Add "Touchpad visualizer" to input developer options

Bug: 286551975
Bug: 350039816
Test: atest TouchpadVisualizerPreferenceControllerTest
Test: Manual testing using
      $ adb shell settings get system touchpad_visualizer
Flag: com.android.hardware.input.touchpad_visualizer

Change-Id: Ic5de704c49aabf1a80d202aa890055f7337d45d4

src/com/android/settings/development/TouchpadVisualizerPreferenceController.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2024 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.development;
+
+import android.content.Context;
+import android.provider.Settings;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.Preference;
+import androidx.preference.SwitchPreference;
+
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settingslib.development.DeveloperOptionsPreferenceController;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import android.hardware.input.InputSettings;
+
+/** PreferenceController that controls the "Touchpad visualizer" developer option. */
+public class TouchpadVisualizerPreferenceController extends
+        DeveloperOptionsPreferenceController implements
+        Preference.OnPreferenceChangeListener, PreferenceControllerMixin {
+
+    private static final String TOUCHPAD_VISUALIZER_KEY = "touchpad_visualizer";
+
+    @VisibleForTesting
+    static final int SETTING_VALUE_ON = 1;
+    @VisibleForTesting
+    static final int SETTING_VALUE_OFF = 0;
+
+    public TouchpadVisualizerPreferenceController(@NonNull Context context) {
+        super(context);
+    }
+
+    @Override
+    public @NonNull String getPreferenceKey() {
+        return TOUCHPAD_VISUALIZER_KEY;
+    }
+
+    @Override
+    public boolean isAvailable(){
+        return InputSettings.isTouchpadVisualizerFeatureFlagEnabled();
+    }
+
+    @Override
+    public boolean onPreferenceChange(@NonNull Preference preference, @Nullable Object newValue) {
+        final boolean isEnabled = newValue != null ? (Boolean) newValue : false;
+        Settings.System.putInt(mContext.getContentResolver(),
+                Settings.System.TOUCHPAD_VISUALIZER,
+                isEnabled ? SETTING_VALUE_ON : SETTING_VALUE_OFF);
+        return true;
+    }
+
+    @Override
+    public void updateState(@NonNull Preference preference) {
+        int touchpadVisualizer = Settings.System.getInt(mContext.getContentResolver(),
+                Settings.System.TOUCHPAD_VISUALIZER, SETTING_VALUE_OFF);
+        ((SwitchPreference) mPreference).setChecked(touchpadVisualizer != SETTING_VALUE_OFF);
+    }
+
+    @Override
+    protected void onDeveloperOptionsSwitchDisabled() {
+        super.onDeveloperOptionsSwitchDisabled();
+        Settings.System.putInt(mContext.getContentResolver(), Settings.System.TOUCHPAD_VISUALIZER,
+                SETTING_VALUE_OFF);
+        ((SwitchPreference) mPreference).setChecked(false);
+    }
+}