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81 lines
4.1 KiB
Racket
81 lines
4.1 KiB
Racket
#lang typed/racket/base
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(require (for-syntax typed/racket/base))
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(require typed/racket/class math/flonum racket/list racket/file)
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(require/typed racket/draw
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[record-dc% (Class (init-field)
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(get-text-extent (String (Instance (Class (init-field))) Any . -> . (values Nonnegative-Real Nonnegative-Real Nonnegative-Real Nonnegative-Real))))]
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[make-font ((#:size Nonnegative-Float) (#:style Symbol) (#:weight Symbol) (#:face String) . -> . (Instance (Class (init-field))))])
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(require/typed racket/serialize [serialize (Any . -> . Any)]
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[deserialize (Any . -> . (HashTable (List String String Symbol Symbol) Measurement-Result-Type))])
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(provide measure-text measure-ascent round-float update-text-cache-file load-text-cache-file)
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(define precision 4.0)
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(define base (expt 10.0 precision))
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(define max-size 1024.0)
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(define dc (new record-dc%))
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(define-type Measurement-Result-Type (List Float Float Float Float))
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(define mrt? (make-predicate Measurement-Result-Type))
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(define current-text-cache (make-parameter ((inst make-hash (List String String Symbol Symbol) Measurement-Result-Type) '())))
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(define current-font-cache (make-parameter ((inst make-hash (List String Symbol Symbol) (Instance (Class (init-field)))) '())))
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(: round-float (Float . -> . Float))
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(define (round-float x)
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(/ (round (* base x)) base))
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(: get-cache-file-path (-> Path))
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(define (get-cache-file-path)
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(build-path "font.cache"))
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(: update-text-cache-file (-> Void))
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(define (update-text-cache-file)
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(write-to-file (serialize (current-text-cache)) (get-cache-file-path) #:exists 'replace))
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(: load-text-cache-file (-> Void))
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(define (load-text-cache-file)
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(define cache-file-path (get-cache-file-path))
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(current-text-cache (if (file-exists? cache-file-path)
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(deserialize (file->value cache-file-path))
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((inst make-hash (List String String Symbol Symbol) Measurement-Result-Type) '()))))
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(: get-cached-font (String Symbol Symbol . -> . (Instance (Class (init-field)))))
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(define (get-cached-font font weight style)
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(hash-ref! (current-font-cache) (list font weight style) (λ() (make-font #:size max-size #:style style #:weight weight #:face font))))
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(: measure-max-size ((String String) (Symbol Symbol) . ->* . Measurement-Result-Type))
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(define (measure-max-size text font [weight 'normal] [style 'normal])
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(: hash-updater (-> Measurement-Result-Type))
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(define (hash-updater)
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#;(current-text-cache-changed? #t)
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(define font-instance (get-cached-font font weight style))
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;; 'combine' boolean only makes a difference for two or more chars, so use (>= (string-length text) 1) for speed
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(define-values (width height descent extra) (send dc get-text-extent text font-instance (>= (string-length text) 1)))
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;; avoid `map` here because it requires a cast to ensure the type
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;; this seems like a bug in TR: doesn't recognize (List Float Float Float Float) as subtype of (Listof Float)?
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(list (fl width) (fl height) (fl descent) (fl extra)))
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((inst hash-ref! (List String String Symbol Symbol) Measurement-Result-Type) (current-text-cache) (list text font weight style) hash-updater))
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(define-syntax-rule (width x) (first x))
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(define-syntax-rule (height x) (second x))
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(define-syntax-rule (descent x) (third x))
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#;(define-syntax-rule (extra x) (fourth x))
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;; works by taking max size and scaling it down. Allows caching of results.
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(: measure-text (String Positive-Float String Symbol Symbol . -> . Float))
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(define (measure-text text size font weight style)
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(define raw-width (width (measure-max-size text font weight style)))
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(round-float (/ (* raw-width size) max-size)))
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;; works by taking max size and scaling it down. Allows caching of results.
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(: measure-ascent ((String Positive-Float String) (Symbol Symbol) . ->* . Float))
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(define (measure-ascent text size font [weight 'normal] [style 'normal])
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(define result-list : Measurement-Result-Type (measure-max-size text font weight style))
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(define raw-baseline-distance (- (height result-list) (descent result-list)))
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(round-float (/ (* raw-baseline-distance size) max-size))) |