Drag and drop to rearrange filter criteria

app/src/main/java/com/todoroo/astrid/core/CriterionViewHolder.kt

@@ -1,5 +1,6 @@
 package com.todoroo.astrid.core
 
+import android.content.Context
 import android.view.View
 import android.widget.ImageView
 import android.widget.TextView
@@ -10,8 +11,14 @@ import butterknife.OnClick
 import org.tasks.Callback
 import org.tasks.R
 import org.tasks.locale.Locale
+import org.tasks.preferences.ResourceResolver
 
-class CriterionViewHolder(itemView: View, private val locale: Locale, private val onClick: Callback<String>) : RecyclerView.ViewHolder(itemView) {
+class CriterionViewHolder(
+        private val context: Context,
+        itemView: View,
+        private val locale: Locale,
+        private val onClick: Callback<String>)
+    : RecyclerView.ViewHolder(itemView) {
 
     @BindView(R.id.divider)
     lateinit var divider: View
@@ -67,4 +74,13 @@ class CriterionViewHolder(itemView: View, private val locale: Locale, private va
 
     @OnClick(R.id.row)
     fun onClick() = this.onClick.call(criterion.id)
+
+    fun setMoving(moving: Boolean) {
+        if (moving) {
+            row.setBackgroundColor(ResourceResolver.getData(context, R.attr.colorControlHighlight))
+        } else {
+            row.setBackgroundResource(ResourceResolver.getResourceId(context, R.attr.selectableItemBackground))
+            row.background.jumpToCurrentState()
+        }
+    }
 }

app/src/main/java/com/todoroo/astrid/core/CustomFilterAdapter.java

@@ -2,11 +2,15 @@ package com.todoroo.astrid.core;
 
 import static com.google.common.collect.Lists.transform;
 
+import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.widget.AsyncDifferConfig;
 import androidx.recyclerview.widget.AsyncListDiffer;
+import androidx.recyclerview.widget.ListUpdateCallback;
 import androidx.recyclerview.widget.RecyclerView;
 import com.google.common.collect.ImmutableList;
 import java.util.List;
@@ -14,7 +18,8 @@ import org.tasks.Callback;
 import org.tasks.R;
 import org.tasks.locale.Locale;
 
-public class CustomFilterAdapter extends RecyclerView.Adapter<CriterionViewHolder> {
+public class CustomFilterAdapter extends RecyclerView.Adapter<CriterionViewHolder> implements
+    ListUpdateCallback {
 
   private final Callback<String> onClick;
   private final Locale locale;
@@ -24,16 +29,16 @@ public class CustomFilterAdapter extends RecyclerView.Adapter<CriterionViewHolde
       List<CriterionInstance> objects, Locale locale, Callback<String> onClick) {
     this.locale = locale;
     this.onClick = onClick;
-    differ = new AsyncListDiffer<>(this, new CriterionDiffCallback());
+    differ = new AsyncListDiffer<>(this, new AsyncDifferConfig.Builder<>(new CriterionDiffCallback()).build());
     submitList(objects);
   }
 
   @NonNull
   @Override
   public CriterionViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
-    View view =
-        LayoutInflater.from(parent.getContext()).inflate(R.layout.custom_filter_row, parent, false);
-    return new CriterionViewHolder(view, locale, onClick);
+    Context context = parent.getContext();
+    View view = LayoutInflater.from(context).inflate(R.layout.custom_filter_row, parent, false);
+    return new CriterionViewHolder(context, view, locale, onClick);
   }
 
   @Override
@@ -53,4 +58,24 @@ public class CustomFilterAdapter extends RecyclerView.Adapter<CriterionViewHolde
   private List<CriterionInstance> getItems() {
     return differ.getCurrentList();
   }
+
+  @Override
+  public void onInserted(int position, int count) {
+    notifyItemRangeInserted(position, count);
+  }
+
+  @Override
+  public void onRemoved(int position, int count) {
+    notifyItemRangeRemoved(position, count);
+  }
+
+  @Override
+  public void onMoved(int fromPosition, int toPosition) {
+    notifyDataSetChanged();
+  }
+
+  @Override
+  public void onChanged(int position, int count, @Nullable Object payload) {
+    notifyItemRangeChanged(position, count);
+  }
 }

app/src/main/java/com/todoroo/astrid/core/CustomFilterItemTouchHelper.kt

@@ -0,0 +1,39 @@
+package com.todoroo.astrid.core
+
+import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.RecyclerView
+import org.tasks.Callback2
+
+class CustomFilterItemTouchHelper(private val onMove: Callback2<Int, Int>, private val onClear: Runnable) : ItemTouchHelper.Callback() {
+    override fun getMovementFlags(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder): Int {
+        return if (viewHolder.adapterPosition > 0) makeMovementFlags(ItemTouchHelper.UP or ItemTouchHelper.DOWN, 0) else 0
+    }
+
+    override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
+        super.onSelectedChanged(viewHolder, actionState)
+
+        if (actionState == ItemTouchHelper.ACTION_STATE_DRAG) {
+            (viewHolder as CriterionViewHolder).setMoving(true);
+        }
+    }
+
+    override fun onMove(
+            recyclerView: RecyclerView, src: RecyclerView.ViewHolder, target: RecyclerView.ViewHolder): Boolean {
+        val toPosition = target.adapterPosition
+        if (toPosition == 0) {
+            return false
+        }
+        onMove.call(src.adapterPosition, toPosition);
+        return true
+    }
+
+    override fun clearView(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder) {
+        super.clearView(recyclerView, viewHolder)
+
+        (viewHolder as CriterionViewHolder).setMoving(false)
+
+        onClear.run()
+    }
+
+    override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {}
+}

app/src/main/java/org/tasks/Callback2.java

@@ -0,0 +1,5 @@
+package org.tasks;
+
+public interface Callback2<T1, T2> {
+  void call(T1 t1, T2 t2);
+}

app/src/main/java/org/tasks/activities/FilterSettingsActivity.java

@@ -21,6 +21,7 @@ import android.widget.EditText;
 import android.widget.FrameLayout;
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AlertDialog;
+import androidx.recyclerview.widget.ItemTouchHelper;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 import butterknife.BindView;
@@ -44,6 +45,7 @@ import com.todoroo.astrid.api.PermaSql;
 import com.todoroo.astrid.api.TextInputCriterion;
 import com.todoroo.astrid.core.CriterionInstance;
 import com.todoroo.astrid.core.CustomFilterAdapter;
+import com.todoroo.astrid.core.CustomFilterItemTouchHelper;
 import com.todoroo.astrid.dao.Database;
 import com.todoroo.astrid.dao.TaskDao.TaskCriteria;
 import com.todoroo.astrid.data.Task;
@@ -116,8 +118,11 @@ public class FilterSettingsActivity extends BaseListSettingsActivity {
       criteria.add(instance);
     }
     adapter = new CustomFilterAdapter(criteria, locale, this::onClick);
+
     recyclerView.setLayoutManager(new LinearLayoutManager(this));
     recyclerView.setAdapter(adapter);
+    new ItemTouchHelper(new CustomFilterItemTouchHelper(this::onMove, this::updateList))
+        .attachToRecyclerView(recyclerView);
 
     fab.setExtended(isNew() || adapter.getItemCount() <= 1);
 
@@ -126,6 +131,12 @@ public class FilterSettingsActivity extends BaseListSettingsActivity {
     updateTheme();
   }
 
+  private void onMove(int from, int to) {
+    CriterionInstance criterion = criteria.remove(from);
+    criteria.add(to, criterion);
+    adapter.notifyItemMoved(from, to);
+  }
+
   private void onClick(String replaceId) {
     CriterionInstance criterionInstance = find(criteria, c -> c.getId().equals(replaceId));
 

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

@@ -1,8 +1,14 @@
 <?xml version="1.0" encoding="utf-8"?>
-<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+  android:layout_width="match_parent"
+  android:layout_height="wrap_content"
+  android:background="@color/window_background"
+  android:orientation="vertical">
+
+    <RelativeLayout
       android:id="@+id/row"
       android:layout_width="fill_parent"
-  android:layout_height="55dip"
+      android:layout_height="wrap_content"
       android:background="?attr/selectableItemBackground"
       android:orientation="horizontal">
 
@@ -37,10 +43,11 @@
           android:layout_toStartOf="@id/filter_count"
           android:layout_width="fill_parent"
           android:layout_height="fill_parent"
-      android:paddingStart="@dimen/keyline_first"
-      android:paddingEnd="@dimen/keyline_first"
+          android:padding="@dimen/keyline_first"
           android:gravity="start|center_vertical"
           android:textAlignment="viewStart"
           android:textSize="18sp" />
 
-</RelativeLayout>
+    </RelativeLayout>
+
+</LinearLayout>