Android Open Source - BBC-News-Reader Category Fragment

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License

The source code is released under:
Copyright (c) 2011, 2012, Digital Lizard (Oscar Key, Thomas Boby) All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the...
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Java Source Code

package com.digitallizard.bbcnewsreader.fragments;
// www.j  av  a2  s  .c o m
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;

import com.actionbarsherlock.app.SherlockFragment;
import com.digitallizard.bbcnewsreader.Item;
import com.digitallizard.bbcnewsreader.ItemAdapter;
import com.digitallizard.bbcnewsreader.R;
import com.digitallizard.bbcnewsreader.ResourceService;
import com.digitallizard.bbcnewsreader.ServiceManager;
import com.digitallizard.bbcnewsreader.ServiceManager.MessageReceiver;
import com.digitallizard.bbcnewsreader.data.DatabaseHandler;
import com.digitallizard.bbcnewsreader.fragments.FrontpageFragment.FrontPageClickHandler;

public class CategoryFragment extends SherlockFragment implements MessageReceiver {
  //public static final int THUMBNAIL_WIDTH_PX = 144;
  //public static final int THUMBNAIL_HEIGHT_PX = 81;
  //public static final int THUMBNAIL_WIDTH_PX = 216;
  //public static final int THUMBNAIL_HEIGHT_PX = 121;
  public static final int THUMBNAIL_WIDTH_PX = 259;
  public static final int THUMBNAIL_HEIGHT_PX = 145;
  public static final int MIN_ROW_LENGTH = 2;
  public static final String KEY_CATEGORY = "category";
  
  DatabaseHandler database;
  ServiceManager service;
  FrontPageClickHandler clickHandler;
  
  GridView grid;
  ArrayList<Item> items;
  
  
  public static CategoryFragment newInstance(String category) {
    CategoryFragment fragment = new CategoryFragment();
    
    Bundle args = new Bundle();
    args.putString(KEY_CATEGORY, category);
    fragment.setArguments(args);
    
    return fragment;
  }
  
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    
    database = new DatabaseHandler(getActivity());
    service = new ServiceManager(getActivity(), this);
    
    service.doBindService();
  }
  
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.category, container, false);
    
    // set up the grid
    grid = (GridView) view.findViewById(R.id.categoryNewsItemGrid);
    
    // add a listener to detect clicks
    grid.setOnItemClickListener(new OnItemClickListener() {
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        // retrieve the NewsItem at the index of the click
        Item item = (Item) grid.getAdapter().getItem(position);
        // view the item
        clickHandler.onItemClick(item.getId());
      }
    });
    
    // add a listener to detect scrolls
    grid.setOnScrollListener(new OnScrollListener() {
      public void onScrollStateChanged(AbsListView list, int state) {
        // check to see if the user has stopped scrolling
        if (state == OnScrollListener.SCROLL_STATE_IDLE) {
          // check to see if all the visible items have images
          int firstVisible = list.getFirstVisiblePosition();
          int lastVisible = list.getLastVisiblePosition();
          for (int i = firstVisible; i <= lastVisible; i++) {
            Item item = (Item) list.getAdapter().getItem(i);
            // if this item doesn't have a thumbnail
            if (item.getThumbnailBytes() == null) {
              // load the thumbnail
              Bundle bundle = new Bundle();
              bundle.putInt(ResourceService.KEY_ITEM_ID, item.getId());
              service.sendMessageToService(ResourceService.MSG_LOAD_THUMB, bundle);
            }
          }
        }
      }
      
      public void onScroll(AbsListView list, int firstVisible, int visibleItems, int totalItems) {
      }
    });
    
    // check if we have been provided with a category to display
    if(getArguments().getString(KEY_CATEGORY) != null) {
      displayCategory(getArguments().getString(KEY_CATEGORY));
    }
    
    return view;
  }
  
  @Override
  public void onAttach(Activity activity) {
    super.onAttach(activity);
    // check that the parent has implemented the correct callbacks
    try {
      clickHandler = (FrontPageClickHandler) activity;
    } catch (ClassCastException e) {
      throw new ClassCastException(activity.toString() + " must implement FrontPageClickHandlers");
    }
  }

  @Override
  public void onDestroy() {
    super.onDestroy();
    service.doUnbindService();
    ((ItemAdapter) grid.getAdapter()).finish();
  }
  
  public void displayCategory(String categoryTitle) {
    // work out the ideal thumbnail size
    int rowPixelWidth = ((WindowManager) getActivity().getSystemService(Context.WINDOW_SERVICE))
        .getDefaultDisplay().getWidth();
    //int rowPixelWidth = this.getView().getLayoutParams().width;
    
    // check the row isn't too small
    int rowLength = (int) Math.floor(rowPixelWidth / THUMBNAIL_WIDTH_PX);
    if(rowLength < MIN_ROW_LENGTH) {
      rowLength = MIN_ROW_LENGTH;
    }
    
    int thumbWidth =  (int) Math.floor(rowPixelWidth / rowLength);
    int thumbHeight = (int) Math.floor(((float) thumbWidth / (float) THUMBNAIL_WIDTH_PX) * (float) THUMBNAIL_HEIGHT_PX);
    grid.setNumColumns(rowLength);
    grid.setColumnWidth(thumbWidth);
    
    // find the items and add them to the list
    items = new ArrayList<Item>(Arrays.asList(database.getItems(categoryTitle, 28))); // specify a high limit for the number of items
    grid.setAdapter(new ItemAdapter(getActivity(), R.layout.list_news_item, items, thumbWidth, thumbHeight));
  }
  
  private void thumbLoadComplete(int id) {
    // load the thumbnail
    byte[] thumbnailBytes = database.getThumbnail(id);
    // loop through and set this thumbnail
    Iterator<Item> iterator = items.iterator();
    while (iterator.hasNext()) {
      Item item = iterator.next();
      if (item.getId() == id) {
        // set the thumbnail bytes
        item.setThumbnailBytes(thumbnailBytes);
      }
    }
    
    // refresh this view in the list
    ((ItemAdapter) grid.getAdapter()).notifyDataSetChanged();
  }
  
  public void handleMessage(Message msg) {
    switch (msg.what) {
    case ResourceService.MSG_THUMB_LOADED:
      // display the thumbnail
      int id = msg.getData().getInt(ResourceService.KEY_ITEM_ID);
      thumbLoadComplete(id);
      break;
    }
  }
}
Java Source Code List
