Let XmpMetadata read from PdfMetadata struct

  Since there can be a substantial amount of metadata having them
  all as parameter is going to be overkill. Hence, splitting this
  out to use the PdfMetadata struct will be easier to add more
  fields.

src/pdf_metadata.rs

@@ -63,13 +63,7 @@ impl PdfMetadata {
 		let metadata = self.clone();
 		let xmp_obj = {
 			if self.conformance.must_have_xmp_metadata() {
-				Some(self.xmp_metadata.into_obj(
-					 	self.conformance.clone(),
-						self.trapping,
-						self.creation_date.clone(),
-						self.modification_date.clone(),
-						self.metadata_date,
-						self.document_title.clone()))
+				Some(self.xmp_metadata.into_obj(&metadata))
 			} else {
 				None
 			}

src/xmp_metadata.rs

@@ -3,7 +3,7 @@
 use crate::OffsetDateTime;
 use lopdf;
 
-use PdfConformance;
+use PdfMetadata;
 use utils::random_character_string_32;
 
 /// Initial struct for Xmp metatdata. This should be expanded later for XML handling, etc.
@@ -34,29 +34,23 @@ impl XmpMetadata {
 
     /// Consumes the XmpMetadata and turns it into a PDF Object.
     /// This is similar to the
-    pub(in crate) fn into_obj<S>(self,
-                           conformance: PdfConformance,
-                           trapping: bool,
-                           creation_date: OffsetDateTime,
-                           modification_date: OffsetDateTime,
-                           metadata_date: OffsetDateTime,
-                           document_title: S)
-    -> lopdf::Object where S: Into<String> + ::std::fmt::Display
+    pub(in crate) fn into_obj(self, m: &PdfMetadata)
+    -> lopdf::Object
     {
         use lopdf::{Stream as LoStream, Dictionary as LoDictionary};
         use lopdf::Object::*;
         use std::iter::FromIterator;
 
         // Shared between XmpMetadata and DocumentInfo
-        let trapping = if trapping { "True" } else { "False" };
+        let trapping = if m.trapping { "True" } else { "False" };
 
         // let xmp_instance_id = "2898d852-f86f-4479-955b-804d81046b19";
         let instance_id = random_character_string_32();
-        let create_date = to_pdf_xmp_date(creation_date);
-        let modification_date = to_pdf_xmp_date(modification_date);
-        let metadata_date = to_pdf_xmp_date(metadata_date);
+        let create_date = to_pdf_xmp_date(m.creation_date);
+        let modification_date = to_pdf_xmp_date(m.modification_date);
+        let metadata_date = to_pdf_xmp_date(m.metadata_date);
 
-        let pdf_x_version = conformance.get_identifier_string();
+        let pdf_x_version = m.conformance.get_identifier_string();
         let document_version = self.document_version.to_string();
         let document_id = self.document_id.to_string();
 
@@ -66,7 +60,7 @@ impl XmpMetadata {
         };
 
         let xmp_metadata = format!(include_str!("../assets/catalog_xmp_metadata.txt"),
-                           create_date, modification_date, metadata_date, document_title, document_id,
+                           create_date, modification_date, metadata_date, m.document_title, document_id,
                            instance_id, rendition_class, document_version, pdf_x_version, trapping);
 
         Stream(LoStream::new(LoDictionary::from_iter(vec![