Announcements: add toggle to distance/speed unit announcement

Fixes #1805.

src/main/res/values/settings.xml

@@ -250,6 +250,8 @@
     <bool name="voice_announce_average_speed_pace_default" translatable="false">true</bool>
     <string name="voice_announce_lap_speed_pace_key" translatable="false">voiceAnnounceLapSpeedPace</string>
     <bool name="voice_announce_lap_speed_pace_default" translatable="false">true</bool>
+    <string name="voice_announce_unit_key" translatable="false">voiceAnnounceUnit</string>
+    <bool name="voice_announce_unit_default" translatable="false">true</bool>
 
     <string name="voice_announce_average_heart_rate_key" translatable="false">voiceAnnounceAverageHeartRate</string>
     <bool name="voice_announce_average_heart_rate_default" translatable="false">false</bool>

src/main/res/values/strings.xml

@@ -14,6 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 -->
 <resources>
+    <string name="empty"></string>
     <string name="about_preference_title">About OpenTracks</string>
     <string name="about_description"><i>OpenTracks</i> is a sport tracking application that completely respects your privacy.</string>
     <string name="about_url">Project web page: <a href="%1$s">%1$s</a></string>
@@ -413,6 +414,7 @@ limitations under the License.
     <string name="settings_announcements_lap_heart_rate">Lap heart rate</string>
     <string name="settings_announcements_average_speed_pace">Average speed/pace</string>
     <string name="settings_announcements_lap_speed_pace">Lap speed/pace</string>
+    <string name="settings_announcements_unit">Distance/speed unit</string>
 
     <!-- Custom Layout -->
 
@@ -602,6 +604,12 @@ limitations under the License.
         other {{n,number,#.0} knots}
         }
     </string>
+    <string name="voiceSpeed">
+        {n, plural,
+        =1 {1}
+        other {{n,number,#.0}}
+        }
+    </string>
     <string name="voice_on_device_speaker_title">Use the device\'s speaker</string>
     <string name="voice_per_kilometer">per kilometer</string>
     <string name="voice_per_mile">per mile</string>
@@ -629,6 +637,13 @@ limitations under the License.
         other {{n,number,#.0} nautical miles}
         }
     </string>
+
+    <string name="voiceDistance">
+        {n, plural,
+        =1 {1 }
+        other {{n,number,#.0}}
+        }
+    </string>
     <string name="average_heart_rate">Average heart rate</string>
     <string name="current_heart_rate">Current heart rate</string>
     <!-- Waypoint Type -->

src/main/res/xml/settings_announcements.xml

@@ -59,6 +59,12 @@
             android:key="@string/voice_announce_lap_speed_pace_key"
             android:title="@string/settings_announcements_lap_speed_pace" />
 
+        <SwitchPreferenceCompat
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:defaultValue="@bool/voice_announce_unit_default"
+            android:key="@string/voice_announce_unit_key"
+            android:title="@string/settings_announcements_unit" />
         <SwitchPreferenceCompat
             android:defaultValue="@bool/voice_announce_average_heart_rate_default"
             android:key="@string/voice_announce_average_heart_rate_key"