Settings: animate the Bluetooth icon.

Fixes #314.

src/main/java/de/dennisguse/opentracks/settings/bluetooth/BluetoothLeSensorPreference.java

@@ -8,6 +8,8 @@ import android.bluetooth.le.ScanResult;
 import android.bluetooth.le.ScanSettings;
 import android.content.Context;
 import android.content.DialogInterface;
+import android.graphics.drawable.Animatable;
+import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.os.ParcelUuid;
 import android.text.TextUtils;
@@ -16,6 +18,7 @@ import android.util.Log;
 import android.widget.Toast;
 
 import androidx.appcompat.app.AlertDialog;
+import androidx.core.content.ContextCompat;
 import androidx.preference.DialogPreference;
 import androidx.preference.PreferenceDialogFragmentCompat;
 
@@ -189,7 +192,11 @@ public abstract class BluetoothLeSensorPreference extends DialogPreference {
                         BluetoothLeSensorPreferenceDialog.this.onClick(dialog, DialogInterface.BUTTON_POSITIVE);
                         dialog.dismiss();
                     });
-            builder.setIcon(R.drawable.ic_bluetooth_searching_24dp);
+
+            Drawable icon = ContextCompat.getDrawable(getContext(), R.drawable.ic_bluetooth_searching_animated_24dp);
+            ((Animatable) icon).start();
+            builder.setIcon(icon);
+
             builder.setPositiveButton(null, null);
         }
 

src/main/res/anim/bluetooth_searching_bigdot.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:ordering="sequentially">
+
+    <objectAnimator
+        android:duration="650"
+        android:interpolator="@android:interpolator/linear"
+        android:propertyName="fillAlpha"
+        android:repeatCount="infinite"
+        android:repeatMode="reverse"
+        android:startOffset="400"
+        android:valueFrom="0"
+        android:valueTo="1"
+        android:valueType="floatType" />
+</set>

src/main/res/anim/bluetooth_searching_smalldot.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android"
+    android:ordering="sequentially">
+
+    <objectAnimator
+        android:duration="650"
+        android:interpolator="@android:interpolator/linear"
+        android:propertyName="fillAlpha"
+        android:repeatCount="infinite"
+        android:repeatMode="reverse"
+        android:valueFrom="0"
+        android:valueTo="1"
+        android:valueType="floatType" />
+</set>

src/main/res/drawable/ic_bluetooth_searching_animated_24dp.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<animated-vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:drawable="@drawable/ic_bluetooth_searching_24dp">
+    <target
+        android:name="smallDot"
+        android:animation="@anim/bluetooth_searching_smalldot" />
+    <target
+        android:name="bigDot"
+        android:animation="@anim/bluetooth_searching_bigdot" />
+</animated-vector>