Scaffolding for -list-images

Changes

@@ -7,13 +7,14 @@ o Spray splits a file to multiple outputs by alternating pages
 o List document and page info in JSON format
 o List page labels in JSON format
 o List fonts in JSON format
-o Identify PDF/A, PDF/X, PDF/E, PDF/VT, PDF/UA
+o Identify PDF/A, PDF/X, PDF/E, PDF/VT, PDF/UA in -info
 o Extract font files from a document
 o List images on a page with -list-images[-json]
 
 Extended features:
 
 o -list-images-used[-json] extends -image-resolution
+o Use -raw with -extract-images to get PNMs
 
 Fixes:
 

cpdfcommand.ml

@@ -4177,8 +4177,13 @@ let go () =
                     Printf.printf "%i, %s, %i, %i, %f, %f\n" pagenum xobject w h wdpi hdpi)
                images
   | Some ListImages ->
-      (* FIXME Implement ListImages *)
-      ()
+      let pdf = get_single_pdf args.op true in
+      let range = parse_pagespec_allow_empty pdf (get_pagespec ()) in
+      let json = Cpdfimage.images pdf range in
+        if args.format_json then
+          flprint (Cpdfyojson.Safe.pretty_to_string json)
+        else
+          flprint "old fashioned output\n"
   | Some MissingFonts ->
       let pdf = get_single_pdf args.op true in
         let range = parse_pagespec_allow_empty pdf (get_pagespec ()) in

cpdfimage.ml

@@ -272,6 +272,8 @@ let image_resolution pdf range dpi =
   image_resolution pdf range dpi;
   rev !image_results
 
+let images pdf range = `Null
+
 let obj_of_jpeg_data data =
   let w, h = Cpdfjpeg.jpeg_dimensions data in
   let d = 

cpdfimage.mli

@@ -8,6 +8,9 @@ val extract_images : ?raw:bool -> ?path_to_p2p:string ->
 (** Report image resolutions. *)        
 val image_resolution : Pdf.t -> int list -> float -> (int * string * int * int * float * float) list
 
+(** List images in JSON format *)
+val images : Pdf.t -> int list -> Cpdfyojson.Safe.t
+
 (**/**)
 val image_of_input : (Pdfio.bytes -> Pdf.pdfobject) -> Pdfio.input -> Pdf.t
 val obj_of_jpeg_data : Pdfio.bytes -> Pdf.pdfobject