Add Pdf.UpdateMetadata

WGneu/Documents/Pdf.cs

@@ -6,6 +6,7 @@ using System.Linq;
 using System.Reflection.Metadata.Ecma335;
 using System.Text;
 using System.Threading.Tasks;
+using PdfSharp.Pdf.IO;
 using PuppeteerSharp;
 using PuppeteerSharp.Media;
 using WGneu.Windows;
@@ -47,6 +48,13 @@ namespace WGneu.Documents {
             });
         }
 
+        public static void UpdateMetadata(string path, string title, string author) {
+            using var doc = PdfReader.Open(path);
+            doc.Info.Title = title;
+            doc.Info.Author = author;
+            doc.Save(path);
+        }
+
         public static void Display(string title, string path) {
             var w = new DocumentViewerWindow(title, path);
             w.Show();