Fix local path to URI conversion for paths with unicode

NAPS2.Lib/EtoForms/EtoDialogHelper.cs

@@ -105,7 +105,7 @@ private void SetDir(SaveFileDialog dialog, string? defaultPath)
         }
         if (path != null)
         {
-            dialog.Directory = new Uri(Path.GetFullPath(path));
+            dialog.Directory = UriHelper.FilePathToFileUri(Path.GetFullPath(path));
         }
     }
 
@@ -121,7 +121,7 @@ public override bool PromptToImport(out string[]? filePaths)
         if (Paths.IsTestAppDataPath)
         {
             // For UI test automation we choose the appdata folder to find the prepared files to import
-            ofd.Directory = new Uri(Path.GetFullPath(Paths.AppData));
+            ofd.Directory = UriHelper.FilePathToFileUri(Path.GetFullPath(Paths.AppData));
         }
         if (ofd.ShowDialog(null) == DialogResult.Ok)
         {

NAPS2.Lib/Util/UriHelper.cs

@@ -0,0 +1,36 @@
+using System.Text;
+
+namespace NAPS2.Util;
+
+public class UriHelper
+{
+    // From https://stackoverflow.com/a/35734486/2112909
+    public static string FilePathToFileUrl(string filePath)
+    {
+        StringBuilder uri = new StringBuilder();
+        foreach (char v in filePath)
+        {
+            if ((v >= 'a' && v <= 'z') || (v >= 'A' && v <= 'Z') || (v >= '0' && v <= '9') ||
+                v == '+' || v == '/' || v == ':' || v == '.' || v == '-' || v == '_' || v == '~' ||
+                v > '\xFF')
+            {
+                uri.Append(v);
+            }
+            else if (v == Path.DirectorySeparatorChar || v == Path.AltDirectorySeparatorChar)
+            {
+                uri.Append('/');
+            }
+            else
+            {
+                uri.Append(String.Format("%{0:X2}", (int)v));
+            }
+        }
+        if (uri.Length >= 2 && uri[0] == '/' && uri[1] == '/') // UNC path
+            uri.Insert(0, "file:");
+        else
+            uri.Insert(0, "file:///");
+        return uri.ToString();
+    }
+
+    public static Uri FilePathToFileUri(string filePath) => new(FilePathToFileUrl(filePath));
+}