Show different color for multiselection

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java

@@ -41,6 +41,7 @@ import com.wireguard.android.model.Tunnel;
 import com.wireguard.android.util.ExceptionLoggers;
 import com.wireguard.android.util.ObservableSortedKeyedList;
 import com.wireguard.android.widget.MonkeyedSnackbar;
+import com.wireguard.android.widget.MultiselectableRelativeLayout;
 import com.wireguard.android.widget.fab.FloatingActionsMenuRecyclerViewScrollListener;
 import com.wireguard.config.Config;
 
@@ -263,30 +264,20 @@ public class TunnelListFragment extends BaseFragment {
         super.onPause();
     }
 
+    private MultiselectableRelativeLayout viewForTunnel(final Tunnel tunnel, final List tunnels) {
+        return (MultiselectableRelativeLayout)binding.tunnelList.findViewHolderForAdapterPosition(tunnels.indexOf(tunnel)).itemView;
+    }
+
     @Override
     public void onSelectedTunnelChanged(@Nullable final Tunnel oldTunnel, @Nullable final Tunnel newTunnel) {
         if (binding == null)
             return;
         Application.getTunnelManager().getTunnels().thenAccept(tunnels -> {
             if (newTunnel != null)
-                binding.tunnelList.findViewHolderForAdapterPosition(tunnels.indexOf(newTunnel)).itemView.setActivated(true);
+                viewForTunnel(newTunnel, tunnels).setSingleSelected(true);
             if (oldTunnel != null)
-                binding.tunnelList.findViewHolderForAdapterPosition(tunnels.indexOf(oldTunnel)).itemView.setActivated(false);
-
+                viewForTunnel(oldTunnel, tunnels).setSingleSelected(false);
         });
-
-        /* Alternative 1: results in sluggish change:
-
-        if (binding.tunnelList.getAdapter() == null)
-            return;
-
-
-         * Alternative 2: results in overly quick change:
-
-        binding.tunnelList.getAdapter().notifyDataSetChanged();
-
-         * Hence, we go with the above.
-         */
     }
 
     private void onTunnelDeletionFinished(final Integer count, @Nullable final Throwable throwable) {
@@ -373,10 +364,9 @@ public class TunnelListFragment extends BaseFragment {
             });
 
             if (actionMode != null)
-                binding.getRoot().setActivated(actionModeListener.checkedItems.contains(position));
+                ((MultiselectableRelativeLayout)binding.getRoot()).setMultiSelected(actionModeListener.checkedItems.contains(position));
             else
-                binding.getRoot().setActivated(getSelectedTunnel() == tunnel);
-
+                ((MultiselectableRelativeLayout)binding.getRoot()).setSingleSelected(getSelectedTunnel() == tunnel);
         });
     }
 
@@ -433,7 +423,6 @@ public class TunnelListFragment extends BaseFragment {
         public void onDestroyActionMode(final ActionMode mode) {
             actionMode = null;
             resources = null;
-
             checkedItems.clear();
             binding.tunnelList.getAdapter().notifyDataSetChanged();
         }

app/src/main/java/com/wireguard/android/widget/MultiselectableRelativeLayout.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright © 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.android.widget;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.widget.RelativeLayout;
+
+import com.wireguard.android.R;
+
+public class MultiselectableRelativeLayout extends RelativeLayout {
+    public MultiselectableRelativeLayout(final Context context) {
+        super(context);
+    }
+    public MultiselectableRelativeLayout(final Context context, final AttributeSet attrs) {
+        super(context, attrs);
+    }
+    public MultiselectableRelativeLayout(final Context context, final AttributeSet attrs, final int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+    public MultiselectableRelativeLayout(final Context context, final AttributeSet attrs, final int defStyleAttr, final int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+    }
+
+    private static final int[] STATE_MULTISELECTED = { R.attr.state_multiselected };
+
+    private boolean multiselected;
+
+    @Override
+    protected int[] onCreateDrawableState(final int extraSpace) {
+        if (multiselected) {
+            final int[] drawableState = super.onCreateDrawableState(extraSpace + 1);
+            mergeDrawableStates(drawableState, STATE_MULTISELECTED);
+            return drawableState;
+        }
+        return super.onCreateDrawableState(extraSpace);
+    }
+
+    public void setMultiSelected(final boolean on) {
+        if (!multiselected) {
+            multiselected = true;
+            refreshDrawableState();
+        }
+        setActivated(on);
+    }
+
+    public void setSingleSelected(final boolean on) {
+        if (multiselected) {
+            multiselected = false;
+            refreshDrawableState();
+        }
+        setActivated(on);
+    }
+}

app/src/main/res/drawable/list_item_background.xml

@@ -1,12 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
-<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
     <item>
         <selector>
-            <item android:state_activated="true">
-                <color android:color="?android:attr/colorControlHighlight" />
-                <!-- TODO(msf): depending on whether or not we are in multiselect mode, choose instead:
+            <item app:state_multiselected="true" android:state_activated="true">
                 <color android:color="?android:attr/colorControlActivated" />
-                -->
+            </item>
+            <item app:state_multiselected="false" android:state_activated="true">
+                <color android:color="?android:attr/colorControlHighlight" />
             </item>
         </selector>
     </item>

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

@@ -25,7 +25,7 @@
             type="com.wireguard.android.fragment.TunnelListFragment" />
     </data>
 
-    <RelativeLayout
+    <com.wireguard.android.widget.MultiselectableRelativeLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:background="@drawable/list_item_background"
@@ -51,5 +51,5 @@
             android:layout_alignParentEnd="true"
             app:checked="@{item.state == State.UP}"
             app:onBeforeCheckedChanged="@{fragment::setTunnelState}" />
-    </RelativeLayout>
+    </com.wireguard.android.widget.MultiselectableRelativeLayout>
 </layout>

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

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <declare-styleable name="Multiselected">
+        <attr name="state_multiselected" format="boolean"/>
+    </declare-styleable>
+</resources>