在变焦集群地图标记出来，在上撤出群集变焦 [英] Clustering map markers on zoom out and unclustering on zoom in

问题描述

我使用的是谷歌地图Android的聚类Utitlity 随着谷歌地图V2播放服务。

I am using the Google Map Android clustering Utitlity With Google Maps v2 play services.

我没有得到我预期的行为。正如你可以在下面的两张图片看，当我放大可以看到20的集群和单个标记了一个向左，但是当我缩小直到他们都在彼此的顶部，我没有看到他们的集群。 ，20个集群还称20而不是21？

I am not getting the behavior I expected. As you can see in the two images below, when zoomed in I can see a cluster of 20 and a single marker up an to the left, but when i zoom out til they are on top of each other i am not seeing them cluster.. the 20 cluster still says 20 and not 21?

是预期的行为？有没有一种方法可以使集群展示的21，而不是20 +

Is that expected behavior? Is there a way can make the cluster show 21 instead of 20+

推荐答案

这是在<指定的默认​​行为href="https://github.com/googlemaps/android-maps-utils/blob/master/library/src/com/google/maps/android/clustering/view/DefaultClusterRenderer.java#L698"><$c$c>DefaultClasterRenderer#onBeforeClusterRendered():

/**
 * Called before the marker for a Cluster is added to the map.
 * The default implementation draws a circle with a rough count of the number of items.
 */
protected void onBeforeClusterRendered(Cluster<T> cluster, MarkerOptions markerOptions) {
    int bucket = getBucket(cluster);
    BitmapDescriptor descriptor = mIcons.get(bucket);
    if (descriptor == null) {
        mColoredCircleBackground.getPaint().setColor(getColor(bucket));
        descriptor = BitmapDescriptorFactory.fromBitmap(mIconGenerator.makeIcon(getClusterText(bucket)));
        mIcons.put(bucket, descriptor);
    }
    // TODO: consider adding anchor(.5, .5) (Individual markers will overlap more often)
    markerOptions.icon(descriptor);
}

需要注意的是文本标记的基础上选择了斗，而不是项目的确切数量的群集

Note that text for the marker is chosen based on the bucket, rather than exact number of items in cluster

对于快速解决将是修改描述创作是这样的：

The quick fix for that would be to modify descriptor creation to be something like:

descriptor = BitmapDescriptorFactory.fromBitmap(mIconGenerator.
                                                 makeIcon(cluster.getSize());

当然你也可以实现自定义的 ClasterRenderer ，并把它提供给<一个href="https://github.com/googlemaps/android-maps-utils/blob/master/library/src/com/google/maps/android/clustering/ClusterManager.java#L74"><$c$c>ClusterManager.通过这种方式，你将负责你的标志呈现的，但如果你想只改变20 +到21 - 我将与第一种方法去

Of course you can implement your custom ClasterRenderer and provide it to the ClusterManager. In this way you will be in charge of rendering of your markers, but if you want to just change the "20+" to "21" - I would go with first approach

编辑：

解决问题问的评论： 如果你想增加/减少间距门槛分组项 - 您可以修改<一个href="https://github.com/googlemaps/android-maps-utils/blob/master/library/src/com/google/maps/android/clustering/algo/NonHierarchicalDistanceBasedAlgorithm.java#L35">default算法可用于群集。就在这个不断播放（在你的情况应该是更小的）：

Addressing question asked in comments: If you want to increase/decrease distance threshold for grouping items - you can modify default algorithm used for clustering. Just play with this constant (in your case should be smaller):

public static final int MAX_DISTANCE_AT_ZOOM = 100; // essentially 100 dp.

但正确的解决将是考虑到标记位图的大小，而不是恒定值。我想先生Broadfood 离开，作为一个功课爱好者：）

But the correct fix would be to take into account Marker bitmap size rather than constant value. I assume Mr. Broadfood left that as a homework to enthusiasts :)

private Bounds createBoundsFromSpan(Point p, double span) {
    // TODO: Use a span that takes into account the visual size of the marker, not just its
    // LatLng.
    double halfSpan = span / 2;
    return new Bounds(
            p.x - halfSpan, p.x + halfSpan,
            p.y - halfSpan, p.y + halfSpan);
}

这篇关于在变焦集群地图标记出来，在上撤出群集变焦的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！