From 6ad1f0faef75cd2b735c9532073a119dba1cf399 Mon Sep 17 00:00:00 2001
From: Peter Serwylo <peter@serwylo.com>
Date: Mon, 19 Dec 2016 12:41:29 +1100
Subject: [PATCH] More concise management of the main recycler view.

No longer bind the views as they become visible. This resulted in
the same view being bound multiple times, but that was unneccesary.
Given that there is only five types of view, and each view type only
ever gets used once, the binding can happen when the view holder is
created, rather than each time it is shown. This fixed a few bugs to
do with views being inflated multiple times.
---
 .../fdroid/views/main/MainViewAdapter.java    | 47 +++++++++++++------
 .../fdroid/views/main/MainViewController.java |  4 --
 2 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/app/src/main/java/org/fdroid/fdroid/views/main/MainViewAdapter.java b/app/src/main/java/org/fdroid/fdroid/views/main/MainViewAdapter.java
index 458bed5bc..7f3762204 100644
--- a/app/src/main/java/org/fdroid/fdroid/views/main/MainViewAdapter.java
+++ b/app/src/main/java/org/fdroid/fdroid/views/main/MainViewAdapter.java
@@ -41,6 +41,30 @@ class MainViewAdapter extends RecyclerView.Adapter<MainViewController> {
 
     @Override
     public MainViewController onCreateViewHolder(ViewGroup parent, int viewType) {
+        MainViewController holder = createEmptyView();
+        switch (viewType) {
+            case R.id.whats_new:
+                holder.bindWhatsNewView();
+                break;
+            case R.id.categories:
+                holder.bindCategoriesView();
+                break;
+            case R.id.nearby:
+                holder.bindSwapView();
+                break;
+            case R.id.my_apps:
+                holder.bindMyApps();
+                break;
+            case R.id.settings:
+                holder.bindSettingsView();
+                break;
+            default:
+                throw new IllegalStateException("Unknown view type " + viewType);
+        }
+        return holder;
+    }
+
+    private MainViewController createEmptyView() {
         FrameLayout frame = new FrameLayout(activity);
         frame.setLayoutParams(new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
         return new MainViewController(activity, frame);
@@ -48,20 +72,10 @@ class MainViewAdapter extends RecyclerView.Adapter<MainViewController> {
 
     @Override
     public void onBindViewHolder(MainViewController holder, int position) {
-        long menuId = getItemId(position);
-        if (menuId == R.id.whats_new) {
-            holder.bindWhatsNewView();
-        } else if (menuId == R.id.categories) {
-            holder.bindCategoriesView();
-        } else if (menuId == R.id.nearby) {
-            holder.bindSwapView();
-        } else if (menuId == R.id.my_apps) {
-            holder.bindMyApps();
-        } else if (menuId == R.id.settings) {
-            holder.bindSettingsView();
-        } else {
-            holder.clearViews();
-        }
+        // The binding happens in onCreateViewHolder. This is because we never have more than one of
+        // each type of view in this main activity. Therefore, there is no benefit to re-binding new
+        // data each time we navigate back to an item, as the recycler view will just use the one we
+        // created earlier.
     }
 
     @Override
@@ -69,6 +83,11 @@ class MainViewAdapter extends RecyclerView.Adapter<MainViewController> {
         return positionToId.size();
     }
 
+    @Override
+    public int getItemViewType(int position) {
+        return positionToId.get(position);
+    }
+
     // The RecyclerViewPager and the BottomNavigationView both use menu item IDs to identify pages.
     @Override
     public long getItemId(int position) {
diff --git a/app/src/main/java/org/fdroid/fdroid/views/main/MainViewController.java b/app/src/main/java/org/fdroid/fdroid/views/main/MainViewController.java
index d67ca6f2b..cecced816 100644
--- a/app/src/main/java/org/fdroid/fdroid/views/main/MainViewController.java
+++ b/app/src/main/java/org/fdroid/fdroid/views/main/MainViewController.java
@@ -30,10 +30,6 @@ class MainViewController extends RecyclerView.ViewHolder {
         this.frame = frame;
     }
 
-    public void clearViews() {
-        frame.removeAllViews();
-    }
-
     /**
      * @see WhatsNewViewBinder
      */