From 8f6b184fca750cce252215fc94117715da22ed41 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Wed, 21 Aug 2019 13:38:29 -0700
Subject: [PATCH] handle more metadata fields

---
 pitfall/pitfall/check-pdf.rkt | 12 +++++++++++-
 pitfall/pitfall/pdf.rkt       |  9 ++++++---
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/pitfall/pitfall/check-pdf.rkt b/pitfall/pitfall/check-pdf.rkt
index 50ed8548..795bc1fa 100644
--- a/pitfall/pitfall/check-pdf.rkt
+++ b/pitfall/pitfall/check-pdf.rkt
@@ -49,6 +49,16 @@
                   (parse-1 ip)
                   (port->bytes ip)) #"z"))
 
+(define excluded-keys
+  (list #"/Producer"
+        #"/Creator"
+        #"/CreationDate"
+        #"/ModDate"
+        #"/Keywords"
+        #"/Title"
+        #"/Author"
+        #"/Subject"))
+
 (define (parse-1 ip)
   (cond
     ;; the complication is that arrays & dicts can contain other arrays & dicts
@@ -62,7 +72,7 @@
        (sort ; put hash into order so it's comparable
         (for/list ([kv (in-slice 2 items)]
                    ;; suppress these keys so we can compare pdfkit & pitfall output
-                   #:unless (member (car kv) (list #"/Producer" #"/Creator" #"/CreationDate")))
+                   #:unless (member (car kv) excluded-keys))
           (apply cons kv))
         bytes<?
         #:key car))
diff --git a/pitfall/pitfall/pdf.rkt b/pitfall/pitfall/pdf.rkt
index 074b5e16..73b1b5ba 100644
--- a/pitfall/pitfall/pdf.rkt
+++ b/pitfall/pitfall/pdf.rkt
@@ -32,9 +32,12 @@
   ;; initial values
   (define pages null)
   (define refs null)
-  (define info (mhasheq 'Producer "PITFALL"
-                        'Creator "PITFALL"
-                        'CreationDate (current-seconds)))
+  (define now (current-seconds))
+  (define producer (format "Racket ~a (Pitfall library)" (version)))
+  (define info (mhasheq 'Producer producer
+                        'Creator producer ; or application program using Pitfall
+                        'CreationDate now
+                        'ModDate now))
   (define opacity-registry (make-hash))
   (define current-fill-color '("black" 1))
   (define ctm default-ctm-value)