android 9 Systemui 动态隐藏导航栏

<string name="ctrl_navigationbar">Hide NavigationBar</string>

  <SwitchPreference
    android:key="ctrl_navigationbar"
    android:title="@string/ctrl_navigationbar"/>

controllers.add(new NavigationBarPreferenceController(context));

package com.android.settings.display;
 
import android.content.Context;
import android.provider.Settings;
import android.support.v14.preference.SwitchPreference;
import android.support.v7.preference.Preference;
import android.support.v7.preference.PreferenceScreen;
 
import com.android.settings.core.PreferenceControllerMixin;
import com.android.settingslib.core.AbstractPreferenceController;
import android.content.Intent;
import android.util.Log;
import android.os.SystemProperties;
 
public class NavigationBarPreferenceController extends AbstractPreferenceController
        implements PreferenceControllerMixin, Preference.OnPreferenceChangeListener {
 
    private static final String TAG = "NavigationBarCtrl";
    private static final boolean DEBUG = true;
    private static final String KEY_NAVIGATION_BAR = "ctrl_navigationbar";
    public static final String ACTION_HIDE_NAVIGATION_BAR = "com.systemui.navigationbar.hide";
    public static final String ACTION_SHOW_NAVIGATION_BAR = "com.systemui.navigationbar.show";
 
    public NavigationBarPreferenceController(Context context) {
        super(context);
    }
 
    @Override
    public String getPreferenceKey() {
        return KEY_NAVIGATION_BAR;
    }
 
    @Override
    public boolean isAvailable() {
        return true;
    }
 
    @Override
    public void displayPreference(PreferenceScreen screen) {
        if (!isAvailable()) {
            setVisible(screen, KEY_NAVIGATION_BAR, false /* visible */);
            return;
        }
 
        final SwitchPreference mNavigationBarPreference = (SwitchPreference)screen.findPreference(KEY_NAVIGATION_BAR);
        if (mNavigationBarPreference != null) {
            String value = SystemProperties.get("persist.sys.navigationbar.enable", "false");
            mNavigationBarPreference.setChecked(value.equals("true"));
            mNavigationBarPreference.setOnPreferenceChangeListener(this);
        }
    }
 
    @Override
    public void updateState(Preference preference) {
        String value = SystemProperties.get("persist.sys.navigationbar.enable", "false");
        ((SwitchPreference) preference).setChecked(value.equals("true"));
    }
 
    @Override
    public boolean onPreferenceChange(Preference preference, Object newValue) {
        boolean value = (Boolean) newValue;
        if (DEBUG) {
            Log.d(TAG, "key value " + value);
        }
 
        Intent intent = new Intent();
        if (value) {
            intent.setAction(ACTION_SHOW_NAVIGATION_BAR);
        } else {
            intent.setAction(ACTION_HIDE_NAVIGATION_BAR);
        }
        mContext.sendBroadcast(intent);
        return true;
    }
}

 <!-- For NavigationBar show or not -->
    <protected-broadcast android:name="com.systemui.navigationbar.show" />
    <protected-broadcast android:name="com.systemui.navigationbar.hide" />

private static final String ACTION_HIDE_NAVIGATION_BAR = "com.systemui.navigationbar.hide";
    private static final String ACTION_SHOW_NAVIGATION_BAR = "com.systemui.navigationbar.show";
    private static final String SYS_PROPERTY_NAVIGATION_BAR = "persist.sys.navigationbar.enable";

if (SystemProperties.getBoolean(SYS_PROPERTY_NAVIGATION_BAR, false)) {
                    createNavigationBar();
                }

if (SystemProperties.getBoolean(SYS_PROPERTY_NAVIGATION_BAR, false)) {
                    createNavigationBar();
                }

else if (ACTION_HIDE_NAVIGATION_BAR.equals(action)) {
                mWindowManager.removeViewImmediate(mNavigationBarView);
                mNavigationBarView = null;
                mStatusBarWindow.setVisibility(View.GONE);
                SystemProperties.set(SYS_PROPERTY_NAVIGATION_BAR, "false");
            } else if (ACTION_SHOW_NAVIGATION_BAR.equals(action)) {
                if(mNavigationBarView == null)
                    createNavigationBar();
                else
                    mNavigationBarView.setVisibility(View.VISIBLE);
                mStatusBarWindow.setVisibility(View.VISIBLE);
                SystemProperties.set(SYS_PROPERTY_NAVIGATION_BAR, "true");
            }