From 30c9b130fd8785f1cc6fe57296bad3d68d43fe96 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Tue, 27 Jan 2015 15:50:15 -0800
Subject: [PATCH] typed measure

---
 quad/measure-typed.rkt | 89 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 quad/measure-typed.rkt

diff --git a/quad/measure-typed.rkt b/quad/measure-typed.rkt
new file mode 100644
index 00000000..d520e7f5
--- /dev/null
+++ b/quad/measure-typed.rkt
@@ -0,0 +1,89 @@
+#lang typed/racket/base
+(require typed/racket/class)
+(require/typed racket/draw [record-dc%  (Class (init-field))]
+               [make-font ((#:size Nonnegative-Flonum) (#:style Symbol) (#:weight Symbol) (#:face String) . -> . (Instance (Class (init-field))))])
+(require/typed sugar/cache [make-caching-proc (Procedure . -> . Procedure)])
+(require/typed racket/serialize [serialize (Any . -> . Any)]
+               [deserialize (Any . -> . (HashTable Any Any))])
+(require math/flonum racket/list (only-in sugar/list values->list) racket/file)
+;(provide measure-text measure-ascent round-float update-text-cache-file load-text-cache-file)
+
+(define precision 4.0)
+(define base (flexpt 10.0 precision))
+
+(define-syntax-rule (round-float x)
+  (fl/ (flround (fl* base (fl x))) base))
+
+
+(define dc (new record-dc%))
+
+(define max-size 1024.0) ; use fixnum to trigger faster bitshift division
+
+;; changing max-size invalidates font cache (because it's based on max size, duh)
+
+
+(define make-font/caching
+  (make-caching-proc (λ (font weight style)
+                       (make-font #:size max-size #:style style #:weight weight #:face font))))
+
+
+(define (get-cache-file-path)
+  (build-path "font.cache"))
+
+
+(define current-text-cache (make-parameter (make-hash '())))
+(define current-text-cache-changed? (make-parameter #f))
+(define current-font-cache (make-parameter (make-hash '())))
+
+
+(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)))
+
+(define (load-text-cache-file) 
+  (define cache-file-path (get-cache-file-path))
+  (current-text-cache (if (file-exists? cache-file-path)
+                          (deserialize (file->value cache-file-path))
+                          (make-hash '()))))
+
+
+(define-type mms-type ((String String) (Symbol Symbol) . ->* . (Listof Nonnegative-Flonum)))
+(: measure-max-size mms-type)
+(define measure-max-size 
+  (cast (make-caching-proc (λ(text font [weight 'normal] [style 'normal])
+                       ;((string? string?) (symbol? symbol?) . ->* . number?)
+                       (define font-instance (hash-ref! (current-font-cache) (list font weight style) (λ() (make-font #:size max-size #:style style #:weight weight #:face font))))
+                       ;; 'combine' boolean only makes a difference for two or more chars
+                       (hash-ref! (current-text-cache) (list text font weight style) (λ() (current-text-cache-changed? #t)
+                                                                                       (values->list (send dc get-text-extent text font-instance (>= (string-length text) 1))))))) mms-type))
+
+
+
+
+(define-syntax-rule (width x) (first x))
+(define-syntax-rule (height x) (second x))
+(define-syntax-rule (descent x) (third x))
+(define-syntax-rule (extra x) (fourth x)) 
+
+
+(define-syntax-rule (measure-text-max-size text font weight style)
+  (width (measure-max-size text font weight style)))
+
+(: measure-text ((String Nonnegative-Flonum String) (Symbol Symbol) . ->* . Nonnegative-Flonum))
+(define (measure-text text size font [weight 'normal] [style 'normal])
+  ;; Native function only accepts integers, so get max-size and scale down to size needed.
+  (define raw-measure (measure-text-max-size text font weight style))
+  (cast (round-float (/ (* (exact->inexact raw-measure) (exact->inexact size)) max-size)) Nonnegative-Flonum))
+
+
+(define-syntax-rule (measure-ascent-max-size text font weight style)
+  (let ([result-list (measure-max-size text font weight style)])
+    (- (height result-list) (descent result-list))))
+
+(: measure-ascent ((String Nonnegative-Flonum String) (Symbol Symbol) . ->* . Nonnegative-Flonum))
+(define (measure-ascent text size font [weight 'normal] [style 'normal])
+  ;  ((string? flonum? string?) (symbol? symbol?) . ->* . flonum?)
+  ;; Native function only accepts integers, so get max-size and scale down to size needed.
+  (define raw-baseline-distance (measure-ascent-max-size text font weight style))
+  (cast (round-float (/ (* (exact->inexact raw-baseline-distance) (exact->inexact size)) max-size)) Nonnegative-Flonum))