Draw timestamp information into BatteryChartView manually (2/2)

screenshot: https://screenshot.googleplex.com/8zJcMJeMDovfhdD

Bug: 183921876
Test: make SettingsRoboTests
Change-Id: I276f70c3cf8ebd2316f987ace0d6537ed2cf8a45

src/com/android/settings/fuelgauge/BatteryChartPreferenceController.java

@@ -40,6 +40,7 @@ import com.android.settingslib.core.lifecycle.events.OnDestroy;
 import com.android.settingslib.core.lifecycle.events.OnPause;
 import com.android.settingslib.utils.StringUtil;
 
+import java.time.Clock;
 import java.util.Arrays;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -256,6 +257,7 @@ public class BatteryChartPreferenceController extends AbstractPreferenceControll
                 : mTrapezoidIndex;
         if (mBatteryChartView != null) {
             mBatteryChartView.setLevels(mBatteryHistoryLevels);
+            setTimestampLabel();
         }
         refreshUi(refreshIndex, /*isForce=*/ true);
     }
@@ -525,6 +527,28 @@ public class BatteryChartPreferenceController extends AbstractPreferenceControll
         return true;
     }
 
+    @VisibleForTesting
+    void setTimestampLabel() {
+        if (mBatteryChartView == null || mBatteryHistoryKeys == null) {
+            return;
+        }
+        long latestTimestamp =
+            mBatteryHistoryKeys[mBatteryHistoryKeys.length - 1];
+        // Uses the current time if we don't have history data.
+        if (latestTimestamp == 0) {
+            latestTimestamp = Clock.systemUTC().millis();
+        }
+        // Generates timestamp label for chart graph (every 8 hours).
+        final long timeSlotOffset = DateUtils.HOUR_IN_MILLIS * 8;
+        final String[] timestampLabels = new String[4];
+        for (int index = 0; index < timestampLabels.length; index++) {
+            timestampLabels[index] =
+                ConvertUtils.utcToLocalTimeHour(
+                    latestTimestamp - (3 - index) * timeSlotOffset);
+        }
+        mBatteryChartView.setTimestamps(timestampLabels);
+    }
+
     private static String utcToLocalTime(long[] timestamps) {
         final StringBuilder builder = new StringBuilder();
         for (int index = 0; index < timestamps.length; index++) {

src/com/android/settings/fuelgauge/ConvertUtils.java

@@ -196,6 +196,11 @@ public final class ConvertUtils {
         for (int index = 0; index < timeSlotSize; index++) {
             final Long currentTimestamp =
                 Long.valueOf(batteryHistoryKeys[index * timestampStride]);
+            // Uses empty list if the timestamp is default value.
+            if (currentTimestamp == 0) {
+                resultMap.put(Integer.valueOf(index), new ArrayList<BatteryDiffEntry>());
+                continue;
+            }
             final Long nextTimestamp =
                 Long.valueOf(batteryHistoryKeys[index * timestampStride + 1]);
             final Long nextTwoTimestamp =

tests/robotests/src/com/android/settings/fuelgauge/BatteryChartPreferenceControllerTest.java

@@ -81,10 +81,7 @@ public final class BatteryChartPreferenceControllerTest {
     public void setUp() {
         MockitoAnnotations.initMocks(this);
         mContext = spy(RuntimeEnvironment.application);
-        mBatteryChartPreferenceController =
+        mBatteryChartPreferenceController = createController();
-            new BatteryChartPreferenceController(
-                mContext, "app_list", /*lifecycle=*/ null,
-                mSettingsActivity, mFragment);
         mBatteryChartPreferenceController.mPrefContext = mContext;
         mBatteryChartPreferenceController.mAppListPrefGroup = mAppListGroup;
         mBatteryChartPreferenceController.mBatteryChartView = mBatteryChartView;
@@ -572,6 +569,52 @@ public final class BatteryChartPreferenceControllerTest {
             .isEqualTo("System usage for past 24 hr");
     }
 
+    @Test
+    public void testSetTimestampLabel_nullBatteryHistoryKeys_ignore() {
+        mBatteryChartPreferenceController = createController();
+        mBatteryChartPreferenceController.mBatteryHistoryKeys = null;
+        mBatteryChartPreferenceController.mBatteryChartView =
+            spy(new BatteryChartView(mContext));
+        mBatteryChartPreferenceController.setTimestampLabel();
+
+        verify(mBatteryChartPreferenceController.mBatteryChartView, never())
+            .setTimestamps(any());
+    }
+
+    @Test
+    public void testSetTimestampLabel_setExpectedTimestampData() {
+        mBatteryChartPreferenceController = createController();
+        mBatteryChartPreferenceController.mBatteryChartView =
+            spy(new BatteryChartView(mContext));
+        setUpBatteryHistoryKeys();
+        // Generates the expected result.
+        final String[] expectedResults = new String[4];
+        final long timeSlotOffset = DateUtils.HOUR_IN_MILLIS * 8;
+        for (int index = 0; index < expectedResults.length; index++) {
+            expectedResults[index] =
+                ConvertUtils.utcToLocalTimeHour(
+                    1619247636826L - (3 - index) * timeSlotOffset);
+        }
+
+        mBatteryChartPreferenceController.setTimestampLabel();
+
+        verify(mBatteryChartPreferenceController.mBatteryChartView)
+            .setTimestamps(expectedResults);
+    }
+
+    @Test
+    public void testSetTimestampLabel_withoutValidTimestamp_setExpectedTimestampData() {
+        mBatteryChartPreferenceController = createController();
+        mBatteryChartPreferenceController.mBatteryChartView =
+            spy(new BatteryChartView(mContext));
+        mBatteryChartPreferenceController.mBatteryHistoryKeys = new long[] {0L};
+
+        mBatteryChartPreferenceController.setTimestampLabel();
+
+        verify(mBatteryChartPreferenceController.mBatteryChartView)
+            .setTimestamps(any());
+    }
+
     private static Map<Long, List<BatteryHistEntry>> createBatteryHistoryMap(int size) {
         final Map<Long, List<BatteryHistEntry>> batteryHistoryMap = new HashMap<>();
         for (int index = 0; index < size; index++) {
@@ -598,4 +641,10 @@ public final class BatteryChartPreferenceControllerTest {
         ConvertUtils.sSimpleDateFormatForHour
              .setTimeZone(TimeZone.getTimeZone("GMT"));
     }
+
+    private BatteryChartPreferenceController createController() {
+        return new BatteryChartPreferenceController(
+            mContext, "app_list", /*lifecycle=*/ null,
+            mSettingsActivity, mFragment);
+    }
 }