CachingUrlTileProvider
This simple utility class acts the same as Google Maps V2 UrlTileProvider but also caches the returned images locally on disk and/or in memory. Depends on the Android Universal Image Loader library.
/*******************************************************************************
* Copyright 2014 Maurice Wohlkönig
*
* 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.falott.localtilecacheoverlay;
import android.content.Context;
import android.graphics.Bitmap;
import android.util.Log;
import com.google.android.gms.maps.model.Tile;
import com.google.android.gms.maps.model.TileOverlayOptions;
import com.google.android.gms.maps.model.TileProvider;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
import java.io.ByteArrayOutputStream;
/**
* <p>Google Maps Android V2 tile overlay provider for cached URL tiles. Caches in memory and/or on disk.</p>
* <p>Uses the famous <a href="https://github.com/nostra13/Android-Universal-Image-Loader/">Android Universal Image Loader</a> library for downloading and caching.</p>
* <p>Usage example:<pre>
googleMap.addTileOverlay(new CachingUrlTileProvider(this, 256, 256) {
@Override
public String getTileUrl(int x, int y, int z) {
return String.format("https://a.tile.openstreetmap.org/%3$s/%1$s/%2$s.png",x,y,z);
}
}.createTileOverlayOptions());
* </pre></p>
*/
public abstract class CachingUrlTileProvider implements TileProvider {
private final int mTileWidth;
private final int mTileHeight;
private final DisplayImageOptions mOptions;
public CachingUrlTileProvider(Context ctx, int mTileWidth, int mTileHeight) {
this.mTileWidth = mTileWidth;
this.mTileHeight = mTileHeight;
// if ImageLoader has not been instantiated by parent application yet
if (!ImageLoader.getInstance().isInited()) {
// Create global configuration and initialize ImageLoader with this config
ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(ctx).build();
ImageLoader.getInstance().init(config);
}
// init ImageLoader display options
DisplayImageOptions.Builder builder = new DisplayImageOptions.Builder();
builder.cacheInMemory(true).cacheOnDisk(true);
setDisplayImageOptions(builder);
mOptions = builder.build();
}
@Override
public Tile getTile(int x, int y, int z) {
byte[] tileImage = getTileImage(x, y, z);
if (tileImage != null) {
return new Tile(mTileWidth / 2, mTileHeight / 2, tileImage);
}
return NO_TILE;
}
/**
* Synchronously loads the requested Tile image either from cache or from the web.</p>
* Background threading/pooling is done by the google maps api so we can do it all synchronously.
*
* @param x x coordinate of the tile
* @param y y coordinate of the tile
* @param z the zoom level
* @return byte data of the image or <i>null</i> if the image could not be loaded.
*/
private byte[] getTileImage(int x, int y, int z) {
Bitmap bitmap = ImageLoader.getInstance().loadImageSync(getTileUrl(x, y, z), mOptions);
if (bitmap == null) {
return null;
}
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
return stream.toByteArray();
}
/**
* Creates a new TileOverlayOptions object to be used with {@link com.google.android.gms.maps.GoogleMap#addTileOverlay(com.google.android.gms.maps.model.TileOverlayOptions) map.addTileOverlay()}
* @return a TileOverlayOptions with this object set as a tile provider plus fadeIn set to false
*/
public TileOverlayOptions createTileOverlayOptions() {
TileOverlayOptions tileOverlayOptions = new TileOverlayOptions().tileProvider(this);
// set fadeIn to false for all GMS versions that support it
try {
Class.forName("com.google.android.gms.maps.model.TileOverlayOptions")
.getMethod("fadeIn", boolean.class)
.invoke(tileOverlayOptions, false);
} catch (Exception e) {
}
return tileOverlayOptions;
}
/**
* Allows you to set additional ImageLoader display options.<p/>
* See https://github.com/nostra13/Android-Universal-Image-Loader/wiki/Display-Options for possible options.<p/>
* Disabling the cache option DOES NOT MAKE SENSE.
*
* @param optionsBuilder options builder for setting de downloader settings
*/
protected void setDisplayImageOptions(DisplayImageOptions.Builder optionsBuilder) {
}
/**
* Return the url to your tiles. For example:
* <pre>
public String getTileUrl(int x, int y, int z) {
return String.format("https://a.tile.openstreetmap.org/%3$s/%1$s/%2$s.png",x,y,z);
}
</pre>
* See <a href="http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames">http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames</a> for more details
*
* @param x x coordinate of the tile
* @param y y coordinate of the tile
* @param z the zoom level
* @return the url to the tile specified by the parameters
*/
public abstract String getTileUrl(int x, int y, int z);
}
Usage
Declare the ImageLoader dependency:
dependencies {
compile 'com.nostra13.universalimageloader:universal-image-loader:1.9.3'
}
Set up your GoogleMap object and declare the new TileOverlay:
mMap.setMapType(GoogleMap.MAP_TYPE_NONE);
mMap.addTileOverlay(new CachingUrlTileProvider(this, 256, 256) {
@Override
public String getTileUrl(int x, int y, int z) {
return String.format("https://a.tile.openstreetmap.org/%3$s/%1$s/%2$s.png",x,y,z);
}
}.createTileOverlayOptions());