com/android/settingslib/widget/RadioButtonPreference.java

/*
 * Copyright (C) 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.settingslib.widget;

import android.content.Context;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.view.View;
import android.widget.TextView;

import androidx.preference.CheckBoxPreference;
import androidx.preference.PreferenceViewHolder;

/**
 * Check box preference with check box replaced by radio button.
 *
 * Functionally speaking, it's actually a CheckBoxPreference. We only modified
 * the widget to RadioButton to make it "look like" a RadioButtonPreference.
 *
 * In other words, there's no "RadioButtonPreferenceGroup" in this
 * implementation. When you check one RadioButtonPreference, if you want to
 * uncheck all the other preferences, you should do that by code yourself.
 */
public class RadioButtonPreference extends CheckBoxPreference {

    /**
     * Interface definition for a callback to be invoked when the preference is clicked.
     */
    public interface OnClickListener {
        /**
         * Called when a preference has been clicked.
         *
         * @param emiter The clicked preference
         */
        void onRadioButtonClicked(RadioButtonPreference emiter);
    }

    private OnClickListener mListener = null;
    private View mAppendix;
    private int mAppendixVisibility = -1;


    /**
     * Perform inflation from XML and apply a class-specific base style.
     *
     * @param context  The {@link Context} this is associated with, through which it can
     *                 access the current theme, resources, {@link SharedPreferences}, etc.
     * @param attrs    The attributes of the XML tag that is inflating the preference
     * @param defStyle An attribute in the current theme that contains a reference to a style
     *                 resource that supplies default values for the view. Can be 0 to not
     *                 look for defaults.
     */
    public RadioButtonPreference(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }


    /**
     * Perform inflation from XML and apply a class-specific base style.
     *
     * @param context The {@link Context} this is associated with, through which it can
     *                access the current theme, resources, {@link SharedPreferences}, etc.
     * @param attrs   The attributes of the XML tag that is inflating the preference
     */
    public RadioButtonPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    /**
     * Constructor to create a preference.
     *
     * @param context The Context this is associated with.
     */
    public RadioButtonPreference(Context context) {
        this(context, null);
    }

    /**
     * Sets the callback to be invoked when this preference is clicked by the user.
     *
     * @param listener The callback to be invoked
     */
    public void setOnClickListener(OnClickListener listener) {
        mListener = listener;
    }

    /**
     * Processes a click on the preference.
     */
    @Override
    public void onClick() {
        if (mListener != null) {
            mListener.onRadioButtonClicked(this);
        }
    }

    /**
     * Binds the created View to the data for this preference.
     *
     * <p>This is a good place to grab references to custom Views in the layout and set
     * properties on them.
     *
     * <p>Make sure to call through to the superclass's implementation.
     *
     * @param holder The ViewHolder that provides references to the views to fill in. These views
     *               will be recycled, so you should not hold a reference to them after this method
     *               returns.
     */
    @Override
    public void onBindViewHolder(PreferenceViewHolder holder) {
        super.onBindViewHolder(holder);

        View summaryContainer = holder.findViewById(R.id.summary_container);
        if (summaryContainer != null) {
            summaryContainer.setVisibility(
                    TextUtils.isEmpty(getSummary()) ? View.GONE : View.VISIBLE);
            mAppendix = holder.findViewById(R.id.appendix);
            if (mAppendix != null && mAppendixVisibility != -1) {
                mAppendix.setVisibility(mAppendixVisibility);
            }
        }

        TextView title = (TextView) holder.findViewById(android.R.id.title);
        if (title != null) {
            title.setSingleLine(false);
            title.setMaxLines(3);
        }
    }

    /**
     * Set the visibility state of appendix view.
     *
     * @param visibility One of {@link View#VISIBLE}, {@link View#INVISIBLE}, or {@link View#GONE}.
     */
    public void setAppendixVisibility(int visibility) {
        if (mAppendix != null) {
            mAppendix.setVisibility(visibility);
        }
        mAppendixVisibility = visibility;
    }

    private void init() {
        setWidgetLayoutResource(R.layout.preference_widget_radiobutton);
        setLayoutResource(R.layout.preference_radio);
        setIconSpaceReserved(false);
    }
}