Add battery chart view model.

Test: manual
Bug: 239491373
Bug: 236101166
Change-Id: I1ae0e5fcc006855ac552fbbdfb4cd73f3dec52e7

src/com/android/settings/fuelgauge/batteryusage/BatteryChartPreferenceControllerV2.java

@@ -29,6 +29,7 @@ import android.text.format.DateFormat;
 import android.text.format.DateUtils;
 import android.util.Log;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.VisibleForTesting;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceGroup;
@@ -53,7 +54,6 @@ import com.android.settingslib.utils.StringUtil;
 import com.android.settingslib.widget.FooterPreference;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -98,13 +98,13 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
     @VisibleForTesting
     boolean mIsExpanded = false;
     @VisibleForTesting
-    int[] mBatteryHistoryLevels;
-    @VisibleForTesting
     long[] mBatteryHistoryKeys;
     @VisibleForTesting
-    int mTrapezoidIndex = BatteryChartViewV2.SELECTED_INDEX_INVALID;
+    BatteryChartViewModel mViewModel;
+    @VisibleForTesting
+    int mTrapezoidIndex = BatteryChartViewModel.SELECTED_INDEX_ALL;
 
-    private boolean mIs24HourFormat = false;
+    private boolean mIs24HourFormat;
     private boolean mIsFooterPrefAdded = false;
     private PreferenceScreen mPreferenceScreen;
     private FooterPreference mFooterPreference;
@@ -252,10 +252,11 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
     @Override
     public void onSelect(int trapezoidIndex) {
         Log.d(TAG, "onChartSelect:" + trapezoidIndex);
-        refreshUi(trapezoidIndex, /*isForce=*/ false);
+        mTrapezoidIndex = trapezoidIndex;
+        refreshUi();
         mMetricsFeatureProvider.action(
                 mPrefContext,
-                trapezoidIndex == BatteryChartViewV2.SELECTED_INDEX_ALL
+                trapezoidIndex == BatteryChartViewModel.SELECTED_INDEX_ALL
                         ? SettingsEnums.ACTION_BATTERY_USAGE_SHOW_ALL
                         : SettingsEnums.ACTION_BATTERY_USAGE_TIME_SLOT);
     }
@@ -276,18 +277,19 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
         if (batteryHistoryMap == null || batteryHistoryMap.isEmpty()) {
             mBatteryIndexedMap = null;
             mBatteryHistoryKeys = null;
-            mBatteryHistoryLevels = null;
+            mViewModel = null;
             addFooterPreferenceIfNeeded(false);
             return;
         }
         mBatteryHistoryKeys = getBatteryHistoryKeys(batteryHistoryMap);
-        mBatteryHistoryLevels = new int[CHART_LEVEL_ARRAY_SIZE];
+        List<Integer> levels = new ArrayList<Integer>();
         for (int index = 0; index < CHART_LEVEL_ARRAY_SIZE; index++) {
             final long timestamp = mBatteryHistoryKeys[index * 2];
             final Map<String, BatteryHistEntry> entryMap = batteryHistoryMap.get(timestamp);
             if (entryMap == null || entryMap.isEmpty()) {
                 Log.e(TAG, "abnormal entry list in the timestamp:"
                         + ConvertUtils.utcToLocalTime(mPrefContext, timestamp));
+                levels.add(0);
                 continue;
             }
             // Averages the battery level in each time slot to avoid corner conditions.
@@ -295,16 +297,17 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
             for (BatteryHistEntry entry : entryMap.values()) {
                 batteryLevelCounter += entry.mBatteryLevel;
             }
-            mBatteryHistoryLevels[index] =
+            levels.add(Math.round(batteryLevelCounter / entryMap.size()));
-                    Math.round(batteryLevelCounter / entryMap.size());
         }
-        forceRefreshUi();
+        final List<String> texts = generateTimestampTexts(mBatteryHistoryKeys, mContext);
+        mViewModel = new BatteryChartViewModel(levels, texts, mTrapezoidIndex);
+        refreshUi();
         Log.d(TAG, String.format(
-                "setBatteryHistoryMap() size=%d key=%s\nlevels=%s",
+                "setBatteryHistoryMap() size=%d key=%s\nview model=%s",
                 batteryHistoryMap.size(),
                 ConvertUtils.utcToLocalTime(mPrefContext,
                         mBatteryHistoryKeys[mBatteryHistoryKeys.length - 1]),
-                Arrays.toString(mBatteryHistoryLevels)));
+                mViewModel));
 
         // Loads item icon and label in the background.
         new LoadAllItemsInfoTask(batteryHistoryMap).execute();
@@ -319,35 +322,20 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
     private void setBatteryChartViewInner(final BatteryChartViewV2 batteryChartView) {
         mBatteryChartView = batteryChartView;
         mBatteryChartView.setOnSelectListener(this);
-        forceRefreshUi();
+        refreshUi();
-    }
-
-    private void forceRefreshUi() {
-        final int refreshIndex =
-                mTrapezoidIndex == BatteryChartViewV2.SELECTED_INDEX_INVALID
-                        ? BatteryChartViewV2.SELECTED_INDEX_ALL
-                        : mTrapezoidIndex;
-        if (mBatteryChartView != null) {
-            mBatteryChartView.setLevels(mBatteryHistoryLevels);
-            mBatteryChartView.setSelectedIndex(refreshIndex);
-            setTimestampLabel();
-        }
-        refreshUi(refreshIndex, /*isForce=*/ true);
     }
 
     @VisibleForTesting
-    boolean refreshUi(int trapezoidIndex, boolean isForce) {
+    boolean refreshUi() {
         // Invalid refresh condition.
-        if (mBatteryIndexedMap == null
+        if (mBatteryIndexedMap == null || mBatteryChartView == null) {
-                || mBatteryChartView == null
-                || (mTrapezoidIndex == trapezoidIndex && !isForce)) {
             return false;
         }
-        Log.d(TAG, String.format("refreshUi: index=%d size=%d isForce:%b",
+        if (mViewModel != null) {
-                trapezoidIndex, mBatteryIndexedMap.size(), isForce));
+            mViewModel.setSelectedIndex(mTrapezoidIndex);
+        }
+        mBatteryChartView.setViewModel(mViewModel);
 
-        mTrapezoidIndex = trapezoidIndex;
-        mBatteryChartView.setSelectedIndex(mTrapezoidIndex);
         mHandler.post(() -> {
             final long start = System.currentTimeMillis();
             removeAndCacheAllPrefs();
@@ -584,20 +572,6 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
         return !contains(packageName, mNotAllowShowEntryPackages);
     }
 
-    @VisibleForTesting
-    void setTimestampLabel() {
-        if (mBatteryChartView == null || mBatteryHistoryKeys == null) {
-            return;
-        }
-        final boolean is24HourFormat = DateFormat.is24HourFormat(mContext);
-        final String[] labels = new String[mBatteryHistoryKeys.length];
-        for (int i = 0; i < mBatteryHistoryKeys.length; i++) {
-            labels[i] = ConvertUtils.utcToLocalTimeHour(mContext, mBatteryHistoryKeys[i],
-                    is24HourFormat);
-        }
-        mBatteryChartView.setAxisLabels(labels);
-    }
-
     private void addFooterPreferenceIfNeeded(boolean containAppItems) {
         if (mIsFooterPrefAdded || mFooterPreference == null) {
             return;
@@ -610,6 +584,17 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
         mHandler.post(() -> mPreferenceScreen.addPreference(mFooterPreference));
     }
 
+    private static List<String> generateTimestampTexts(
+            @NonNull long[] timestamps, Context context) {
+        final boolean is24HourFormat = DateFormat.is24HourFormat(context);
+        final List<String> texts = new ArrayList<String>();
+        for (int index = 0; index < CHART_LEVEL_ARRAY_SIZE; index++) {
+            texts.add(ConvertUtils.utcToLocalTimeHour(context, timestamps[index * 2],
+                    is24HourFormat));
+        }
+        return texts;
+    }
+
     private static boolean contains(String target, CharSequence[] packageNames) {
         if (target != null && packageNames != null) {
             for (CharSequence packageName : packageNames) {
@@ -654,7 +639,7 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
                         getBatteryHistoryKeys(batteryHistoryMap),
                         batteryHistoryMap,
                         /*purgeLowPercentageAndFakeData=*/ true);
-        return batteryIndexedMap.get(BatteryChartViewV2.SELECTED_INDEX_ALL);
+        return batteryIndexedMap.get(BatteryChartViewModel.SELECTED_INDEX_ALL);
     }
 
     /** Used for {@link AppBatteryPreferenceController}. */
@@ -735,7 +720,7 @@ public class BatteryChartPreferenceControllerV2 extends AbstractPreferenceContro
             // Posts results back to main thread to refresh UI.
             mHandler.post(() -> {
                 mBatteryIndexedMap = indexedUsageMap;
-                forceRefreshUi();
+                refreshUi();
             });
         }
     }

src/com/android/settings/fuelgauge/batteryusage/BatteryChartViewModel.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.fuelgauge.batteryusage;
+
+import androidx.annotation.NonNull;
+import androidx.core.util.Preconditions;
+
+import java.util.List;
+import java.util.Locale;
+import java.util.Objects;
+
+/** The view model of {@code BatteryChartViewV2} */
+class BatteryChartViewModel {
+    private static final String TAG = "BatteryChartViewModel";
+
+    public static final int SELECTED_INDEX_ALL = -1;
+    public static final int SELECTED_INDEX_INVALID = -2;
+
+    // We need at least 2 levels to draw a trapezoid.
+    private static final int MIN_LEVELS_DATA_SIZE = 2;
+
+    private final List<Integer> mLevels;
+    private final List<String> mTexts;
+    private int mSelectedIndex;
+
+    BatteryChartViewModel(
+            @NonNull List<Integer> levels, @NonNull List<String> texts, int selectedIndex) {
+        Preconditions.checkArgument(
+                levels.size() == texts.size()
+                        && levels.size() >= MIN_LEVELS_DATA_SIZE
+                        && selectedIndex >= SELECTED_INDEX_ALL
+                        && selectedIndex < levels.size(),
+                String.format(Locale.getDefault(), "Invalid BatteryChartViewModel"
+                                + "  levels.size: %d\ntexts.size: %d\nselectedIndex: %d.",
+                        levels.size(), texts.size(), selectedIndex));
+        mLevels = levels;
+        mTexts = texts;
+        mSelectedIndex = selectedIndex;
+    }
+
+    public int size() {
+        return mLevels.size();
+    }
+
+    public List<Integer> levels() {
+        return mLevels;
+    }
+
+    public List<String> texts() {
+        return mTexts;
+    }
+
+    public int selectedIndex() {
+        return mSelectedIndex;
+    }
+
+    public void setSelectedIndex(int index) {
+        mSelectedIndex = index;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(mLevels, mTexts, mSelectedIndex);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        } else if (!(other instanceof BatteryChartViewModel)) {
+            return false;
+        }
+        final BatteryChartViewModel batteryChartViewModel = (BatteryChartViewModel) other;
+        return Objects.equals(mLevels, batteryChartViewModel.mLevels)
+                && Objects.equals(mTexts, batteryChartViewModel.mTexts)
+                && mSelectedIndex == batteryChartViewModel.mSelectedIndex;
+    }
+
+    @Override
+    public String toString() {
+        return String.format(Locale.getDefault(), "levels: %s\ntexts: %s\nselectedIndex: %d",
+                Objects.toString(mLevels), Objects.toString(mTexts), mSelectedIndex);
+    }
+}

src/com/android/settings/fuelgauge/batteryusage/BatteryChartViewV2.java

@@ -20,7 +20,6 @@ import static com.android.settings.Utils.formatPercentage;
 import static java.lang.Math.round;
 
 import android.accessibilityservice.AccessibilityServiceInfo;
-import android.annotation.NonNull;
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Canvas;
@@ -38,6 +37,7 @@ import android.view.View;
 import android.view.accessibility.AccessibilityManager;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.VisibleForTesting;
 import androidx.appcompat.widget.AppCompatImageView;
 
@@ -61,16 +61,14 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
     private static final int DIVIDER_COLOR = Color.parseColor("#CDCCC5");
     private static final long UPDATE_STATE_DELAYED_TIME = 500L;
 
-    /** Selects all trapezoid shapes. */
-    public static final int SELECTED_INDEX_ALL = -1;
-    public static final int SELECTED_INDEX_INVALID = -2;
-
     /** A callback listener for selected group index is updated. */
     public interface OnSelectListener {
         /** The callback function for selected group index is updated. */
         void onSelect(int trapezoidIndex);
     }
 
+    private BatteryChartViewModel mViewModel;
+
     private int mDividerWidth;
     private int mDividerHeight;
     private float mTrapezoidVOffset;
@@ -79,9 +77,7 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
     private String[] mPercentages = getPercentages();
 
     @VisibleForTesting
-    int mHoveredIndex = SELECTED_INDEX_INVALID;
+    int mHoveredIndex = BatteryChartViewModel.SELECTED_INDEX_INVALID;
-    @VisibleForTesting
-    int mSelectedIndex = SELECTED_INDEX_INVALID;
     @VisibleForTesting
     String[] mAxisLabels;
 
@@ -103,7 +99,6 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
     @VisibleForTesting
     final Runnable mUpdateClickableStateRun = () -> updateClickableState();
 
-    private int[] mLevels;
     private Paint mTextPaint;
     private Paint mDividerPaint;
     private Paint mTrapezoidPaint;
@@ -126,44 +121,26 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
         initializeColors(context);
         // Registers the click event listener.
         setOnClickListener(this);
-        setSelectedIndex(SELECTED_INDEX_ALL);
         setClickable(false);
+        requestLayout();
     }
 
-    /** Sets all levels value to draw the trapezoid shape */
+    /** Sets the data model of this view. */
-    public void setLevels(int[] levels) {
+    public void setViewModel(BatteryChartViewModel viewModel) {
-        Log.d(TAG, "setLevels() " + (levels == null ? "null" : levels.length));
+        if (viewModel == null) {
-        // At least 2 levels to draw a trapezoid.
+            mViewModel = null;
-        if (levels == null || levels.length < 2) {
-            mLevels = null;
             invalidate();
             return;
         }
-        mLevels = levels;
 
-        // Initialize trapezoid slots.
+        Log.d(TAG, String.format("setViewModel(): size: %d, selectedIndex: %d.",
-        mTrapezoidSlots = new TrapezoidSlot[mLevels.length - 1];
+                viewModel.size(), viewModel.selectedIndex()));
-        for (int index = 0; index < mTrapezoidSlots.length; index++) {
+        mViewModel = viewModel;
-            mTrapezoidSlots[index] = new TrapezoidSlot();
-        }
 
-        setClickable(false);
+        initializeTrapezoidSlots(viewModel.size() - 1);
-        invalidate();
+        initializeAxisLabels(viewModel.texts());
-        // Sets the chart is clickable if there is at least one valid item in it.
+        setClickable(hasNonZeroTrapezoid(viewModel.levels()));
-        for (int index = 0; index < mLevels.length - 1; index++) {
+        requestLayout();
-            if (mLevels[index] != 0 && mLevels[index + 1] != 0) {
-                setClickable(true);
-                break;
-            }
-        }
-    }
-
-    /** Sets the selected group index to draw highlight effect. */
-    public void setSelectedIndex(int index) {
-        if (mSelectedIndex != index) {
-            mSelectedIndex = index;
-            invalidate();
-        }
     }
 
     /** Sets the callback to monitor the selected group index. */
@@ -184,26 +161,6 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
         requestLayout();
     }
 
-    /**
-     * Sets the X-axis labels list for each level. This class will choose some labels among the
-     * input list to show.
-     *
-     * @param labels The length of this parameter should be the same as the length of
-     *               {@code levels}.
-     */
-    public void setAxisLabels(@NonNull String[] labels) {
-        if (mAxisLabels == null) {
-            mAxisLabels = new String[DEFAULT_AXIS_LABEL_COUNT];
-        }
-        // Current logic is always showing {@code AXIS_LABEL_GAPS_COUNT} labels.
-        // TODO: Support different count of labels for different levels sizes.
-        final int step = (labels.length - 1) / AXIS_LABEL_GAPS_COUNT;
-        for (int index = 0; index < DEFAULT_AXIS_LABEL_COUNT; index++) {
-            mAxisLabels[index] = labels[index * step];
-        }
-        requestLayout();
-    }
-
     @Override
     public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
@@ -240,7 +197,7 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
         // Before mLevels initialized, the count of trapezoids is unknown. Only draws the
         // horizontal percentages and dividers.
         drawHorizontalDividers(canvas);
-        if (mLevels == null) {
+        if (mViewModel == null) {
             return;
         }
         drawVerticalDividers(canvas);
@@ -282,7 +239,7 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
     public void onHoverChanged(boolean hovered) {
         super.onHoverChanged(hovered);
         if (!hovered) {
-            mHoveredIndex = SELECTED_INDEX_INVALID; // reset
+            mHoveredIndex = BatteryChartViewModel.SELECTED_INDEX_INVALID; // reset
             invalidate();
         }
     }
@@ -295,13 +252,15 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
         }
         final int trapezoidIndex = getTrapezoidIndex(mTouchUpEventX);
         // Ignores the click event if the level is zero.
-        if (trapezoidIndex == SELECTED_INDEX_INVALID
+        if (trapezoidIndex == BatteryChartViewModel.SELECTED_INDEX_INVALID
                 || !isValidToDraw(trapezoidIndex)) {
             return;
         }
         if (mOnSelectListener != null) {
+            // Selects all if users click the same trapezoid item two times.
             mOnSelectListener.onSelect(
-                    trapezoidIndex == mSelectedIndex ? SELECTED_INDEX_ALL : trapezoidIndex);
+                    trapezoidIndex == mViewModel.selectedIndex()
+                            ? BatteryChartViewModel.SELECTED_INDEX_ALL : trapezoidIndex);
         }
         view.performHapticFeedback(HapticFeedbackConstants.CONTEXT_CLICK);
     }
@@ -350,8 +309,8 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
             mTrapezoidCurvePaint.setStrokeWidth(mDividerWidth * 2);
         } else if (mIsSlotsClickabled) {
             mTrapezoidCurvePaint = null;
-            // Sets levels again to force update the click state.
+            // Sets view model again to force update the click state.
-            setLevels(mLevels);
+            setViewModel(mViewModel);
         }
         invalidate();
     }
@@ -366,6 +325,28 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
         super.setClickable(clickable);
     }
 
+    private void initializeTrapezoidSlots(int count) {
+        mTrapezoidSlots = new TrapezoidSlot[count];
+        for (int index = 0; index < mTrapezoidSlots.length; index++) {
+            mTrapezoidSlots[index] = new TrapezoidSlot();
+        }
+    }
+
+    /**
+     * Initializes the displayed X-axis labels list selected from the model all texts list.
+     */
+    private void initializeAxisLabels(@NonNull List<String> allTexts) {
+        if (mAxisLabels == null) {
+            mAxisLabels = new String[DEFAULT_AXIS_LABEL_COUNT];
+        }
+        // Current logic is always showing {@code AXIS_LABEL_GAPS_COUNT} labels.
+        // TODO: Support different count of labels for different levels sizes.
+        final int step = (allTexts.size() - 1) / AXIS_LABEL_GAPS_COUNT;
+        for (int index = 0; index < DEFAULT_AXIS_LABEL_COUNT; index++) {
+            mAxisLabels[index] = allTexts.get(index * step);
+        }
+    }
+
     private void initializeColors(Context context) {
         setBackgroundColor(Color.TRANSPARENT);
         mTrapezoidSolidColor = Utils.getColorAccentDefaultColor(context);
@@ -498,7 +479,7 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
 
     private void drawTrapezoids(Canvas canvas) {
         // Ignores invalid trapezoid data.
-        if (mLevels == null) {
+        if (mViewModel == null) {
             return;
         }
         final float trapezoidBottom =
@@ -519,17 +500,17 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
                 continue;
             }
             // Configures the trapezoid paint color.
-            final int trapezoidColor =
+            final int trapezoidColor = mIsSlotsClickabled && (mViewModel.selectedIndex() == index
-                    !mIsSlotsClickabled
+                    || mViewModel.selectedIndex() == BatteryChartViewModel.SELECTED_INDEX_ALL)
-                            ? mTrapezoidColor
+                    ? mTrapezoidSolidColor : mTrapezoidColor;
-                            : mSelectedIndex == index || mSelectedIndex == SELECTED_INDEX_ALL
-                                    ? mTrapezoidSolidColor : mTrapezoidColor;
             final boolean isHoverState =
                     mIsSlotsClickabled && mHoveredIndex == index && isValidToDraw(mHoveredIndex);
             mTrapezoidPaint.setColor(isHoverState ? mTrapezoidHoverColor : trapezoidColor);
 
-            final float leftTop = round(trapezoidBottom - mLevels[index] * unitHeight);
+            final float leftTop = round(
-            final float rightTop = round(trapezoidBottom - mLevels[index + 1] * unitHeight);
+                    trapezoidBottom - mViewModel.levels().get(index) * unitHeight);
+            final float rightTop = round(
+                    trapezoidBottom - mViewModel.levels().get(index + 1) * unitHeight);
             trapezoidPath.reset();
             trapezoidPath.moveTo(mTrapezoidSlots[index].mLeft, trapezoidBottom);
             trapezoidPath.lineTo(mTrapezoidSlots[index].mLeft, leftTop);
@@ -568,15 +549,25 @@ public class BatteryChartViewV2 extends AppCompatImageView implements View.OnCli
                 return index;
             }
         }
-        return SELECTED_INDEX_INVALID;
+        return BatteryChartViewModel.SELECTED_INDEX_INVALID;
     }
 
     private boolean isValidToDraw(int trapezoidIndex) {
-        return mLevels != null
+        return mViewModel != null
                 && trapezoidIndex >= 0
-                && trapezoidIndex < mLevels.length - 1
+                && trapezoidIndex < mViewModel.size() - 1
-                && mLevels[trapezoidIndex] != 0
+                && mViewModel.levels().get(trapezoidIndex) != 0
-                && mLevels[trapezoidIndex + 1] != 0;
+                && mViewModel.levels().get(trapezoidIndex + 1) != 0;
+    }
+
+    private static boolean hasNonZeroTrapezoid(List<Integer> levels) {
+        // Sets the chart is clickable if there is at least one valid item in it.
+        for (int index = 0; index < levels.size() - 1; index++) {
+            if (levels.get(index) != 0 && levels.get(index + 1) != 0) {
+                return true;
+            }
+        }
+        return false;
     }
 
     private static String[] getPercentages() {

tests/robotests/src/com/android/settings/fuelgauge/batteryusage/BatteryChartPreferenceControllerV2Test.java

@@ -55,6 +55,7 @@ import org.robolectric.RuntimeEnvironment;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.TimeZone;
@@ -173,11 +174,11 @@ public final class BatteryChartPreferenceControllerV2Test {
         for (int index = 0; index < DESIRED_HISTORY_SIZE; index++) {
             assertThat(mBatteryChartPreferenceController.mBatteryHistoryKeys[index])
                     // These values is are calculated by hand from createBatteryHistoryMap().
-                    .isEqualTo(index + 1);
+                    .isEqualTo(generateTimestamp(index));
         }
         // Verifies the created battery levels array.
         for (int index = 0; index < 13; index++) {
-            assertThat(mBatteryChartPreferenceController.mBatteryHistoryLevels[index])
+            assertThat(mBatteryChartPreferenceController.mViewModel.levels().get(index))
                     // These values is are calculated by hand from createBatteryHistoryMap().
                     .isEqualTo(100 - index * 2);
         }
@@ -193,79 +194,63 @@ public final class BatteryChartPreferenceControllerV2Test {
         for (int index = 0; index < DESIRED_HISTORY_SIZE; index++) {
             assertThat(mBatteryChartPreferenceController.mBatteryHistoryKeys[index])
                     // These values is are calculated by hand from createBatteryHistoryMap().
-                    .isEqualTo(index + 1);
+                    .isEqualTo(generateTimestamp(index));
         }
         // Verifies the created battery levels array.
         for (int index = 0; index < 13; index++) {
-            assertThat(mBatteryChartPreferenceController.mBatteryHistoryLevels[index])
+            assertThat(mBatteryChartPreferenceController.mViewModel.levels().get(index))
                     // These values is are calculated by hand from createBatteryHistoryMap().
                     .isEqualTo(100 - index * 2);
         }
         assertThat(mBatteryChartPreferenceController.mBatteryIndexedMap).hasSize(13);
     }
 
+    @Test
+    public void testSetBatteryChartViewModel() {
+        verify(mBatteryChartPreferenceController.mBatteryChartView)
+                .setViewModel(new BatteryChartViewModel(
+                        List.of(100, 98, 96, 94, 92, 90, 88, 86, 84, 82, 80, 78, 76),
+                        List.of("7 am", "9 am", "11 am", "1 pm", "3 pm", "5 pm", "7 pm",
+                                "9 pm", "11 pm", "1 am", "3 am", "5 am", "7 am"),
+                        BatteryChartViewModel.SELECTED_INDEX_ALL));
+    }
+
+    @Test
+    public void testRefreshUi_refresh() {
+        assertThat(mBatteryChartPreferenceController.refreshUi()).isTrue();
+    }
+
     @Test
     public void testRefreshUi_batteryIndexedMapIsNull_ignoreRefresh() {
         mBatteryChartPreferenceController.setBatteryHistoryMap(null);
-        assertThat(mBatteryChartPreferenceController.refreshUi(
+        assertThat(mBatteryChartPreferenceController.refreshUi()).isFalse();
-                /*trapezoidIndex=*/ 1, /*isForce=*/ false)).isFalse();
     }
 
     @Test
     public void testRefreshUi_batteryChartViewIsNull_ignoreRefresh() {
         mBatteryChartPreferenceController.mBatteryChartView = null;
-        assertThat(mBatteryChartPreferenceController.refreshUi(
+        assertThat(mBatteryChartPreferenceController.refreshUi()).isFalse();
-                /*trapezoidIndex=*/ 1, /*isForce=*/ false)).isFalse();
-    }
-
-    @Test
-    public void testRefreshUi_trapezoidIndexIsNotChanged_ignoreRefresh() {
-        final int trapezoidIndex = 1;
-        mBatteryChartPreferenceController.mTrapezoidIndex = trapezoidIndex;
-        assertThat(mBatteryChartPreferenceController.refreshUi(
-                trapezoidIndex, /*isForce=*/ false)).isFalse();
-    }
-
-    @Test
-    public void testRefreshUi_forceUpdate_refreshUi() {
-        final int trapezoidIndex = 1;
-        mBatteryChartPreferenceController.mTrapezoidIndex = trapezoidIndex;
-        assertThat(mBatteryChartPreferenceController.refreshUi(
-                trapezoidIndex, /*isForce=*/ true)).isTrue();
-    }
-
-    @Test
-    public void testForceRefreshUi_updateTrapezoidIndexIntoSelectAll() {
-        mBatteryChartPreferenceController.mTrapezoidIndex =
-                BatteryChartViewV2.SELECTED_INDEX_INVALID;
-        mBatteryChartPreferenceController.setBatteryHistoryMap(
-                createBatteryHistoryMap());
-
-        assertThat(mBatteryChartPreferenceController.mTrapezoidIndex)
-                .isEqualTo(BatteryChartViewV2.SELECTED_INDEX_ALL);
     }
 
     @Test
     public void testRemoveAndCacheAllPrefs_emptyContent_ignoreRemoveAll() {
-        final int trapezoidIndex = 1;
+        mBatteryChartPreferenceController.mTrapezoidIndex = 1;
         doReturn(0).when(mAppListGroup).getPreferenceCount();
 
-        mBatteryChartPreferenceController.refreshUi(
+        mBatteryChartPreferenceController.refreshUi();
-                trapezoidIndex, /*isForce=*/ true);
         verify(mAppListGroup, never()).removeAll();
     }
 
     @Test
     public void testRemoveAndCacheAllPrefs_buildCacheAndRemoveAllPreference() {
-        final int trapezoidIndex = 1;
+        mBatteryChartPreferenceController.mTrapezoidIndex = 1;
         doReturn(1).when(mAppListGroup).getPreferenceCount();
         doReturn(mPowerGaugePreference).when(mAppListGroup).getPreference(0);
         doReturn(PREF_KEY).when(mPowerGaugePreference).getKey();
         // Ensures the testing data is correct.
         assertThat(mBatteryChartPreferenceController.mPreferenceCache).isEmpty();
 
-        mBatteryChartPreferenceController.refreshUi(
+        mBatteryChartPreferenceController.refreshUi();
-                trapezoidIndex, /*isForce=*/ true);
 
         assertThat(mBatteryChartPreferenceController.mPreferenceCache.get(PREF_KEY))
                 .isEqualTo(mPowerGaugePreference);
@@ -522,7 +507,7 @@ public final class BatteryChartPreferenceControllerV2Test {
     @Test
     public void testOnSelect_selectAll_logMetric() {
         mBatteryChartPreferenceController.onSelect(
-                BatteryChartViewV2.SELECTED_INDEX_ALL /*slot index*/);
+                BatteryChartViewModel.SELECTED_INDEX_ALL /*slot index*/);
 
         verify(mMetricsFeatureProvider)
                 .action(mContext, SettingsEnums.ACTION_BATTERY_USAGE_SHOW_ALL);
@@ -562,7 +547,7 @@ public final class BatteryChartPreferenceControllerV2Test {
                 spy(new ExpandDividerPreference(mContext));
         // Simulates select all condition.
         mBatteryChartPreferenceController.mTrapezoidIndex =
-                BatteryChartViewV2.SELECTED_INDEX_ALL;
+                BatteryChartViewModel.SELECTED_INDEX_ALL;
 
         mBatteryChartPreferenceController.refreshCategoryTitle();
 
@@ -580,44 +565,6 @@ public final class BatteryChartPreferenceControllerV2Test {
                 .isEqualTo("System usage for past 24 hr");
     }
 
-    @Test
-    public void testSetTimestampLabel_nullBatteryHistoryKeys_ignore() {
-        mBatteryChartPreferenceController = createController();
-        mBatteryChartPreferenceController.mBatteryHistoryKeys = null;
-        mBatteryChartPreferenceController.mBatteryChartView =
-                spy(new BatteryChartViewV2(mContext));
-        mBatteryChartPreferenceController.setTimestampLabel();
-
-        verify(mBatteryChartPreferenceController.mBatteryChartView, never())
-                .setAxisLabels(any());
-    }
-
-    @Test
-    public void testSetTimestampLabel_setExpectedTimestampData() {
-        mBatteryChartPreferenceController = createController();
-        mBatteryChartPreferenceController.mBatteryChartView =
-                spy(new BatteryChartViewV2(mContext));
-        setUpBatteryHistoryKeys();
-
-        mBatteryChartPreferenceController.setTimestampLabel();
-
-        verify(mBatteryChartPreferenceController.mBatteryChartView)
-                .setAxisLabels(new String[] {"4 pm", "12 am", "7 am"});
-    }
-
-    @Test
-    public void testSetTimestampLabel_withoutValidTimestamp_setExpectedTimestampData() {
-        mBatteryChartPreferenceController = createController();
-        mBatteryChartPreferenceController.mBatteryChartView =
-                spy(new BatteryChartViewV2(mContext));
-        mBatteryChartPreferenceController.mBatteryHistoryKeys = new long[]{0L};
-
-        mBatteryChartPreferenceController.setTimestampLabel();
-
-        verify(mBatteryChartPreferenceController.mBatteryChartView)
-                .setAxisLabels(new String[] {"12 am"});
-    }
-
     @Test
     public void testOnSaveInstanceState_restoreSelectedIndexAndExpandState() {
         final int expectedIndex = 1;
@@ -663,6 +610,11 @@ public final class BatteryChartPreferenceControllerV2Test {
                 .isFalse();
     }
 
+    private static Long generateTimestamp(int index) {
+        // "2021-04-23 07:00:00 UTC" + index hours
+        return 1619247600000L + index * DateUtils.HOUR_IN_MILLIS;
+    }
+
     private static Map<Long, Map<String, BatteryHistEntry>> createBatteryHistoryMap() {
         final Map<Long, Map<String, BatteryHistEntry>> batteryHistoryMap = new HashMap<>();
         for (int index = 0; index < DESIRED_HISTORY_SIZE; index++) {
@@ -671,7 +623,7 @@ public final class BatteryChartPreferenceControllerV2Test {
             final BatteryHistEntry entry = new BatteryHistEntry(values);
             final Map<String, BatteryHistEntry> entryMap = new HashMap<>();
             entryMap.put("fake_entry_key" + index, entry);
-            batteryHistoryMap.put(Long.valueOf(index + 1), entryMap);
+            batteryHistoryMap.put(generateTimestamp(index), entryMap);
         }
         return batteryHistoryMap;
     }

tests/robotests/src/com/android/settings/fuelgauge/batteryusage/BatteryChartViewV2Test.java

@@ -42,6 +42,7 @@ import org.robolectric.RuntimeEnvironment;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Locale;
 
 @RunWith(RobolectricTestRunner.class)
@@ -100,13 +101,15 @@ public final class BatteryChartViewV2Test {
 
     @Test
     public void onClick_invokesCallback() {
-        mBatteryChartView.setLevels(new int[] {90, 80, 70, 60});
+        final int originalSelectedIndex = 2;
+        mBatteryChartView.setViewModel(
+                new BatteryChartViewModel(List.of(90, 80, 70, 60), List.of("", "", "", ""),
+                        originalSelectedIndex));
         for (int i = 0; i < mBatteryChartView.mTrapezoidSlots.length; i++) {
             mBatteryChartView.mTrapezoidSlots[i] = new BatteryChartViewV2.TrapezoidSlot();
             mBatteryChartView.mTrapezoidSlots[i].mLeft = i;
             mBatteryChartView.mTrapezoidSlots[i].mRight = i + 0.5f;
         }
-        mBatteryChartView.mSelectedIndex = 2;
         final int[] selectedIndex = new int[1];
         mBatteryChartView.setOnSelectListener(
                 trapezoidIndex -> {
@@ -123,7 +126,7 @@ public final class BatteryChartViewV2Test {
         mBatteryChartView.mTouchUpEventX = 2;
         selectedIndex[0] = Integer.MIN_VALUE;
         mBatteryChartView.onClick(mMockView);
-        assertThat(selectedIndex[0]).isEqualTo(BatteryChartViewV2.SELECTED_INDEX_ALL);
+        assertThat(selectedIndex[0]).isEqualTo(BatteryChartViewModel.SELECTED_INDEX_ALL);
     }
 
     @Test
@@ -178,11 +181,14 @@ public final class BatteryChartViewV2Test {
 
     @Test
     public void clickable_restoreFromNonClickableState() {
-        final int[] levels = new int[13];
+        final List<Integer> levels = new ArrayList<Integer>();
-        for (int index = 0; index < levels.length; index++) {
+        final List<String> texts = new ArrayList<String>();
-            levels[index] = index + 1;
+        for (int index = 0; index < 13; index++) {
+            levels.add(index + 1);
+            texts.add("");
         }
-        mBatteryChartView.setLevels(levels);
+        mBatteryChartView.setViewModel(new BatteryChartViewModel(
+                levels, texts, BatteryChartViewModel.SELECTED_INDEX_ALL));
         mBatteryChartView.setClickableForce(true);
         when(mPowerUsageFeatureProvider.isChartGraphSlotsEnabled(mContext))
                 .thenReturn(true);