Add png, pdf and jpeg image support to the latex backend

CHANGES.md

@@ -1,5 +1,9 @@
 # Unreleased
 
+### Added
+
+- Added support for (local) images in the latex backend (@Octachron, #1297)
+
 ### Changed
 
 - Drop support for OCaml < 4.08 (@jonludlam, #1300)

src/latex/generator.ml

@@ -97,7 +97,7 @@ let elt_size (x : elt) =
   | Code_fragment _ | Tag _ | Break _ | Ligaturable _ ->
       Small
   | List _ | Section _ | Verbatim _ | Raw _ | Code_block _ | Indented _
-  | Description _ ->
+  | Description _ | Image _ ->
       Large
   | Table _ | Layout_table _ -> Huge
 
@@ -167,6 +167,7 @@ let rec pp_elt ppf = function
   | Indented x -> Raw.indent pp ppf x
   | Ligaturable s -> Fmt.string ppf s
   | Tag (s, t) -> tag s ppf t
+  | Image target -> Raw.includegraphics Fpath.pp ppf target
 
 and pp ppf = function
   | [] -> ()
@@ -277,13 +278,30 @@ let non_empty_code_fragment c =
   let s = source (inline ~verbatim:false ~in_source:true) c in
   match s with [] -> [] | _ :: _ as l -> [ Code_fragment l ]
 
+let alt_text ~in_source (target : Target.t) alt =
+  let text = txt ~verbatim:false ~in_source:false [ alt ] in
+  let break = if in_source then [] else [ Break Paragraph ] in
+  match target with
+  | Internal _ -> text @ break
+  | External l -> [ External_ref (l, Some text) ] @ break
+
+let image ~in_source (internal_url : Url.t) alt =
+  let dir, file = Link.get_dir_and_file internal_url.page in
+  match Fpath.(get_ext @@ v file) with
+  (* list imported from pdftex.def *)
+  | "" | ".pdf" | ".png" | ".jpg" | ".mps" | ".jpeg" | ".jbig2" | ".jb2"
+  | ".PDF" | ".PNG" | ".JPG" | ".JPEG" | ".JBIG2" | ".JB2" ->
+      let fpath = Fpath.v (String.concat Fpath.dir_sep (dir @ [ file ])) in
+      [ Image fpath ]
+  | _ -> alt_text ~in_source (Internal (Resolved internal_url)) alt
+
 let rec block ~in_source (l : Block.t) =
   let one (t : Block.one) =
     match t.desc with
     | Inline i -> inline ~verbatim:false ~in_source:false i
-    | Audio (_, content) | Video (_, content) | Image (_, content) ->
-        txt ~verbatim:false ~in_source:false [ content ]
-        @ if in_source then [] else [ Break Paragraph ]
+    | Image (Internal (Resolved x), alt) -> image ~in_source x alt
+    | Image (t, alt) | Audio (t, alt) | Video (t, alt) ->
+        alt_text ~in_source t alt
     | Paragraph i ->
         inline ~in_source:false ~verbatim:false i
         @ if in_source then [] else [ Break Paragraph ]

src/latex/raw.ml

@@ -126,6 +126,8 @@ let code_block pp ppf x =
   Fmt.cut ppf ();
   mend ppf name
 
+let includegraphics pp = create "includegraphics" pp
+
 let section pp = create "section" pp
 
 let subsection pp = create "subsection" pp

src/latex/raw.mli

@@ -66,6 +66,8 @@ val small_table : ('a, Types.alignment list option * 'a list list) tr
 
 val input : Fpath.t Fmt.t
 
+val includegraphics : 'a t
+
 (** {1 Required OCaml-specific primitives}
     All the macro should be implemented as "ocaml"-suffixed macro in the latex
     preamble *)

src/latex/types.ml

@@ -26,6 +26,7 @@ type elt =
   | Layout_table of layout_table
   | Table of table
   | Ligaturable of string
+  | Image of Fpath.t
 
 and section = { level : int; label : string option; content : t }
 

test/pages/medias.t/index.mld

@@ -7,7 +7,7 @@
 Some image:
 
 - Without alt text:{image!caml.gif}
-- With an alt text: {{image!caml.gif}With alt text and {b emphasis}}
+- With an alt text: {{image!caml.png}With alt text and {b emphasis}}
 - Unresolved without alt text: {image!caqzdqzdml.gif}
 - Unresolved with alt text: {{image!camezfzeffl.gif}With alt text and {b emphasis}}
 

test/pages/medias.t/run.t

@@ -3,6 +3,7 @@ We need to odoc-compile the package mld file, listing its children
   $ odoc compile index.mld --parent-id pkg1/ --output-dir _odoc
 
   $ odoc compile-asset --parent-id pkg1/ --output-dir _odoc --name caml.gif
+  $ odoc compile-asset --parent-id pkg1/ --output-dir _odoc --name caml.png
   $ odoc compile-asset --parent-id pkg1/ --output-dir _odoc --name Cri_du_chameau.ogg
   $ odoc compile-asset --parent-id pkg1/ --output-dir _odoc --name flower.webm
 
@@ -28,8 +29,8 @@ Testing the working references:
   $ cat html/pkg1/index.html | grep img
         <a href="caml.gif" class="img-link">
          <img src="caml.gif" alt="caml.gif"/>
-        <a href="caml.gif" class="img-link">
-         <img src="caml.gif" alt="With alt text and {b emphasis}"/>
+        <a href="caml.png" class="img-link">
+         <img src="caml.png" alt="With alt text and {b emphasis}"/>
         <a href="https://picsum.photos/200/300" class="img-link">
          <img src="https://picsum.photos/200/300" alt="reference"/>
         <a href="https://picsum.photos/200/300" class="img-link">
@@ -72,6 +73,9 @@ Testing latex and manpages
   caml.gif
   ./caqzdqzdml.gif
 
+  $ cat latex/pkg1/index.tex | grep png
+  \includegraphics{pkg1/caml.png}}%
+
   $ odoc man-generate -o man _odoc/pkg1/page-index.odocl
   $ cat man/pkg1/index.3o | grep gif
   caml\.gif