src/com/android/photos/GalleryActivity.java

/*
 * Copyright (C) 2013 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.photos;

import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.os.Bundle;
import androidx.legacy.app.FragmentPagerAdapter;
import androidx.viewpager.widget.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
import android.view.ViewGroup;

import com.android.gallery3d.R;

import java.util.ArrayList;

public class GalleryActivity extends Activity implements MultiChoiceManager.Provider {

    private MultiChoiceManager mMultiChoiceManager;
    private ViewPager mViewPager;
    private TabsAdapter mTabsAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mMultiChoiceManager = new MultiChoiceManager(this);
        mViewPager = new ViewPager(this);
        mViewPager.setId(R.id.viewpager);
        setContentView(mViewPager);

        ActionBar ab = getActionBar();
        ab.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        ab.setDisplayShowHomeEnabled(false);
        ab.setDisplayShowTitleEnabled(false);

        mTabsAdapter = new TabsAdapter(this, mViewPager);
        mTabsAdapter.addTab(ab.newTab().setText(R.string.tab_photos),
                PhotoSetFragment.class, null);
        mTabsAdapter.addTab(ab.newTab().setText(R.string.tab_albums),
                AlbumSetFragment.class, null);

        if (savedInstanceState != null) {
            ab.setSelectedNavigationItem(savedInstanceState.getInt("tab", 0));
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt("tab", getActionBar().getSelectedNavigationIndex());
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.gallery, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case R.id.menu_camera:
            // TODO: Call the correct Camera intent.
            throw new RuntimeException("Not implemented yet.");
//            Intent intent = new Intent(this, CameraActivity.class);
//            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
//            startActivity(intent);
//            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }

    public static class TabsAdapter extends FragmentPagerAdapter implements
            ActionBar.TabListener, ViewPager.OnPageChangeListener {

        private final GalleryActivity mActivity;
        private final ActionBar mActionBar;
        private final ViewPager mViewPager;
        private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();

        static final class TabInfo {

            private final Class<?> clss;
            private final Bundle args;

            TabInfo(Class<?> _class, Bundle _args) {
                clss = _class;
                args = _args;
            }
        }

        public TabsAdapter(GalleryActivity activity, ViewPager pager) {
            super(activity.getFragmentManager());
            mActivity = activity;
            mActionBar = activity.getActionBar();
            mViewPager = pager;
            mViewPager.setAdapter(this);
            mViewPager.setOnPageChangeListener(this);
        }

        public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
            TabInfo info = new TabInfo(clss, args);
            tab.setTag(info);
            tab.setTabListener(this);
            mTabs.add(info);
            mActionBar.addTab(tab);
            notifyDataSetChanged();
        }

        @Override
        public int getCount() {
            return mTabs.size();
        }

        @Override
        public Fragment getItem(int position) {
            TabInfo info = mTabs.get(position);
            return Fragment.instantiate(mActivity, info.clss.getName(),
                    info.args);
        }

        @Override
        public void onPageScrolled(int position, float positionOffset,
                int positionOffsetPixels) {
        }

        @Override
        public void onPageSelected(int position) {
            mActionBar.setSelectedNavigationItem(position);
        }

        @Override
        public void setPrimaryItem(ViewGroup container, int position, Object object) {
            super.setPrimaryItem(container, position, object);
            mActivity.mMultiChoiceManager.setDelegate((MultiChoiceManager.Delegate) object);
        }

        @Override
        public void onPageScrollStateChanged(int state) {
        }

        @Override
        public void onTabSelected(Tab tab, FragmentTransaction ft) {
            Object tag = tab.getTag();
            for (int i = 0; i < mTabs.size(); i++) {
                if (mTabs.get(i) == tag) {
                    mViewPager.setCurrentItem(i);
                }
            }
        }

        @Override
        public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        }

        @Override
        public void onTabReselected(Tab tab, FragmentTransaction ft) {
        }
    }

    @Override
    public MultiChoiceManager getMultiChoiceManager() {
        return mMultiChoiceManager;
    }
}