Added logic to switch between now playing screens.

app/src/main/java/com/kabouzeid/gramophone/preferences/NowPlayingScreenPreference.java

@@ -0,0 +1,27 @@
+package com.kabouzeid.gramophone.preferences;
+
+import android.content.Context;
+import android.util.AttributeSet;
+
+import com.kabouzeid.appthemehelper.common.prefs.supportv7.ATEDialogPreference;
+
+/**
+ * @author Karim Abou Zeid (kabouzeid)
+ */
+public class NowPlayingScreenPreference extends ATEDialogPreference {
+    public NowPlayingScreenPreference(Context context) {
+        super(context);
+    }
+
+    public NowPlayingScreenPreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public NowPlayingScreenPreference(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    public NowPlayingScreenPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+    }
+}

app/src/main/java/com/kabouzeid/gramophone/preferences/NowPlayingScreenPreferenceDialog.java

@@ -0,0 +1,135 @@
+package com.kabouzeid.gramophone.preferences;
+
+import android.annotation.SuppressLint;
+import android.app.Dialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.DialogFragment;
+import android.support.v4.view.PagerAdapter;
+import android.support.v4.view.ViewPager;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import com.afollestad.materialdialogs.DialogAction;
+import com.afollestad.materialdialogs.MaterialDialog;
+import com.heinrichreimersoftware.materialintro.view.InkPageIndicator;
+import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.ui.fragments.player.NowPlayingScreen;
+import com.kabouzeid.gramophone.util.PreferenceUtil;
+import com.kabouzeid.gramophone.util.ViewUtil;
+
+import butterknife.ButterKnife;
+
+/**
+ * @author Karim Abou Zeid (kabouzeid)
+ */
+public class NowPlayingScreenPreferenceDialog extends DialogFragment implements MaterialDialog.SingleButtonCallback, ViewPager.OnPageChangeListener {
+    public static final String TAG = NowPlayingScreenPreferenceDialog.class.getSimpleName();
+
+    private DialogAction whichButtonClicked;
+    private int viewPagerPosition;
+
+    public static NowPlayingScreenPreferenceDialog newInstance() {
+        return new NowPlayingScreenPreferenceDialog();
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        @SuppressLint("InflateParams") View view = LayoutInflater.from(getContext()).inflate(R.layout.preference_dialog_now_playing_screen, null);
+        ViewPager viewPager = ButterKnife.findById(view, R.id.now_playing_screen_view_pager);
+        viewPager.setAdapter(new NowPlayingScreenAdapter(getContext()));
+        viewPager.addOnPageChangeListener(this);
+        viewPager.setPageMargin((int) ViewUtil.convertDpToPixel(32, getResources()));
+        viewPager.setCurrentItem(PreferenceUtil.getInstance(getContext()).getNowPlayingScreen().ordinal());
+
+        InkPageIndicator pageIndicator = ButterKnife.findById(view, R.id.page_indicator);
+        pageIndicator.setViewPager(viewPager);
+
+        return new MaterialDialog.Builder(getContext())
+                .title(R.string.pref_title_now_playing_screen_appearance)
+                .positiveText(android.R.string.ok)
+                .negativeText(android.R.string.cancel)
+                .onAny(this)
+                .customView(view, false)
+                .build();
+    }
+
+    @Override
+    public void onClick(@NonNull MaterialDialog dialog, @NonNull DialogAction which) {
+        whichButtonClicked = which;
+    }
+
+    @Override
+    public void onDismiss(DialogInterface dialog) {
+        super.onDismiss(dialog);
+        if (whichButtonClicked == DialogAction.POSITIVE) {
+            PreferenceUtil.getInstance(getContext()).setNowPlayingScreen(NowPlayingScreen.values()[viewPagerPosition]);
+        }
+    }
+
+    @Override
+    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
+
+    }
+
+    @Override
+    public void onPageSelected(int position) {
+        this.viewPagerPosition = position;
+    }
+
+    @Override
+    public void onPageScrollStateChanged(int state) {
+
+    }
+
+    private static class NowPlayingScreenAdapter extends PagerAdapter {
+
+        private Context context;
+
+        public NowPlayingScreenAdapter(Context context) {
+            this.context = context;
+        }
+
+        @Override
+        public Object instantiateItem(ViewGroup collection, int position) {
+            NowPlayingScreen nowPlayingScreen = NowPlayingScreen.values()[position];
+
+            LayoutInflater inflater = LayoutInflater.from(context);
+            ViewGroup layout = (ViewGroup) inflater.inflate(R.layout.preference_now_playing_screen_item, collection, false);
+            collection.addView(layout);
+
+            ImageView image = ButterKnife.findById(layout, R.id.image);
+            TextView title = ButterKnife.findById(layout, R.id.title);
+            image.setImageResource(nowPlayingScreen.drawableResId);
+            title.setText(nowPlayingScreen.titleRes);
+
+            return layout;
+        }
+
+        @Override
+        public void destroyItem(ViewGroup collection, int position, Object view) {
+            collection.removeView((View) view);
+        }
+
+        @Override
+        public int getCount() {
+            return NowPlayingScreen.values().length;
+        }
+
+        @Override
+        public boolean isViewFromObject(View view, Object object) {
+            return view == object;
+        }
+
+        @Override
+        public CharSequence getPageTitle(int position) {
+            return context.getString(NowPlayingScreen.values()[position].titleRes);
+        }
+    }
+}