From f3868f9d7be48f24a1505cd596f5b73ae733e916 Mon Sep 17 00:00:00 2001
From: Ekaitz Zarraga <ekaitz@elenq.tech>
Date: Tue, 16 Jul 2024 17:13:02 +0200
Subject: Add PDF cover creation system

---
 Makefile.scm | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

(limited to 'Makefile.scm')

diff --git a/Makefile.scm b/Makefile.scm
index 6a40e43..72565b4 100644
--- a/Makefile.scm
+++ b/Makefile.scm
@@ -4,6 +4,7 @@ exec chibi-scheme -A utils/ $0 $@
 |#
 (import (chibi)
         (chibi json)
+        (chibi string)
         (only (chibi filesystem)
               directory-files
               create-directory*
@@ -11,7 +12,6 @@ exec chibi-scheme -A utils/ $0 $@
         (chibi process)
         (only (chibi pathname) path-strip-directory path-extension make-path)
         ;(chibi app)
-        (only (chibi string) string-prefix? string-trim-right string-join)
         (prefix (chibi io) io:)
         (utils cover cover)
         (srfi 1)
@@ -180,6 +180,20 @@ exec chibi-scheme -A utils/ $0 $@
         files)
       "Error in ebook creation")))
 
+(define (get-print-box svg-file)
+  "SVG covers have a rectangle `meta-content-box` prepared to serve as the
+  printing bounding box. Its position is the (x0,y0) and (width,height) is
+  (x1,y1). This function extracts that information."
+  (string-join
+    (string-split
+      (process->string-or-fail
+        `("inkscape"
+          ,svg-file
+          "-I" "meta-content-box"
+          "-XYWH")
+        "Error: impossible to extract cover printing bounding box")
+      #\newline)
+    ":"))
 (define (make-cover lang output input)
   (let* ((outpath  (make-path output lang))
          (files    (directory-sources lang input))
@@ -197,7 +211,18 @@ exec chibi-scheme -A utils/ $0 $@
           "--export-filename" ,(make-path outpath "cover.pdf")
           "--export-type=pdf"
           ,svg-file))
-      "Error in cover creation")))
+      "Error in PDF cover creation")
+
+    (process->string-or-fail
+      (append
+        `("inkscape"
+          ,svg-file
+          "--export-filename" ,(make-path outpath "cover.png")
+          "--export-type=png"
+          "--export-background=white"
+          "--export-background-opacity=1.0"
+          "--export-area" ,(get-print-box svg-file)))
+      "Error in PNG cover creation")))
 
 (define (build-lang lang output input)
   (pandoc-web         lang output input)
-- 
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