6.10  font%

A font is an object which determines the appearance of text, primarily when drawing text to a device context. A font is determined by seven properties:

• size -- The size of the text, either in points (the default) or logical drawing units, depending on the ``size-in-pixels?'' property (see below).

• family -- A platform- and device-independent font designation. The families are:

  • 'default

  • 'decorative

  • 'roman

  • 'script

  • 'swiss

  • 'modern (fixed width)

  • 'symbol (Greek letters and more)

  • 'system (used to draw control labels)

  The 'modern designation is special under Mac OS X and X with fontconfig/Xft; characters in the ``ASCII'' range 0-255 are converted to Unicode characters that match Adobe symbols. For example, ``a'' is converted to the Greek letter alpha.

• face -- A string face name, such as "Courier" (under Windows and Mac OS X), "-*-courier" (under X), or " Luxi Sans" (under X with fontconfig/Xft; note the leading space). The format and meaning of a face name is platform- and device-specific. If a font's face name is #f, then the font's appearance depends only on the family. If a face is provided but no mapping is available for the face name (for a specific platform or device), then the face name is ignored and the family is used. See font-name-directory<%> for information about how face names are mapped for drawing text.

• style -- The slant style of the font, one of:

  • 'normal

  • 'slant (Windows, Mac OS X: same as 'italic; X: tries 'italic if 'slant font does not exist)

  • 'italic (X: tries 'slant if 'italic font does not exist)

• weight -- The weight of the font, one of:

  • 'normal

  • 'light

  • 'bold

• underline? -- #t for underlined, #f for plain.

• smoothing -- Amount of anti-alias smoothing, one of:

  • 'default (platform-specific, sometimes user-configurable)

  • 'partly-smoothed (Windows: TrueType when available; Mac OS X: 4-bit, pixel-aligned smoothing; X: fontconfig/Xft when available)

  • 'smoothed (Windows: ClearType when available, XP and up; Mac OS X: Quartz smoothing; X: fontconfig/Xft when available)

  • 'unsmoothed

  Special case: 'default corresponds to 'partly-smoothed when used with the 'modern family and a font size between 9 and 13 (inclusive).

• size-in-pixels? -- #t if the size of the font is in logical drawing units (i.e., pixels for an unscaled screen or bitmap drawing context), #f if the size of the font is in points (which can depend on screen resolution).

To avoid creating multiple fonts with the same characteristics, use the global font-list% object the-font-list.

See also font-name-directory<%>.

• (make-object font%) -> font% object

  Creates an instance of the default font.

  
  

• (make-object font% size family style weight underline? smoothing size-in-pixels?) -> font% object
     size : exact integer in [1, 255]
     family : symbol in '(default decorative roman script swiss modern symbol system)
   style = 'normal : symbol in '(normal italic slant)
   weight = 'normal : symbol in '(normal bold light)
   underline? = #f : boolean
     smoothing = 'default : symbol in '(default partly-smoothed smoothed unsmoothed)
   size-in-pixels? = #f : boolean

  Creates a font with a family, but no face name.

  See font% for information about family, style, and weight. font-name-directory<%>.

  
  

• (make-object font% size face family style weight underline? smoothing size-in-pixels?) -> font% object
     size : exact integer in [1, 255]
     face : string
     family : symbol in '(default decorative roman script swiss modern symbol system)
   style = 'normal : symbol in '(normal italic slant)
   weight = 'normal : symbol in '(normal bold light)
   underline? = #f : boolean
     smoothing = 'default : symbol in '(default partly-smoothed smoothed unsmoothed)
   size-in-pixels? = #f : boolean

  See font% for information about family, style, and weight. See also font-name-directory<%> for information about the way face is interpreted for drawing text on various platforms and devices. When a platform- or device-specific interpretation of face is not available, the family is used to draw text.

  
  

Methods
    get-face
    get-family
    get-font-id
    get-point-size
    get-size-in-pixels
    get-smoothing
    get-style
    get-underlined
    get-weight
    screen-glyph-exists?