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69 lines
3.2 KiB
Racket
69 lines
3.2 KiB
Racket
#lang racket/base
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(require math/flonum racket/draw racket/class sugar/debug sugar/list racket/list sugar/cache racket/serialize racket/file)
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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 (flexpt 10.0 precision))
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(define-syntax-rule (round-float x)
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(fl/ (flround (fl* base (fl x))) base))
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(define dc (new record-dc%))
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(define max-size 1024) ; use fixnum to trigger faster bitshift division
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;; changing max-size invalidates font cache (because it's based on max size, duh)
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(define/caching (make-font/caching font weight style)
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(make-font #:size max-size #:style style #:weight weight #:face font))
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(define (get-cache-file-path)
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(build-path "font.cache"))
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(define (update-text-cache-file)
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(when (current-text-cache-changed?)
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(write-to-file (serialize (current-text-cache)) (get-cache-file-path) #:exists 'replace)
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(current-text-cache-changed? #f)))
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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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(make-hash))))
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(define current-text-cache (make-parameter (make-hash)))
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(define current-text-cache-changed? (make-parameter #f))
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(define current-font-cache (make-parameter (make-hash)))
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(define/caching (measure-max-size text font [weight 'normal] [style 'normal])
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;((string? string?) (symbol? symbol?) . ->* . number?)
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(define font-instance (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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;; 'combine' boolean only makes a difference for two or more chars
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(hash-ref! (current-text-cache) (list text font weight style) (λ() (current-text-cache-changed? #t)
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(values->list (send dc get-text-extent text font-instance (>= (string-length text) 1))))))
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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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(define-syntax-rule (measure-text-max-size text font weight style)
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(width (measure-max-size text font weight style)))
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(define (measure-text text size font [weight 'normal] [style 'normal])
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; ((string? flonum? string?) (symbol? symbol?) . ->* . flonum?)
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;; Native function only accepts integers, so get max-size and scale down to size needed.
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(define raw-measure (measure-text-max-size text font weight style))
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(round-float (/ (* (exact->inexact raw-measure) (exact->inexact size)) max-size)))
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(define-syntax-rule (measure-ascent-max-size text font weight style)
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(let ([result-list (measure-max-size text font weight style)])
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(- (height result-list) (descent result-list))))
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(define (measure-ascent text size font [weight 'normal] [style 'normal])
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; ((string? flonum? string?) (symbol? symbol?) . ->* . flonum?)
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;; Native function only accepts integers, so get max-size and scale down to size needed.
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(define raw-baseline-distance (measure-ascent-max-size text font weight style))
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(round-float (/ (* (exact->inexact raw-baseline-distance) (exact->inexact size)) max-size)))
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