scrolling trick

scrolling tricks.java

/*
 * Copyright 2012 Roman Nurik + Nick Butcher
 *
 * 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.example.android.scrolltricks;

import android.app.ActionBar;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;

/**
 * Demo activity for quick return + sticky views in scroll containers.
 */
public class MainActivity extends FragmentActivity implements ActionBar.TabListener {
    ViewPager mPager;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        PagerAdapter adapter = new FragmentStatePagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int position) {
                switch (position) {
                    case 0:
                        return new QuickReturnFragment();
                    case 1:
                        return new StickyFragment();
                }
                return null;
            }

            @Override
            public int getCount() {
                return 2;
            }

            @Override
            public CharSequence getPageTitle(int position) {
                switch (position) {
                    case 0:
                        return getString(R.string.quick_return_item);
                    case 1:
                        return getString(R.string.sticky_item);
                }
                return null;
            }
        };

        mPager = (ViewPager) findViewById(R.id.pager);
        mPager.setAdapter(adapter);
        mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                getActionBar().setSelectedNavigationItem(position);
            }
        });

        mPager.setPageMargin(getResources().getDimensionPixelSize(R.dimen.page_margin));

        getActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        for (int position = 0; position < adapter.getCount(); position++) {
            getActionBar().addTab(getActionBar().newTab()
                    .setText(adapter.getPageTitle(position))
                    .setTabListener(this));
        }

        getActionBar().setDisplayShowHomeEnabled(false);
        getActionBar().setDisplayShowTitleEnabled(false);
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        mPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    }
}