Add discrete contrast UI slider in the setting

This slider is temporary and will be replaced by the final UI in the next couple weeks.

In this first version, the slider is added in Settings -> Accessibility -> Color and motion. It is discrete with three values.

The slider manipulates the setting currently named CONTRAST_LEVEL in Settings.Secure. This setting is ranging from [-1, 1] with a default value of 0. However, the three values of the slider correspond to the contrast values [0, 0.5, 1] respectively

Test: Manual: put a log before Settings.System.putFloatForUser, move the slider manually and verify the logs
Test: make RunSettingsRoboTests ROBOTEST_FILTER=ContrastLevelSeekBar
Bug: 259091608
Change-Id: I2eaf751d6008ad20b3564dde2c0f4648cc6c8178

tests/robotests/src/com/android/settings/accessibility/ContrastLevelSeekBarPreferenceTest.java

@@ -0,0 +1,69 @@
+/*
+ * 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.accessibility;
+
+import static com.android.settings.accessibility.ContrastLevelSeekBarPreference.CONTRAST_SLIDER_TICKS;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.LinearLayout;
+
+import androidx.preference.PreferenceViewHolder;
+
+import com.android.settings.testutils.shadow.ShadowInteractionJankMonitor;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(shadows = {ShadowInteractionJankMonitor.class})
+public class ContrastLevelSeekBarPreferenceTest {
+
+    private Context mContext;
+    private AttributeSet mAttrs;
+    private PreferenceViewHolder mHolder;
+    private ContrastLevelSeekBar mSeekBar;
+    private ContrastLevelSeekBarPreference mSeekBarPreference;
+
+    @Before
+    public void setUp() {
+        mContext = RuntimeEnvironment.application;
+        mSeekBarPreference = new ContrastLevelSeekBarPreference(mContext, mAttrs);
+        LayoutInflater inflater = LayoutInflater.from(mContext);
+        final View view =
+                inflater.inflate(mSeekBarPreference.getLayoutResource(),
+                        new LinearLayout(mContext), false);
+        mHolder = PreferenceViewHolder.createInstanceForTests(view);
+        mSeekBar = view.findViewById(com.android.internal.R.id.seekbar);
+    }
+
+    @Test
+    public void seekBarPreferenceOnBindViewHolder_shouldInitSeekBarValue() {
+        mSeekBarPreference.onBindViewHolder(mHolder);
+
+        assertThat(mSeekBar.getMax()).isEqualTo(CONTRAST_SLIDER_TICKS);
+        assertThat(mSeekBar.getProgress()).isEqualTo(0);
+    }
+}

tests/robotests/src/com/android/settings/accessibility/ContrastLevelSeekBarTest.java

@@ -0,0 +1,106 @@
+/*
+ * 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.accessibility;
+
+import static android.view.HapticFeedbackConstants.CLOCK_TICK;
+import static android.view.HapticFeedbackConstants.CONTEXT_CLICK;
+
+import static com.android.settings.accessibility.ContrastLevelSeekBarPreference.CONTRAST_SLIDER_TICKS;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.robolectric.Shadows.shadowOf;
+
+import android.content.Context;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.widget.SeekBar;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(RobolectricTestRunner.class)
+public class ContrastLevelSeekBarTest {
+
+    private Context mContext;
+    private ContrastLevelSeekBar mSeekBar;
+    private SeekBar.OnSeekBarChangeListener mProxySeekBarListener;
+
+    @Before
+    public void setUp() {
+        mContext = RuntimeEnvironment.application;
+        mSeekBar = new ContrastLevelSeekBar(mContext, null);
+        mProxySeekBarListener = shadowOf(mSeekBar).getOnSeekBarChangeListener();
+    }
+
+    @Test
+    public void onProgressChanged_minimumValue_shouldModifyContrast() {
+        // Assign the test value of SeekBar progress
+        mProxySeekBarListener.onProgressChanged(mSeekBar, 0, true);
+
+        assertThat(Settings.Secure.getFloatForUser(
+                mContext.getContentResolver(), Settings.Secure.CONTRAST_LEVEL,
+                -10f, UserHandle.USER_CURRENT)).isEqualTo(0);
+    }
+
+    @Test
+    public void onProgressChanged_centerValue_shouldModifyContrast() {
+        // Assign the test value of SeekBar progress
+        mProxySeekBarListener.onProgressChanged(mSeekBar, CONTRAST_SLIDER_TICKS / 2, true);
+
+        assertThat(Settings.Secure.getFloatForUser(
+                mContext.getContentResolver(), Settings.Secure.CONTRAST_LEVEL,
+                -10f, UserHandle.USER_CURRENT)).isWithin(1e-8f).of(0.5f);
+    }
+
+    @Test
+    public void onProgressChanged_maximumValue_shouldModifyContrast() {
+        // Assign the test value of SeekBar progress
+        mProxySeekBarListener.onProgressChanged(mSeekBar, CONTRAST_SLIDER_TICKS, true);
+
+        assertThat(Settings.Secure.getFloatForUser(
+                mContext.getContentResolver(), Settings.Secure.CONTRAST_LEVEL,
+                -10f, UserHandle.USER_CURRENT)).isEqualTo(1);
+    }
+
+    @Test
+    public void onProgressChanged_minimumValue_clockTickFeedbackPerformed() {
+        mSeekBar.performHapticFeedback(CONTEXT_CLICK);
+        mProxySeekBarListener.onProgressChanged(mSeekBar, 0, true);
+
+        assertThat(shadowOf(mSeekBar).lastHapticFeedbackPerformed()).isEqualTo(CLOCK_TICK);
+    }
+
+    @Test
+    public void onProgressChanged_centerValue_clockTickFeedbackPerformed() {
+        mSeekBar.performHapticFeedback(CONTEXT_CLICK);
+        mProxySeekBarListener.onProgressChanged(mSeekBar, CONTRAST_SLIDER_TICKS / 2, true);
+
+        assertThat(shadowOf(mSeekBar).lastHapticFeedbackPerformed()).isEqualTo(CLOCK_TICK);
+    }
+
+    @Test
+    public void onProgressChanged_maximumValue_clockTickFeedbackPerformed() {
+        mSeekBar.performHapticFeedback(CONTEXT_CLICK);
+        mProxySeekBarListener.onProgressChanged(mSeekBar, CONTRAST_SLIDER_TICKS, true);
+
+        assertThat(shadowOf(mSeekBar).lastHapticFeedbackPerformed()).isEqualTo(CLOCK_TICK);
+    }
+}