Merge pull request #387 from doompadee/library-categories

Make Library categories configurable

app/build.gradle

@@ -125,6 +125,7 @@ dependencies {
     implementation('com.h6ah4i.android.widget.advrecyclerview:advrecyclerview:0.11.0@aar') {
         transitive = true
     }
+    implementation 'com.google.code.gson:gson:2.8.2'
     implementation 'com.crashlytics.sdk.android:crashlytics:2.8.0'
     implementation('com.crashlytics.sdk.android:answers:1.3.13@aar') {
         transitive = true

app/src/main/java/com/kabouzeid/gramophone/adapter/CategoryInfoAdapter.java

@@ -0,0 +1,108 @@
+package com.kabouzeid.gramophone.adapter;
+
+import android.annotation.SuppressLint;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.helper.ItemTouchHelper;
+import android.view.LayoutInflater;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.CheckBox;
+import android.widget.TextView;
+
+import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.model.CategoryInfo;
+import com.kabouzeid.gramophone.util.SwipeAndDragHelper;
+
+import java.util.ArrayList;
+
+public class CategoryInfoAdapter extends RecyclerView.Adapter<CategoryInfoAdapter.ViewHolder> implements SwipeAndDragHelper.ActionCompletionContract {
+    private ArrayList<CategoryInfo> categoryInfos;
+    private ItemTouchHelper touchHelper;
+
+    public CategoryInfoAdapter(ArrayList<CategoryInfo> categoryInfos) {
+        this.categoryInfos = categoryInfos;
+        SwipeAndDragHelper swipeAndDragHelper = new SwipeAndDragHelper(this);
+        touchHelper = new ItemTouchHelper(swipeAndDragHelper);
+    }
+
+    @Override
+    public CategoryInfoAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.preference_dialog_library_categories_listitem, parent, false);
+        return new ViewHolder(view);
+    }
+
+    @SuppressLint("ClickableViewAccessibility")
+    @Override
+    public void onBindViewHolder(CategoryInfoAdapter.ViewHolder holder, int position) {
+        CategoryInfo categoryInfo = categoryInfos.get(position);
+
+        holder.checkBox.setChecked(categoryInfo.visible);
+        holder.title.setText(holder.title.getResources().getString(categoryInfo.category.stringRes));
+
+        holder.itemView.setOnClickListener(v -> {
+            if (!(categoryInfo.visible && isLastCheckedCategory(categoryInfo))) {
+                categoryInfo.visible = !categoryInfo.visible;
+                holder.checkBox.setChecked(categoryInfo.visible);
+            }
+        });
+
+        holder.dragView.setOnTouchListener((view, event) -> {
+                    if (event.getActionMasked() == MotionEvent.ACTION_DOWN) {
+                        touchHelper.startDrag(holder);
+                    }
+                    return false;
+                }
+        );
+    }
+
+    @Override
+    public int getItemCount() {
+        return categoryInfos.size();
+    }
+
+
+    public void setCategoryInfos(ArrayList<CategoryInfo> categoryInfos) {
+        this.categoryInfos = categoryInfos;
+        notifyDataSetChanged();
+    }
+
+    @Override
+    public void onViewMoved(int oldPosition, int newPosition) {
+        CategoryInfo categoryInfo = categoryInfos.get(oldPosition);
+        categoryInfos.remove(oldPosition);
+        categoryInfos.add(newPosition, categoryInfo);
+        notifyItemMoved(oldPosition, newPosition);
+    }
+
+    public void attachToRecyclerView(RecyclerView recyclerView) {
+        touchHelper.attachToRecyclerView(recyclerView);
+    }
+
+    public ArrayList<CategoryInfo> getCategoryInfos() {
+        return categoryInfos;
+    }
+
+    private boolean isLastCheckedCategory(CategoryInfo categoryInfo) {
+        if (categoryInfo.visible) {
+            for (CategoryInfo c : categoryInfos) {
+                if (c != categoryInfo && c.visible) return false;
+            }
+        }
+        return true;
+    }
+
+    static class ViewHolder extends RecyclerView.ViewHolder {
+        public CheckBox checkBox;
+        public TextView title;
+        public View dragView;
+
+        public ViewHolder(View view) {
+            super(view);
+            checkBox = view.findViewById(R.id.checkbox);
+            title = view.findViewById(R.id.title);
+            dragView = view.findViewById(R.id.drag_view);
+        }
+    }
+}
+

app/src/main/java/com/kabouzeid/gramophone/adapter/MusicLibraryPagerAdapter.java

@@ -9,15 +9,17 @@ import android.support.v4.app.FragmentPagerAdapter;
 import android.util.SparseArray;
 import android.view.ViewGroup;
 
-import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.model.CategoryInfo;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.AlbumsFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.ArtistsFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.GenresFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.PlaylistsFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.SongsFragment;
+import com.kabouzeid.gramophone.util.PreferenceUtil;
 
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 
@@ -30,33 +32,28 @@ public class MusicLibraryPagerAdapter extends FragmentPagerAdapter {
     @NonNull
     private final Context mContext;
 
-    @NonNull
-    private final String[] titles;
-
     public MusicLibraryPagerAdapter(@NonNull final Context context, final FragmentManager fragmentManager) {
         super(fragmentManager);
         mContext = context;
-        titles = new String[]{
+        setCategoryInfos(PreferenceUtil.getInstance(context).getLibraryCategoryInfos());
-                context.getResources().getString(R.string.songs),
-                context.getResources().getString(R.string.albums),
-                context.getResources().getString(R.string.artists),
-                context.getResources().getString(R.string.genres),
-                context.getResources().getString(R.string.playlists)
-        };
-        final MusicFragments[] fragments = MusicFragments.values();
-        for (final MusicLibraryPagerAdapter.MusicFragments fragment : fragments) {
-            add(fragment.getFragmentClass(), null);
-        }
     }
 
-    @SuppressWarnings("synthetic-access")
+    public void setCategoryInfos(@NonNull ArrayList<CategoryInfo> categoryInfos) {
-    public void add(@NonNull final Class<? extends Fragment> className, final Bundle params) {
+        mHolderList.clear();
-        final Holder mHolder = new Holder();
-        mHolder.mClassName = className.getName();
-        mHolder.mParams = params;
 
-        final int mPosition = mHolderList.size();
+        for (CategoryInfo categoryInfo : categoryInfos) {
-        mHolderList.add(mPosition, mHolder);
+            if (categoryInfo.visible) {
+                MusicFragments fragment = MusicFragments.valueOf(categoryInfo.category.toString());
+                Holder holder = new Holder();
+                holder.mClassName = fragment.getFragmentClass().getName();
+                holder.title = mContext.getResources()
+                        .getString(categoryInfo.category.stringRes)
+                        .toUpperCase(Locale.getDefault());
+                mHolderList.add(holder);
+            }
+        }
+
+        alignCache();
         notifyDataSetChanged();
     }
 
@@ -68,6 +65,23 @@ public class MusicLibraryPagerAdapter extends FragmentPagerAdapter {
         return getItem(position);
     }
 
+    @Override
+    public int getItemPosition(@NonNull Object fragment) {
+        for (int i = 0, size = mHolderList.size(); i < size; i++) {
+            Holder holder = mHolderList.get(i);
+            if (holder.mClassName.equals(fragment.getClass().getName())) {
+                return i;
+            }
+        }
+        return POSITION_NONE;
+    }
+
+    @Override
+    public long getItemId(int position) {
+        // as fragment position is not fixed, we can't use position as id
+        return MusicFragments.of(getFragment(position).getClass()).ordinal();
+    }
+
     @NonNull
     @Override
     public Object instantiateItem(@NonNull final ViewGroup container, final int position) {
@@ -104,16 +118,40 @@ public class MusicLibraryPagerAdapter extends FragmentPagerAdapter {
     @NonNull
     @Override
     public CharSequence getPageTitle(final int position) {
-        return titles[position]
+        return mHolderList.get(position).title;
-                .toUpperCase(Locale.getDefault());
+    }
+
+    /**
+     * Aligns the fragment cache with the current category layout.
+     */
+    private void alignCache() {
+        if (mFragmentArray.size() == 0) return;
+
+        HashMap<String, WeakReference<Fragment>> mappings = new HashMap<>(mFragmentArray.size());
+
+        for (int i = 0, size = mFragmentArray.size(); i < size; i++) {
+            WeakReference<Fragment> ref = mFragmentArray.valueAt(i);
+            Fragment fragment = ref.get();
+            if (fragment != null) {
+                mappings.put(fragment.getClass().getName(), ref);
+            }
+        }
+        for (int i = 0, size = mHolderList.size(); i < size; i++) {
+            WeakReference<Fragment> ref = mappings.get(mHolderList.get(i).mClassName);
+            if (ref != null) {
+                mFragmentArray.put(i, ref);
+            } else {
+                mFragmentArray.remove(i);
+            }
+        }
     }
 
     public enum MusicFragments {
-        SONG(SongsFragment.class),
+        SONGS(SongsFragment.class),
-        ALBUM(AlbumsFragment.class),
+        ALBUMS(AlbumsFragment.class),
-        ARTIST(ArtistsFragment.class),
+        ARTISTS(ArtistsFragment.class),
         GENRES(GenresFragment.class),
-        PLAYLIST(PlaylistsFragment.class);
+        PLAYLISTS(PlaylistsFragment.class);
 
         private final Class<? extends Fragment> mFragmentClass;
 
@@ -124,10 +162,25 @@ public class MusicLibraryPagerAdapter extends FragmentPagerAdapter {
         public Class<? extends Fragment> getFragmentClass() {
             return mFragmentClass;
         }
+
+        public static MusicFragments of(Class<?> cl) {
+            MusicFragments[] fragments = All.FRAGMENTS;
+            for (int i = 0; i < fragments.length; i++) {
+                if (cl.equals(fragments[i].mFragmentClass))
+                    return fragments[i];
+            }
+
+            throw new IllegalArgumentException("Unknown music fragment " + cl);
+        }
+
+        private static class All {
+            public static final MusicFragments[] FRAGMENTS = values();
+        }
     }
 
     private final static class Holder {
         String mClassName;
         Bundle mParams;
+        String title;
     }
 }

app/src/main/java/com/kabouzeid/gramophone/model/CategoryInfo.java

@@ -0,0 +1,27 @@
+package com.kabouzeid.gramophone.model;
+
+import com.kabouzeid.gramophone.R;
+
+public class CategoryInfo {
+    public Category category;
+    public boolean visible;
+
+    public CategoryInfo(Category category, boolean visible) {
+        this.category = category;
+        this.visible = visible;
+    }
+
+    public enum Category {
+        SONGS(R.string.songs),
+        ALBUMS(R.string.albums),
+        ARTISTS(R.string.artists),
+        GENRES(R.string.genres),
+        PLAYLISTS(R.string.playlists);
+
+        public final int stringRes;
+
+        Category(int stringRes) {
+            this.stringRes = stringRes;
+        }
+    }
+}

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

@@ -0,0 +1,24 @@
+package com.kabouzeid.gramophone.preferences;
+
+import android.content.Context;
+import android.util.AttributeSet;
+
+import com.kabouzeid.appthemehelper.common.prefs.supportv7.ATEDialogPreference;
+
+public class LibraryPreference extends ATEDialogPreference {
+    public LibraryPreference(Context context) {
+        super(context);
+    }
+
+    public LibraryPreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public LibraryPreference(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    public LibraryPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+    }
+}

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

@@ -0,0 +1,68 @@
+package com.kabouzeid.gramophone.preferences;
+
+import android.app.Dialog;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.DialogFragment;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.view.View;
+
+import com.afollestad.materialdialogs.MaterialDialog;
+import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.adapter.CategoryInfoAdapter;
+import com.kabouzeid.gramophone.model.CategoryInfo;
+import com.kabouzeid.gramophone.util.PreferenceUtil;
+
+import java.util.ArrayList;
+
+
+public class LibraryPreferenceDialog extends DialogFragment {
+    public static LibraryPreferenceDialog newInstance() {
+        return new LibraryPreferenceDialog();
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        View view = getActivity().getLayoutInflater().inflate(R.layout.preference_dialog_library_categories, null);
+
+        CategoryInfoAdapter adapter = new CategoryInfoAdapter(PreferenceUtil.getInstance(getContext()).getLibraryCategoryInfos());
+
+        RecyclerView recyclerView = view.findViewById(R.id.recycler_view);
+        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
+        recyclerView.setAdapter(adapter);
+
+        adapter.attachToRecyclerView(recyclerView);
+
+        return new MaterialDialog.Builder(getContext())
+                .title(R.string.library_categories)
+                .customView(view, false)
+                .positiveText(android.R.string.ok)
+                .negativeText(android.R.string.cancel)
+                .neutralText(R.string.reset_action)
+                .autoDismiss(false)
+                .onNeutral((dialog, action) -> adapter.setCategoryInfos(PreferenceUtil.getInstance(getContext()).getDefaultLibraryCategoryInfos()))
+                .onNegative((dialog, action) -> dismiss())
+                .onPositive((dialog, action) -> {
+                    updateCategories(adapter.getCategoryInfos());
+                    dismiss();
+                })
+                .build();
+    }
+
+    private void updateCategories(ArrayList<CategoryInfo> categories) {
+        if (getSelected(categories) == 0) return;
+
+        PreferenceUtil.getInstance(getContext()).setLibraryCategoryInfos(categories);
+    }
+
+    private int getSelected(ArrayList<CategoryInfo> categories) {
+        int selected = 0;
+        for (CategoryInfo categoryInfo : categories) {
+            if (categoryInfo.visible)
+                selected++;
+        }
+        return selected;
+    }
+}

app/src/main/java/com/kabouzeid/gramophone/ui/activities/SettingsActivity.java

@@ -31,6 +31,8 @@ import com.kabouzeid.gramophone.appshortcuts.DynamicShortcutManager;
 import com.kabouzeid.gramophone.misc.NonProAllowedColors;
 import com.kabouzeid.gramophone.preferences.BlacklistPreference;
 import com.kabouzeid.gramophone.preferences.BlacklistPreferenceDialog;
+import com.kabouzeid.gramophone.preferences.LibraryPreference;
+import com.kabouzeid.gramophone.preferences.LibraryPreferenceDialog;
 import com.kabouzeid.gramophone.preferences.NowPlayingScreenPreference;
 import com.kabouzeid.gramophone.preferences.NowPlayingScreenPreferenceDialog;
 import com.kabouzeid.gramophone.ui.activities.base.AbsBaseActivity;
@@ -167,6 +169,8 @@ public class SettingsActivity extends AbsBaseActivity implements ColorChooserDia
                 return NowPlayingScreenPreferenceDialog.newInstance();
             } else if (preference instanceof BlacklistPreference) {
                 return BlacklistPreferenceDialog.newInstance();
+            } else if (preference instanceof LibraryPreference) {
+                return LibraryPreferenceDialog.newInstance();
             }
             return super.onCreatePreferenceDialog(preference);
         }

app/src/main/java/com/kabouzeid/gramophone/ui/fragments/mainactivity/library/LibraryFragment.java

@@ -3,6 +3,7 @@ package com.kabouzeid.gramophone.ui.fragments.mainactivity.library;
 
 import android.app.Activity;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
@@ -34,6 +35,7 @@ import com.kabouzeid.gramophone.ui.activities.MainActivity;
 import com.kabouzeid.gramophone.ui.activities.SearchActivity;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.AbsMainActivityFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.AbsLibraryPagerRecyclerViewCustomGridSizeFragment;
+import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.PlaylistsFragment;
 import com.kabouzeid.gramophone.util.PhonographColorUtil;
 import com.kabouzeid.gramophone.util.PreferenceUtil;
 import com.kabouzeid.gramophone.util.Util;
@@ -42,7 +44,7 @@ import butterknife.BindView;
 import butterknife.ButterKnife;
 import butterknife.Unbinder;
 
-public class LibraryFragment extends AbsMainActivityFragment implements CabHolder, MainActivity.MainActivityFragmentCallbacks, ViewPager.OnPageChangeListener {
+public class LibraryFragment extends AbsMainActivityFragment implements CabHolder, MainActivity.MainActivityFragmentCallbacks, ViewPager.OnPageChangeListener, SharedPreferences.OnSharedPreferenceChangeListener {
     public static final String TAG = LibraryFragment.class.getSimpleName();
 
     private Unbinder unbinder;
@@ -75,6 +77,7 @@ public class LibraryFragment extends AbsMainActivityFragment implements CabHolde
 
     @Override
     public void onDestroyView() {
+        PreferenceUtil.getInstance(getActivity()).unregisterOnSharedPreferenceChangedListener(this);
         super.onDestroyView();
         pager.removeOnPageChangeListener(this);
         unbinder.unbind();
@@ -82,6 +85,7 @@ public class LibraryFragment extends AbsMainActivityFragment implements CabHolde
 
     @Override
     public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+        PreferenceUtil.getInstance(getActivity()).registerOnSharedPreferenceChangedListener(this);
         setStatusbarColorAuto(view);
         getMainActivity().setNavigationbarColorAuto();
         getMainActivity().setTaskDescriptionColorAuto();
@@ -90,6 +94,20 @@ public class LibraryFragment extends AbsMainActivityFragment implements CabHolde
         setUpViewPager();
     }
 
+    @Override
+    public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
+        if (PreferenceUtil.LIBRARY_CATEGORIES.equals(key)) {
+            Fragment current = getCurrentFragment();
+            pagerAdapter.setCategoryInfos(PreferenceUtil.getInstance(getActivity()).getLibraryCategoryInfos());
+            pager.setOffscreenPageLimit(pagerAdapter.getCount() - 1);
+            int position = pagerAdapter.getItemPosition(current);
+            pager.setCurrentItem(position > -1 ? position : 0);
+
+            // hide the tab bar with single tab
+            tabs.setVisibility(pagerAdapter.getCount() == 1 ? View.GONE : View.VISIBLE);
+        }
+    }
+
     private void setUpToolbar() {
         int primaryColor = ThemeStore.primaryColor(getActivity());
         appbar.setBackgroundColor(primaryColor);
@@ -125,7 +143,7 @@ public class LibraryFragment extends AbsMainActivityFragment implements CabHolde
     }
 
     private boolean isPlaylistPage() {
-        return pager.getCurrentItem() == MusicLibraryPagerAdapter.MusicFragments.PLAYLIST.ordinal();
+        return getCurrentFragment() instanceof PlaylistsFragment;
     }
 
     @NonNull

app/src/main/java/com/kabouzeid/gramophone/util/PreferenceUtil.java

@@ -7,12 +7,18 @@ import android.preference.PreferenceManager;
 import android.support.annotation.NonNull;
 import android.support.annotation.StyleRes;
 
+import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
+import com.google.gson.reflect.TypeToken;
 import com.kabouzeid.gramophone.R;
 import com.kabouzeid.gramophone.helper.SortOrder;
+import com.kabouzeid.gramophone.model.CategoryInfo;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.folders.FoldersFragment;
 import com.kabouzeid.gramophone.ui.fragments.player.NowPlayingScreen;
 
 import java.io.File;
+import java.lang.reflect.Type;
+import java.util.ArrayList;
 
 public final class PreferenceUtil {
     public static final String GENERAL_THEME = "general_theme";
@@ -74,6 +80,8 @@ public final class PreferenceUtil {
 
     public static final String INITIALIZED_BLACKLIST = "initialized_blacklist";
 
+    public static final String LIBRARY_CATEGORIES = "library_categories";
+
     private static PreferenceUtil sInstance;
 
     private final SharedPreferences mPreferences;
@@ -426,4 +434,41 @@ public final class PreferenceUtil {
     public final boolean initializedBlacklist() {
         return mPreferences.getBoolean(INITIALIZED_BLACKLIST, false);
     }
+
+    public void setLibraryCategoryInfos(ArrayList<CategoryInfo> categories) {
+        Gson gson = new Gson();
+        Type collectionType = new TypeToken<ArrayList<CategoryInfo>>() {
+        }.getType();
+
+        final SharedPreferences.Editor editor = mPreferences.edit();
+        editor.putString(LIBRARY_CATEGORIES, gson.toJson(categories, collectionType));
+        editor.apply();
+    }
+
+    public ArrayList<CategoryInfo> getLibraryCategoryInfos() {
+        String data = mPreferences.getString(LIBRARY_CATEGORIES, null);
+        if (data != null) {
+            Gson gson = new Gson();
+            Type collectionType = new TypeToken<ArrayList<CategoryInfo>>() {
+            }.getType();
+
+            try {
+                return gson.fromJson(data, collectionType);
+            } catch (JsonSyntaxException e) {
+                e.printStackTrace();
+            }
+        }
+
+        return getDefaultLibraryCategoryInfos();
+    }
+
+    public ArrayList<CategoryInfo> getDefaultLibraryCategoryInfos() {
+        ArrayList<CategoryInfo> defaultCategoryInfos = new ArrayList<>(5);
+        defaultCategoryInfos.add(new CategoryInfo(CategoryInfo.Category.SONGS, true));
+        defaultCategoryInfos.add(new CategoryInfo(CategoryInfo.Category.ALBUMS, true));
+        defaultCategoryInfos.add(new CategoryInfo(CategoryInfo.Category.ARTISTS, true));
+        defaultCategoryInfos.add(new CategoryInfo(CategoryInfo.Category.GENRES, true));
+        defaultCategoryInfos.add(new CategoryInfo(CategoryInfo.Category.PLAYLISTS, true));
+        return defaultCategoryInfos;
+    }
 }

app/src/main/java/com/kabouzeid/gramophone/util/SwipeAndDragHelper.java

@@ -0,0 +1,56 @@
+package com.kabouzeid.gramophone.util;
+
+import android.graphics.Canvas;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.helper.ItemTouchHelper;
+
+public class SwipeAndDragHelper extends ItemTouchHelper.Callback {
+
+    private ActionCompletionContract contract;
+
+    public SwipeAndDragHelper(ActionCompletionContract contract) {
+        this.contract = contract;
+    }
+
+    @Override
+    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
+        int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
+        return makeMovementFlags(dragFlags, 0);
+    }
+
+    @Override
+    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
+        contract.onViewMoved(viewHolder.getAdapterPosition(), target.getAdapterPosition());
+        return true;
+    }
+
+    @Override
+    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
+    }
+
+    @Override
+    public boolean isLongPressDragEnabled() {
+        return false;
+    }
+
+    @Override
+    public void onChildDraw(Canvas c,
+                            RecyclerView recyclerView,
+                            RecyclerView.ViewHolder viewHolder,
+                            float dX,
+                            float dY,
+                            int actionState,
+                            boolean isCurrentlyActive) {
+        if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
+            float alpha = 1 - (Math.abs(dX) / recyclerView.getWidth());
+            viewHolder.itemView.setAlpha(alpha);
+        }
+        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
+    }
+
+    public interface ActionCompletionContract {
+        void onViewMoved(int oldPosition, int newPosition);
+    }
+
+}
+

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

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+    <android.support.v7.widget.RecyclerView
+        android:id="@+id/recycler_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+</android.support.constraint.ConstraintLayout>

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

@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:descendantFocusability="blocksDescendants"
+    android:focusable="true"
+    android:foreground="?attr/rectSelector"
+    android:minHeight="@dimen/md_listitem_height"
+    android:orientation="horizontal"
+    android:paddingEnd="@dimen/md_dialog_frame_margin"
+    android:paddingLeft="@dimen/md_dialog_frame_margin"
+    android:paddingRight="@dimen/md_dialog_frame_margin"
+    android:paddingStart="@dimen/md_dialog_frame_margin"
+    tools:gravity="start|center_vertical">
+
+    <com.kabouzeid.appthemehelper.common.views.ATECheckBox
+        android:id="@+id/checkbox"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:background="@null"
+        android:clickable="false"
+        android:focusable="false"
+        android:gravity="center_vertical" />
+
+    <TextView
+        android:id="@+id/title"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_weight="1"
+        android:ellipsize="end"
+        android:gravity="center_vertical"
+        android:minHeight="@dimen/md_listitem_height"
+        android:paddingBottom="@dimen/md_listitem_vertical_margin_choice"
+        android:paddingLeft="@dimen/md_listitem_control_margin"
+        android:paddingStart="@dimen/md_listitem_control_margin"
+        android:paddingTop="@dimen/md_listitem_vertical_margin_choice"
+        android:singleLine="true"
+        android:textSize="@dimen/md_listitem_textsize"
+        tools:text="Item" />
+
+    <com.kabouzeid.gramophone.views.IconImageView
+        android:id="@+id/drag_view"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_gravity="end|center_vertical"
+        android:clickable="false"
+        android:focusable="false"
+        android:minHeight="@dimen/md_listitem_height"
+        android:tint="?attr/iconColor"
+        android:tintMode="src_in"
+        app:srcCompat="@drawable/ic_drag_vertical_white_24dp"
+        tools:ignore="ContentDescription" />
+
+</LinearLayout>

app/src/main/res/values-de/strings.xml

@@ -140,6 +140,7 @@
     <string name="remove_action">Entfernen</string>
     <string name="rename_action">Umbenennen</string>
     <string name="create_action">Erstellen</string>
+    <string name="reset_action">Zurücksetzen</string>
     <string name="x_selected">%1$d ausgewählt</string>
     <string name="primary_color">Hauptfarbe</string>
     <string name="accent_color">Akzentfarbe</string>
@@ -284,4 +285,8 @@
     <string name="pref_summary_blacklist">Der Inhalt der Ordner auf der Blacklist wird in deiner Bibliothek verborgen.</string>
     <string name="reset_artist_image">Künstler-Bild zurücksetzen</string>
     <string name="set_artist_image">Künstler-Bild festlegen</string>
+    <string name="library_categories">Bibliothek</string>
+    <string name="pref_summary_library_categories">Anzeige und Anordnung der einzelnen Kategorien festlegen.</string>
+    <string name="edit_categories">Kategorien bearbeiten</string>
+    <string name="at_least_one_category_must_be_enabled">Zumindest eine Kategorie muss aktiv sein.</string>
 </resources>

app/src/main/res/values/strings.xml

@@ -141,6 +141,7 @@
     <string name="remove_action">Remove</string>
     <string name="rename_action">Rename</string>
     <string name="create_action">Create</string>
+    <string name="reset_action">Reset</string>
     <string name="x_selected">%1$d selected</string>
     <string name="primary_color">Primary color</string>
     <string name="accent_color">Accent color</string>
@@ -294,4 +295,8 @@
     <string name="pref_summary_blacklist">The content of blacklisted folders is hidden from your library.</string>
     <string name="reset_artist_image">Reset artist image</string>
     <string name="set_artist_image">Set artist image</string>
+    <string name="library_categories">Library categories</string>
+    <string name="pref_summary_library_categories">Configure visibility and order of library categories.</string>
+    <string name="edit_categories">Edit categories</string>
+    <string name="at_least_one_category_must_be_enabled">At least one category must be enabled.</string>
 </resources>

app/src/main/res/xml/pref_general.xml

@@ -20,6 +20,11 @@
             android:positiveButtonText="@null"
             android:title="@string/pref_title_general_theme" />
 
+        <com.kabouzeid.gramophone.preferences.LibraryPreference
+            android:key="library_categories"
+            android:summary="@string/pref_summary_library_categories"
+            android:title="@string/library_categories" />
+
     </com.kabouzeid.appthemehelper.common.prefs.supportv7.ATEPreferenceCategory>
 
 </android.support.v7.preference.PreferenceScreen>