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#lang fontkit/racket
( require xenomorph )
( provide ( all-defined-out ) )
#|
approximates
https://github.com/mbutterick/fontkit/blob/master/src/tables/hmtx.js
|#
( define-subclass Struct ( Rhmtx ) )
( define HmtxEntry ( +Struct
( dictify
' advance uint16be
' bearing int16be ) ) )
( define hmtx ( +Rhmtx
( dictify
' metrics ( +LazyArray HmtxEntry ( λ ( this-array ) ( · this-array parent hhea numberOfMetrics ) ) )
' bearings ( +LazyArray int16be ( λ ( this-array ) ( - ( · this-array parent maxp numGlyphs )
( · this-array parent hhea numberOfMetrics ) ) ) ) ) ) )
( test-module
;; same as hmtx but doesn't require resolution of function to get length
( define hmtx-test ( +Rhmtx
( dictify
' metrics ( +LazyArray HmtxEntry ( λ ( t ) 229 ) )
' bearing ( +LazyArray int16be ( λ ( t ) 0 ) ) ) ) )
( define ip ( open-input-file charter-path ) )
( define dir ( deserialize ( read ( open-input-file charter-directory-path ) ) ) )
( define hmtx-offset ( · dir tables hmtx offset ) )
( define hmtx-length ( · dir tables hmtx length ) )
( check-equal? hmtx-offset 456 )
( check-equal? hmtx-length 916 )
( define hmtx-bytes ( peek-bytes hmtx-length hmtx-offset ip ) )
( define hmtx-data ( decode hmtx-test hmtx-bytes ) )
( check-equal? ( send hmtx-test size ) ( * 229 ( send HmtxEntry size ) ) )
( define H-gid 41 ) ( define OE-gid 142 )
( check-equal? ( dump ( send ( · hmtx-data metrics ) get H-gid ) ) ' #hasheq ( ( advance . 738 ) ( bearing . 33 ) ) )
( check-equal? ( dump ( send ( · hmtx-data metrics ) get OE-gid ) ) ' #hasheq ( ( advance . 993 ) ( bearing . 43 ) ) )
)