From 06c15fd9e6d4335583512377f1b8401b9ea3ccf6 Mon Sep 17 00:00:00 2001
From: ByteHamster <info@bytehamster.com>
Date: Fri, 3 May 2019 11:06:04 +0200
Subject: Simplify empty view handling on recycler views

---
 .../danoeh/antennapod/view/EmptyViewHandler.java   | 92 +++++++++++++++-------
 .../antennapod/view/SimpleAdapterDataObserver.java | 41 ++++++++++
 2 files changed, 105 insertions(+), 28 deletions(-)
 create mode 100644 app/src/main/java/de/danoeh/antennapod/view/SimpleAdapterDataObserver.java

(limited to 'app/src/main/java/de/danoeh/antennapod/view')

diff --git a/app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java b/app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java
index e3fd63235..42c11bc8e 100644
--- a/app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java
+++ b/app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java
@@ -1,59 +1,95 @@
 package de.danoeh.antennapod.view;
 
-import android.app.Activity;
 import android.content.Context;
+import android.support.v7.widget.RecyclerView;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ListView;
+import android.widget.RelativeLayout;
 import android.widget.TextView;
 
 import de.danoeh.antennapod.R;
 
-public class EmptyViewHandler extends View {
-    private Activity activity;
-    private int title;
-    private int message;
+public class EmptyViewHandler {
+    private boolean layoutAdded = false;
+    private RecyclerView recyclerView;
+    private RecyclerView.Adapter adapter;
 
-    public EmptyViewHandler(Context context) {
-        super(context);
-        this.setActivity((Activity) context);
-    }
+    private final View emptyView;
+    private final TextView tvTitle;
+    private final TextView tvMessage;
 
-    public int getTitle() {
-        return title;
+    public EmptyViewHandler(Context context) {
+        emptyView = View.inflate(context, R.layout.empty_view_layout, null);
+        tvTitle = emptyView.findViewById(R.id.emptyViewTitle);
+        tvMessage = emptyView.findViewById(R.id.emptyViewMessage);
     }
 
     public void setTitle(int title) {
-        this.title = title;
-    }
-
-    public int getMessage() {
-        return message;
+        tvTitle.setText(title);
     }
 
     public void setMessage(int message) {
-        this.message = message;
+        tvMessage.setText(message);
     }
 
-    public void attachToListView(ListView listView){
+    public void hide() {
+        emptyView.setVisibility(View.GONE);
+    }
 
-        View  emptyView = getActivity().getLayoutInflater().inflate(R.layout.empty_view_layout, null);
+    public void attachToListView(ListView listView) {
+        if (layoutAdded) {
+            throw new IllegalStateException("Can not attach to ListView multiple times");
+        }
+        layoutAdded = true;
         ((ViewGroup) listView.getParent()).addView(emptyView);
         listView.setEmptyView(emptyView);
+    }
 
-        TextView tvTitle = (TextView) emptyView.findViewById(R.id.emptyViewTitle);
-        tvTitle.setText(title);
-
-        TextView tvMessage = (TextView) emptyView.findViewById(R.id.emptyViewMessage);
-        tvMessage.setText(message);
+    public void attachToRecyclerView(RecyclerView recyclerView) {
+        if (layoutAdded) {
+            throw new IllegalStateException("Can not attach to ListView multiple times");
+        }
+        layoutAdded = true;
+        this.recyclerView = recyclerView;
+        ViewGroup parent = ((ViewGroup) recyclerView.getParent());
+        parent.addView(emptyView);
+        updateAdapter(recyclerView.getAdapter());
 
+        if (parent instanceof RelativeLayout) {
+            RelativeLayout.LayoutParams layoutParams =
+                    (RelativeLayout.LayoutParams)emptyView.getLayoutParams();
+            layoutParams.addRule(RelativeLayout.CENTER_IN_PARENT, RelativeLayout.TRUE);
+            emptyView.setLayoutParams(layoutParams);
+        }
     }
 
-    public Activity getActivity() {
-        return activity;
+    public void updateAdapter(RecyclerView.Adapter adapter) {
+        if (this.adapter != null) {
+            this.adapter.unregisterAdapterDataObserver(adapterObserver);
+        }
+        this.adapter = adapter;
+        if (adapter != null) {
+            adapter.registerAdapterDataObserver(adapterObserver);
+        }
+        updateVisibility();
     }
 
-    public void setActivity(Activity activity) {
-        this.activity = activity;
+    private final SimpleAdapterDataObserver adapterObserver = new SimpleAdapterDataObserver() {
+        @Override
+        public void anythingChanged() {
+            updateVisibility();
+        }
+    };
+
+    private void updateVisibility() {
+        boolean empty;
+        if (adapter == null) {
+            empty = true;
+        } else {
+            empty = adapter.getItemCount() == 0;
+        }
+        recyclerView.setVisibility(empty ? View.GONE : View.VISIBLE);
+        emptyView.setVisibility(empty ? View.VISIBLE : View.GONE);
     }
 }
diff --git a/app/src/main/java/de/danoeh/antennapod/view/SimpleAdapterDataObserver.java b/app/src/main/java/de/danoeh/antennapod/view/SimpleAdapterDataObserver.java
new file mode 100644
index 000000000..45c3a35bd
--- /dev/null
+++ b/app/src/main/java/de/danoeh/antennapod/view/SimpleAdapterDataObserver.java
@@ -0,0 +1,41 @@
+package de.danoeh.antennapod.view;
+
+import android.support.annotation.Nullable;
+import android.support.v7.widget.RecyclerView;
+
+/**
+ * AdapterDataObserver that relays all events to the method anythingChanged().
+ */
+public abstract class SimpleAdapterDataObserver extends RecyclerView.AdapterDataObserver {
+    public abstract void anythingChanged();
+
+    @Override
+    public void onChanged() {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeChanged(int positionStart, int itemCount) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeChanged(int positionStart, int itemCount, @Nullable Object payload) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeInserted(int positionStart, int itemCount) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeRemoved(int positionStart, int itemCount) {
+        anythingChanged();
+    }
+}
-- 
cgit v1.2.3