;; ===================================================================
;; Functional PostScript
;; Copyright (C) 1996 by Wandy Sae-Tan and Olin Shivers

;; fps.scm

;; This file contains global constants and variables.

;; pi 1/4pi 1/2pi 3/4pi 5/4pi 3/2pi 7/4pi 2pi
;; origin identity-matrix
;; FPS_AFM_PATH

;; ===================================================================

;; Constants
(define pi 3.141593)
(define 1/4pi (* 1/4 pi))
(define 1/2pi (* 1/2 pi))
(define 3/4pi (* 2/3 pi))
(define 5/4pi (* 5/4 pi))
(define 3/2pi (* 3/2 pi))
(define 7/4pi (* 7/4 pi))
(define 2pi   (* 2   pi))

(define origin              (make-pt 0 0))
(define identity-matrix     (make-matrix 1 0 0 1 0 0))

;; System Defaults
;; the system maintains a default style that's dynamically scoped
(define default-style (make-parameter (make-default-style)))
(define default-font   #f)
(define default-afm-dir-path (list "./AFM" (string-append (repository-path) "/AFM")))


;; ===== Scsh dependent AFM files path mechanism =====================

;; These procedures are for reading environment variables to find
;; out where the AFM files for a font might be. These procedures
;; are scsh dependent. They would need to be reimplemented to have
;; the equivelant function if scsh is not used. These procedures
;; are used procedure "read-in-afm-file" in fps.afm.scm.


;; Given a filename, either return a port, or return a #f on any error.

(define (maybe-open-input-file filename)
  (and (file-exists? filename)
       (open-input-file filename)))

;; Returns the value of the environment variable FPS_AFM_PATH
;; For example: if we did "setenv FPS_AFM_PATH "/mydir:/yourdir"
;; (afm-directory-list) would return ("/mydir" "/yourdir")

(define afm-directory-list
  (let ((splitter (lambda (s) (string-split-fields s ":" #:infix))))
    (lambda ()
      (cond ((get-environment-variable "FPS_AFM_PATH") => splitter)
	    (else default-afm-dir-path)))))

;; ===== End of fps.scm ==============================================