MainActivity.java

package hk.hku.cs.srli.factfinder;

import android.app.AlertDialog;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.Intent;
import android.os.Bundle;
import android.support.v13.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.SlidingPaneLayout;
import android.view.View;

import com.actionbarsherlock.app.ActionBar;
import com.actionbarsherlock.app.SherlockActivity;
import com.actionbarsherlock.view.Menu;
import com.actionbarsherlock.view.MenuItem;

import hk.hku.cs.srli.widget.HoverFrame;

import java.util.Locale;

public class MainActivity extends SherlockActivity implements ActionBar.TabListener {

    private SectionsPagerAdapter mSectionsPagerAdapter;
    private ViewPager mViewPager;
    
    private HoverFrame mWrapper;
    private HoverFrame mPagerFrame;
    private HoverFrame mOrderFrame;
    private SlidingPaneLayout mSlidingPane;
    
    // flag indicating ViewPager pages are being switched
    private boolean mPageSwitching = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // set theme of the app
        int theme = FFApp.getApp(this).getFFTheme();
        if (theme != 0) setTheme(theme);
        setContentView(R.layout.activity_main);

        // Set up the action bar tabs
        final ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        mWrapper = (HoverFrame) findViewById(R.id.wrapper);
        mPagerFrame = (HoverFrame) findViewById(R.id.pager_frame);
        mOrderFrame = (HoverFrame) findViewById(R.id.order_frame);
        mSlidingPane = (SlidingPaneLayout) findViewById(R.id.slidingPaneLayout);
        mSlidingPane.openPane();
        
        // Create the adapter that will return a fragment for each category
        mSectionsPagerAdapter = new SectionsPagerAdapter(getFragmentManager());

        if (mSectionsPagerAdapter.getCount() < 5) {
            // a cosmetic hack to adjust ActionBar tab position  
            View view = findViewById(R.id.abs__action_bar_title);
            view.setPaddingRelative(0, 0, 55, 0);
        }
        
        // Set up the ViewPager with the adapter.
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        // When swiping between different sections, select the corresponding
        // tab. We can also use ActionBar.Tab#select() to do this if we have
        // a reference to the Tab.
        mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                if (!mPageSwitching) {
                    // use the flag to prevent event from bouncing between ViewPager and tabs 
                    mPageSwitching = true;
                    actionBar.setSelectedNavigationItem(position);
                    mPageSwitching = false;
                }
            }
            
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                if (positionOffset > 0) {
                    // in middle of scrolling
                    updateHoverEdge(true, true);
                } else updateHoverEdge();
            }
        });
        
        mSlidingPane.setPanelSlideListener(new SlidingPaneLayout.SimplePanelSlideListener() {
            @Override
            public void onPanelClosed(View panel) {
                mWrapper.setEnabled(false);
                mOrderFrame.setHorizontalScrollable(true, false);
            }
            
            @Override
            public void onPanelOpened(View panel) {
                // workaround to show edge effect when the right edge of
                // order frame is outside of the screen.
                mWrapper.setEnabled(true);
                mOrderFrame.setHorizontalScrollable(false, true);
            }
        });

        // For each of the category, add a tab to the action bar.
        for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
            actionBar.addTab(
                    actionBar.newTab()
                            .setText(mSectionsPagerAdapter.getPageTitle(i))
                            .setTabListener(this));
        }
    }
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getSupportMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        if (!mPageSwitching) {
            mPageSwitching = true;
            // When the given tab is selected, switch to the corresponding page in
            // the ViewPager.
            mViewPager.setCurrentItem(tab.getPosition());
            mPageSwitching = false;
        }
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        // do nothing
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        // do nothing
    }
    
    private void updateHoverEdge() {
        int nPages = mSectionsPagerAdapter.getCount();
        if (nPages <= 0) return;
        // only one page
        if (nPages == 1) {
            updateHoverEdge(false, false);
        } else if (mViewPager.getCurrentItem() == 0) {
            // leftmost page
            updateHoverEdge(false, true);
        } else if (mViewPager.getCurrentItem() == nPages - 1) {
            // rightmost page
            updateHoverEdge(true, false);
        } else {
            updateHoverEdge(true, true);
        }
    }
    
    private void updateHoverEdge(boolean leftScrollable, boolean rightScrollable) {
        mPagerFrame.setHorizontalScrollable(leftScrollable, rightScrollable);
    }
    
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == R.id.action_info) {
            // show "about" dialog
            AlertDialog dialog = new AlertDialog.Builder(this)
                    .setMessage(R.string.dialog_info_message)
                    .setTitle(R.string.dialog_info_title).create();
            dialog.show();
            return true;
        } else if (item.getItemId() == R.id.action_config) {
            FFApp.getOrder(this).clear();
            Intent i = new Intent(this, ConfigActivity.class);
            // new task
            i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            // start configuration screen
            startActivity(i);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            // getItem is called to instantiate the fragment for the given page.
            // Return a SectionFragment with the page number as its lone argument.
            Fragment fragment = new SectionFragment();
            Bundle args = new Bundle();
            args.putInt(SectionFragment.ARG_SECTION_NUMBER, position);
            fragment.setArguments(args);
            return fragment;
        }

        @Override
        public int getCount() {
            // Total number of sections.
            return FFApp.getData(MainActivity.this).getNumberOfCategories();
        }

        @Override
        public CharSequence getPageTitle(int position) {
            Locale l = Locale.getDefault();
            String name = FFApp.getData(MainActivity.this).getCategoryAt(position).getName();
            return name.toUpperCase(l);
        }
    }

}