[gnome-epub-thumbnailer/wip/hadess/fix-cover-properties: 2/2] epub: Fix thumbnailing of books with ePub 3.2 "cover-image"

[Bastien Nocera <hadess src gnome org>]

commit a0c0d13b7b8869641f16aba7ceda57dffe9ac4f3
Author: Bastien Nocera <hadess hadess net>
Date:   Wed Aug 4 12:03:58 2021 +0200

    epub: Fix thumbnailing of books with ePub 3.2 "cover-image"
    
    Look for the "cover-image" manifest item property as defined in the
    EPUB 3.2 spec:
    https://www.w3.org/publishing/epub3/epub-packages.html#bib-epub32
    
    Closes: #2

 gnome-epub-thumbnailer.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)
---
diff --git a/gnome-epub-thumbnailer.c b/gnome-epub-thumbnailer.c
index 490f387..841d8c7 100644
--- a/gnome-epub-thumbnailer.c
+++ b/gnome-epub-thumbnailer.c
@@ -215,8 +215,6 @@ get_cover_path_from_root_file (const char *metafile,
        char *root_path;
        char *root_file;
        gsize root_length;
-       char *content_name;
-       char *xpath;
        char *cover_path, *full_cover_path;
 
        cover_path = NULL;
@@ -242,15 +240,23 @@ get_cover_path_from_root_file (const char *metafile,
        xpath_ctx = xmlXPathNewContext(doc);
        xmlXPathRegisterNs (xpath_ctx, BAD_CAST ("ns"), BAD_CAST (OPF_NAMESPACE));
 
-       content_name = get_prop_for_xpath (doc, xpath_ctx, "//ns:package/ns:metadata/ns:meta[@name='cover']", 
"content");
-       if (!content_name)
-               goto bail;
-       g_debug ("Found content_name '%s'", content_name);
+       /* Look for "cover-image" manifest item property
+        * https://www.w3.org/publishing/epub3/epub-packages.html#sec-item-property-values */
+       cover_path = get_prop_for_xpath (doc, xpath_ctx, 
"//ns:package/ns:manifest/ns:item[@properties='cover-image']", "href");
+
+       if (!cover_path) {
+               g_autofree char *xpath = NULL;
+               g_autofree char *content_name = NULL;
+
+               content_name = get_prop_for_xpath (doc, xpath_ctx, 
"//ns:package/ns:metadata/ns:meta[@name='cover']", "content");
+               if (!content_name)
+                       goto bail;
+               g_debug ("Found content_name '%s'", content_name);
+
+               xpath = g_strdup_printf ("//ns:package/ns:manifest/ns:item[@id='%s']", content_name);
+               cover_path = get_prop_for_xpath (doc, xpath_ctx, xpath, "href");
+       }
 
-       xpath = g_strdup_printf ("//ns:package/ns:manifest/ns:item[@id='%s']", content_name);
-       g_free (content_name);
-       cover_path = get_prop_for_xpath (doc, xpath_ctx, xpath, "href");
-       g_free (xpath);
        g_debug ("Found cover_path '%s'", cover_path);
 
        full_cover_path = resolve_cover_path (cover_path, root_path);