samples/HoneycombGallery/src/com/example/android/hcgallery/TitlesFragment.java - platform/development - Git at Google

 /*
  * Copyright (C) 2011 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.example.android.hcgallery;

 import android.app.ActionBar;
 import android.app.Activity;
 import android.app.FragmentTransaction;
 import android.app.ListFragment;
 import android.content.ClipData;
 import android.content.res.TypedArray;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.view.View;
 import android.view.ViewTreeObserver;
 import android.widget.AdapterView;
 import android.widget.AdapterView.OnItemLongClickListener;
 import android.widget.ArrayAdapter;
 import android.widget.FrameLayout;
 import android.widget.FrameLayout.LayoutParams;
 import android.widget.ListView;
 import android.widget.TextView;

 /**
  * Fragment that shows the list of images
  * As an extension of ListFragment, this fragment uses a default layout
  * that includes a single ListView, which you can acquire with getListView()
  * When running on a screen size smaller than "large", this fragment appears alone
  * in MainActivity. In this case, selecting a list item opens the ContentActivity,
  * which likewise holds only the ContentFragment.
  */
 public class TitlesFragment extends ListFragment implements ActionBar.TabListener {
     OnItemSelectedListener mListener;
     private int mCategory = 0;
     private int mCurPosition = 0;
     private boolean mDualFragments = false;

     /** Container Activity must implement this interface and we ensure
      * that it does during the onAttach() callback
      */
     public interface OnItemSelectedListener {
         public void onItemSelected(int category, int position);
     }

     @Override
     public void onAttach(Activity activity) {
         super.onAttach(activity);
         // Check that the container activity has implemented the callback interface
         try {
             mListener = (OnItemSelectedListener) activity;
         } catch (ClassCastException e) {
             throw new ClassCastException(activity.toString()
                     + " must implement OnItemSelectedListener");
         }
     }

     /** This is where we perform setup for the fragment that's either
      * not related to the fragment's layout or must be done after the layout is drawn.
      * Notice that this fragment does not implement onCreateView(), because it extends
      * ListFragment, which includes a ListView as the root view by default, so there's
      * no need to set up the layout.
      */
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);

         ContentFragment frag = (ContentFragment) getFragmentManager()
                 .findFragmentById(R.id.content_frag);
         if (frag != null) mDualFragments = true;

         ActionBar bar = getActivity().getActionBar();
         bar.setDisplayHomeAsUpEnabled(false);
         bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

         // Must call in order to get callback to onCreateOptionsMenu()
         setHasOptionsMenu(true);

         Directory.initializeDirectory();
         for (int i = 0; i < Directory.getCategoryCount(); i++) {
             bar.addTab(bar.newTab().setText(Directory.getCategory(i).getName())
                     .setTabListener(this));
         }

         //Current position should survive screen rotations.
         if (savedInstanceState != null) {
             mCategory = savedInstanceState.getInt("category");
             mCurPosition = savedInstanceState.getInt("listPosition");
             bar.selectTab(bar.getTabAt(mCategory));
         }

         populateTitles(mCategory);
         ListView lv = getListView();
         lv.setCacheColorHint(Color.TRANSPARENT); // Improves scrolling performance

         if (mDualFragments) {
             // Highlight the currently selected item
             lv.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
             // Enable drag and dropping
             lv.setOnItemLongClickListener(new OnItemLongClickListener() {
                 public boolean onItemLongClick(AdapterView<?> av, View v, int pos, long id) {
                     final String title = (String) ((TextView) v).getText();

                     // Set up clip data with the category||entry_id format.
                     final String textData = String.format("%d||%d", mCategory, pos);
                     ClipData data = ClipData.newPlainText(title, textData);
                     v.startDrag(data, new MyDragShadowBuilder(v), null, 0);
                     return true;
                 }
             });
         }

         // If showing both fragments, select the appropriate list item by default
         if (mDualFragments) selectPosition(mCurPosition);

         // Attach a GlobalLayoutListener so that we get a callback when the layout
         // has finished drawing. This is necessary so that we can apply top-margin
         // to the ListView in order to dodge the ActionBar. Ordinarily, that's not
         // necessary, but we've set the ActionBar to "overlay" mode using our theme,
         // so the layout does not account for the action bar position on its own.
         ViewTreeObserver observer = getListView().getViewTreeObserver();
         observer.addOnGlobalLayoutListener(layoutListener);
     }

     @Override
     public void onDestroyView() {
       super.onDestroyView();
       // Always detach ViewTreeObserver listeners when the view tears down
       getListView().getViewTreeObserver().removeGlobalOnLayoutListener(layoutListener);
     }

     /** Attaches an adapter to the fragment's ListView to populate it with items */
     public void populateTitles(int category) {
         DirectoryCategory cat = Directory.getCategory(category);
         String[] items = new String[cat.getEntryCount()];
         for (int i = 0; i < cat.getEntryCount(); i++)
             items[i] = cat.getEntry(i).getName();
         // Convenience method to attach an adapter to ListFragment's ListView
         setListAdapter(new ArrayAdapter<String>(getActivity(),
                 R.layout.title_list_item, items));
         mCategory = category;
     }

     @Override
     public void onListItemClick(ListView l, View v, int position, long id) {
         // Send the event to the host activity via OnItemSelectedListener callback
         mListener.onItemSelected(mCategory, position);
         mCurPosition = position;
     }

     /** Called to select an item from the listview */
     public void selectPosition(int position) {
         // Only if we're showing both fragments should the item be "highlighted"
         if (mDualFragments) {
             ListView lv = getListView();
             lv.setItemChecked(position, true);
         }
         // Calls the parent activity's implementation of the OnItemSelectedListener
         // so the activity can pass the event to the sibling fragment as appropriate
         mListener.onItemSelected(mCategory, position);
     }

     @Override
     public void onSaveInstanceState (Bundle outState) {
         super.onSaveInstanceState(outState);
         outState.putInt("listPosition", mCurPosition);
         outState.putInt("category", mCategory);
     }

     /** This defines how the draggable list items appear during a drag event */
     private class MyDragShadowBuilder extends View.DragShadowBuilder {
         private Drawable mShadow;

         public MyDragShadowBuilder(View v) {
             super(v);

             final TypedArray a = v.getContext().obtainStyledAttributes(R.styleable.AppTheme);
             mShadow = a.getDrawable(R.styleable.AppTheme_listDragShadowBackground);
             mShadow.setCallback(v);
             mShadow.setBounds(0, 0, v.getWidth(), v.getHeight());
             a.recycle();
         }

         @Override
         public void onDrawShadow(Canvas canvas) {
             super.onDrawShadow(canvas);
             mShadow.draw(canvas);
             getView().draw(canvas);
         }
     }

     // Because the fragment doesn't have a reliable callback to notify us when
     // the activity's layout is completely drawn, this OnGlobalLayoutListener provides
     // the necessary callback so we can add top-margin to the ListView in order to dodge
     // the ActionBar. Which is necessary because the ActionBar is in overlay mode, meaning
     // that it will ordinarily sit on top of the activity layout as a top layer and
     // the ActionBar height can vary. Specifically, when on a small/normal size screen,
     // the action bar tabs appear in a second row, making the action bar twice as tall.
     ViewTreeObserver.OnGlobalLayoutListener layoutListener = new ViewTreeObserver.OnGlobalLayoutListener() {
         @Override
         public void onGlobalLayout() {
             int barHeight = getActivity().getActionBar().getHeight();
             ListView listView = getListView();
             FrameLayout.LayoutParams params = (LayoutParams) listView.getLayoutParams();
             // The list view top-margin should always match the action bar height
             if (params.topMargin != barHeight) {
                 params.topMargin = barHeight;
                 listView.setLayoutParams(params);
             }
             // The action bar doesn't update its height when hidden, so make top-margin zero
             if (!getActivity().getActionBar().isShowing()) {
               params.topMargin = 0;
               listView.setLayoutParams(params);
             }
         }
     };


     /* The following are callbacks implemented for the ActionBar.TabListener,
      * which this fragment implements to handle events when tabs are selected.
      */

     public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
         TitlesFragment titleFrag = (TitlesFragment) getFragmentManager()
                 .findFragmentById(R.id.titles_frag);
         titleFrag.populateTitles(tab.getPosition());

         if (mDualFragments) {
             titleFrag.selectPosition(0);
         }
     }

     /* These must be implemented, but we don't use them */

     public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
     }

     public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {
     }

 }
	/*
	* Copyright (C) 2011 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.example.android.hcgallery;

	import android.app.ActionBar;
	import android.app.Activity;
	import android.app.FragmentTransaction;
	import android.app.ListFragment;
	import android.content.ClipData;
	import android.content.res.TypedArray;
	import android.graphics.Canvas;
	import android.graphics.Color;
	import android.graphics.drawable.Drawable;
	import android.os.Bundle;
	import android.view.View;
	import android.view.ViewTreeObserver;
	import android.widget.AdapterView;
	import android.widget.AdapterView.OnItemLongClickListener;
	import android.widget.ArrayAdapter;
	import android.widget.FrameLayout;
	import android.widget.FrameLayout.LayoutParams;
	import android.widget.ListView;
	import android.widget.TextView;

	/**
	* Fragment that shows the list of images
	* As an extension of ListFragment, this fragment uses a default layout
	* that includes a single ListView, which you can acquire with getListView()
	* When running on a screen size smaller than "large", this fragment appears alone
	* in MainActivity. In this case, selecting a list item opens the ContentActivity,
	* which likewise holds only the ContentFragment.
	*/
	public class TitlesFragment extends ListFragment implements ActionBar.TabListener {
	OnItemSelectedListener mListener;
	private int mCategory = 0;
	private int mCurPosition = 0;
	private boolean mDualFragments = false;

	/** Container Activity must implement this interface and we ensure
	* that it does during the onAttach() callback
	*/
	public interface OnItemSelectedListener {
	public void onItemSelected(int category, int position);
	}

	@Override
	public void onAttach(Activity activity) {
	super.onAttach(activity);
	// Check that the container activity has implemented the callback interface
	try {
	mListener = (OnItemSelectedListener) activity;
	} catch (ClassCastException e) {
	throw new ClassCastException(activity.toString()
	+ " must implement OnItemSelectedListener");
	}
	}

	/** This is where we perform setup for the fragment that's either
	* not related to the fragment's layout or must be done after the layout is drawn.
	* Notice that this fragment does not implement onCreateView(), because it extends
	* ListFragment, which includes a ListView as the root view by default, so there's
	* no need to set up the layout.
	*/
	@Override
	public void onActivityCreated(Bundle savedInstanceState) {
	super.onActivityCreated(savedInstanceState);

	ContentFragment frag = (ContentFragment) getFragmentManager()
	.findFragmentById(R.id.content_frag);
	if (frag != null) mDualFragments = true;

	ActionBar bar = getActivity().getActionBar();
	bar.setDisplayHomeAsUpEnabled(false);
	bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

	// Must call in order to get callback to onCreateOptionsMenu()
	setHasOptionsMenu(true);

	Directory.initializeDirectory();
	for (int i = 0; i < Directory.getCategoryCount(); i++) {
	bar.addTab(bar.newTab().setText(Directory.getCategory(i).getName())
	.setTabListener(this));
	}

	//Current position should survive screen rotations.
	if (savedInstanceState != null) {
	mCategory = savedInstanceState.getInt("category");
	mCurPosition = savedInstanceState.getInt("listPosition");
	bar.selectTab(bar.getTabAt(mCategory));
	}

	populateTitles(mCategory);
	ListView lv = getListView();
	lv.setCacheColorHint(Color.TRANSPARENT); // Improves scrolling performance

	if (mDualFragments) {
	// Highlight the currently selected item
	lv.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
	// Enable drag and dropping
	lv.setOnItemLongClickListener(new OnItemLongClickListener() {
	public boolean onItemLongClick(AdapterView<?> av, View v, int pos, long id) {
	final String title = (String) ((TextView) v).getText();

	// Set up clip data with the category\|\|entry_id format.
	final String textData = String.format("%d\|\|%d", mCategory, pos);
	ClipData data = ClipData.newPlainText(title, textData);
	v.startDrag(data, new MyDragShadowBuilder(v), null, 0);
	return true;
	}
	});
	}

	// If showing both fragments, select the appropriate list item by default
	if (mDualFragments) selectPosition(mCurPosition);

	// Attach a GlobalLayoutListener so that we get a callback when the layout
	// has finished drawing. This is necessary so that we can apply top-margin
	// to the ListView in order to dodge the ActionBar. Ordinarily, that's not
	// necessary, but we've set the ActionBar to "overlay" mode using our theme,
	// so the layout does not account for the action bar position on its own.
	ViewTreeObserver observer = getListView().getViewTreeObserver();
	observer.addOnGlobalLayoutListener(layoutListener);
	}

	@Override
	public void onDestroyView() {
	super.onDestroyView();
	// Always detach ViewTreeObserver listeners when the view tears down
	getListView().getViewTreeObserver().removeGlobalOnLayoutListener(layoutListener);
	}

	/** Attaches an adapter to the fragment's ListView to populate it with items */
	public void populateTitles(int category) {
	DirectoryCategory cat = Directory.getCategory(category);
	String[] items = new String[cat.getEntryCount()];
	for (int i = 0; i < cat.getEntryCount(); i++)
	items[i] = cat.getEntry(i).getName();
	// Convenience method to attach an adapter to ListFragment's ListView
	setListAdapter(new ArrayAdapter<String>(getActivity(),
	R.layout.title_list_item, items));
	mCategory = category;
	}

	@Override
	public void onListItemClick(ListView l, View v, int position, long id) {
	// Send the event to the host activity via OnItemSelectedListener callback
	mListener.onItemSelected(mCategory, position);
	mCurPosition = position;
	}

	/** Called to select an item from the listview */
	public void selectPosition(int position) {
	// Only if we're showing both fragments should the item be "highlighted"
	if (mDualFragments) {
	ListView lv = getListView();
	lv.setItemChecked(position, true);
	}
	// Calls the parent activity's implementation of the OnItemSelectedListener
	// so the activity can pass the event to the sibling fragment as appropriate
	mListener.onItemSelected(mCategory, position);
	}

	@Override
	public void onSaveInstanceState (Bundle outState) {
	super.onSaveInstanceState(outState);
	outState.putInt("listPosition", mCurPosition);
	outState.putInt("category", mCategory);
	}

	/** This defines how the draggable list items appear during a drag event */
	private class MyDragShadowBuilder extends View.DragShadowBuilder {
	private Drawable mShadow;

	public MyDragShadowBuilder(View v) {
	super(v);

	final TypedArray a = v.getContext().obtainStyledAttributes(R.styleable.AppTheme);
	mShadow = a.getDrawable(R.styleable.AppTheme_listDragShadowBackground);
	mShadow.setCallback(v);
	mShadow.setBounds(0, 0, v.getWidth(), v.getHeight());
	a.recycle();
	}

	@Override
	public void onDrawShadow(Canvas canvas) {
	super.onDrawShadow(canvas);
	mShadow.draw(canvas);
	getView().draw(canvas);
	}
	}

	// Because the fragment doesn't have a reliable callback to notify us when
	// the activity's layout is completely drawn, this OnGlobalLayoutListener provides
	// the necessary callback so we can add top-margin to the ListView in order to dodge
	// the ActionBar. Which is necessary because the ActionBar is in overlay mode, meaning
	// that it will ordinarily sit on top of the activity layout as a top layer and
	// the ActionBar height can vary. Specifically, when on a small/normal size screen,
	// the action bar tabs appear in a second row, making the action bar twice as tall.
	ViewTreeObserver.OnGlobalLayoutListener layoutListener = new ViewTreeObserver.OnGlobalLayoutListener() {
	@Override
	public void onGlobalLayout() {
	int barHeight = getActivity().getActionBar().getHeight();
	ListView listView = getListView();
	FrameLayout.LayoutParams params = (LayoutParams) listView.getLayoutParams();
	// The list view top-margin should always match the action bar height
	if (params.topMargin != barHeight) {
	params.topMargin = barHeight;
	listView.setLayoutParams(params);
	}
	// The action bar doesn't update its height when hidden, so make top-margin zero
	if (!getActivity().getActionBar().isShowing()) {
	params.topMargin = 0;
	listView.setLayoutParams(params);
	}
	}
	};


	/* The following are callbacks implemented for the ActionBar.TabListener,
	* which this fragment implements to handle events when tabs are selected.
	*/

	public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
	TitlesFragment titleFrag = (TitlesFragment) getFragmentManager()
	.findFragmentById(R.id.titles_frag);
	titleFrag.populateTitles(tab.getPosition());

	if (mDualFragments) {
	titleFrag.selectPosition(0);
	}
	}

	/* These must be implemented, but we don't use them */

	public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
	}

	public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {
	}

	}