Support favorites prev page load

app/src/main/java/com/hippo/ehviewer/ui/scene/FavoritesScene.java

@@ -837,6 +837,7 @@ public class FavoritesScene extends BaseScene implements
             else
                 pages = Integer.MAX_VALUE;
 
+            mHelper.prevPg = result.prevPage;
             mHelper.nextPg = result.nextPage;
             mHelper.onGetPageData(taskId, pages, mHelper.pgCounter + 1, result.galleryInfoList);
 
@@ -1158,6 +1159,7 @@ public class FavoritesScene extends BaseScene implements
 
     private class FavoritesHelper extends GalleryInfoContentHelper {
         public int pgCounter = 0;
+        public String prevPg = null;
         public String nextPg = null;
 
         @Override
@@ -1219,7 +1221,15 @@ public class FavoritesScene extends BaseScene implements
                 final String keyword = mUrlBuilder.getKeyword();
                 SimpleHandler.getInstance().post(() -> onGetFavoritesLocal(keyword, taskId));
             } else {
-                mUrlBuilder.setNext(jumpTo == null ? nextPg : Integer.toString(minGid));
+                String prevPage = null, nextPage = null;
+                if (page != 0) {
+                    if (page >= mHelper.getPageForTop())
+                        nextPage = nextPg;
+                    else
+                        prevPage = prevPg;
+                }
+                mUrlBuilder.setPrev(prevPage);
+                mUrlBuilder.setNext(jumpTo == null ? nextPage : Integer.toString(minGid));
 
                 mUrlBuilder.setJumpTo(jumpTo);
                 jumpTo = null;
@@ -1295,12 +1305,14 @@ public class FavoritesScene extends BaseScene implements
         @Override
         protected void beforeRefresh() {
             super.beforeRefresh();
+            prevPg = null;
             nextPg = null;
         }
 
         @Override
         protected Parcelable saveInstanceState(Parcelable superState) {
             Bundle bundle = (Bundle) super.saveInstanceState(superState);
+            bundle.putString(KEY_PREV_PAGE, prevPg);
             bundle.putString(KEY_NEXT_PAGE, nextPg);
             return bundle;
         }
@@ -1308,6 +1320,7 @@ public class FavoritesScene extends BaseScene implements
         @Override
         protected Parcelable restoreInstanceState(Parcelable state) {
             Bundle bundle = (Bundle) state;
+            prevPg = bundle.getString(KEY_PREV_PAGE);
             nextPg = bundle.getString(KEY_NEXT_PAGE);
             return super.restoreInstanceState(state);
         }

app/src/main/java/com/hippo/ehviewer/widget/GalleryInfoContentHelper.kt

@@ -136,6 +136,7 @@ abstract class GalleryInfoContentHelper : ContentHelper<GalleryInfo?>() {
         private const val KEY_DATA_MAP = "data_map"
         private const val KEY_MAX_GID = "max_gid"
         private const val KEY_MIN_GID = "min_gid"
+        const val KEY_PREV_PAGE = "prev_page"
         const val KEY_NEXT_PAGE = "next_page"
     }
 }