Grey out scrolling speed slider bar

When ever the mouse scrolling acceleration settings is toggled to
set "enabled", the mouse scrolling speed slider bar should be
greyed out.

Bug: 383555305
Bug: 384795606
Test: Local DUT with aconfig flags enabled, verified settings appears
      and is togglable. Verified toggle affects scrolling acceleration.
Flag: com.android.hardware.input.mouse_scrolling_acceleration
Change-Id: Ib96a4437864a0395c8c185bbd8cfb13f3979c84f

src/com/android/settings/inputmethod/MouseScrollingSpeedPreferenceController.java

@@ -16,29 +16,55 @@
 
 package com.android.settings.inputmethod;
 
+import android.content.ContentResolver;
 import android.content.Context;
+import android.database.ContentObserver;
 import android.hardware.input.InputSettings;
+import android.os.Handler;
+import android.os.Looper;
+import android.provider.Settings;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.preference.Preference;
 import androidx.preference.PreferenceScreen;
 
 import com.android.settings.core.SliderPreferenceController;
 import com.android.settings.widget.SeekBarPreference;
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+import com.android.settingslib.core.lifecycle.events.OnStart;
+import com.android.settingslib.core.lifecycle.events.OnStop;
 
-public class MouseScrollingSpeedPreferenceController extends SliderPreferenceController {
+
+public class MouseScrollingSpeedPreferenceController extends SliderPreferenceController implements
+        Preference.OnPreferenceChangeListener, LifecycleObserver, OnStop, OnStart  {
+
+    private final ContentResolver mContentResolver;
+    private final ContentObserver mContentObserver;
+
+    @Nullable
+    private SeekBarPreference mPreference;
 
     public MouseScrollingSpeedPreferenceController(@NonNull Context context, @NonNull String key) {
         super(context, key);
+
+        mContentResolver = context.getContentResolver();
+        mContentObserver = new ContentObserver(new Handler(Looper.getMainLooper())) {
+            @Override
+            public void onChange(boolean selfChange) {
+                updateAvailabilityStatus();
+            }
+        };
     }
 
     @Override
     public void displayPreference(@NonNull PreferenceScreen screen) {
         super.displayPreference(screen);
-        SeekBarPreference preference = screen.findPreference(getPreferenceKey());
+        mPreference = screen.findPreference(getPreferenceKey());
-        preference.setMax(getMax());
+        mPreference.setMax(getMax());
-        preference.setMin(getMin());
+        mPreference.setMin(getMin());
-        preference.setProgress(getSliderPosition());
+        mPreference.setProgress(getSliderPosition());
-        updateState(preference);
+        updateState(mPreference);
     }
 
     @Override
@@ -46,7 +72,7 @@ public class MouseScrollingSpeedPreferenceController extends SliderPreferenceCon
         if (!InputSettings.isMouseScrollingAccelerationFeatureFlagEnabled()) {
             return UNSUPPORTED_ON_DEVICE;
         }
-        return AVAILABLE;
+        return shouldEnableSlideBar() ? AVAILABLE : DISABLED_DEPENDENT_SETTING;
     }
 
     @Override
@@ -73,4 +99,30 @@ public class MouseScrollingSpeedPreferenceController extends SliderPreferenceCon
     public int getMax() {
         return InputSettings.MAX_MOUSE_SCROLLING_SPEED;
     }
+
+    /**
+     * Returns whether the mouse scrolling speed slide bar should allow users to customize or not.
+     */
+    public boolean shouldEnableSlideBar() {
+        return !InputSettings.isMouseScrollingAccelerationEnabled(mContext);
+    }
+
+    @Override
+    public void onStart() {
+        mContentResolver.registerContentObserver(
+                Settings.System.getUriFor(
+                        Settings.System.MOUSE_SCROLLING_ACCELERATION),
+                /* notifyForDescendants= */ false, mContentObserver);
+    }
+
+    @Override
+    public void onStop() {
+        mContentResolver.unregisterContentObserver(mContentObserver);
+    }
+
+    private void updateAvailabilityStatus() {
+        if (mPreference != null) {
+            mPreference.setEnabled(shouldEnableSlideBar());
+        }
+    }
 }