本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

搭配 Amazon Location Service 使用適用於 Android 的 Tangram ES

Tangram ES 是 C++ 程式庫，用於使用 OpenGL ES 從向量資料轉譯 2D 和 3D 映射。這是 Tangram 的原生複本。

使用來自 的映射時，為搭配 Tilezen 結構描述使用而建置的 Tangram 樣式在很大程度上與 Amazon Location 相容HERE。其中包含：

本指南說明如何使用名為 Cinnabar 的 Tangram 樣式，將適用於 Android 的 Tangram ES 與 Amazon Location 整合。此範例可作為 Amazon Location Service 範例儲存庫的一部分GitHub。

雖然其他 Tangram 樣式最好搭配編碼地形資訊的光柵圖磚，但 Amazon Location 尚不支援此功能。

建置應用程式：初始化

若要初始化您的應用程式：

建置應用程式：組態

若要使用 資源和 AWS 區域設定應用程式：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="identityPoolId">us-east-1:54f2ba88-9390-498d-aaa5-0d97fb7ca3bd</string>
    <string name="mapName">TangramExampleMap</string>
    <string name="awsRegion">us-east-1</string>
    <string name="sceneUrl">https://www.nextzen.org/carto/cinnabar-style/9/cinnabar-style.zip</string>
    <string name="attribution">© 2020 HERE</string>
</resources>

建置應用程式：活動配置

編輯 app/src/main/res/layout/activity_main.xml：

這也會設定地圖的初始中心點。

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
 
    <com.mapzen.tangram.MapView
        android:id="@+id/map"
        android:layout_height="match_parent"
        android:layout_width="match_parent" />
 
    <TextView
        android:id="@+id/attributionView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#80808080"
        android:padding="5sp"
        android:textColor="@android:color/black"
        android:textSize="10sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        tools:ignore="SmallSp" />
</androidx.constraintlayout.widget.ConstraintLayout>

建置應用程式：請求轉換

建立名為 的類別SigV4Interceptor來攔截 AWS 請求，並使用 Signature 第 4 版簽署請求。這將在建立主要活動時，向用來擷取地圖資源的HTTP用戶端註冊。

package aws.location.demo.okhttp
 
import com.amazonaws.DefaultRequest
import com.amazonaws.auth.AWS4Signer
import com.amazonaws.auth.AWSCredentialsProvider
import com.amazonaws.http.HttpMethodName
import com.amazonaws.util.IOUtils
import okhttp3.HttpUrl
import okhttp3.Interceptor
import okhttp3.Request
import okhttp3.Response
import okio.Buffer
import java.io.ByteArrayInputStream
import java.net.URI
 
class SigV4Interceptor(
    private val credentialsProvider: AWSCredentialsProvider,
    private val serviceName: String
) : Interceptor {
    override fun intercept(chain: Interceptor.Chain): Response {
        val originalRequest = chain.request()
 
        if (originalRequest.url().host().contains("amazonaws.com")) {
            val signer = if (originalRequest.url().encodedPath().contains("@")) {
                // the presence of "@" indicates that it doesn't need to be double URL-encoded
                AWS4Signer(false)
            } else {
                AWS4Signer()
            }
 
            val awsRequest = toAWSRequest(originalRequest, serviceName)
            signer.setServiceName(serviceName)
            signer.sign(awsRequest, credentialsProvider.credentials)
 
            return chain.proceed(toSignedOkHttpRequest(awsRequest, originalRequest))
        }
 
        return chain.proceed(originalRequest)
    }
 
    companion object {
        fun toAWSRequest(request: Request, serviceName: String): DefaultRequest<Any> {
            // clone the request (AWS-style) so that it can be populated with credentials
            val dr = DefaultRequest<Any>(serviceName)
 
            // copy request info
            dr.httpMethod = HttpMethodName.valueOf(request.method())
            with(request.url()) {
                dr.resourcePath = uri().path
                dr.endpoint = URI.create("${scheme()}://${host()}")
 
                // copy parameters
                for (p in queryParameterNames()) {
                    if (p != "") {
                        dr.addParameter(p, queryParameter(p))
                    }
                }
            }
 
            // copy headers
            for (h in request.headers().names()) {
                dr.addHeader(h, request.header(h))
            }
 
            // copy the request body
            val bodyBytes = request.body()?.let { body ->
                val buffer = Buffer()
                body.writeTo(buffer)
                IOUtils.toByteArray(buffer.inputStream())
            }
 
            dr.content = ByteArrayInputStream(bodyBytes ?: ByteArray(0))
 
            return dr
        }
 
        fun toSignedOkHttpRequest(
            awsRequest: DefaultRequest<Any>,
            originalRequest: Request
        ): Request {
            // copy signed request back into an OkHttp Request
            val builder = Request.Builder()
 
            // copy headers from the signed request
            for ((k, v) in awsRequest.headers) {
                builder.addHeader(k, v)
            }
 
            // start building an HttpUrl
            val urlBuilder = HttpUrl.Builder()
                .host(awsRequest.endpoint.host)
                .scheme(awsRequest.endpoint.scheme)
                .encodedPath(awsRequest.resourcePath)
 
            // copy parameters from the signed request
            for ((k, v) in awsRequest.parameters) {
                urlBuilder.addQueryParameter(k, v)
            }
 
            return builder.url(urlBuilder.build())
                .method(originalRequest.method(), originalRequest.body())
                .build()
        }
    }
}

建置應用程式：主要活動

主要活動負責初始化將向使用者顯示的檢視。這涉及：

MainActivity 也負責將生命週期事件轉送至地圖檢視。

package aws.location.demo.tangram
 
import android.os.Bundle
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import aws.location.demo.okhttp.SigV4Interceptor
import com.amazonaws.auth.CognitoCachingCredentialsProvider
import com.amazonaws.regions.Regions
import com.mapzen.tangram.*
import com.mapzen.tangram.networking.DefaultHttpHandler
import com.mapzen.tangram.networking.HttpHandler
 
private const val SERVICE_NAME = "geo"
 
class MainActivity : AppCompatActivity(), MapView.MapReadyCallback {
    private var mapView: MapView? = null
 
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
 
        setContentView(R.layout.activity_main)
 
        mapView = findViewById(R.id.map)
 
        mapView?.getMapAsync(this, getHttpHandler())
        findViewById<TextView>(R.id.attributionView).text = getString(R.string.attribution)
    }
 
    override fun onMapReady(mapController: MapController?) {
        val sceneUpdates = arrayListOf(
            SceneUpdate(
                "sources.mapzen.url",
                "https://maps.geo.${getString(R.string.awsRegion)}.amazonaws.com/maps/v0/maps/${
                    getString(
                        R.string.mapName
                    )
                }/tiles/{z}/{x}/{y}"
            )
        )
 
        mapController?.let { map ->
            map.updateCameraPosition(
                CameraUpdateFactory.newLngLatZoom(
                    LngLat(-123.1187, 49.2819),
                    12F
                )
            )
            map.loadSceneFileAsync(
                getString(R.string.sceneUrl),
                sceneUpdates
            )
        }
    }
 
    private fun getHttpHandler(): HttpHandler {
        val builder = DefaultHttpHandler.getClientBuilder()
 
        val credentialsProvider = CognitoCachingCredentialsProvider(
            applicationContext,
            getString(R.string.identityPoolId),
            Regions.US_EAST_1
        )
 
        return DefaultHttpHandler(
            builder.addInterceptor(
                SigV4Interceptor(
                    credentialsProvider,
                    SERVICE_NAME
                )
            )
        )
    }
 
    override fun onResume() {
        super.onResume()
        mapView?.onResume()
    }
 
    override fun onPause() {
        super.onPause()
        mapView?.onPause()
    }
 
    override fun onLowMemory() {
        super.onLowMemory()
        mapView?.onLowMemory()
    }
 
    override fun onDestroy() {
        super.onDestroy()
        mapView?.onDestroy()
    }
}

執行此應用程式會以您選擇的樣式顯示全螢幕地圖。此範例可作為 Amazon Location Service 範例儲存庫的一部分GitHub。