) (*Font, error)
ParseReaderAt parses an SFNT font, such as TTF or OTF data, from an io.ReaderAt data source.
func (*Font) Bounds ¶
func (f *Font) Bounds(b *Buffer, ppem fixed.Int26_6, h font.Hinting) (fixed.Rectangle26_6, error)
Bounds returns the union of a Font's glyphs' bounds.
In the returned Rectangle26_6's (x, y) coordinates, the Y axis increases down.
func (*Font) GlyphAdvance ¶
func (f *Font) GlyphAdvance(b *Buffer, x GlyphIndex, ppem fixed.Int26_6, h font.Hinting) (fixed.Int26_6, error)
GlyphAdvance returns the advance width for the x'th glyph. ppem is the number of pixels in 1 em.
It returns ErrNotFound if the glyph index is out of range.
func (*Font) GlyphIndex ¶
func (f *Font) GlyphIndex(b *Buffer, r rune) (GlyphIndex, error)
GlyphIndex returns the glyph index for the given rune.
It returns (0, nil) if there is no glyph for r. https://www.microsoft.com/typography/OTSPEC/cmap.htm says that "Character codes that do not correspond to any glyph in the font should be mapped to glyph index 0. The glyph at this location must be a special glyph representing a missing character, commonly known as .notdef."
func (*Font) GlyphName ¶
func (f *Font) GlyphName(b *Buffer, x GlyphIndex) (string, error)
GlyphName returns the name of the x'th glyph.
Not every font contains glyph names. If not present, GlyphName will return ("", nil).
If present, the glyph name, provided by the font, is assumed to follow the Adobe Glyph List Specification: https://github.com/adobe-type-tools/agl-specification/blob/master/README.md
This is also known as the "Adobe Glyph Naming convention", the "Adobe document [for] Unicode and Glyph Names" or "PostScript glyph names".
It returns ErrNotFound if the glyph index is out of range.
func (*Font) Kern ¶
func (f *Font) Kern(b *Buffer, x0, x1 GlyphIndex, ppem fixed.Int26_6, h font.Hinting) (fixed.Int26_6, error)
Kern returns the horizontal adjustment for the kerning pair (x0, x1). A positive kern means to move the glyphs further apart. ppem is the number of pixels in 1 em.
It returns ErrNotFound if either glyph index is out of range.
func (*Font) LoadGlyph ¶
func (f *Font) LoadGlyph(b *Buffer, x GlyphIndex, ppem fixed.Int26_6, opts *LoadGlyphOptions) ([]Segment, error)
LoadGlyph returns the vector segments for the x'th glyph. ppem is the number of pixels in 1 em.
If b is non-nil, the segments become invalid to use once b is re-used.
In the returned Segments' (x, y) coordinates, the Y axis increases down.
It returns ErrNotFound if the glyph index is out of range. It returns ErrColoredGlyph if the glyph is not a monochrome vector glyph, such as a colored (bitmap or vector) emoji glyph.
func (*Font) Name ¶
func (f *Font) Name(b *Buffer, id NameID) (string, error)
Name returns the name value keyed by the given NameID.
It returns ErrNotFound if there is no value for that key.
func (*Font) NumGlyphs ¶
func (f *Font) NumGlyphs() int
NumGlyphs returns the number of glyphs in f.
func (*Font) UnitsPerEm ¶
func (f *Font) UnitsPerEm() Units
UnitsPerEm returns the number of units per em for f.
type GlyphIndex ¶
GlyphIndex is a glyph index in a Font.
type GlyphIndex uint16
type LoadGlyphOptions ¶
LoadGlyphOptions are the options to the Font.LoadGlyph method.
type LoadGlyphOptions struct {
}
type NameID ¶
NameID identifies a name table entry.
See the "Name IDs" section of https://www.microsoft.com/typography/otspec/name.htm
type NameID uint16
const (
NameIDCopyright NameID = 0
NameIDFamily = 1
NameIDSubfamily = 2
NameIDUniqueIdentifier = 3
NameIDFull = 4
NameIDVersion = 5
NameIDPostScript = 6
NameIDTrademark = 7
NameIDManufacturer = 8
NameIDDesigner = 9
NameIDDescription = 10
NameIDVendorURL = 11
NameIDDesignerURL = 12
NameIDLicense = 13
NameIDLicenseURL = 14
NameIDTypographicFamily = 16
NameIDTypographicSubfamily = 17
NameIDCompatibleFull = 18
NameIDSampleText = 19
NameIDPostScriptCID = 20
NameIDWWSFamily = 21
NameIDWWSSubfamily = 22
NameIDLightBackgroundPalette = 23
NameIDDarkBackgroundPalette = 24
NameIDVariationsPostScriptPrefix = 25
)
type Segment ¶
Segment is a segment of a vector path.
type Segment struct {
// Op is the operator.
Op SegmentOp
// Args is up to three (x, y) coordinates. The Y axis increases down.
Args [3]fixed.Point26_6
}
type SegmentOp ¶
SegmentOp is a vector path segment's operator.
type SegmentOp uint32
const (
SegmentOpMoveTo SegmentOp = iota
SegmentOpLineTo
SegmentOpQuadTo
SegmentOpCubeTo
)
type Units ¶
Units are an integral number of abstract, scalable "font units". The em square is typically 1000 or 2048 "font units". This would map to a certain number (e.g. 30 pixels) of physical pixels, depending on things like the display resolution (DPI) and font size (e.g. a 12 point font).
type Units int32