#lang racket/base
(require (for-syntax)
         sugar/unstable/dict
         sugar/unstable/js
         "unsafe/freetype.rkt"
         "helper.rkt")
(provide (all-defined-out))



#|
approximates
https://github.com/mbutterick/fontkit/blob/master/src/glyph/Glyph.js
|#

; Glyph objects represent a glyph in the font. They have various properties for accessing metrics and
; the actual vector path the glyph represents, and methods for rendering the glyph to a graphics context.
;
; You do not create glyph objects directly. They are created by various methods on the font object.
; There are several subclasses of the base Glyph class internally that may be returned depending
; on the font format, but they all inherit from this class.


(struct glyph (id codepoints font is-mark? is-ligature? metrics) #:transparent #:mutable)

(define (+glyph id codepoints font
                [is-mark? (andmap is-mark? codepoints)]
                [is-ligature? (> (length codepoints) 1)]
                [metrics #f]
                #:constructor [constructor glyph])
  (constructor id codepoints font is-mark? is-ligature? metrics))

#;(define-stub-stop _getPath)
#;(define-stub-stop _getCBox)
#;(define-stub-stop _getBBox)
#;(define-stub-stop _getTableMetrics)

(define (glyph-advance-width g)
  (hash-ref (get-glyph-metrics g) 'advanceWidth))

(define (get-glyph-metrics g)
  (unless (glyph-metrics g)
    (define face (· (glyph-font g) ft-face))
    (FT_Load_Glyph face (glyph-id g) FT_LOAD_NO_RECURSE)
    (define glyph (FT_FaceRec-glyph face))
    (define ft-glyph-metrics (FT_GlyphSlotRec-metrics glyph))
    (set-glyph-metrics! g (mhash))
    (hash-set*! (glyph-metrics g)
                'advanceWidth (FT_Glyph_Metrics-horiAdvance ft-glyph-metrics)
                'leftBearing (FT_Glyph_Metrics-horiBearingX ft-glyph-metrics)))
  (glyph-metrics g))