Integrate asset delivery (native)

Use the steps in this guide to access your app’s asset packs from your C and C++ code.

Sample integration code is available on GitHub.

Build for native

Use the following steps to build Play Asset Delivery into your project’s Android App Bundle. You don't need to use Android Studio to perform these steps.

  1. Update the version of the Android Gradle plugin in your project’s build.gradle file to 4.0.0 or later.

  2. In the top-level directory of your project, create a directory for the asset pack. This directory name is used as the asset pack name. Asset pack names must start with a letter and can only contain letters, numbers, and underscores.

  3. In the asset pack directory, create a build.gradle file and add the following code. Make sure to specify the name of the asset pack and only one delivery type:

    // In the asset pack’s build.gradle file:
plugins {
    id 'com.android.asset-pack'
}

assetPack {
    packName = "asset-pack-name" // Directory name for the asset pack
    dynamicDelivery {
        deliveryType = "[ install-time | fast-follow | on-demand ]"
    }
}

  4. In the project’s app build.gradle file, add the name of every asset pack in your project as shown below:

    // In the app build.gradle file:
android {
    ...
    assetPacks = [":asset-pack-name", ":asset-pack2-name"]
}

  5. In the project’s settings.gradle file, include all asset packs in your project as shown below:

    // In the settings.gradle file:
include ':app'
include ':asset-pack-name'
include ':asset-pack2-name'

  6. In the asset pack directory, create the following subdirectory: src/main/assets.

  7. Place assets in the src/main/assets directory. You can create subdirectories in here as well. The directory structure for your app should now look like the following:

    • build.gradle
    • settings.gradle
    • app/
    • asset-pack-name/build.gradle
    • asset-pack-name/src/main/assets/your-asset-directories

  8. Build the Android App Bundle with Gradle. In the generated app bundle, the root-level directory now includes the following:

    • asset-pack-name/manifest/AndroidManifest.xml: Configures the asset pack’s identifier and delivery mode
    • asset-pack-name/assets/your-asset-directories: Directory that contains all assets delivered as part of the asset pack

    Gradle generates the manifest for each asset pack and outputs the assets/ directory for you.

  9. (Optional) Configure your app bundle to support different texture compression formats.

Integrate with Play Asset Delivery Library

You implement this API according to the delivery type of the asset pack you wish to access. These steps are shown in the following flowchart.

Asset pack flow diagram for native code

Figure 1. Flow diagram for accessing asset packs

The Play Core Native SDK provides the C header file play/asset_pack.h for requesting asset packs, managing downloads, and accessing the assets.

Set up your development environment for Play Core Native SDK

Download Play Core Native SDK

Before downloading, you must agree to the following terms and conditions.

Terms and Conditions

Last modified: September 24, 2020
  1. By using the Play Core Software Development Kit, you agree to these terms in addition to the Google APIs Terms of Service ("API ToS"). If these terms are ever in conflict, these terms will take precedence over the API ToS. Please read these terms and the API ToS carefully.
  2. For purposes of these terms, "APIs" means Google's APIs, other developer services, and associated software, including any Redistributable Code.
  3. “Redistributable Code” means Google-provided object code or header files that call the APIs.
  4. Subject to these terms and the terms of the API ToS, you may copy and distribute Redistributable Code solely for inclusion as part of your API Client. Google and its licensors own all right, title and interest, including any and all intellectual property and other proprietary rights, in and to Redistributable Code. You will not modify, translate, or create derivative works of Redistributable Code.
  5. Google may make changes to these terms at any time with notice and the opportunity to decline further use of the Play Core Software Development Kit. Google will post notice of modifications to the terms at https://developer.android.com/guide/playcore/license. Changes will not be retroactive.
Download Play Core Native SDK

play-core-native-sdk-1.12.1.zip

  1. Do either of the following:

  2. Prepare Android Studio for native development by using the SDK Manager to install the latest CMake and Android Native Development Kit (NDK). For more information on creating or importing native projects, see Getting Started with the NDK.

  3. Download the zip file and extract it alongside your project.

    Download Link Size SHA-256 Checksum
    70.9 MiB 84c9e9579f05d6e29bbbd9c9cde2fde8210947f2007866b0045f4c40fabb7368

  4. Update your app’s build.gradle file as shown below:

    Groovy

        // App build.gradle

    plugins {
      id 'com.android.application'
    }

    // Define a path to the extracted Play Core SDK files.
    // If using a relative path, wrap it with file() since CMake requires absolute paths.
    def playcoreDir = file('../path/to/playcore-native-sdk')

    android {
        defaultConfig {
            ...
            externalNativeBuild {
                cmake {
                    // Define the PLAYCORE_LOCATION directive.
                    arguments "-DANDROID_STL=c++_static",
                              "-DPLAYCORE_LOCATION=$playcoreDir"
                }
            }
            ndk {
                // Skip deprecated ABIs. Only required when using NDK 16 or earlier.
                abiFilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64'
            }
        }
        buildTypes {
            release {
                // Include Play Core Library proguard config files to strip unused code while retaining the Java symbols needed for JNI.
                proguardFile '$playcoreDir/proguard/common.pgcfg'
                proguardFile '$playcoreDir/proguard/gms_task.pgcfg'
                proguardFile '$playcoreDir/proguard/per-feature-proguard-files'
                ...
            }
            debug {
                ...
            }
        }
        externalNativeBuild {
            cmake {
                path 'src/main/CMakeLists.txt'
            }
        }
    }

    dependencies {
        // Import these feature-specific AARs for each Google Play Core library.
        implementation 'com.google.android.play:app-update:2.0.0'
        implementation 'com.google.android.play:asset-delivery:2.0.0'
        implementation 'com.google.android.play:integrity:1.0.1'
        implementation 'com.google.android.play:review:2.0.0'

        // Import these common dependencies.
        implementation 'com.google.android.gms:play-services-tasks:18.0.2'
        implementation files("$playcoreDir/playcore-native-metadata.jar")
        ...
    }

    Kotlin

    // App build.gradle

plugins {
    id("com.android.application")
}

// Define a path to the extracted Play Core SDK files.
// If using a relative path, wrap it with file() since CMake requires absolute paths.
val playcoreDir = file("../path/to/playcore-native-sdk")

android {
    defaultConfig {
        ...
        externalNativeBuild {
            cmake {
                // Define the PLAYCORE_LOCATION directive.
                arguments += listOf("-DANDROID_STL=c++_static", "-DPLAYCORE_LOCATION=$playcoreDir")
            }
        }
        ndk {
            // Skip deprecated ABIs. Only required when using NDK 16 or earlier.
            abiFilters.clear()
            abiFilters += listOf("armeabi-v7a", "arm64-v8a", "x86", "x86_64")
        }
    }
    buildTypes {
        release {
            // Include Play Core Library proguard config files to strip unused code while retaining the Java symbols needed for JNI.
            proguardFile("$playcoreDir/proguard/common.pgcfg")
            proguardFile("$playcoreDir/proguard/gms_task.pgcfg")
            proguardFile("$playcoreDir/proguard/per-feature-proguard-files")
            ...
        }
        debug {
            ...
        }
    }
    externalNativeBuild {
        cmake {
            path = "src/main/CMakeLists.txt"
        }
    }
}

dependencies {
    // Import these feature-specific AARs for each Google Play Core library.
    implementation("com.google.android.play:app-update:2.0.0")
    implementation("com.google.android.play:asset-delivery:2.0.0")
    implementation("com.google.android.play:integrity:1.0.1")
    implementation("com.google.android.play:review:2.0.0")

    // Import these common dependencies.
    implementation("com.google.android.gms:play-services-tasks:18.0.2")
    implementation(files("$playcoreDir/playcore-native-metadata.jar"))
    ...
}

  5. Update your app’s CMakeLists.txt files as shown below:

    cmake_minimum_required(VERSION 3.6)

...

# Add a static library called “playcore” built with the c++_static STL.
include(${PLAYCORE_LOCATION}/playcore.cmake)
add_playcore_static_library()

// In this example “main” is your native code library, i.e. libmain.so.
add_library(main SHARED
        ...)

target_include_directories(main PRIVATE
        ${PLAYCORE_LOCATION}/include
        ...)

target_link_libraries(main
        android
        playcore
        ...)

Data Collection

The Play Core Native SDK may collect version related data to allow Google to improve the product, including:

  • App’s package name
  • App’s package version
  • Play Core Native SDK's version

This data will be collected when you upload your app package to the Play Console. To opt-out of this data collection process, remove the $playcoreDir/playcore-native-metadata.jar import in the build.gradle file.

Note, this data collection related to your use of the Play Core Native SDK and Google’s use of the collected data is separate and independent of Google’s collection of library dependencies declared in Gradle when you upload your app package to the Play Console.

Install-time delivery

Asset packs configured as install-time are immediately available at app launch. Use the NDK AAssetManager API to access assets served in this mode:

#include <android/asset_manager.h>
#include <android_native_app_glue.h>
...
AAssetManager* assetManager = app->activity->assetManager;
AAsset* asset = AAssetManager_open(assetManager, "asset-name", AASSET_MODE_BUFFER);
size_t assetLength = AAsset_getLength(asset);
char* buffer = (char*) malloc(assetLength + 1);
AAsset_read(asset, buffer, assetLength);

Fast-follow and on-demand delivery

The following sections show how to initialize the API, how to get information about asset packs before downloading them, how to call the API to start the download, and how to access the downloaded packs. These sections apply to fast-follow and on-demand asset packs.

App launch

Always call AssetPackManager_init() to initialize the asset pack API before calling any other function. Check for any asset pack error codes.

#include "play/asset_pack.h"
...
AssetPackErrorCode AssetPackManager_init(JavaVM* jvm, jobject android_context);

Also be sure to call the following functions in the onPause() and onResume() of ANativeActivityCallbacks:

Get download information about asset packs

Apps are required to disclose the size of the download before fetching the asset pack. Use the AssetPackManager_requestInfo() function to start an asynchronous request for the size of the download and whether the pack is already downloading. Then use AssetPackManager_getDownloadState() to poll for the download state (for example, call this function once per frame in your game loop). If a request fails, check the asset pack error codes.

AssetPackErrorCode AssetPackManager_requestInfo();      // Call once
AssetPackErrorCode AssetPackManager_getDownloadState(); // Call once per frame in your game loop

The AssetPackManager_getDownloadState() function returns the opaque type AssetPackDownloadState as an output pointer. Use this pointer to call the following functions:

AssetPackDownloadState* state;
AssetPackErrorCode error_code = AssetPackManager_getDownloadState(asset-pack-name, &state);
AssetPackDownloadStatus status = AssetPackDownloadState_getStatus(state);
uint64_t downloadedBytes = AssetPackDownloadState_getBytesDownloaded(state);
uint64_t totalBytes = AssetPackDownloadState_getTotalBytesToDownload(state));
AssetPackDownloadState_destroy(state);

Install

Use AssetPackManager_requestDownload() to start downloading an asset pack for the first time or to request for an asset pack update to complete:

AssetPackErrorCode AssetPackManager_requestDownload();  // Call once
AssetPackErrorCode AssetPackManager_getDownloadState(); // Call once per frame in your game loop

The AssetPackManager_getDownloadState() function returns the opaque type AssetPackDownloadState. For information on how to use this type, see Get download information.

Large downloads

If the download is larger than 150MB and the user is not on Wi-Fi, the download does not start until the user explicitly gives their consent to proceed with the download using a mobile data connection. Similarly, if the download is large and the user loses Wi-Fi, the download pauses and explicit consent is required to proceed using a mobile data connection. A paused pack has state WAITING_FOR_WIFI. To trigger the UI flow to prompt the user for consent, use the following:

Access asset packs

You can access an asset pack using file system calls after the download request reaches the COMPLETED state. Each asset pack is stored in a separate directory in the app's internal storage. Use AssetPackManager_getAssetPackLocation() to get an AssetPackLocation for the specified asset pack. Use AssetPackLocation_getStorageMethod() on that location to determine the storage method:

  • ASSET_PACK_STORAGE_APK: The asset pack is installed as an APK. See Install-time delivery to access these assets.
  • ASSET_PACK_STORAGE_FILES: Use AssetPackLocation_getAssetsPath() to get a file path to the directory containing the assets, or null if the assets have not been downloaded. Do not modify downloaded files in this file path.
AssetPackLocation* location;

AssetPackErrorCode error_code = AssetPackManager_getAssetPackLocation(asset-pack-name, &location);

if (error_code == ASSET_PACK_NO_ERROR) {
    AssetPackStorageMethod storage_method = AssetPackLocation_getStorageMethod(location);
    const char* assets_path = AssetPackLocation_getAssetsPath(location);
    AssetPackLocation_destroy(location);
}

Once you locate the assets, use functions like fopen or ifstream to access the files.

Other Play Core API methods

The following are some additional API methods you may want to use in your app.

Cancel request

Use AssetPackManager_cancelDownload() to cancel an active asset pack request. Note that this request is a best-effort operation.

Request removal

Use AssetPackManager_requestRemoval() to schedule the removal of an asset pack.

Next step

Test Play Asset Delivery locally and from Google Play.