UserVisibleHintFragment.java

/*
 * Copyright 2014 Yaroslav Mytkalyk
 * 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.docd.purefm.ui.fragments;

import android.app.Fragment;

/**
 * Fragment that manages resumed and visible states combining them
 */
public abstract class UserVisibleHintFragment extends Fragment {

    private boolean mResumed;

    @Override
    public final void setUserVisibleHint(final boolean isVisibleToUser) {
        final boolean needUpdate = mResumed && isVisibleToUser != getUserVisibleHint();
        super.setUserVisibleHint(isVisibleToUser);
        if (needUpdate) {
            if (isVisibleToUser) {
                this.onVisible();
            } else {
                this.onInvisible();
            }
        }
    }

    @Override
    public final void onResume() {
        super.onResume();
        mResumed = true;
        if (this.getUserVisibleHint()) {
            this.onVisible();
        }
    }

    @Override
    public final void onPause() {
        super.onPause();
        mResumed = false;
        this.onInvisible();
    }

    /**
     * Returns true if the fragment is in resumed state and userVisibleHint was set to true
     *
     * @return true if resumed and visible
     */
    protected final boolean isResumedAndVisible() {
        return mResumed && getUserVisibleHint();
    }

    /**
     * Called when onResume was called and userVisibleHint is set to true or vice-versa
     */
    protected abstract void onVisible();

    /**
     * Called when onStop was called or userVisibleHint is set to false
     */
    protected abstract void onInvisible();
}