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在 Amazon Location Service 上使用 Android 版 Tangram ES

Tangram ES 是一个 C++ 库，用于使用 OpenGL ES 根据矢量数据渲染 2D 和 3D 地图。它是 Tangram 的原生对应部分。

使用 HERE 中的地图时，专为 Tilezen 架构而设计的 Tangram 风格在很大程度上与 Amazon Location 兼容。其中包括：

本指南介绍如何使用名为 Cinnabar 的 Tangram 风格将 Android 的 Tangram ES 与 Amazon Location 集成。此示例作为 Amazon Location Service 示例存储库的一部分提供GitHub。

虽然其他 Tangram 风格最好搭配编码地形信息的栅格图块，但 Amazon Location 尚不支持此功能。

构建应用程序：初始化

要初始化应用程序，请执行以下操作：

构建应用程序：配置

要使用您的资源和 AWS 区域配置应用程序，请执行以下操作：

<?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>

构建应用程序：活动布局

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

这还将设置地图的初始中心点。

<?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>

构建应用程序：请求转换

创建一个名为 SigV4Interceptor，拦截 AWS 请求的类，并使用 Signature Version 4 对请求进行签名。创建主活动时，将在用于获取地图资源的 HTTP 客户端中进行注册。

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()
        }
    }
}

构建应用程序：主活动

主活动负责初始化将向用户显示的视图。这涉及：

MainActivity 还负责将生命周期事件转发到地图视图。

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()
    }
}

运行此应用程序会以您选择的样式显示全屏地图。此示例作为 Amazon Location Service 示例存储库的一部分提供GitHub。