Class Font

constructor

• new Font(face: Face): Font

  Parameters

  • face: Face

    A Face to create the font from.

  Returns Font

• new Font(existingPtr: number): Font
  Internal

  Wrap an existing font pointer.

  Parameters

  • existingPtr: number

  Returns Font

Readonlyptr

face

• get face(): Face

  The Face associated with this font.

  Returns Face

drawGlyph

• drawGlyph(glyphId: number, drawFuncs: DrawFuncs, drawData?: unknown): void

  Draws the outline that corresponds to a glyph in the specified font.

  The outline is returned by way of calls to the callbacks of the drawFuncs object, with drawData passed to them.

  Parameters

  • glyphId: number

    The glyph ID.

  • drawFuncs: DrawFuncs

    The DrawFuncs to draw to.

  • OptionaldrawData: unknown

    User data to pass to draw callbacks.

  Returns void

drawGlyphOrFail

• drawGlyphOrFail(
      glyphId: number,
      drawFuncs: DrawFuncs,
      drawData?: unknown,
  ): boolean

  Draws the outline that corresponds to a glyph in the specified font.

  This is a newer name for Font.drawGlyph, that returns false if the font has no outlines for the glyph.

  The outline is returned by way of calls to the callbacks of the drawFuncs object, with drawData passed to them.

  Parameters

  • glyphId: number

    The glyph ID.

  • drawFuncs: DrawFuncs

    The DrawFuncs to draw to.

  • OptionaldrawData: unknown

    User data to pass to draw callbacks.

  Returns boolean

  true if the glyph was drawn, false otherwise.

getGlyphColorPng

• getGlyphColorPng(glyphId: number): Uint8Array<ArrayBufferLike> | undefined

  Fetches the PNG image for a glyph.

  To get an optimally sized PNG blob, the PPEM values must be set on the font. If PPEM is unset, the blob returned will be the largest PNG available.

  Parameters

  • glyphId: number

    A glyph index.

  Returns Uint8Array<ArrayBufferLike> | undefined

  The PNG image for the glyph, or undefined if the glyph has no PNG image.

getLigatureCarets

• getLigatureCarets(direction: Direction, glyph: number): number[]

  Fetches a list of the caret positions defined for a ligature glyph in the GDEF table of the font.

  Note that a ligature that is formed from n characters will have n-1 caret positions. The first character is not represented in the array, since its caret position is the glyph position.

  The positions returned by this function are 'unshaped', and will have to be fixed up for kerning that may be applied to the ligature glyph.

  Parameters

  • direction: Direction

    The text direction to use.

  • glyph: number

    The glyph to query.

  Returns number[]

  An array of caret positions.

getLookupOpticalBound

• getLookupOpticalBound(
      lookupIndex: number,
      direction: Direction,
      glyph: number,
  ): number

  Fetches the optical bound of a glyph positioned at the margin of text. The direction identifies which edge of the glyph to query.

  Parameters

  • lookupIndex: number

    Index of the feature lookup to query.

  • direction: Direction

    Edge of the glyph to query.

  • glyph: number

    A glyph id.

  Returns number

  Adjustment value. Negative values mean the glyph will stick out of the margin.

getMetricPosition

• getMetricPosition(metricsTag: number): number | undefined

  Fetches metrics value corresponding to metricsTag from the font.

  Parameters

  • metricsTag: number

    MetricsTag of metrics value you like to fetch.

  Returns number | undefined

  The metrics value, or undefined if not found in the font.

getMetricPositionWithFallback

• getMetricPositionWithFallback(metricsTag: number): number

  Fetches metrics value corresponding to metricsTag from the font, and synthesizes a value if the value is missing in the font.

  Parameters

  • metricsTag: number

    MetricsTag of metrics value you like to fetch.

  Returns number

  The metrics value.

getMetricVariation

• getMetricVariation(metricsTag: number): number

  Fetches metrics value corresponding to metricsTag from the font with the current font variation settings applied.

  Parameters

  • metricsTag: number

    MetricsTag of metrics value you like to fetch.

  Returns number

  The requested metric value.

getMetricXVariation

• getMetricXVariation(metricsTag: number): number

  Fetches horizontal metrics value corresponding to metricsTag from the font with the current font variation settings applied.

  Parameters

  • metricsTag: number

    MetricsTag of metrics value you like to fetch.

  Returns number

  The requested metric value.

getMetricYVariation

• getMetricYVariation(metricsTag: number): number

  Fetches vertical metrics value corresponding to metricsTag from the font with the current font variation settings applied.

  Parameters

  • metricsTag: number

    MetricsTag of metrics value you like to fetch.

  Returns number

  The requested metric value.

glyph

• glyph(unicode: number, variationSelector?: number): number | undefined

  Fetches the glyph ID for a Unicode code point in the specified font, with an optional variation selector.

  If variationSelector is 0, it is equivalent to Font.nominalGlyph; otherwise it is equivalent to Font.variationGlyph.

  Parameters

  • unicode: number

    The Unicode code point to query.

  • variationSelector: number = 0

    A variation-selector code point.

  Returns number | undefined

  The glyph ID, or undefined if not found.

glyphExtents

• glyphExtents(glyphId: number): GlyphExtents | undefined

  Return glyph extents.

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns GlyphExtents | undefined

  An object with xBearing, yBearing, width, and height, or undefined.

glyphFromName

• glyphFromName(name: string): number | undefined

  Return glyph ID from name.

  Parameters

  • name: string

    Name of the requested glyph in the font.

  Returns number | undefined

  The glyph ID, or undefined if not found.

glyphHAdvance

• glyphHAdvance(glyphId: number): number

  Return glyph horizontal advance.

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns number

  The horizontal advance width.

glyphHOrigin

• glyphHOrigin(glyphId: number): [number, number] | undefined

  Return glyph horizontal origin.

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns [number, number] | undefined

  [x, y] origin coordinates, or undefined if not available.

glyphName

• glyphName(glyphId: number): string

  Return glyph name.

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns string

  The glyph name string.

glyphToJson

• glyphToJson(glyphId: number): SvgPathCommand[]

  Return a glyph as a JSON path string based on format described on https://svgwg.org/specs/paths/#InterfaceSVGPathSegment

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns SvgPathCommand[]

  An array of path segment objects with type and values.

glyphToPath

• glyphToPath(glyphId: number): string

  Return a glyph as an SVG path string.

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns string

  SVG path data string.

glyphVAdvance

• glyphVAdvance(glyphId: number): number

  Return glyph vertical advance.

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns number

  The vertical advance height.

glyphVOrigin

• glyphVOrigin(glyphId: number): [number, number] | undefined

  Return glyph vertical origin.

  Parameters

  • glyphId: number

    ID of the requested glyph in the font.

  Returns [number, number] | undefined

  [x, y] origin coordinates, or undefined if not available.

hExtents

• hExtents(): FontExtents

  Return font horizontal extents.

  Returns FontExtents

  Object with ascender, descender, and lineGap properties.

nominalGlyph

• nominalGlyph(unicode: number): number | undefined

  Fetches the nominal glyph ID for a Unicode code point in the specified font.

  This version of the function should not be used to fetch glyph IDs for code points modified by variation selectors. For variation-selector support, use Font.variationGlyph or Font.glyph.

  Parameters

  • unicode: number

    The Unicode code point to query.

  Returns number | undefined

  The glyph ID, or undefined if not found.

paintGlyph

• paintGlyph(
      glyphId: number,
      paintFuncs: PaintFuncs,
      paintData?: unknown,
      paletteIndex?: number,
      foreground?: Color,
  ): void

  Paints the glyph. This function is similar to Font.paintGlyphOrFail, but if painting a color glyph failed, it will fall back to painting an outline monochrome glyph.

  The painting instructions are returned by way of calls to the callbacks of the paintFuncs object, with paintData passed to them.

  If the font has color palettes, then paletteIndex selects the palette to use. If the font only has one palette, this will be 0.

  Parameters

  • glyphId: number

    The glyph ID.

  • paintFuncs: PaintFuncs

    The PaintFuncs to paint with.

  • OptionalpaintData: unknown

    User data to pass to paint callbacks.

  • paletteIndex: number = 0

    The index of the font's color palette to use.

  • foreground: Color = ...

    The foreground color, unpremultiplied.

  Returns void

paintGlyphOrFail

• paintGlyphOrFail(
      glyphId: number,
      paintFuncs: PaintFuncs,
      paintData?: unknown,
      paletteIndex?: number,
      foreground?: Color,
  ): boolean

  Paints a color glyph.

  Succeeds if the glyph has color paint layers (COLRv0), a color paint graph (COLRv1), or a bitmap image that the font's callbacks render successfully. Returns false if the font has no color data for the glyph; the client can then fall back to Font.drawGlyphOrFail for the monochrome outline.

  The painting instructions are returned by way of calls to the callbacks of the paintFuncs object, with paintData passed to them.

  If the font has color palettes, then paletteIndex selects the palette to use. If the font only has one palette, this will be 0.

  Parameters

  • glyphId: number

    The glyph ID.

  • paintFuncs: PaintFuncs

    The PaintFuncs to paint with.

  • OptionalpaintData: unknown

    User data to pass to paint callbacks.

  • paletteIndex: number = 0

    The index of the font's color palette to use.

  • foreground: Color = ...

    The foreground color, unpremultiplied.

  Returns boolean

  true if the glyph was painted, false otherwise.

setFuncs

• setFuncs(fontFuncs: FontFuncs): void

  Set the font's font functions.

  Parameters

  • fontFuncs: FontFuncs

  Returns void

setScale

• setScale(xScale: number, yScale: number): void

  Set the font's scale factor, affecting the position values returned from shaping.

  Parameters

  • xScale: number

    Units to scale in the X dimension.

  • yScale: number

    Units to scale in the Y dimension.

  Returns void

setVariations

• setVariations(variations: Variation[]): void

  Applies a list of font-variation settings to a font.

  Note that this overrides all existing variations set on the font. Axes not included in variations will be effectively set to their default values.

  Parameters

  • variations: Variation[]

    Array of variation settings to apply.

  Returns void

subFont

• subFont(): Font

  Create a sub font that inherits this font's properties.

  Returns Font

  A new Font object representing the sub font.

variationGlyph

• variationGlyph(unicode: number, variationSelector: number): number | undefined

  Fetches the glyph ID for a Unicode code point when followed by by the specified variation-selector code point, in the specified font.

  Parameters

  • unicode: number

    The Unicode code point to query.

  • variationSelector: number

    The variation-selector code point to query.

  Returns number | undefined

  The glyph ID, or undefined if not found.

vExtents

• vExtents(): FontExtents

  Return font vertical extents.

  Returns FontExtents

  Object with ascender, descender, and lineGap properties.