Detailed explanation of shuttle unity interworking principle

The whole idea

This article mainly introduces a flutter-unity Principle of open source framework for interoperability , Address github, The use process is very clear in the warehouse , We mainly look at how to make a unity The scene is displayed quickly and excellently in flutter Developed app in .

ok, First, let's talk about the overall design idea .
From the result theory, we can deduce , We are going to put a unity The scene is transformed into a flutter Of widget, Want to get a flutter Of widget, The best solution is naturally to create a native native Level of view perhaps UIView Convert to flutter Of widget. So we're going to put native Level of unityPlayerActivity perhaps viewController Convert to native Layer of view perhaps UIView. and unityPlayerActivity and viewController By unity In Engineering export Android and export iOS Export the corresponding generated . Here is a difficulty in how we put the original unity There are only export android apk and export ios bundle Two button options , Normal to be flutter Words used , You have to turn it into module Or a pod library .

This is the whole idea , It's simple , In order to figure out how to realize the difficulties , Let's sort it out first unity pack Android and iOS Structure .

tips： This article untiy Version is 2019.4.3f1, It is recommended to use this version ,2020 I've tried this version. There will be various packaging problems .
The principle is mainly explained here Android 了 ,iOS The basic process is similar .

unity pack

We directly build Out android apk Then decompile to see the structure , Attach the figure of some key points .

This is decompilation apk The directory structure ,assets The lower level corresponds to the scene unity resources , It contains unity Most resources in the scene will be integrated data.unity3d Binary ,lib What's going down is unity dependent so file . It is obvious that we will take module We all need these documents for formal quotation , Let's see AndroidManifest.xml in , Obviously a normal one unity Of the scene apk load unity The scene is here UnityPlayerActivity in , Let's see UnityPlayerActivity.smali Code for


Here we can see , It is equivalent to creating a new UnityPlayer object , And then directly setContentView Went in. , So it's very simple , We can take this UnityPlayer Understand as a view 了 .

unity The scene is flutter Medium display principle

export

First step , We need to solve how to unity export apk convert to android module The problem of .
Look up unity Official documents we found , pack api by BuildPipeline.BuildPlayer(), See documentation unity documentation.unity Support custom adding projects menu item, stay Build.cs Add logic to the file .
Here we can actually do such operations , Type it out apk Next assets In the catalog unity Related resource files ,AndroidManifest.xml,build.gradle Wait for the file to be copied to a module Under the table of contents , Then modify it in the file , For example build.gradle Under the com.android.application Change to com.android.library Change its declaration to a library module Wait for the operation . It can be understood as directly modifying a file form with code phone module Change to library module. And in android native layer settings.gradle This is in the document library module Quote in , These are all android Basic knowledge of .

The code is as follows ：

Pay attention here , In consideration of generality , So that it can be modified directly through the relative path , Need to put unity Move the project to your flutter Under the project of unity Under the table of contents .

ok, After this step, we can play a game like this module 了 .

thus android native The work of the layer is done , This part of the work is mainly cumbersome , The logic is clear .

flutter module

native After the work of layer is completed, we will build a flutter plugin, to flutter project Used .

First realize registerWith Method , Code is located FlutterUnityWidgetPlugin.kt in , Here to LifecycleOwner Made special treatment and judgment , Yes LifecycleOwner Unfamiliar students can watch here .

The next step is to create FlutterUnityWidgetFactory Integrate PlatformViewFactory, To achieve its create Method to create UnityView.

Let's turn to FlutterUnityWidgetController.kt, It inherited the PlatformView.

Here we create and load our UnityView. Here we should pay attention to the need to introduce unity-class.jar, Otherwise flutter It is not available in the project , The principle here and native Layer de loading UnityPlayerActivity Empathy .
Here we also need to pay attention to onMethodCall Method

Respectively in UnityPlayerUtils Class implements several related lifecycle methods for flutter call .
Next we just have to flutter plugin Layer to create corresponding UnityWidget That's it . Code in unity_view.dart in .

data communication

Data communication , We can see mainly through native turnover ,flutter and native Communication between ,native And again unity To communicate

ok, Basically, the principle is like this .