處理點擊事件

您可以讓地圖項目圖層回應使用者的 click 事件，以便取得所點擊邊界的地點 ID 和地圖項目類型。以下地圖範例顯示「Country」圖層的邊界，並列出設定所點選多邊形樣式的事件處理常式，以及顯示與所選國家/地區相關聯的點選多邊形。

編寫點擊事件處理常式

當地圖項目圖層發生點擊事件時，Maps SDK for Android 會將 FeatureClickEvent 物件傳遞至事件處理常式。使用 FeatureClickEvent 取得點擊事件的經緯度座標，以及受點擊事件影響的地貌項目清單。

處理地圖項目圖層事件

請按照下列步驟處理地圖項目圖層上的事件。在這個範例中，您會為「Country」地圖項目圖層定義點擊事件處理常式，將紅色填充圖案套用至代表所選國家/地區的多邊形。

呼叫 FeatureLayer.setFeatureStyle() 時，樣式工廠函式會設定地圖項目圖層中所有地圖項目的樣式。如要在事件處理常式中更新地圖項目的樣式，您必須呼叫 FeatureLayer.setFeatureStyle()，為所有地圖項目設定更新後的樣式。

1. 如果尚未建立新的地圖 ID 和地圖樣式，請按照「開始使用」一文中的步驟進行。請務必啟用「國家/地區」地圖項目圖層。

2. 請確認您的類別實作 FeatureLayer.OnFeatureClickListener。

3. 呼叫 FeatureLayer.addOnFeatureClickListener()，註冊地圖項目點擊事件的事件處理常式。

   Java

   private FeatureLayer countryLayer;
   
   @Override
   public void onMapReady(GoogleMap map) {
   
     // Get the COUNTRY feature layer.
     countryLayer = map.getFeatureLayer(new FeatureLayerOptions.Builder()
       .featureType(FeatureType.COUNTRY)
       .build());
   
     // Register the click event handler for the Country layer.
     countryLayer.addOnFeatureClickListener(this);
   
     // Apply default style to all countries on load to enable clicking.
     styleCountryLayer();
   }
   
   // Set default fill and border for all countries to ensure that they respond
   // to click events.
   private void styleCountryLayer() {
     FeatureLayer.StyleFactory styleFactory = (Feature feature) -> {
       return new FeatureStyle.Builder()
         // Set the fill color for the country as white with a 10% opacity.
         .fillColor(Color.argb(0.1, 0, 0, 0))
         // Set border color to solid black.
         .strokeColor(Color.BLACK)
         .build();
     };
   
     // Apply the style factory function to the country feature layer.
     countryLayer.setFeatureStyle(styleFactory);
   }

   Kotlin

   private var countryLayer: FeatureLayer? = null
   
   override fun onMapReady(googleMap: GoogleMap) {
     // Get the COUNTRY feature layer.
     countryLayer = googleMap.getFeatureLayer(FeatureLayerOptions.Builder()
       .featureType(FeatureType.COUNTRY)
       .build())
   
     // Register the click event handler for the Country layer.
     countryLayer?.addOnFeatureClickListener(this)
   
     // Apply default style to all countries on load to enable clicking.
     styleCountryLayer()
   }
   
   // Set default fill and border for all countries to ensure that they respond
   // to click events.
   private fun styleCountryLayer() {
     val styleFactory = FeatureLayer.StyleFactory { feature: Feature ->
       return@StyleFactory FeatureStyle.Builder()
         // Set the fill color for the country as white with a 10% opacity.
         .fillColor(Color.argb(0.1f, 0f, 0f, 0f))
         // Set border color to solid black.
         .strokeColor(Color.BLACK)
         .build()
     }
   
     // Apply the style factory function to the country feature layer.
     countryLayer?.setFeatureStyle(styleFactory)
   }

4. 為所選國家/地區套用紅色填滿色彩。只有可見的地圖項目可供點選。

   Java

   @Override
   // Define the click event handler.
   public void onFeatureClick(FeatureClickEvent event) {
   
     // Get the list of features affected by the click using
     // getPlaceIds() defined below.
     List<String> selectedPlaceIds = getPlaceIds(event.getFeatures());
   
     if (!selectedPlaceIds.isEmpty()) {
       FeatureLayer.StyleFactory styleFactory = (Feature feature) -> {
         // Use PlaceFeature to get the placeID of the country.
         if (feature instanceof PlaceFeature) {
           if (selectedPlaceIds.contains(((PlaceFeature) feature).getPlaceId())) {
             return new FeatureStyle.Builder()
                 // Set the fill color to red.
                 .fillColor(Color.RED)
                 .build();
           }
         }
         return null;
       };
   
       // Apply the style factory function to the feature layer.
       countryLayer.setFeatureStyle(styleFactory);
     }
   }
   
   // Get a List of place IDs from the FeatureClickEvent object.
   private List<String> getPlaceIds(List<Feature> features) {
     List<String> placeIds = new ArrayList<>();
     for (Feature feature : features) {
       if (feature instanceof PlaceFeature) {
           placeIds.add(((PlaceFeature) feature).getPlaceId());
       }
     }
     return placeIds;
   }

   Kotlin

   // Define the click event handler.
   override fun onFeatureClick(event: FeatureClickEvent) {
   
     // Get the list of features affected by the click using
     // getPlaceIds() defined below.
     val selectedPlaceIds = getPlaceIds(event.getFeatures())
     if (!selectedPlaceIds.isEmpty()) {
         val styleFactory = FeatureLayer.StyleFactory { feature: Feature ->
             // Use PlaceFeature to get the placeID of the country.
             if (feature is PlaceFeature) {
                 if (selectedPlaceIds.contains((feature as PlaceFeature).getPlaceId())) {
                     return@StyleFactory FeatureStyle.Builder()
                         // Set the fill color to red.
                         .fillColor(Color.RED)
                         .build()
                 }
             }
             return@StyleFactory null
         }
   
         // Apply the style factory function to the feature layer.
         countryLayer?.setFeatureStyle(styleFactory)
     }
   }
   
   // Get a List of place IDs from the FeatureClickEvent object.
   private fun getPlaceIds(features: List<Feature>): List<String> {
     val placeIds: MutableList<String> = ArrayList()
     for (feature in features) {
         if (feature is PlaceFeature) {
             placeIds.add((feature as PlaceFeature).getPlaceId())
         }
     }
     return placeIds
   }