From b676ab49239279c86faab57aad1439210c063b6e Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Tue, 24 Sep 2024 20:40:14 +0100
Subject: [PATCH] Optional absolute rectangles

---
 Changes        |  4 ++++
 cpdfcoord.ml   | 27 ++++++++++++++++++++-------
 cpdfmanual.tex |  1 +
 3 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/Changes b/Changes
index d36cb07..023a43c 100644
--- a/Changes
+++ b/Changes
@@ -19,6 +19,10 @@ New features:
 o -stretch scales without preserving aspect ratio
 o -redact removes whole pages
 
+Extended features:
+
+o Rectangle may be specified as x y x2 y2 rather than x y w h
+
 * = Supported by a grant from NLnet
 
 2.7.1 (July 2024)
diff --git a/cpdfcoord.ml b/cpdfcoord.ml
index c69f41d..125051a 100644
--- a/cpdfcoord.ml
+++ b/cpdfcoord.ml
@@ -207,20 +207,33 @@ let parse_units_string pdf page s =
     fs
 
 let parse_rectangle pdf s =
-  try
-    match parse_units_string pdf emptypage s with
-    | [x; y; w; h] -> x, y, w, h
-    | _ -> error ("Bad rectangle specification " ^ s)
-  with
-    e -> error ("Bad rectangle specification " ^ s ^ " : " ^ Printexc.to_string e)
+  (* If it begins with ? it's absolute *)
+  let s, absolute =
+    match explode s with
+    | '?'::r -> implode r, true
+    | _ -> s, false
+  in
+    try
+      match parse_units_string pdf emptypage s with
+      | [x; y; w; h] ->
+          if absolute then x, y, w -. x, h -. y else x, y, w, h
+      | _ -> error ("Bad rectangle specification " ^ s)
+    with
+      e -> error ("Bad rectangle specification " ^ s ^ " : " ^ Printexc.to_string e)
 
 let parse_rectangles pdf s =
+  (* If it begins with ? it's absolute *)
+  let s, absolute =
+    match explode s with
+    | '?'::r -> implode r, true
+    | _ -> s, false
+  in
   try
     let pages = Pdfpage.pages_of_pagetree pdf in
     let groups = List.map (fun page -> parse_units_string pdf page s) pages in
       List.map
         (function
-         | [x; y; w; h] -> (x, y, w, h)
+         | [x; y; w; h] -> if absolute then x, y, w -. x, h -. y else x, y, w, h
          | _ -> error ("Bad rectangle specification " ^ s))
         groups
   with
diff --git a/cpdfmanual.tex b/cpdfmanual.tex
index 653fe0b..03407ca 100644
--- a/cpdfmanual.tex
+++ b/cpdfmanual.tex
@@ -1,5 +1,6 @@
 %Document -stretch
 %Document -redact
+%Document ?x0 y0 x1 y1 rectangle specifications
 \documentclass{book}
 % Edit here to produce cpdfmanual.pdf, cpdflibmanual.pdf, pycpdfmanual.pdf,
 % dotnetcpdflibmanual.pdf, jcpdflibmanual.pdf jscpdflibmanual.pdf etc.