-Added play buttons to channel fragment similar to playlist fragment.

-Fixed abstract info play queue reloading the same initial page.
-Fixed OOB on get item for abstract play queue.

app/src/main/java/org/schabi/newpipe/fragments/list/channel/ChannelFragment.java

@@ -3,6 +3,7 @@ package org.schabi.newpipe.fragments.list.channel;
 import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
@@ -10,6 +11,7 @@ import android.support.v4.content.ContextCompat;
 import android.support.v7.app.ActionBar;
 import android.text.TextUtils;
 import android.util.Log;
+import android.view.Gravity;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -19,6 +21,7 @@ import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.ImageView;
 import android.widget.TextView;
+import android.widget.Toast;
 
 import com.jakewharton.rxbinding2.view.RxView;
 
@@ -30,10 +33,14 @@ import org.schabi.newpipe.extractor.channel.ChannelInfo;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
 import org.schabi.newpipe.fragments.list.BaseListInfoFragment;
 import org.schabi.newpipe.fragments.subscription.SubscriptionService;
+import org.schabi.newpipe.playlist.ChannelPlayQueue;
+import org.schabi.newpipe.playlist.PlayQueue;
 import org.schabi.newpipe.report.UserAction;
 import org.schabi.newpipe.util.AnimationUtils;
 import org.schabi.newpipe.util.ExtractorHelper;
 import org.schabi.newpipe.util.Localization;
+import org.schabi.newpipe.util.NavigationHelper;
+import org.schabi.newpipe.util.PermissionHelper;
 
 import java.util.List;
 import java.util.concurrent.TimeUnit;
@@ -69,6 +76,10 @@ public class ChannelFragment extends BaseListInfoFragment<ChannelInfo> {
     private TextView headerSubscribersTextView;
     private Button headerSubscribeButton;
 
+    private Button headerPlayAllButton;
+    private Button headerPopupButton;
+    private Button headerBackgroundButton;
+
     private MenuItem menuRssButton;
 
     public static ChannelFragment getInstance(int serviceId, String url, String name) {
@@ -125,6 +136,10 @@ public class ChannelFragment extends BaseListInfoFragment<ChannelInfo> {
         headerSubscribersTextView = headerRootLayout.findViewById(R.id.channel_subscriber_view);
         headerSubscribeButton = headerRootLayout.findViewById(R.id.channel_subscribe_button);
 
+        headerPlayAllButton = headerRootLayout.findViewById(R.id.playlist_play_all_button);
+        headerPopupButton = headerRootLayout.findViewById(R.id.playlist_play_popup_button);
+        headerBackgroundButton = headerRootLayout.findViewById(R.id.playlist_play_bg_button);
+
         return headerRootLayout;
     }
 
@@ -391,6 +406,42 @@ public class ChannelFragment extends BaseListInfoFragment<ChannelInfo> {
         if (subscribeButtonMonitor != null) subscribeButtonMonitor.dispose();
         updateSubscription(result);
         monitorSubscription(result);
+
+        headerPlayAllButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                NavigationHelper.playOnMainPlayer(activity, getPlayQueue());
+            }
+        });
+        headerPopupButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && !PermissionHelper.checkSystemAlertWindowPermission(activity)) {
+                    Toast toast = Toast.makeText(activity, R.string.msg_popup_permission, Toast.LENGTH_LONG);
+                    TextView messageView = toast.getView().findViewById(android.R.id.message);
+                    if (messageView != null) messageView.setGravity(Gravity.CENTER);
+                    toast.show();
+                    return;
+                }
+                NavigationHelper.playOnPopupPlayer(activity, getPlayQueue());
+            }
+        });
+        headerBackgroundButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                NavigationHelper.playOnBackgroundPlayer(activity, getPlayQueue());
+            }
+        });
+    }
+
+    private PlayQueue getPlayQueue() {
+        return new ChannelPlayQueue(
+                currentInfo.service_id,
+                currentInfo.url,
+                currentInfo.next_streams_url,
+                infoListAdapter.getItemsList(),
+                0
+        );
     }
 
     @Override

app/src/main/java/org/schabi/newpipe/playlist/AbstractInfoPlayQueue.java

@@ -26,7 +26,7 @@ abstract class AbstractInfoPlayQueue<T extends ListInfo, U extends InfoItem> ext
     transient Disposable fetchReactor;
 
     AbstractInfoPlayQueue(final U item) {
-        this(item.service_id, item.url, item.url, Collections.<InfoItem>emptyList(), 0);
+        this(item.service_id, item.url, null, Collections.<InfoItem>emptyList(), 0);
     }
 
     AbstractInfoPlayQueue(final int serviceId,
@@ -55,7 +55,7 @@ abstract class AbstractInfoPlayQueue<T extends ListInfo, U extends InfoItem> ext
         return new SingleObserver<T>() {
             @Override
             public void onSubscribe(@NonNull Disposable d) {
-                if (isComplete || (fetchReactor != null && !fetchReactor.isDisposed())) {
+                if (isComplete || !isInitial || (fetchReactor != null && !fetchReactor.isDisposed())) {
                     d.dispose();
                 } else {
                     fetchReactor = d;
@@ -64,6 +64,7 @@ abstract class AbstractInfoPlayQueue<T extends ListInfo, U extends InfoItem> ext
 
             @Override
             public void onSuccess(@NonNull T result) {
+                isInitial = false;
                 if (!result.has_more_streams) isComplete = true;
                 nextUrl = result.next_streams_url;
 
@@ -86,7 +87,7 @@ abstract class AbstractInfoPlayQueue<T extends ListInfo, U extends InfoItem> ext
         return new SingleObserver<ListExtractor.NextItemsResult>() {
             @Override
             public void onSubscribe(@NonNull Disposable d) {
-                if (isComplete || (fetchReactor != null && !fetchReactor.isDisposed())) {
+                if (isComplete || isInitial || (fetchReactor != null && !fetchReactor.isDisposed())) {
                     d.dispose();
                 } else {
                     fetchReactor = d;

app/src/main/java/org/schabi/newpipe/playlist/PlayQueue.java

@@ -123,7 +123,7 @@ public abstract class PlayQueue implements Serializable {
      * May throw {@link IndexOutOfBoundsException}.
      * */
     public PlayQueueItem getItem(int index) {
-        if (index >= streams.size() || streams.get(index) == null) return null;
+        if (index < 0 || index >= streams.size() || streams.get(index) == null) return null;
         return streams.get(index);
     }
 

app/src/main/res/layout/channel_header.xml

@@ -5,8 +5,12 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/channel_header_layout"
     android:layout_width="match_parent"
-    android:layout_height="wrap_content"
+    android:layout_height="wrap_content">
-    android:layout_marginBottom="12dp">
+
+    <RelativeLayout
+        android:id="@+id/channel_metadata"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
 
         <ImageView
             android:id="@+id/channel_banner_image"
@@ -78,3 +82,61 @@
             tools:ignore="RtlHardcoded"
             tools:visibility="visible"/>
     </RelativeLayout>
+
+    <RelativeLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:id="@+id/play_control"
+        android:layout_marginRight="2dp"
+        android:layout_marginEnd="2dp"
+        android:layout_below="@+id/channel_metadata">
+
+        <Button
+            android:id="@+id/playlist_play_bg_button"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_vertical|right"
+            android:layout_marginRight="2dp"
+            android:layout_toLeftOf="@+id/playlist_play_all_button"
+            android:layout_toStartOf="@+id/playlist_play_all_button"
+            android:text="@string/controls_background_title"
+            android:textSize="@dimen/channel_rss_title_size"
+            android:textColor="?attr/colorAccent"
+            android:theme="@style/RedButton"
+            android:drawableLeft="?attr/audio"
+            android:drawablePadding="4dp"
+            tools:ignore="RtlHardcoded"
+            tools:visibility="visible" />
+
+        <Button
+            android:id="@+id/playlist_play_all_button"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_vertical|right"
+            android:layout_marginRight="2dp"
+            android:layout_toLeftOf="@+id/playlist_play_popup_button"
+            android:layout_toStartOf="@+id/playlist_play_popup_button"
+            android:text="@string/play_all"
+            android:textSize="@dimen/channel_rss_title_size"
+            android:textColor="?attr/colorAccent"
+            android:theme="@style/RedButton"
+            tools:ignore="RtlHardcoded"
+            tools:visibility="visible"/>
+
+        <Button
+            android:id="@+id/playlist_play_popup_button"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_vertical|right"
+            android:layout_alignParentRight="true"
+            android:text="@string/controls_popup_title"
+            android:textSize="@dimen/channel_rss_title_size"
+            android:textColor="?attr/colorAccent"
+            android:theme="@style/RedButton"
+            android:drawableLeft="?attr/popup"
+            android:drawablePadding="4dp"
+            tools:ignore="RtlHardcoded"
+            tools:visibility="visible" />
+    </RelativeLayout>
+
+</RelativeLayout>