little adjustment about load more logic

Pixiview/Illust/RelatedIllustsPage.xaml.cs

@@ -9,6 +9,8 @@ namespace Pixiview.Illust
 {
     public partial class RelatedIllustsPage : IllustRecommendsCollectionPage
     {
+        private const int STEP = 18;
+
         private readonly IllustItem illustItem;
         private int startIndex;
         private int nextIndex;
@@ -53,15 +55,16 @@ namespace Pixiview.Illust
                 {
                     return null;
                 }
-                var ids = illustIds.Skip(startIndex).Take(18).ToArray();
-                nextIndex = startIndex + ids.Length;
+                var ids = illustIds.Skip(startIndex).Take(STEP).ToArray();
+                data = Stores.LoadIllustRecommendsListData(illustItem.Id, ids);
+                nextIndex = startIndex + STEP;
                 if (ids.Length == 0 || nextIndex >= illustIds.Length)
                 {
                     // done
+
                     App.DebugPrint($"download completed: {startIndex}");
-                    return null;
+                    startIndex = nextIndex;
                 }
-                data = Stores.LoadIllustRecommendsListData(illustItem.Id, ids);
             }
             return data;
         }
@@ -96,6 +99,13 @@ namespace Pixiview.Illust
             {
                 return;
             }
+            // release
+            var collection = IllustCollection;
+            if (collection != null)
+            {
+                collection.Running = false;
+                IllustCollection = null;
+            }
             startIndex = -1;
             nextIndex = 0;
             illustIds = null;