Demo clustering with ViewModel (#506)

* Differentiate between initial start and configuration change restore Only move the camera to the starting location when not restoring * Add removeItems() to ClusterManager and Algorithm Avoid locking and unlocking the algorithm in a tight loop when removing many cluster items * Move algorithm lock from ClusterManager to Algorithm Allow the algorithm to handle its own locking, so it can be reused in another ClusterManager instance. Also allow adding/removing items with proper locking outside of ClusterManager. For best ViewModel support.
googlemaps · Oct 21, 2019 · bb3587f · bb3587f
1 parent 75a2956
commit bb3587f
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diff --git a/demo/build.gradle b/demo/build.gradle
@@ -30,6 +30,7 @@ dependencies {
 
     implementation 'com.google.android.gms:play-services-maps:17.0.0'
     implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
 }
 
 task startDemo(type: Exec) {

diff --git a/demo/src/main/AndroidManifest.xml b/demo/src/main/AndroidManifest.xml
@@ -53,6 +53,7 @@
         <activity android:name=".BigClusteringDemoActivity" />
         <activity android:name=".VisibleClusteringDemoActivity" />
         <activity android:name=".CustomMarkerClusteringDemoActivity" />
+        <activity android:name=".ClusteringViewModelDemoActivity"/>
         <activity android:name=".TileProviderAndProjectionDemo" />
         <activity android:name=".HeatmapsDemoActivity" />
         <activity android:name=".HeatmapsPlacesDemoActivity" />

diff --git a/demo/src/main/java/com/google/maps/android/utils/demo/ClusteringViewModel.java b/demo/src/main/java/com/google/maps/android/utils/demo/ClusteringViewModel.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2019 Google Inc.
+ *
+ * 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.google.maps.android.utils.demo;
+
+import androidx.lifecycle.ViewModel;
+import android.content.res.Resources;
+
+import com.google.android.gms.maps.model.LatLng;
+import com.google.maps.android.clustering.algo.NonHierarchicalViewBasedAlgorithm;
+import com.google.maps.android.utils.demo.model.MyItem;
+
+import org.json.JSONException;
+
+import java.io.InputStream;
+import java.util.List;
+
+public class ClusteringViewModel extends ViewModel {
+
+    private NonHierarchicalViewBasedAlgorithm<MyItem> mAlgorithm = new NonHierarchicalViewBasedAlgorithm<>(0, 0);
+
+    NonHierarchicalViewBasedAlgorithm<MyItem> getAlgorithm() {
+        return mAlgorithm;
+    }
+
+    void readItems(Resources resources) throws JSONException {
+        InputStream inputStream = resources.openRawResource(R.raw.radar_search);
+        List<MyItem> items = new MyItemReader().read(inputStream);
+        mAlgorithm.lock();
+        try {
+            for (int i = 0; i < 100; i++) {
+                double offset = i / 60d;
+                for (MyItem item : items) {
+                    LatLng position = item.getPosition();
+                    double lat = position.latitude + offset;
+                    double lng = position.longitude + offset;
+                    MyItem offsetItem = new MyItem(lat, lng);
+                    mAlgorithm.addItem(offsetItem);
+                }
+            }
+        } finally {
+            mAlgorithm.unlock();
+        }
+    }
+}
diff --git a/demo/src/main/java/com/google/maps/android/utils/demo/ClusteringViewModelDemoActivity.java b/demo/src/main/java/com/google/maps/android/utils/demo/ClusteringViewModelDemoActivity.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2019 Google Inc.
+ *
+ * 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.google.maps.android.utils.demo;
+
+import androidx.lifecycle.ViewModelProviders;
+import android.os.Bundle;
+import android.util.DisplayMetrics;
+import android.widget.Toast;
+
+import com.google.android.gms.maps.CameraUpdateFactory;
+import com.google.android.gms.maps.model.LatLng;
+import com.google.maps.android.clustering.ClusterManager;
+import com.google.maps.android.utils.demo.model.MyItem;
+
+import org.json.JSONException;
+
+public class ClusteringViewModelDemoActivity extends BaseDemoActivity {
+    private ClusterManager<MyItem> mClusterManager;
+    private ClusteringViewModel mViewModel;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        mViewModel = ViewModelProviders.of(this).get(ClusteringViewModel.class);
+        if (savedInstanceState == null) {
+            try {
+                mViewModel.readItems(getResources());
+            } catch (JSONException e) {
+                Toast.makeText(this, "Problem reading list of markers.", Toast.LENGTH_LONG).show();
+            }
+        }
+    }
+
+    @Override
+    protected void startDemo(boolean isRestore) {
+        if (!isRestore) {
+            getMap().moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(51.503186, -0.126446), 10));
+        }
+
+        DisplayMetrics metrics = new DisplayMetrics();
+        getWindowManager().getDefaultDisplay().getMetrics(metrics);
+        mViewModel.getAlgorithm().updateViewSize(metrics.widthPixels, metrics.heightPixels);
+
+        mClusterManager = new ClusterManager<>(this, getMap());
+        mClusterManager.setAlgorithm(mViewModel.getAlgorithm());
+
+        getMap().setOnCameraIdleListener(mClusterManager);
+    }
+}
diff --git a/demo/src/main/java/com/google/maps/android/utils/demo/MainActivity.java b/demo/src/main/java/com/google/maps/android/utils/demo/MainActivity.java
@@ -40,7 +40,8 @@ protected void onCreate(Bundle savedInstanceState) {
         addDemo("Clustering", ClusteringDemoActivity.class);
         addDemo("Clustering: Custom Look", CustomMarkerClusteringDemoActivity.class);
         addDemo("Clustering: 2K markers", BigClusteringDemoActivity.class);
-        addDemo("Clustering: 20k only visible markers", VisibleClusteringDemoActivity.class);
+        addDemo("Clustering: 20K only visible markers", VisibleClusteringDemoActivity.class);
+        addDemo("Clustering: ViewModel", ClusteringViewModelDemoActivity.class);
         addDemo("PolyUtil.decode", PolyDecodeDemoActivity.class);
         addDemo("PolyUtil.simplify", PolySimplifyDemoActivity.class);
         addDemo("IconGenerator", IconGeneratorDemoActivity.class);

diff --git a/demo/src/main/res/values/strings.xml b/demo/src/main/res/values/strings.xml
@@ -5,9 +5,9 @@
     <string name="button_send">Go!</string>
     <string name="police_stations">Police Stations in Victoria</string>
     <string name="medicare">Medicare Offices</string>
-    <string name="attrib_format">Data from &lt;a href = "%s">data.gov.au&lt;/a>, modified under &lt;a href = \"http://creativecommons.org/licenses/by/3.0/au/\">CC BY 3.0 AU&lt;/a></string>
-    <string name="police_stations_url">http://data.gov.au/dataset/police-station-locations/resource/76110b24-0f0a-4c29-9583-3f99eaba486c</string>
-    <string name="medicare_url">http://data.gov.au/dataset/location-of-medicare-offices/resource/5d38e1be-4011-49c4-8b8b-75405eeb1088</string>
+    <string name="attrib_format">Data from &lt;a href = "%s">data.gov.au&lt;/a>, modified under &lt;a href = \"https://creativecommons.org/licenses/by/3.0/au/\">CC BY 3.0 AU&lt;/a></string>
+    <string name="police_stations_url">https://data.gov.au/dataset/police-station-locations/resource/76110b24-0f0a-4c29-9583-3f99eaba486c</string>
+    <string name="medicare_url">https://data.gov.au/dataset/location-of-medicare-offices/resource/5d38e1be-4011-49c4-8b8b-75405eeb1088</string>
     <string name="kml_url">https://googlemaps.github.io/kml-samples/morekml/Polygons/Polygons.Google_Campus.kml</string>
     <string name="geojson_url">https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_day.geojson</string>
     <string-array name="heatmaps_datasets_array">

diff --git a/library/src/main/java/com/google/maps/android/clustering/ClusterManager.java b/library/src/main/java/com/google/maps/android/clustering/ClusterManager.java
@@ -52,7 +52,6 @@ public class ClusterManager<T extends ClusterItem> implements
     private final MarkerManager.Collection mClusterMarkers;
 
     private ScreenBasedAlgorithm<T> mAlgorithm;
-    private final ReadWriteLock mAlgorithmLock = new ReentrantReadWriteLock();
     private ClusterRenderer<T> mRenderer;
 
     private GoogleMap mMap;
@@ -118,15 +117,15 @@ public void setAlgorithm(Algorithm<T> algorithm) {
     }
 
     public void setAlgorithm(ScreenBasedAlgorithm<T> algorithm) {
-        mAlgorithmLock.writeLock().lock();
+        algorithm.lock();
         try {
             if (mAlgorithm != null) {
                 algorithm.addItems(mAlgorithm.getItems());
             }
 
             mAlgorithm = algorithm;
         } finally {
-            mAlgorithmLock.writeLock().unlock();
+            algorithm.unlock();
         }
 
         if (mAlgorithm.shouldReclusterOnMapMovement()) {
@@ -149,39 +148,47 @@ public Algorithm<T> getAlgorithm() {
     }
 
     public void clearItems() {
-        mAlgorithmLock.writeLock().lock();
+        mAlgorithm.lock();
         try {
             mAlgorithm.clearItems();
         } finally {
-            mAlgorithmLock.writeLock().unlock();
+            mAlgorithm.unlock();
         }
     }
 
     public void addItems(Collection<T> items) {
-        mAlgorithmLock.writeLock().lock();
+        mAlgorithm.lock();
         try {
             mAlgorithm.addItems(items);
         } finally {
-            mAlgorithmLock.writeLock().unlock();
+            mAlgorithm.unlock();
         }
-
     }
 
     public void addItem(T myItem) {
-        mAlgorithmLock.writeLock().lock();
+        mAlgorithm.lock();
         try {
             mAlgorithm.addItem(myItem);
         } finally {
-            mAlgorithmLock.writeLock().unlock();
+            mAlgorithm.unlock();
+        }
+    }
+
+    public void removeItems(Collection<T> items) {
+        mAlgorithm.lock();
+        try {
+            mAlgorithm.removeItems(items);
+        } finally {
+            mAlgorithm.unlock();
         }
     }
 
     public void removeItem(T item) {
-        mAlgorithmLock.writeLock().lock();
+        mAlgorithm.lock();
         try {
             mAlgorithm.removeItem(item);
         } finally {
-            mAlgorithmLock.writeLock().unlock();
+            mAlgorithm.unlock();
         }
     }
 
@@ -238,11 +245,11 @@ public void onInfoWindowClick(Marker marker) {
     private class ClusterTask extends AsyncTask<Float, Void, Set<? extends Cluster<T>>> {
         @Override
         protected Set<? extends Cluster<T>> doInBackground(Float... zoom) {
-            mAlgorithmLock.readLock().lock();
+            mAlgorithm.lock();
             try {
                 return mAlgorithm.getClusters(zoom[0]);
             } finally {
-                mAlgorithmLock.readLock().unlock();
+                mAlgorithm.unlock();
             }
         }
 

diff --git a/library/src/main/java/com/google/maps/android/clustering/algo/AbstractAlgorithm.java b/library/src/main/java/com/google/maps/android/clustering/algo/AbstractAlgorithm.java
@@ -0,0 +1,24 @@
+package com.google.maps.android.clustering.algo;
+
+import com.google.maps.android.clustering.ClusterItem;
+
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+/**
+ * Base Algorithm class that implements lock/unlock functionality.
+ */
+public abstract class AbstractAlgorithm<T extends ClusterItem> implements Algorithm<T> {
+
+    private final ReadWriteLock mLock = new ReentrantReadWriteLock();
+
+    @Override
+    public void lock() {
+        mLock.writeLock().lock();
+    }
+
+    @Override
+    public void unlock() {
+        mLock.writeLock().unlock();
+    }
+}
diff --git a/library/src/main/java/com/google/maps/android/clustering/algo/Algorithm.java b/library/src/main/java/com/google/maps/android/clustering/algo/Algorithm.java
@@ -26,6 +26,7 @@
  * Logic for computing clusters
  */
 public interface Algorithm<T extends ClusterItem> {
+
     void addItem(T item);
 
     void addItems(Collection<T> items);
@@ -34,11 +35,17 @@ public interface Algorithm<T extends ClusterItem> {
 
     void removeItem(T item);
 
+    void removeItems(Collection<T> items);
+
     Set<? extends Cluster<T>> getClusters(float zoom);
 
     Collection<T> getItems();
 
     void setMaxDistanceBetweenClusteredItems(int maxDistance);
 
     int getMaxDistanceBetweenClusteredItems();
+
+    void lock();
+
+    void unlock();
 }
diff --git a/library/src/main/java/com/google/maps/android/clustering/algo/GridBasedAlgorithm.java b/library/src/main/java/com/google/maps/android/clustering/algo/GridBasedAlgorithm.java
@@ -31,7 +31,7 @@
 /**
  * Groups markers into a grid.
  */
-public class GridBasedAlgorithm<T extends ClusterItem> implements Algorithm<T> {
+public class GridBasedAlgorithm<T extends ClusterItem> extends AbstractAlgorithm<T> {
     private static final int DEFAULT_GRID_SIZE = 100;
 
     private int mGridSize = DEFAULT_GRID_SIZE;
@@ -58,6 +58,11 @@ public void removeItem(T item) {
         mItems.remove(item);
     }
 
+    @Override
+    public void removeItems(Collection<T> items) {
+        mItems.removeAll(items);
+    }
+
     @Override
     public void setMaxDistanceBetweenClusteredItems(int maxDistance) {
         mGridSize = maxDistance;