io.github.meness.easyintro.utils.BackPressImpl.java Source code

Introduction

Here is the source code for io.github.meness.easyintro.utils.BackPressImpl.java

Source

/*
 * Copyright 2016 Alireza Eskandarpour Shoferi
 *
 * 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 io.github.meness.easyintro.utils;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;

import io.github.meness.easyintro.listeners.OnBackPressListener;

public class BackPressImpl implements OnBackPressListener {
    private final Fragment parentFragment;

    public BackPressImpl(Fragment parentFragment) {
        this.parentFragment = parentFragment;
    }

    @Override
    public boolean onBackPressed() {

        if (parentFragment == null)
            return false;

        int childCount = parentFragment.getChildFragmentManager().getBackStackEntryCount();

        if (childCount == 0) {
            // it has no child Fragment
            // can not handle the onBackPressed task by itself
            return false;

        } else {
            // get the child Fragment
            FragmentManager childFragmentManager = parentFragment.getChildFragmentManager();
            OnBackPressListener childFragment = (OnBackPressListener) childFragmentManager.getFragments().get(0);

            // propagate onBackPressed method call to the child Fragment
            if (!childFragment.onBackPressed()) {
                // child Fragment was unable to handle the task
                // It could happen when the child Fragment is last last leaf of a chain
                // removing the child Fragment from stack
                childFragmentManager.popBackStackImmediate();

            }

            // either this Fragment or its child handled the task
            // either way we are successful and done here
            return true;
        }
    }
}