main
Matthew Butterick 9 years ago
parent 3ce0f2061b
commit d6ab5bf39e

@ -6,7 +6,7 @@
(get-text-extent (String (Instance (Class (init-field))) Any . -> . (values Nonnegative-Real Nonnegative-Real Nonnegative-Real Nonnegative-Real))))]
[make-font ((#:size Nonnegative-Float) (#:style Symbol) (#:weight Symbol) (#:face String) . -> . (Instance (Class (init-field))))])
(require/typed racket/serialize [serialize (Any . -> . Any)]
[deserialize (Any . -> . (HashTable Any Any))])
[deserialize (Any . -> . (HashTable (List String String Symbol Symbol) Measurement-Result-Type))])
(provide measure-text measure-ascent round-float update-text-cache-file load-text-cache-file)
(define precision 4.0)
@ -15,9 +15,7 @@
(define dc (new record-dc%))
(define-type Measurement-Result-Type (List Float Float Float Float))
(define mrt? (make-predicate Measurement-Result-Type))
(define-type MMS-Type ((String String) (Symbol Symbol) . ->* . Measurement-Result-Type))
(define current-text-cache (make-parameter ((inst make-hash (List String String Symbol Symbol) Measurement-Result-Type) '())))
(define current-text-cache-changed? : (Parameterof Boolean) (make-parameter #f))
(define current-font-cache (make-parameter ((inst make-hash (List String Symbol Symbol) (Instance (Class (init-field)))) '())))
@ -25,6 +23,7 @@
(define (round-float x)
(/ (round (* base x)) base))
(: get-cache-file-path (-> Path))
(define (get-cache-file-path)
(build-path "font.cache"))
@ -32,16 +31,14 @@
(: update-text-cache-file (-> Void))
(define (update-text-cache-file)
(when (current-text-cache-changed?)
(write-to-file (serialize (current-text-cache)) (get-cache-file-path) #:exists 'replace)
(current-text-cache-changed? #f)))
(write-to-file (serialize (current-text-cache)) (get-cache-file-path) #:exists 'replace))
(: load-text-cache-file (-> Void))
(define (load-text-cache-file)
(define cache-file-path (get-cache-file-path))
(current-text-cache (if (file-exists? cache-file-path)
(cast (deserialize (file->value cache-file-path)) (HashTable (List String String Symbol Symbol) Measurement-Result-Type))
(deserialize (file->value cache-file-path))
((inst make-hash (List String String Symbol Symbol) Measurement-Result-Type) '()))))
@ -50,27 +47,19 @@
(hash-ref! (current-font-cache) (list font weight style) (λ() (make-font #:size max-size #:style style #:weight weight #:face font))))
(: measure-max-size-base (String String Symbol Symbol . -> . Measurement-Result-Type))
(define (measure-max-size-base text font weight style)
(: measure-max-size ((String String) (Symbol Symbol) . ->* . Measurement-Result-Type))
(define (measure-max-size text font [weight 'normal] [style 'normal])
(: hash-updater (-> Measurement-Result-Type))
(define (hash-updater)
(current-text-cache-changed? #t)
#;(current-text-cache-changed? #t)
(define font-instance (get-cached-font font weight style))
;; 'combine' boolean only makes a difference for two or more chars, so use (>= (string-length text) 1) for speed
(define-values (width height descent extra) (send dc get-text-extent text font-instance (>= (string-length text) 1)))
;; avoid `map` here because it requires a cast to ensure the type
;; this seems like a bug in TR: doesn't recognize (List Float Float Float Float) as subtype of (Listof Float)
;; this seems like a bug in TR: doesn't recognize (List Float Float Float Float) as subtype of (Listof Float)?
(list (fl width) (fl height) (fl descent) (fl extra)))
((inst hash-ref! (List String String Symbol Symbol) Measurement-Result-Type) (current-text-cache) (list text font weight style) hash-updater))
;; rather than use define/caching from the (untyped) sugar/cache, implement the cache "manually"
(define measure-cache ((inst make-hash (List String String Symbol Symbol) Measurement-Result-Type)))
(: measure-max-size MMS-Type)
(define (measure-max-size text font [weight 'normal] [style 'normal])
(hash-ref! measure-cache (list text font weight style) (λ () (measure-max-size-base text font weight style))))
(define-syntax-rule (width x) (first x))
(define-syntax-rule (height x) (second x))
(define-syntax-rule (descent x) (third x))
@ -78,8 +67,8 @@
;; works by taking max size and scaling it down. Allows caching of results.
(: measure-text ((String Positive-Float String) (Symbol Symbol) . ->* . Float))
(define (measure-text text size font [weight 'normal] [style 'normal])
(: measure-text (String Positive-Float String Symbol Symbol . -> . Float))
(define (measure-text text size font weight style)
(define raw-width (width (measure-max-size text font weight style)))
(round-float (/ (* raw-width size) max-size)))

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