Android-Maps-Extensions load marker images asynchronously

androidandroid-maps-extensionsandroid-maps-v2google mapsgoogle-maps-markers

I'm trying to show images (downloaded from a server) as map markers on a Google Map. I'm using Android-Maps-Extensions because i wasn't happy with Google Map-Utils performance.

Now i'm wondering how to load map marker images aynchronously with AME. The task is to show the image itself if it is not a cluster.
If it is a cluster, i want to display the image of the first marker and the number of elements in the cluster.

Up to this point i've done the following:

1) Setup the Map Clusterer

private void setupMapClusterer() {
    mClusterOptions = new EClusterOptionsProvider(getContext());
    ClusteringSettings clusteringSettings = new ClusteringSettings();
    clusteringSettings.addMarkersDynamically(true);
    clusteringSettings.clusterOptionsProvider(mClusterOptions);
    mMap.setClustering(clusteringSettings);
}

2) Create the Cluster Options Provider

public EClusterOptionsProvider(Context context) {
    mClusterOptions = new ClusterOptions();
    mContext = context;
    mIconGenerator = new IconGenerator(context);

    // Inflate Layout
    View markerView = LayoutInflater.from(context).inflate(R.layout.map_marker, null);
    mImageView = (ImageView) markerView.findViewById(R.id.map_marker_image);
    mTextView = (TextView) markerView.findViewById(R.id.map_marker_text);

    // Setup Icon Generator
    mIconGenerator.setContentView(markerView);
}

public Bitmap createIcon(Bitmap bmp, String text) {
    mImageView.setImageBitmap(bmp);
    mTextView.setText(text);
    return mIconGenerator.makeIcon();
}

@Override
public ClusterOptions getClusterOptions(List<Marker> list) {
    // Get Bitmap from first marker
    Marker first = list.get(0);
    mClusterOptions.icon(BitmapDescriptorFactory.fromBitmap(mIconGenerator.makeIcon()));
    return mClusterOptions;
}

This gives me a Map where clusters have my custom view (which is correct), but i can't figure out where to download the images and how to put them into the single markers and especially the clusters.

Of course i don't want to download all images in advance (we're talking about 500+) images.

On a sidenode: I'm using Volley to dl the images asynchronously.

Best Answer

I created simple example of using clustering and loading markers async.
Hope you find some useful here. https://github.com/pengrad/android-maps-async-markers

We will load icons with Glide, I found it more stable than Picasso.
Call loadIconMarker for every marker you are adding to the map.

MarkerOptions markerOptions = ...
// you should pass some icon before new loaded, or leave default one
//markerOptions.icon(BitmapDescriptorFactory.fromResource(R.drawable.default_marker));
Marker marker = mMap.addMarker(markerOptions);
loadMarkerIcon(marker);


private void loadMarkerIcon(final Marker marker) {
    Glide.with(this).load("http://www.myiconfinder.com/uploads/iconsets/256-256-a5485b563efc4511e0cd8bd04ad0fe9e.png")
            .asBitmap().fitCenter().into(new SimpleTarget<Bitmap>() {
        @Override
        public void onResourceReady(Bitmap bitmap, GlideAnimation<? super Bitmap> glideAnimation) {
            BitmapDescriptor icon = BitmapDescriptorFactory.fromBitmap(bitmap);
            marker.setIcon(icon);
        }
    });
}

Create ClusterIcon is a little harder. This is my ClusterOptionsProvider.
I use base bitmap R.drawable.m1 and add text on it representing number of markers in cluster.

public class ClusterIconProvider implements ClusterOptionsProvider {

    Resources resources;
    Paint paint;
    Bitmap base;

    public ClusterIconProvider(Resources resources) {
        this.resources = resources;

        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setColor(Color.WHITE);
        paint.setTextAlign(Paint.Align.CENTER);
        paint.setTextSize(15);

        base = BitmapFactory.decodeResource(resources, R.drawable.m1);
    }

    @Override
    public ClusterOptions getClusterOptions(List<Marker> list) {
        Bitmap bitmap = base.copy(Bitmap.Config.ARGB_8888, true);

        Rect bounds = new Rect();
        String text = String.valueOf(list.size());
        paint.getTextBounds(text, 0, text.length(), bounds);
        float x = bitmap.getWidth() / 2.0f;
        float y = (bitmap.getHeight() - bounds.height()) / 2.0f - bounds.top;

        Canvas canvas = new Canvas(bitmap);
        canvas.drawText(text, x, y, paint);
        BitmapDescriptor icon = BitmapDescriptorFactory.fromBitmap(bitmap);

        return new ClusterOptions().anchor(0.5f, 0.5f).icon(icon);
    }
}

Related Solutions

Android – How to lazy load images in ListView in Android

Here's what I created to hold the images that my app is currently displaying. Please note that the "Log" object in use here is my custom wrapper around the final Log class inside Android.

package com.wilson.android.library;

/*
 Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you 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.
*/
import java.io.IOException;

public class DrawableManager {
    private final Map<String, Drawable> drawableMap;

    public DrawableManager() {
        drawableMap = new HashMap<String, Drawable>();
    }

    public Drawable fetchDrawable(String urlString) {
        if (drawableMap.containsKey(urlString)) {
            return drawableMap.get(urlString);
        }

        Log.d(this.getClass().getSimpleName(), "image url:" + urlString);
        try {
            InputStream is = fetch(urlString);
            Drawable drawable = Drawable.createFromStream(is, "src");


            if (drawable != null) {
                drawableMap.put(urlString, drawable);
                Log.d(this.getClass().getSimpleName(), "got a thumbnail drawable: " + drawable.getBounds() + ", "
                        + drawable.getIntrinsicHeight() + "," + drawable.getIntrinsicWidth() + ", "
                        + drawable.getMinimumHeight() + "," + drawable.getMinimumWidth());
            } else {
              Log.w(this.getClass().getSimpleName(), "could not get thumbnail");
            }

            return drawable;
        } catch (MalformedURLException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        } catch (IOException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        }
    }

    public void fetchDrawableOnThread(final String urlString, final ImageView imageView) {
        if (drawableMap.containsKey(urlString)) {
            imageView.setImageDrawable(drawableMap.get(urlString));
        }

        final Handler handler = new Handler() {
            @Override
            public void handleMessage(Message message) {
                imageView.setImageDrawable((Drawable) message.obj);
            }
        };

        Thread thread = new Thread() {
            @Override
            public void run() {
                //TODO : set imageView to a "pending" image
                Drawable drawable = fetchDrawable(urlString);
                Message message = handler.obtainMessage(1, drawable);
                handler.sendMessage(message);
            }
        };
        thread.start();
    }

    private InputStream fetch(String urlString) throws MalformedURLException, IOException {
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpGet request = new HttpGet(urlString);
        HttpResponse response = httpClient.execute(request);
        return response.getEntity().getContent();
    }
}

Javascript – Google Maps JS API v3 – Simple Multiple Marker Example

This is the simplest I could reduce it to:

<!DOCTYPE html>
<html> 
<head> 
  <meta http-equiv="content-type" content="text/html; charset=UTF-8" /> 
  <title>Google Maps Multiple Markers</title> 
  <script src="http://maps.google.com/maps/api/js?key=YOUR_API_KEY" 
          type="text/javascript"></script>
</head> 
<body>
  <div id="map" style="width: 500px; height: 400px;"></div>

  <script type="text/javascript">
    var locations = [
      ['Bondi Beach', -33.890542, 151.274856, 4],
      ['Coogee Beach', -33.923036, 151.259052, 5],
      ['Cronulla Beach', -34.028249, 151.157507, 3],
      ['Manly Beach', -33.80010128657071, 151.28747820854187, 2],
      ['Maroubra Beach', -33.950198, 151.259302, 1]
    ];
    
    var map = new google.maps.Map(document.getElementById('map'), {
      zoom: 10,
      center: new google.maps.LatLng(-33.92, 151.25),
      mapTypeId: google.maps.MapTypeId.ROADMAP
    });
    
    var infowindow = new google.maps.InfoWindow();

    var marker, i;
    
    for (i = 0; i < locations.length; i++) {  
      marker = new google.maps.Marker({
        position: new google.maps.LatLng(locations[i][1], locations[i][2]),
        map: map
      });
      
      google.maps.event.addListener(marker, 'click', (function(marker, i) {
        return function() {
          infowindow.setContent(locations[i][0]);
          infowindow.open(map, marker);
        }
      })(marker, i));
    }
  </script>
</body>
</html>

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SCREENSHOT

Google Maps Multiple Markers

There is some closure magic happening when passing the callback argument to the addListener method. This can be quite a tricky topic if you are not familiar with how closures work. I would suggest checking out the following Mozilla article for a brief introduction if it is the case:

❯ Mozilla Dev Center: Working with Closures

Best Answer

Related Solutions

Android – How to lazy load images in ListView in Android

Javascript – Google Maps JS API v3 – Simple Multiple Marker Example

Related Topic