From 074f72f58af667b54999ec5030d37aeb25e6cc58 Mon Sep 17 00:00:00 2001
From: Conny Duck <gitlab@connyduck.at>
Date: Fri, 15 Feb 2019 07:28:57 +0000
Subject: [PATCH] fix activity transitions by limiting view rebinding

---
 .../views/categories/AppPreviewAdapter.java   |  5 +++
 .../views/categories/CategoryAdapter.java     | 32 +++++++++++--------
 .../views/whatsnew/WhatsNewAdapter.java       |  5 +++
 3 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/app/src/main/java/org/fdroid/fdroid/views/categories/AppPreviewAdapter.java b/app/src/main/java/org/fdroid/fdroid/views/categories/AppPreviewAdapter.java
index 10388e305..4f38abcac 100644
--- a/app/src/main/java/org/fdroid/fdroid/views/categories/AppPreviewAdapter.java
+++ b/app/src/main/java/org/fdroid/fdroid/views/categories/AppPreviewAdapter.java
@@ -5,6 +5,7 @@ import android.database.Cursor;
 import android.support.annotation.NonNull;
 import android.support.v7.widget.RecyclerView;
 import android.view.ViewGroup;
+
 import org.fdroid.fdroid.R;
 import org.fdroid.fdroid.data.App;
 
@@ -36,6 +37,10 @@ class AppPreviewAdapter extends RecyclerView.Adapter<AppCardController> {
     }
 
     public void setAppCursor(Cursor cursor) {
+        if (this.cursor == cursor) {
+            //don't notify when the cursor did not change
+            return;
+        }
         this.cursor = cursor;
         notifyDataSetChanged();
     }
diff --git a/app/src/main/java/org/fdroid/fdroid/views/categories/CategoryAdapter.java b/app/src/main/java/org/fdroid/fdroid/views/categories/CategoryAdapter.java
index e8aa99449..3c144e93f 100644
--- a/app/src/main/java/org/fdroid/fdroid/views/categories/CategoryAdapter.java
+++ b/app/src/main/java/org/fdroid/fdroid/views/categories/CategoryAdapter.java
@@ -3,22 +3,32 @@ package org.fdroid.fdroid.views.categories;
 import android.app.Activity;
 import android.support.annotation.NonNull;
 import android.support.v4.app.LoaderManager;
-import android.support.v7.widget.RecyclerView;
+import android.support.v7.recyclerview.extensions.ListAdapter;
+import android.support.v7.util.DiffUtil;
 import android.view.ViewGroup;
+
 import org.fdroid.fdroid.R;
 
-import java.util.Collections;
 import java.util.List;
 
-public class CategoryAdapter extends RecyclerView.Adapter<CategoryController> {
-
-    @NonNull
-    private List<String> unlocalizedCategoryNames = Collections.<String>emptyList();
+public class CategoryAdapter extends ListAdapter<String, CategoryController> {
 
     private final Activity activity;
     private final LoaderManager loaderManager;
 
     public CategoryAdapter(Activity activity, LoaderManager loaderManager) {
+        super(new DiffUtil.ItemCallback<String>() {
+            @Override
+            public boolean areItemsTheSame(String oldItem, String newItem) {
+                return oldItem.equals(newItem);
+            }
+
+            @Override
+            public boolean areContentsTheSame(String oldItem, String newItem) {
+                return false;
+            }
+        });
+
         this.activity = activity;
         this.loaderManager = loaderManager;
     }
@@ -32,17 +42,11 @@ public class CategoryAdapter extends RecyclerView.Adapter<CategoryController> {
 
     @Override
     public void onBindViewHolder(@NonNull CategoryController holder, int position) {
-        holder.bindModel(unlocalizedCategoryNames.get(position));
-    }
-
-    @Override
-    public int getItemCount() {
-        return unlocalizedCategoryNames.size();
+        holder.bindModel(getItem(position));
     }
 
     public void setCategories(@NonNull List<String> unlocalizedCategoryNames) {
-        this.unlocalizedCategoryNames = unlocalizedCategoryNames;
-        notifyDataSetChanged();
+        submitList(unlocalizedCategoryNames);
     }
 
 }
diff --git a/app/src/main/java/org/fdroid/fdroid/views/whatsnew/WhatsNewAdapter.java b/app/src/main/java/org/fdroid/fdroid/views/whatsnew/WhatsNewAdapter.java
index cf6ee8df9..fbec4c440 100644
--- a/app/src/main/java/org/fdroid/fdroid/views/whatsnew/WhatsNewAdapter.java
+++ b/app/src/main/java/org/fdroid/fdroid/views/whatsnew/WhatsNewAdapter.java
@@ -11,6 +11,7 @@ import android.support.v7.widget.GridLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.view.View;
 import android.view.ViewGroup;
+
 import org.fdroid.fdroid.BuildConfig;
 import org.fdroid.fdroid.R;
 import org.fdroid.fdroid.data.App;
@@ -102,6 +103,10 @@ public class WhatsNewAdapter extends RecyclerView.Adapter<AppCardController> {
     }
 
     public void setAppsCursor(Cursor cursor) {
+        if (this.cursor == cursor) {
+            //don't notify when the cursor did not change
+            return;
+        }
         this.cursor = cursor;
         notifyDataSetChanged();
     }