[android] Keep CompassView's state up to date when compass is enabled. (#15606)

* [android] Keep CompassView's state up to date when compass is enabled.

* [android] Add unit test for updating compass view.

* [android] Add change log.

platform/android/CHANGELOG.md

@@ -6,6 +6,7 @@ Mapbox welcomes participation and contributions from everyone.  If you'd like to
 
 ### Bug fixes
  - Fixed constant repainting for the sources with invisible layers, caused by `RenderSource::hasFadingTiles()` returning `true` all the time. [#15600](https://github.com/mapbox/mapbox-gl-native/pull/15600)
+ - Fixed an issue that caused the state of CompassView not up to date when `UiSettings.setCompassEnabled()` is set to true. [#15606](https://github.com/mapbox/mapbox-gl-native/pull/15606)
 
 ## 8.4.0-alpha.2 - September 11, 2019
 [Changes](https://github.com/mapbox/mapbox-gl-native/compare/android-v8.4.0-alpha.1...android-v8.4.0-alpha.2) since [Mapbox Maps SDK for Android v8.4.0](https://github.com/mapbox/mapbox-gl-native/releases/tag/android-v8.4.0-alpha.1): 

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/UiSettings.java

@@ -417,10 +417,6 @@ public final class UiSettings {
   }
 
   void update(@NonNull CameraPosition cameraPosition) {
-    if (!isCompassEnabled()) {
-      return;
-    }
-
     double clockwiseBearing = -cameraPosition.bearing;
     compassView.update(clockwiseBearing);
   }
@@ -1073,6 +1069,7 @@ public final class UiSettings {
    */
   public void invalidate() {
     setLogoMargins(getLogoMarginLeft(), getLogoMarginTop(), getLogoMarginRight(), getLogoMarginBottom());
+    setCompassEnabled(isCompassEnabled());
     setCompassMargins(getCompassMarginLeft(), getCompassMarginTop(), getCompassMarginRight(), getCompassMarginBottom());
     setAttributionMargins(getAttributionMarginLeft(), getAttributionMarginTop(), getAttributionMarginRight(),
       getAttributionMarginBottom());

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/widgets/CompassView.java

@@ -91,6 +91,7 @@ public final class CompassView extends ImageView implements Runnable {
       resetAnimation();
       setAlpha(1.0f);
       setVisibility(View.VISIBLE);
+      update(rotation);
     } else {
       resetAnimation();
       setAlpha(0.0f);

platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/maps/UiSettingsTest.java

@@ -5,6 +5,7 @@ import android.view.View;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
 
+import com.mapbox.mapboxsdk.camera.CameraPosition;
 import com.mapbox.mapboxsdk.maps.widgets.CompassView;
 
 import org.junit.Before;
@@ -17,6 +18,7 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.verify;
 
 public class UiSettingsTest {
 
@@ -412,4 +414,20 @@ public class UiSettingsTest {
     assertEquals("Zoom rate should be 0.83f", 0.83f,
       uiSettings.getZoomRate(), 0);
   }
+
+  @Test
+  public void testUpdateWhenCompassViewNotHidden() {
+    CameraPosition cameraPosition = new CameraPosition.Builder(CameraPosition.DEFAULT).bearing(24.0f).build();
+    when(compassView.isHidden()).thenReturn(false);
+    uiSettings.update(cameraPosition);
+    verify(compassView).update(-24.0f);
+  }
+
+  @Test
+  public void testUpdateWhenCompassViewHidden() {
+    CameraPosition cameraPosition = new CameraPosition.Builder(CameraPosition.DEFAULT).bearing(24.0f).build();
+    when(compassView.isHidden()).thenReturn(true);
+    uiSettings.update(cameraPosition);
+    verify(compassView).update(-24.0f);
+  }
 }