feat: check that Media Overlays are only defined for XHTML and SVG co…

…ntent documents

Add a schema rule to check the media type of items declaring
a `media-overlay` attribute

See #1176

src/main/resources/com/adobe/epubcheck/schema/30/package-30.sch

@@ -287,9 +287,12 @@
 			<let name="ref" value="./normalize-space(@media-overlay)"/>
 			<let name="item" value="//opf:manifest/opf:item[normalize-space(@id) = $ref]"/>
 			<let name="item-media-type" value="normalize-space($item/@media-type)"/>
+            <let name="media-type" value="normalize-space(@media-type)"/>
 			<assert test="$item-media-type = 'application/smil+xml'">media overlay items must be of
 				the "application/smil+xml" type (given type was "<value-of select="$item-media-type"
 				/>")</assert>
+            <assert test="$media-type='application/xhtml+xml' or $media-type='image/svg+xml'"
+                >The media-overlay attribute is only allowed on XHTML and SVG content documents.</assert>
 		</rule>
 	</pattern>
 
@@ -322,8 +325,8 @@
 		<rule context="opf:meta[normalize-space(@property)='media:playback-active-class']">
 			<report test="@refines"> @refines must not be used with the media:playback-active-class property</report>
 		</rule>
-	</pattern>
-	
+    </pattern>
+
 
 
 	<!-- EPUB 3.2 New Checks -->

src/test/resources/epub3/files/package-document/mediaoverlays-non-contentdoc-error.opf

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<package xmlns="http://www.idpf.org/2007/opf" version="3.0" unique-identifier="uid"
+	xmlns:dc="http://purl.org/dc/elements/1.1/">
+	<metadata>
+		<dc:title>Title</dc:title>
+		<dc:language>en</dc:language>
+		<dc:identifier id="uid">NOID</dc:identifier>
+		<meta property="dcterms:modified">2019-01-01T12:00:00Z</meta>
+		<!-- Media Overlays Duration Properties -->
+		<meta property="media:duration">0:01:30.200</meta>
+		<meta refines="#mo001" property="media:duration">0:01:30.200</meta>
+	</metadata>
+	<manifest>
+		<item id="t001" href="contents.xhtml" properties="nav" media-type="application/xhtml+xml" media-overlay="mo001"/>
+		<item id="img001" href="cover.jpg" media-type="image/jpeg" media-overlay="mo001"/>
+		<item id="mo001" href="mediaoverlay_001.smil" media-type="application/smil+xml"/>
+	</manifest>
+	<spine>
+		<itemref idref="t001"/>
+	</spine>
+</package>

src/test/resources/epub3/mediaoverlays-package-document.feature

@@ -23,6 +23,12 @@ Feature: EPUB 3 ▸ Media Overlays ▸ Package Document Checks
     And the message contains 'must be of the "application/smil+xml" type'
     And no other errors or warnings are reported
 
+  Scenario: Report use of the media-overlay attribute on non-EPUB Content Documents
+    When checking file 'mediaoverlays-non-contentdoc-error.opf'
+    Then error RSC-005 is reported
+    And the message contains 'media-overlay attribute is only allowed'
+    And no other errors or warnings are reported
+
   ## 3.5.2 Package Metadata
 
   Scenario: the entire publication duration must be defined
@@ -36,6 +42,8 @@ Feature: EPUB 3 ▸ Media Overlays ▸ Package Document Checks
     Then error RSC-005 is reported
     And the message contains "item media:duration meta element not set"
     And no other errors or warnings are reported
+
+
 
   # C. Media Overlays Metadata Vocabulary
   # see https://www.w3.org/publishing/epub32/epub-mediaoverlays.html#app-overlays-vocab