Android Open Source - android-open-street-map Remote Async Tile Loader

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License

The source code is released under:

Apache License

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Java Source Code

package com.android.lib.map.osm;
/*from w  ww .ja  v a 2  s . c  om*/

import com.android.lib.map.osm.models.MapTile;

import android.os.Handler;
import android.os.Message;

public class RemoteAsyncTileLoader {
  
  private static final int NB_THREAD_FOR_TILE_REQUEST = 3;
  
  private TileRequestTask[] mDownloadTileTasks;
  private int mIterator;

  
  public RemoteAsyncTileLoader(Handler handler) {
    
    mIterator = 0;
    mDownloadTileTasks = new TileRequestTask[NB_THREAD_FOR_TILE_REQUEST];
    
    for (int i = 0; i < mDownloadTileTasks.length; i++) {
      mDownloadTileTasks[i] = new TileRequestTask(handler);
    }
  }

  public void queueTileRequest(Tile tile) {
    
    // Make sure the zoom is not > to the actual max Tile OSM zoom 
    if (tile.zoom > OsmMapViewBase.MIN_ZOOM_LEVEL_FOR_TILES)
      return;
    //---
      
    // Check if tile is not already in a thread
    for (int i = 0; i < mDownloadTileTasks.length; i++) {
      if (mDownloadTileTasks[i].mRequestsQueue.contains(tile))
        return;
    }
    //---

    // if not add it
    mDownloadTileTasks[mIterator].queue(tile);
    //--
    
    mIterator++;
    if (mIterator == mDownloadTileTasks.length)
      mIterator = 0;
  }

  public void interruptThreads() {
    for (int i = 0; i < mDownloadTileTasks.length; i++) {
      mDownloadTileTasks[i].interrupt();
    }
  }
  
  private class TileRequestTask extends Thread {
    
    private static final int MAX_QUEUE_REQUEST = 6;
    
    public RequestsQueue mRequestsQueue;
    
    private RequestTile mRequestTile;
    private Handler mHandler;
    
    public TileRequestTask(Handler handler) {
      mHandler = handler;
      mRequestTile = new RequestTile();
      mRequestsQueue = new RequestsQueue(1, MAX_QUEUE_REQUEST);
      start();
    }

    public void queue(Tile tile) {
      mRequestsQueue.queue(tile);
      
      synchronized (this) {
        this.notify();  
      }
    }
    
    @Override
    public void run() {

      Tile tile;
      
      while (true) {
        tile = null;
        if (mRequestsQueue.hasRequest()) {
          tile = mRequestsQueue.dequeue();
        }
        if (tile != null) {
          loadTileAndSendMessage(tile);
        }
        try {
          synchronized (this) {
            if (mRequestsQueue.size() == 0) {
              this.wait();
            }
          }
          Thread.sleep(150);
        } catch (InterruptedException e) {
          break;
        }
      }
    }
    
    public void loadTileAndSendMessage(Tile remoteTile) {

      if (remoteTile != null && remoteTile.key != null) {
        try {
          remoteTile.bitmap = mRequestTile.loadBitmap(remoteTile);

          Message message = mHandler.obtainMessage();
          
          if (remoteTile != null && remoteTile.bitmap != null && remoteTile.bitmap.length > 0) {
            MapTile.insertTile(remoteTile, remoteTile.bitmap);
            message.what = TileHandler.TILE_LOADED;
          } else {
            message.what = TileHandler.TILE_NOT_LOADED;
          }

          mHandler.sendMessage(message);
          
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    }
  
  }
}

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