Android Open Source - InfinitePager Infinite Fragment State Pager Activity

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright 2013 Adam Parr//  ww  w.j  a  va2 s  .co m
 * 
 * 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.github.paradam.infinitepager.demo.v4;

import com.github.paradam.infinitepager.InfiniteViewPager;
import com.github.paradam.infinitepager.demo.R;
import com.github.paradam.support.v4.infinitepager.InfiniteFragmentStatePagerAdapter;

import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/**
 * Demo class for the use of an 
 * {@link com.github.paradam.support.v4.infinitepager.InfiniteFragmentStatePagerAdapter InfiniteFragmentStatePagerAdapter}
 * using the v4 support package.
 * 
 * <p>The activity shows an initial {@link com.github.paradam.infinitepager.InfinitePagerView}
 * of three items, that are initially not infinitely scrollable. A menu item is inflated from
 * an XML resource, that allows the user to add two more Fragments to the list or remove those
 * added Fragments if already added. Upon adding the additional Fragments, the InfiniteViewPager
 * and InfinitePagerAdapter re-check if the number of items match or exceed 
 * {#link com.github.paradam.infinitepager.InfinitePagerAdapter#MIN}, if so behaving as if there
 * were an infinite number of the same Fragments, allowing the user to continuously scroll left or
 * right without reaching the end of the ViewPager. When InfinitePagerAdapter#MIN is not reached
 * the InfiniteViewPager behaves like a normal ViewPager.</p>
 * 
 * @author Adam Parr
 *
 */
public class InfiniteFragmentStatePagerActivity extends FragmentActivity {
  /**
   * The InfinitePagerAdapter
   */
  private DemoInfiniteFragmentStatePagerAdapter pagerAdapter;
  private InfiniteViewPager viewPager;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    // Create the InfiniitePagerAdapter, providing the support FragmentManager to it.
    pagerAdapter = new DemoInfiniteFragmentStatePagerAdapter(getSupportFragmentManager());
    
    // Get the InfiniteViewPager inflated from the resource at R.layout.activity_main
    viewPager = ((InfiniteViewPager)findViewById(R.id.viewPager)); // Our ViewPager inflated from
    // the XML resource file is an InfiniteViewPager.
    viewPager.setAdapter(pagerAdapter); // Set the adapter for the InfiniteViewPager.
    viewPager.setRelativeCurrentItem(1,false); // Show the middle item initially
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);

    menu.findItem(R.id.action_show_extras).setVisible(!pagerAdapter.showExtras);
    menu.findItem(R.id.action_hide_extras).setVisible(pagerAdapter.showExtras);
    
    return true;
  }
  
  @Override
  public boolean onMenuItemSelected(int featureId, MenuItem item) {
    // Get the current selected item.
    switch (item.getItemId()) {
      case R.id.action_show_extras:
        pagerAdapter.showExtras(true);
        break;
      case R.id.action_hide_extras:
        pagerAdapter.showExtras(false);
        break;
      default:
        return super.onMenuItemSelected(featureId, item);
    }
    supportInvalidateOptionsMenu();
    return true;
  }
  
  /**
   * Extends InfiniteFragmentStatePagerAdapter and implements the needed methods to allow
   * retrieving and manipulation of the number of Fragments visible in the InfiniteViewPager
   * this InfiniteFragmentStatePagerAdapter is attached to.
   * 
   * @author Adam Parr
   *
   */
  public class DemoInfiniteFragmentStatePagerAdapter extends InfiniteFragmentStatePagerAdapter {
    /**
     * Key to use in saving and restoring the state of the {@link #tabNames} ArrayList.
     */
    public static final String TAB_NAMES = "DemoInfinatePagerAdapter:tab_names";
    
    /**
     * Key to use in saving and restoring the state of the boolean value {@link #showExtras}.
     */
    public static final String SHOW_EXTRA = "DemoInfinatePagerAdapter:show_extra";
    
    /**
     * The Tab names to the associated fragments in {@link #fragments}.
     */
    private String[] tabNames = new String[]{"Fragment at position: 0", "Fragment at position: 1", "Fragment at position: 2", "Fragment at position: 3", "Fragment at position: 4"};
    /**
     * Store all Fragments in this array.
     */
    private Fragment[] fragments = new Fragment[tabNames.length];
    
    /**
     * <tt>true</tt> to show the fragments at 3 and 4,
     * <tt>false</tt> to show only the first three.
     */
    private boolean showExtras = false;
    
    /**
     * Constructor that accepts a FragmentManager.
     * @param fm FragmentManager.
     */
    public DemoInfiniteFragmentStatePagerAdapter(FragmentManager fm) {
      super(fm);
    }
    
    @Override
    public Parcelable saveState() {
      Bundle state = new Bundle();
      state.putParcelable("SUPER", super.saveState());
      state.putBoolean(SHOW_EXTRA, showExtras);
      state.putStringArray(TAB_NAMES, tabNames); // Store the title String array to be restored later.
      return state;
    }
    
    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {
      tabNames = ((Bundle) state).getStringArray(TAB_NAMES); // Restore the title String array.
      showExtras(((Bundle) state).getBoolean(SHOW_EXTRA, showExtras)); // Update the state.
      
      super.restoreState(((Bundle) state).getParcelable("SUPER"), loader);
      int x = 0;
      for (Fragment f : getFragments()) {
        fragments[x++] = f;
      }
    }
    
    @Override
    public int getRelativeCount() {
      return fragments.length - (showExtras ? 0 : 2);
    }
    
    @Override
    public int getRelativeItemPosition(Object object) {
      int x = 0;
      int length = getRelativeCount();
      for (Fragment f : fragments) {
        if (x >= length) break;
        if (f == object) {
          return x;
        }
        x++;
      }
      return POSITION_NONE;
    }

    @Override
    public Fragment getRelativeItem(int position) {
      /*
       * Reuse Fragment if it still exists.
       */
      if(fragments[position] == null) {
        Fragment fragment = new PagerFragment();
        Bundle args = new Bundle();
        args.putString(PagerFragment.TEXT, "Fragment "+position);
        fragment.setArguments(args);
        fragments[position] = fragment;
      }
      return fragments[position];
    }

    @Override
    public CharSequence getRelativePageTitle(int position) {
      return tabNames[position];
    }
    
    public void showExtras(boolean showExtras) {
      this.showExtras = showExtras;
      
      // Alert the PagerAdapter the data has changed and it should update itself
      // to reflect those changes.
      notifyDataSetChanged();
    }
  }
  
  /**
   * Fragment to instantiate in DemoInfinatePagerAdapter.
   * 
   * @author Adam Parr
   */
  public static class PagerFragment extends Fragment {
    
    /**
     * Key to use in arguments Bundle to pass a String to the Fragment.
     */
    public static final String TEXT = "PagerFragment:text";
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
      return inflater.inflate(R.layout.fragment, container, false);
    }
    
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
      super.onActivityCreated(savedInstanceState);
      
      ((TextView)getView().findViewById(R.id.text)).setText(getArguments().getString(TEXT));
    }
  }
}

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