Android 展开设置里的”高级“折叠项

相关方法：

//system_dashboard_fragment.xml的处理类
//vendor/mediatek/proprietary/packages/apps/MtkSettings/src/com/android/settings/system/SystemDashboardFragment.java
@Override
 public void onCreate(Bundle icicle) {
     super.onCreate(icicle);

     final PreferenceScreen screen = getPreferenceScreen();
     // We do not want to display an advanced button if only one setting is hidden
     if (getVisiblePreferenceCount(screen) == screen.getInitialExpandedChildrenCount() + 1) {
         screen.setInitialExpandedChildrenCount(Integer.MAX_VALUE);
     }

     showRestrictionDialog();
 }

private int getVisiblePreferenceCount(PreferenceGroup group) {
    int visibleCount = 0;
    for (int i = 0; i < group.getPreferenceCount(); i++) {
        final Preference preference = group.getPreference(i);
        if (preference instanceof PreferenceGroup) {
            visibleCount += getVisiblePreferenceCount((PreferenceGroup) preference);
        } else if (preference.isVisible()) {
            visibleCount++;
        }
    }
    return visibleCount;
}

//SystemDashboardFragment继承DashboardFragment
//vendor/mediatek/proprietary/packages/apps/MtkSettings/src/com/android/settings/dashboard/DashboardFragment.java
private void displayResourceTiles() {
     final int resId = getPreferenceScreenResId();
     if (resId <= 0) {
         return;
     }
     addPreferencesFromResource(resId);
     final PreferenceScreen screen = getPreferenceScreen();
     screen.setOnExpandButtonClickListener(this);
     displayResourceTilesToScreen(screen);
 }

 /**
  * Perform {@link AbstractPreferenceController#displayPreference(PreferenceScreen)}
  * on all {@link AbstractPreferenceController}s.
  */
 protected void displayResourceTilesToScreen(PreferenceScreen screen) {
     mPreferenceControllers.values().stream().flatMap(Collection::stream).forEach(
             controller -> controller.displayPreference(screen));
 }