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#lang racket/base
(require (for-syntax racket/base)
(provide latex->bitmap latex->bitmap+ascent
latex-preamble add-preamble latex-dpi latex-debug?
latex-path dvipng-path
(struct-out exn:latex)
(struct-out exn:dvipng)
(define used-files (make-hash))
(define cached-bitmaps (make-hash))
;; Document contents
(define latex-preamble (make-parameter ""))
(define (add-preamble . latex-strs)
(latex-preamble (string-join (cons (latex-preamble) latex-strs) "\n")))
;; Formatting options
(define latex-dpi (make-parameter 300))
;; Spam the console with debugging info?
(define latex-debug? (make-parameter #t))
(define (find-executable name [defaultdir "/usr/bin"])
(cond [(find-executable-path name) => (λ (p) p)]
[(find-executable-path (string-append name ".exe")) => (λ (p) p)]
[else (build-path defaultdir name)]))
;; Default paths
(define latex-path (make-parameter (find-executable "latex" "/usr/bin")))
(define dvipng-path (make-parameter (find-executable "dvipng" "/usr/bin")))
(define cache-path (make-parameter (find-system-path 'temp-dir)))
;; Exceptions raised
(struct exn:latex exn:fail (message))
(struct exn:dvipng exn:fail ())
;; base+ext : path? string? -> path?
(define (base+ext file-base ext)
(build-path (string-append (path->string file-base) ext)))
;; text-file->string : path? -> string?
(define (text-file->string file)
(call-with-input-file file #:mode 'text port->string))
;; string->text-file : string? path? -> void?
(define (string->text-file str file)
(with-output-to-file file #:mode 'text #:exists 'truncate
(lambda () (printf "~a" str))))
;; text-file->string-list : path? -> (listof string?)
(define (text-file->string-list file)
(call-with-input-file file #:mode 'text port->lines))
;; Example error:
;; ./latex125249806.tex:18: Undefined control sequence.
;; parse-latex-log : path? -> string?
;; Returns the first error message and context string found in the log
(define (parse-latex-log base-file)
(define error-regexp
(regexp (format ".*~a.*:[0-9]+:" (path->string base-file))))
(let loop ([lines (text-file->string-list (base+ext base-file ".log"))])
(cond [(empty? lines) "unknown"]
[(regexp-match error-regexp (first lines))
(let* ([info (regexp-split #rx":" (first lines))]
[msg (string-join (drop info 2) ":")]
[ctx (string-join (take (rest lines) 2) "\n")])
(format "~a ~a" msg ctx))]
[else (loop (rest lines))])))
;; compile-latex : path? -> void?
(define (compile-latex file-base)
(define tex-file (base+ext file-base ".tex"))
(define dvi-file (base+ext file-base ".dvi"))
(define png-file (base+ext file-base ".png"))
(define latex-args
(list "-interaction=batchmode" "-file-line-error" "-halt-on-error"
(path->string tex-file)))
(define dvipng-args
(list "--follow" "-bg" "Transparent" "--truecolor"
"-D" (number->string (exact->inexact (latex-dpi)))
"-T" "tight"
"-o" (path->string png-file) (path->string dvi-file)))
(when (latex-debug?)
(printf "INFO: ~a ~a~n" (latex-path) (string-join latex-args " ")))
(when (not (zero? (parameterize ([current-output-port (open-output-nowhere)])
(apply system*/exit-code (latex-path) latex-args))))
(when (latex-debug?)
(printf "ERROR: latex error, here's the log:~n")
(printf "~a~n" (text-file->string (base+ext file-base ".log"))))
(raise (exn:latex "latex failed" (current-continuation-marks)
(parse-latex-log file-base))))
(when (latex-debug?)
(printf "INFO: ~a ~a~n" (dvipng-path) (string-join dvipng-args " ")))
(parameterize ([current-output-port (open-output-nowhere)])
(apply system*/exit-code (dvipng-path) dvipng-args)
(when (not (file-exists? png-file))
(raise (exn:dvipng (format "dvipng failed to convert ~e" dvi-file)
;; latex-doc->file-base : string? -> string?
(define (latex-doc->file-base doc-str)
(format "latex2bitmap-~a"
(call-with-input-string (string-append (number->string (latex-dpi))
;; ensure-png : string? -> void?
(define (ensure-png file-base doc-str)
(define tex-file (base+ext file-base ".tex"))
(define png-file (base+ext file-base ".png"))
(unless (file-exists? png-file)
(when (latex-debug?) (printf "INFO: generating ~a~n" png-file))
(string->text-file doc-str tex-file)
(compile-latex file-base))
(hash-set! used-files png-file #t))
;; latex->latex-doc : string? -> string?
(define (latex->latex-doc latex-str)
(string-append "\\documentclass[12pt]{article}\n"
(format "~a~n" (latex-preamble))
(format "\\begin{document}~n")
(format "~a~n" latex-str)
;; latex->bitmap : string? -> bitmap%
(define (latex->bitmap latex-str)
(define doc-str (latex->latex-doc latex-str))
(define file-base (latex-doc->file-base doc-str))
(define png-file (base+ext file-base ".png"))
cached-bitmaps file-base
(λ () (parameterize ([current-directory (cache-path)])
(ensure-png file-base doc-str)
(when (latex-debug?) (printf "INFO: loading ~a~n" png-file))
(make-object bitmap% png-file 'png/mask #f)))))
(define (get-column-alpha bm x)
(let* ([height (send bm get-height)]
[b (make-bytes (* 4 height))])
(send bm get-argb-pixels x 0 1 height b #t)
(build-vector height (λ (y) (bytes-ref b (* 4 y))))))
(define (find-first-largest v [idx 0] [lidx 0])
(cond [(idx . >= . (vector-length v)) lidx]
[((vector-ref v idx) . > . (vector-ref v lidx))
(find-first-largest v (add1 idx) idx)]
[else (find-first-largest v (add1 idx) lidx)]))
(define (blank-column? v)
(zero? (vector-count (compose not zero?) v)))
(define (find-first-column bm x0)
(cond [(x0 . >= . (send bm get-width)) (send bm get-width)]
[(blank-column? (get-column-alpha bm x0))
(find-first-column bm (add1 x0))]
[else x0]))
(define (latex->bitmap+ascent latex-str)
(define 1/2px-in (exact->inexact (/ 1 (latex-dpi) 2)))
(define back-in (exact->inexact (/ 5 (latex-dpi))))
(define baseline-dot (format "\\rule{~ain}{~ain}" 1/2px-in 1/2px-in))
(define bm (latex->bitmap (format "\\makebox[0px][l]{\\hspace{-~ain}~a}~a"
back-in baseline-dot latex-str)))
(define ascent (+ 1 (find-first-largest (get-column-alpha bm 0))))
(define x0 (find-first-column bm 1))
(values bm ascent x0))
(define (set-latex-cache-path cpath)
(when (file-exists? cpath)
(error 'set-cache "~e exists as a regular file" cpath))
(when (not (directory-exists? cpath))
(make-directory cpath))
(when (latex-debug?) (printf "INFO: latex compile path set to ~a~n" cpath))
(cache-path cpath))
(define (tidy-latex-cache)
(for ([file (directory-list (cache-path))])
(when (and (regexp-match #rx"^latex2bitmap-" (path->string file))
(not (hash-has-key? used-files file)))
(when (latex-debug?) (printf "INFO: deleting unused file ~a~n" file))
(delete-file (build-path (cache-path) file)))))
(define (setup-local-cache stx)
(let ([src (syntax-source stx)])
(if (path? src)
(let-values ([(base-dir modname _) (split-path src)])
(set-latex-cache-path (path->directory-path
(build-path base-dir (format "~a-latex" modname)))))
(printf "WARNING: not a path: ~a~n" src))))
(define-syntax (setup-local-latex-cache stx)
(syntax-case stx ()
[(local-name) #'(setup-local-cache #'local-name)]))