car-chassis-lib/src/com/android/car/chassis/preference/ListPreferenceDialogFragment.java

/*
 * Copyright 2019 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.car.chassis.preference;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.preference.ListPreference;

/**
 * Presents a dialog with a list of options associated with a {@link ListPreference}.
 *
 * <p>Note: this is borrowed as-is from androidx.preference.ListPreferenceDialogFragmentCompat
 * with updates to formatting to match the project style. Automotive applications should use this
 * implementations in order to launch the system themed platform {@link AlertDialog} instead of the
 * one in the support library.
 */
public class ListPreferenceDialogFragment extends PreferenceDialogFragment {

    private static final String SAVE_STATE_INDEX = "ListPreferenceDialogFragment.index";
    private static final String SAVE_STATE_ENTRIES = "ListPreferenceDialogFragment.entries";
    private static final String SAVE_STATE_ENTRY_VALUES =
            "ListPreferenceDialogFragment.entryValues";

    private int mClickedDialogEntryIndex;
    private CharSequence[] mEntries;
    private CharSequence[] mEntryValues;

    /**
     * Returns a new instance of {@link ListPreferenceDialogFragment} for the {@link
     * ListPreference} with the given {@code key}.
     */
    public static ListPreferenceDialogFragment newInstance(String key) {
        ListPreferenceDialogFragment fragment = new ListPreferenceDialogFragment();
        Bundle b = new Bundle(/* capacity= */ 1);
        b.putString(ARG_KEY, key);
        fragment.setArguments(b);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (savedInstanceState == null) {
            ListPreference preference = getListPreference();

            if (preference.getEntries() == null || preference.getEntryValues() == null) {
                throw new IllegalStateException(
                        "ListPreference requires an entries array and an entryValues array.");
            }

            mClickedDialogEntryIndex = preference.findIndexOfValue(preference.getValue());
            mEntries = preference.getEntries();
            mEntryValues = preference.getEntryValues();
        } else {
            mClickedDialogEntryIndex = savedInstanceState.getInt(SAVE_STATE_INDEX, 0);
            mEntries = savedInstanceState.getCharSequenceArray(SAVE_STATE_ENTRIES);
            mEntryValues = savedInstanceState.getCharSequenceArray(SAVE_STATE_ENTRY_VALUES);
        }
    }

    @Override
    public void onSaveInstanceState(@NonNull Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(SAVE_STATE_INDEX, mClickedDialogEntryIndex);
        outState.putCharSequenceArray(SAVE_STATE_ENTRIES, mEntries);
        outState.putCharSequenceArray(SAVE_STATE_ENTRY_VALUES, mEntryValues);
    }

    private ListPreference getListPreference() {
        return (ListPreference) getPreference();
    }

    @Override
    protected void onPrepareDialogBuilder(AlertDialog.Builder builder) {
        super.onPrepareDialogBuilder(builder);

        builder.setSingleChoiceItems(mEntries, mClickedDialogEntryIndex,
                (dialog, which) -> {
                    mClickedDialogEntryIndex = which;

                    // Clicking on an item simulates the positive button click, and dismisses the
                    // dialog.
                    ListPreferenceDialogFragment.this.onClick(dialog,
                            DialogInterface.BUTTON_POSITIVE);
                    dialog.dismiss();
                });

        // The typical interaction for list-based dialogs is to have click-on-an-item dismiss the
        // dialog instead of the user having to press 'Ok'.
        builder.setPositiveButton(null, null);
    }

    @Override
    public void onDialogClosed(boolean positiveResult) {
        if (positiveResult && mClickedDialogEntryIndex >= 0) {
            String value = mEntryValues[mClickedDialogEntryIndex].toString();
            ListPreference preference = getListPreference();
            if (preference.callChangeListener(value)) {
                preference.setValue(value);
            }
        }
    }

}