You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
127 lines
4.0 KiB
Racket
127 lines
4.0 KiB
Racket
#lang fontkit/racket
|
|
(require "glyph.rkt" restructure)
|
|
(provide (all-defined-out))
|
|
|
|
;; The header for both simple and composite glyphs
|
|
(define-subclass Struct (RGlyfHeader))
|
|
(define GlyfHeader (+RGlyfHeader
|
|
(dictify 'numberOfContours int16be ;; if negative, this is a composite glyph
|
|
'xMin int16be
|
|
'yMin int16be
|
|
'xMax int16be
|
|
'yMax int16be)))
|
|
|
|
;; Flags for simple glyphs
|
|
(match-define (list ON_CURVE
|
|
X_SHORT_VECTOR
|
|
Y_SHORT_VECTOR
|
|
REPEAT
|
|
SAME_X
|
|
SAME_Y)
|
|
(map (curry expt 2) (range 6)))
|
|
|
|
;; Flags for composite glyphs
|
|
(match-define (list ARG_1_AND_2_ARE_WORDS
|
|
ARGS_ARE_XY_VALUES
|
|
ROUND_XY_TO_GRID
|
|
WE_HAVE_A_SCALE
|
|
MORE_COMPONENTS
|
|
WE_HAVE_AN_X_AND_Y_SCALE
|
|
WE_HAVE_A_TWO_BY_TWO
|
|
WE_HAVE_INSTRUCTIONS
|
|
USE_MY_METRICS
|
|
OVERLAP_COMPOUND
|
|
SCALED_COMPONENT_OFFSET
|
|
UNSCALED_COMPONENT_OFFSET)
|
|
(map (curry expt 2) (range 12)))
|
|
|
|
;; Represents a point in a simple glyph
|
|
(define-subclass object% (Point onCurve endContour [x 0] [y 0])
|
|
|
|
(define/public (copy)
|
|
(+Point onCurve endContour x y)))
|
|
|
|
;; Represents a component in a composite glyph
|
|
(define-subclass object% (Component glyphID dx dy)
|
|
(field [pos 0]
|
|
[scaleX 1]
|
|
[scaleY 1]
|
|
[scale01 0]
|
|
[scale10 0])
|
|
)
|
|
|
|
;; Represents a TrueType glyph.
|
|
(define-subclass Glyph (TTFGlyph)
|
|
(inherit-field _font id)
|
|
|
|
;; Parses just the glyph header and returns the bounding box
|
|
(define/override (_getCBox internal)
|
|
(unfinished))
|
|
|
|
;; Parses a single glyph coordinate
|
|
(define/public (_parseGlyphCoord steam prev short same)
|
|
(unfinished))
|
|
|
|
;; Decodes the glyph data into points for simple glyphs,
|
|
;; or components for composite glyphs
|
|
(define/public (_decode)
|
|
(define offsets (hash-ref (send _font _getTable 'loca) 'offsets))
|
|
(define glyfPos (list-ref offsets id))
|
|
(define nextPos (list-ref offsets (add1 id)))
|
|
|
|
;; Nothing to do if there is no data for this glyph
|
|
(unless (= glyfPos nextPos)
|
|
(define stream (send _font _getTableStream 'glyf))
|
|
(increment-field! pos stream glyfPos)
|
|
(define startPos (· stream pos))
|
|
|
|
(define glyph (send GlyfHeader decode stream))
|
|
|
|
(let ([contour-count (· glyph numberOfContours)])
|
|
(cond
|
|
[(positive? contour-count)
|
|
(_decodeSimple glyph stream)]
|
|
[(negative? contour-count)
|
|
(_decodeComposite glyph stream startPos)]))
|
|
|
|
glyph))
|
|
|
|
(define/public (_decodeSimple glyph stream)
|
|
(unless (RGlyfHeader? glyph)
|
|
(raise-argument-error 'TTFGlyph-_decodeSimple "RGlyfHeader" glyph))
|
|
|
|
(unless (DecodeStream? stream)
|
|
(raise-argument-error 'TTFGlyph-_decodeSimple "DecodeStream" stream))
|
|
|
|
;; this is a simple glyph
|
|
(hash-set! glyph 'points empty)
|
|
|
|
(define endPtsOfContours (send (+Array uint16be (· glyph numberOfContours)) decode stream))
|
|
(hash-set! glyph 'instructions (send (+Array uint8be uint16be) decode stream))
|
|
|
|
(define numCoords (add1 (list-ref endPtsOfContours (sub1 (length endPtsOfContours)))))
|
|
|
|
(define flags
|
|
(reverse
|
|
(for/fold ([flags empty])
|
|
([i (in-naturals)]
|
|
#:when (< (length flags) numCoords))
|
|
(define flag (send stream readUInt8))
|
|
|
|
;; check for repeat flag
|
|
(define repeated-flags
|
|
(cond
|
|
[(not (zero? (bitwise-and flag REPEAT)))
|
|
(define count (send stream readUInt8))
|
|
(make-list count flag)]
|
|
[else empty]))
|
|
|
|
(append repeated-flags (cons flag flags)))))
|
|
|
|
(unfinished))
|
|
|
|
(define/public (_decodeComposite glyph stream [offset 0])
|
|
(unfinished)))
|
|
|
|
|