Google Play Instant (#52)

* Google Play Instant - init commit

* Fixed grammar mistakes. The repository has moved to Defold account.

* Information about testing

* update manual

* rename manual

docs/en/en.json

@@ -630,6 +630,10 @@
                         "path": "/extension-gpgs",
                         "name": "Google Play Game Services"
                     },
+                    {
+                        "path": "/manuals/extension-google-play-instant",
+                        "name": "Google Play Instant"
+                    },
                     {
                         "path": "/extension-iap",
                         "name": "In-app purchases"

docs/en/manuals/extension-google-play-instant.md

@@ -0,0 +1,128 @@
+---
+title: Google Play Instant
+brief: This manual explains how to create Google Play Instant game with Defold.
+---
+
+# Google Play Instant
+
+Google Play Instant enables native games to launch on devices running Android 6.0+ without being installed.
+
+
+![GooglePlayInstant](images/gpi/gpi-try-now.png)
+
+## Publishing process
+
+To be able to publish your game as Google Play Instant app you need to set up your project properly:
+
+1. Create custom `AndroidManifest.xml` file and add the following attributes to the `<manifest>` element:
+
+```lua
+xmlns:dist="http://schemas.android.com/apk/distribution"
+android:targetSandboxVersion="2"
+```
+The following declaration need to be added right after manifest element:
+```lua
+<dist:module dist:instant="true" />
+```
+
+This is what it would look like with the default AndroidManifest.xml:
+
+```lua
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+        package="{{android.package}}"
+        android:versionCode="{{android.version_code}}"
+        android:versionName="{{project.version}}"
+        android:installLocation="auto"
+        xmlns:dist="http://schemas.android.com/apk/distribution"
+        android:targetSandboxVersion="2">
+      <dist:module dist:instant="true" />
+```
+
+2. Add a dependency to the Google Instant Apps extension in your “game.project” file. Add “https://github.com/defold/extension-instantapp/archive/master.zip” or point to the ZIP file of a [specific release](https://github.com/defold/extension-instantapp/releases) to the Dependencies property.
+
+![Project settings](images/gpi/game_project.png)
+
+3. Download libraries: Project->Fetch Libraries
+4. Bundle `aab` Project->Bundle->Android Application
+5. Upload your `aab` in Google Play Console as Android Instant App
+
+### Version codes
+Pay attention to [the recommendations about the version codes](https://developer.android.com/topic/google-play-instant/getting-started/game-instant-app#version-codes): Instant Game version code needs to be less than the version code of the installable game.
+
+![Project settings](images/gpi/version_code.png)
+
+### android:targetSandboxVersion="2"
+
+If you set `android:targetSandboxVersion="2"` in the main installable game you will be able to access the same files as instant game (a save file for example). But then you would have restrictions in the main application. More information in [the official documentation](https://developer.android.com/guide/topics/manifest/manifest-element#targetSandboxVersion).
+::: sidenote
+Once an app is installed, you can only update its target sandbox value to a higher value. To downgrade the target sandbox value, you must uninstall the app and replace it with a version whose manifest contains a lower value for this attribute.
+:::
+Even if you set different `android:targetSandboxVersion` in the installable game and instant game you are still able to use `instantapp.set_cookie()` and `instantapp.get_cookie()` for communication between the game versions.
+
+## API Usage
+
+The Google Play Instant extension is accessible through the `instantapp.*` namespace where it wraps Java [PackageManagerCompat methods](https://developers.google.com/android/reference/com/google/android/gms/instantapps/PackageManagerCompat) in a Lua API.
+
+If you are working on a cross-platform application the best practice is to check the existence of `instantapp` module since this module exists only in android bundle:
+```lua
+if instantapp then
+  -- call instantapp methods
+end
+```
+For example:
+
+```lua
+if instantapp and instantapp.is_instant_app() then
+  -- if this is instant app save data for the main app and show install prompt
+  local cookie_size = instantapp.get_cookie_max_size()
+  if cookie_size > 0 then
+    instantapp.set_cookie(bytes_of_save_data)
+  end
+  instantapp.show_install_prompt()
+else
+  -- regular app logic
+end
+```
+
+Refer to the extension [API documentation](https://github.com/defold/extension-instantapp/blob/master/README.md) for details on how to use the Google Instant API in Defold.
+
+## Technical Requirements
+According to the [Google Play Instant Technical Requirements](https://developer.android.com/topic/google-play-instant/game-tech-requirements) `apk` size must be less than or equal to 15 MB. Information about application size optimisation available [here](extension-fbinstant/#reducing-bundle-size).
+
+## Testing
+![Testing Instant game](images/gpi/start_instant.png)
+
+1. Download Android SDK tools:
+- macOS: https://dl.google.com/android/repository/tools_r25.2.3-macosx.zip
+- Windows: https://dl.google.com/android/repository/tools_r25.2.3-windows.zip
+- Linux: https://dl.google.com/android/repository/tools_r25.2.3-linux.zip
+2. Unpack and copy the `tools` folder into `android-sdk` folder.
+3. Install build tools:
+```console
+./android-sdk/tools/bin/sdkmanager --verbose “build-tools;25.0.3”
+```
+4. Install `extra-google-instantapps` tools:
+```console
+sh ./android-sdk/tools/android update sdk --no-ui --all --filter extra-google-instantapps
+```
+5. Launch `apk` as Instant game on your device:
+```console
+android-sdk/extras/google/instantapps/ia run path_to_your_game.apk
+```
+
+It's also possible to use this script for preparation instead of p.1-p.4:
+```console
+mkdir ~/android
+cd ~/android
+mkdir android-sdk
+# Supported: macosx,linux,windows
+PLATFORM=macosx
+TOOL_VERSION=25.2.3
+wget https://dl.google.com/android/repository/tools_r$TOOL_VERSION-$PLATFORM.zip
+tar xvf tools_r$TOOL_VERSION-$PLATFORM.zip
+mv tools android-sdk/tools
+./android-sdk/tools/bin/sdkmanager --verbose "build-tools;25.0.3"
+sh ./android-sdk/tools/android update sdk --no-ui --all --filter extra-google-instantapps
+```
+
+More information about debugging on mobile devices available in the [Debugging manual](/manuals/debugging/#_debugging_on_mobile_devices).