From 65fec4d2758d9b16456c9e5005fc13e79a3c453e Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Mon, 6 May 2024 15:37:58 +0800
Subject: [PATCH] Allow typesetting of the empty document

---
 cpdftexttopdf.ml |  7 +++++--
 cpdftype.ml      | 17 ++++++++---------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/cpdftexttopdf.ml b/cpdftexttopdf.ml
index e456704..0424084 100644
--- a/cpdftexttopdf.ml
+++ b/cpdftexttopdf.ml
@@ -56,8 +56,11 @@ let typeset ~papersize ~font ~fontsize text =
   in
   let instrs = of_utf8_with_newlines fontpack fontsize (Pdfio.string_of_bytes text) in
   let margin = Pdfunits.points (Pdfpaper.width papersize) (Pdfpaper.unit papersize) /. 15.  in
-  let firstfont = hd (keep (function Cpdftype.Font _ -> true | _ -> false) instrs) in 
-  let instrs = [firstfont; Cpdftype.BeginDocument] @ instrs in
+  let instrs =
+    if instrs = [] then [] else
+      let firstfont = hd (keep (function Cpdftype.Font _ -> true | _ -> false) instrs) in 
+        [firstfont; Cpdftype.BeginDocument] @ instrs
+  in
   let pages = Cpdftype.typeset margin margin margin margin papersize pdf instrs in
     let pdf, pageroot = Pdfpage.add_pagetree pages pdf in
       Pdfpage.add_root pageroot [] pdf
diff --git a/cpdftype.ml b/cpdftype.ml
index c1a4b47..8812a8b 100644
--- a/cpdftype.ml
+++ b/cpdftype.ml
@@ -208,15 +208,14 @@ let typeset lmargin rmargin tmargin bmargin papersize pdf i =
   let thisdestrectangles = ref [] in
   let pages = ref [] in
   let write_page () =
-    if !ops <> [] then
-      let page =
-        {Pdfpage.content = [Pdfops.stream_of_ops (rev !ops)];
-         Pdfpage.mediabox = Pdfpage.rectangle_of_paper papersize;
-         Pdfpage.resources = make_resources !thispagefontnums;
-         Pdfpage.rotate = Pdfpage.Rotate0;
-         Pdfpage.rest = make_annotations pdf !thispageannotations}
-      in
-        pages := page :: !pages
+    let page =
+      {Pdfpage.content = if !ops = [] then [] else [Pdfops.stream_of_ops (rev !ops)];
+       Pdfpage.mediabox = Pdfpage.rectangle_of_paper papersize;
+       Pdfpage.resources = make_resources !thispagefontnums;
+       Pdfpage.rotate = Pdfpage.Rotate0;
+       Pdfpage.rest = make_annotations pdf !thispageannotations}
+    in
+      pages := page :: !pages
   in
   let rec typeset_element = function
     | Text cps ->