UniRx 基于Unity的响应式编程框架

什么是UniRx?


UniRx(Unity的响应式编程框架)是.Net响应式编程框架的重新实现版本。官方的Rx的实现方式是非常棒的。但是,在Unity中使用会有一些问题;在IOS的IL2CPP中有兼容性的问题。UniRx修复这些问题,并针对Unity添加了一些特别的工具。支持的平台包括PC/Mac/Android/iOS/WebGL/WindowsStore/等等。

UniRx可在Asset Store(免费)中下载: http://u3d.as/content/neuecc/uni-rx-reactive-extensions-for-unity/7tT

博客信息更新:https://medium.com/@neuecc

Unity Forums 在线支持,有问题随时向我提问:http://forum.unity3d.com/threads/248535-UniRx-Reactive-Extensions-for-Unity

发现说明: UniRx/releases

UniRx 作为核心库+平台适配器(MainThreadScheduler/FromCoroutinue/etf)+框架(ObservableTriggers/ReactiveProperty/etc)

注意:async/await 集成(UniRx.Async)被分离到Cysharp/UniTask 7.0之后的版本

为什么使用Rx?


通常,在Unity对网络操作要求使用WWW和Coroutine.但是出于以下几点原因(或者其它原因)使用协程来进行异步操作并不顺手:

1.虽然协程的返回类型必须是IEnumerator,但是协程不能返回任何值。
2.因为yield return 语句不能被try-catch结构体包裹,协程中不能处理异常。

这种缺乏可组合性导致程序的紧耦合,往往造成IEnumators中逻辑过于复杂。

Rx可以解决异步调用的“伤痛”,Rx 是一个使用可观察集合和LINQ风格查询运算符组合成的基于异步和基于事件的可编程库。

游戏循环(every Update,OnCollisionEnter),传感器数据(Kinect,Leap Motion,VR Input 等等)这些类型的事件。Rx将事件表示为响应式序列。通过使用LINQ查询运算符,Rx变得容易组合且支持基于时间的操作。

Unity通常是单线程的,但是UniRx促进了多线程joins、cancel 访问GameObject,等等。

UniRx为UGUI提供了UI编程。所有的UI事件(clicked,valuechanged,等)均可以被转化为UniRx的事件流。

Unity 在2017之后支持C# 中的astnc/await。UniRx 为Unity提供了更轻量、强大的async/await集成。请看: Cysharp/UniTask.

介绍


非常棒的介绍Rx的文章:The introduction to Reactive Programming you’ve been missing.

以下代码使用UniRx实现了文章中的双击检测事例:

var clickStream=Observable.EveryUpdate()
.Where(_=>Input.GetMouseButtonDown(0));

clickStream.Buffer(clickStream.Throttle(TimeSpan.FromMilliseconds(250)))
    .Where(xs => xs.Count >= 2)
    .Subscribe(xs => Debug.Log("DoubleClick Detected! Count:" + xs.Count));

本事例演示了以下功能(仅仅使用5行代码):

  • 游戏循环(Update)作为事件流
  • 可组合事件流
  • 合并自身流
  • 易于处理基于时间的操作

网络操作


使用ObservableWWW 进行一步网络操作。它的Get/Post函数返回可订阅的IObservables.

ObservableWWW.Get("http://google.co.jp/")
.Subscribe(
    x=Debug.Log(x.Substring(0,100)),
    ex=Debug.LogExecption(ex)
);

Rx是可组合也是可以取消的,你可以使用LINQ 查询表达式:

var query=from google in ObservableWWW.Get("http://google.com/")
          from bing in ObservableWWW.Get("http://bing.com/")
          from unknow in ObservableWWW(goole+bing)
          select new {google,bing,unknow};
var cancel=query.Subscribe(x=>Debug.Log(x));

cancel.Dispose();

使用Observable.WhenAll 执行并行请求(parallel):

var parallel=Observable.WhenAll(
    ObservableWWW.Get("http://google.com/"),
    ObservableWWW.Get("http://bing.com/"),
    ObservableWWW.Get("http://unity3d.com/")
);
parallel.Subscribe(xs=>{
    Debug.Log(xs[0].Substring(0,100));// google
    Debug.Log(xs[1].Substring(0,100));// bing
    Debug.Log(xs[2].Substring(0,100));// unity
});

提供进度信息:

// notifier for progress use ScheduledNotifier or new Progress<float>(/* action */)
var progressNotifier=new ScheduledNotifier<float>();
// pass notifier to WWW.Get/Post
progressNotifier.Subscribe(x=>Debug.Log(x));

错误处理:

// If WWW has .error, ObservableWWW throws WWWErrorException to onError pipeline.
// WWWErrorException has RawErrorMessage, HasResponse, StatusCode, ResponseHeaders
ObservableWWW.Get("http://www.google.com/404")
    .CatchIgnore((WWWErrorException ex) =>
    {
        Debug.Log(ex.RawErrorMessage);
        if (ex.HasResponse)
        {
            Debug.Log(ex.StatusCode);
        }
        foreach (var item in ex.ResponseHeaders)
        {
            Debug.Log(item.Key + ":" + item.Value);
        }
    })
    .Subscribe();

使用IEnumators (Coroutines)


IEnumator(Coroutine)是Unity的基本异步工具,UniRx集成了协程和IObservables,你可以在协程中写异步代码,并使用UniRx编排他们。这是控制异步流最好的方式。

// two coroutines
IEnumerator AsyncA()
{
    Debug.Log("a start");
    yield return new WaitForSeconds(1);
    Debug.Log("a end");
}

IEnumerator AsyncB()
{
    Debug.Log("b start");
    yield return new WaitForEndOfFrame();
    Debug.Log("b end");
}
// main code
// Observable.FromCoroutine converts IEnumerator to Observable<Unit>.
// You can also use the shorthand, AsyncA().ToObservable()
        
// after AsyncA completes, run AsyncB as a continuous routine.
// UniRx expands SelectMany(IEnumerator) as SelectMany(IEnumerator.ToObservable())
var cancel = Observable.FromCoroutine(AsyncA)
    .SelectMany(AsyncB)
    .Subscribe();

// you can stop a coroutine by calling your subscription's Dispose.
cancel.Dispose();

在Unity5.3中,你可以使用ToYieldInstruction将Observable转化为Coroutine:

IEnumerator TestNewCustomYieldInstruction()
{
    // wait Rx Observable.
    yield return Observable.Timer(TimeSpan.FromSeconds(1)).ToYieldInstruction();

    // you can change the scheduler(this is ignore Time.scale)
    yield return Observable.Timer(TimeSpan.FromSeconds(1), Scheduler.MainThreadIgnoreTimeScale).ToYieldInstruction();

    // get return value from ObservableYieldInstruction
    var o = ObservableWWW.Get("http://unity3d.com/").ToYieldInstruction(throwOnError: false);
    yield return o;

    if (o.HasError) { Debug.Log(o.Error.ToString()); }
    if (o.HasResult) { Debug.Log(o.Result); }

    // other sample(wait until transform.position.y >= 100) 
    yield return this.transform.ObserveEveryValueChanged(x => x.position).FirstOrDefault(p => p.y >= 100).ToYieldInstruction();
}

通常情况下,当我们想要协程返回一个值时,我们必须使用回调。Observable.FromCoroutine 可以将协程转化为可取消的IObservable[T]。

public static IObservable<string> GetWWW(string url)
{
    // convert coroutine to IObservable
    return Observable.FromCoroutine<string>((observer, cancellationToken) => GetWWWCore(url, observer, cancellationToken));
}

// IObserver is a callback publisher
// Note: IObserver's basic scheme is "OnNext* (OnError | Oncompleted)?" 
static IEnumerator GetWWWCore(string url, IObserver<string> observer, CancellationToken cancellationToken)
{
    var www = new UnityEngine.WWW(url);
    while (!www.isDone && !cancellationToken.IsCancellationRequested)
    {
        yield return null;
    }

    if (cancellationToken.IsCancellationRequested) yield break;

    if (www.error != null)
    {
        observer.OnError(new Exception(www.error));
    }
    else
    {
        observer.OnNext(www.text);
        observer.OnCompleted(); // IObserver needs OnCompleted after OnNext!
    }
}

这还有更多的示例,下方展示多个OnNext的形式:

public static IObservable<float> ToObservable(this UnityEngine.AsyncOperation asyncOperation)
{
    if (asyncOperation == null) throw new ArgumentNullException("asyncOperation");

    return Observable.FromCoroutine<float>((observer, cancellationToken) => RunAsyncOperation(asyncOperation, observer, cancellationToken));
}

static IEnumerator RunAsyncOperation(UnityEngine.AsyncOperation asyncOperation, IObserver<float> observer, CancellationToken cancellationToken)
{
    while (!asyncOperation.isDone && !cancellationToken.IsCancellationRequested)
    {
        observer.OnNext(asyncOperation.progress);
        yield return null;
    }
    if (!cancellationToken.IsCancellationRequested)
    {
        observer.OnNext(asyncOperation.progress); // push 100%
        observer.OnCompleted();
    }
}

// usecase
Application.LoadLevelAsync("testscene")
    .ToObservable()
    .Do(x => Debug.Log(x)) // output progress
    .Last() // last sequence is load completed
    .Subscribe();

多线程的使用


// Observable.Start is start factory methods on specified scheduler
// default is on ThreadPool
var heavyMethod = Observable.Start(() =>
{
    // heavy method...
    System.Threading.Thread.Sleep(TimeSpan.FromSeconds(1));
    return 10;
});

var heavyMethod2 = Observable.Start(() =>
{
    // heavy method...
    System.Threading.Thread.Sleep(TimeSpan.FromSeconds(3));
    return 10;
});

// Join and await two other thread values
Observable.WhenAll(heavyMethod, heavyMethod2)
    .ObserveOnMainThread() // return to main thread
    .Subscribe(xs =>
    {
        // Unity can't touch GameObject from other thread
        // but use ObserveOnMainThread, you can touch GameObject naturally.
        (GameObject.Find("myGuiText")).guiText.text = xs[0] + ":" + xs[1];
    }); 

DefaultScheduler(默认调度器)


UniRx默认是基于时间操作的(Interval、Timer、Buffer(timeSpan)等等),使用Scheduler.MainThread作为它们的调度器。UniRx中的大多数运算符(Observable.Start除外)都是在单个线程上执行的;因此不需要ObserverOn,并且可以忽略线程安全问题。虽然和标准 .NET 中的Rx实现不同,但是这更符合Unity的环境。
Scheduler.Mainthread的执行受Time.timeScale的影响,如果你想要在执行时忽略TimeScale,你可以使用Scheduler.MainThreadIgnoreTimeScale代替。

MonoBehaviour triggers


UniRx使用UniRx.Triggers处理MonoBehaviour事件:

using UniRx;
using UniRx.Triggers; // need UniRx.Triggers namespace

public class MyComponent : MonoBehaviour
{
    void Start()
    {
        // Get the plain object
        var cube = GameObject.CreatePrimitive(PrimitiveType.Cube);

        // Add ObservableXxxTrigger for handle MonoBehaviour's event as Observable
        cube.AddComponent<ObservableUpdateTrigger>()
            .UpdateAsObservable()
            .SampleFrame(30)
            .Subscribe(x => Debug.Log("cube"), () => Debug.Log("destroy"));

        // destroy after 3 second:)
        GameObject.Destroy(cube, 3f);
    }
}

支持的triggers如列表所示:UniRx.wiki#UniRx.Triggers

通过直接订阅Component/GameObject上的扩展方法返回的Observables(可观察对象),可以更轻松的处理事件,这些方法被自动注入到ObservableTrigger中(除了ObservableEventTrigger和ObservableStateMachineTrigger):

using UniRx;
using UniRx.Triggers;
public class DragAndDropOnce:MonoBehaviour{
    void Start(){
        this.OnMouseDownAsObservable()
        .SelectMany(_=>this.UpdateAsObservable())
        .TakeUntil(this.OnMouseUpAsObservable())
        .Select(_=>Input.mousePosition)
        .Subscribe(x=>Debug.Log(x));
    }
}

之前版本中UniRx提供了ObservableMonoBehaiour.新版本中以不再对其提供支持,请使用UniRx.Triggers代替。

创建自定义Triggers

将Unity事件转化为Observable(可观察对象)是处理Unity事件最好的方式。如果UniRx提供的标准的triggers不够使用的话,你可以自定义triggers.为了演示,下方提供了一个基于UGUI的LongTap(长按)触发演示:

public class ObservableLongPointerDownTrigger : ObservableTriggerBase, IPointerDownHandler, IPointerUpHandler{
    public float IntervalSecond=1f;
    Subject<Unit> onLongPointerDown;
    float> raiseTime;

    void Update(){
        if (raiseTime!=null&&raiseTime<=Time.realtimeSinceStartup){
            if (onLongPointerDown!=null)onLongPointerDown.OnNext(Unit.Default);
            raiseTime=null;
        }
    }
     void IPointerDownHandler.OnPointerDown(PointerEventData eventData)
    {
        raiseTime = Time.realtimeSinceStartup + IntervalSecond;
    }
    void IPointerUpHandler.OnPointerUp(PointerEventData eventData)
    {
        raiseTime = null;
    }
    public IObservable<Unit> OnLongPointerDownAsObservable()
    {
        return onLongPointerDown ?? (onLongPointerDown = new Subject<Unit>());
    }
    protected override void RaiseOnCompletedOnDestroy()
    {
        if (onLongPointerDown != null)
        {
            onLongPointerDown.OnCompleted();
        }
    }
}

它的使用像标准triggers一样简单:

var trigger = button.AddComponent<ObservableLongPointerDownTrigger>();
trigger.OnLongPointerDownAsObservable().Subscribe();

Observable 生命周期管理


什么时候调用OnCompleted? 使用UniRx时,必须考虑订阅的生命周期管理。当与GameObject对象相连的游戏对象被销毁时,ObservableTriggers会调用OnCompleted.其它的静态生成器方法(Observable.Timer、Observable.EveryUpdate…等等,并不会自动停止,他们的订阅需要被手动管理。

Rx提供了一些辅助方法,比如,IDisposable.AddTo运行你一次释放多个订阅:

// CompositeDisposable is similar with List<IDisposable>, manage multiple IDisposable
CompositeDisposable disposables = new CompositeDisposable(); // field

void Start()
{
    Observable.EveryUpdate().Subscribe(x => Debug.Log(x)).AddTo(disposables);
}
void OnTriggerEnter(Collider other)
{
    // .Clear() => Dispose is called for all inner disposables, and the list is cleared.
    // .Dispose() => Dispose is called for all inner disposables, and Dispose is called immediately after additional Adds.
    disposables.Clear();
}

如果你想在GameObject被销毁时自动释放,你可以使用AddTo(GameObject/Component):

void Start(){
    Observable.IntervalFrame(30).Subscribe(x=Debug.Log(x)).AddTo(this);
}

AddTo可以促进流的自动释放,如果你需要在管道中队OnCompleted进行特殊处理,那么你可以使用TakeWhile、TakeUntil、TakeUntilDestroy和TakeUntilDisable代替:

Observable.IntervalFrame(30).TakeUntilDisable(this)
    .Subscribe(x => Debug.Log(x), () => Debug.Log("completed!"));

当你处理事件时,Repeat是一种重要但危险的方法,它可能会造成程序的无线循环,因此,请谨慎使用它:

using UniRx;
using UniRx.Triggers;
public class DangerousDragAndDrop:MonoBehaviour{
    void Start(){
        this.gameObject.OnMouseDownAsObservable()
        .SelectMany(_=>this.gameObject.UpdateAsObservable())
        .TakeUtil(this.gameObject.OnMouseUpAsObservable())
        .Select(_=>Input.mousePosition)
        .Repeat()
        .Subscribe(x=>Debug.Log(x));
    }
}

UniRx另外提供了一种安全使用Repeat的方法。RepeatSafe:
如果重复调用OnComplete,Repeat将会停止。RepeatUntilDestroy(gameObject/component), RepeatUntilDisable(gameObject/component)允许在目标对象被销毁时停止。

this.gameObject.OnMouseDownAsObservable()
    .SelectMany(_ => this.gameObject.UpdateAsObservable())
    .TakeUntil(this.gameObject.OnMouseUpAsObservable())
    .Select(_ => Input.mousePosition)
    .RepeatUntilDestroy(this) // safety way
    .Subscribe(x => Debug.Log(x));  

UniRx确保hot Observable(FromEvent/Subject/ReactiveProperty/UnityUI.AsObservable…, 类似事件)可以持续的处理异常。什么意思?如果在Subscribe中订阅,这不分离事件。

button.OnClickAsObservable().Subscribe(_ =>
{
    // If throws error in inner subscribe, but doesn't detached OnClick event.
    ObservableWWW.Get("htttp://error/").Subscribe(x =>
    {
        Debug.Log(x);
    });
});

这种行为有时很有用,比如用户事件的处理。

每一个类的实例都提供了一个ObserveEveryValueChanged的方法。这个方法可以每一帧检测某个值发生的变化:

// watch position change
this.transform.ObserveEveryValueChanged(x => x.position).Subscribe(x => Debug.Log(x));

这是非常有用的,如果观察的目标是一个GameObject;当GameObject被销毁时,订阅将自动停止并调用OnCompleted.如果观察的对象是一个原生的C#对象,OnCompleted将在GC时被调用。

将Unity回调转化为IObservables(可观察对象)


使用Subject(或者AsyncSubject进行异步操作):

public class LogCallback
{
    public string Condition;
    public string StackTrace;
    public UnityEngine.LogType LogType;
}

public static class LogHelper
{
    static Subject<LogCallback> subject;

    public static IObservable<LogCallback> LogCallbackAsObservable()
    {
        if (subject == null)
        {
            subject = new Subject<LogCallback>();

            // Publish to Subject in callback
            UnityEngine.Application.RegisterLogCallback((condition, stackTrace, type) =>
            {
                subject.OnNext(new LogCallback { Condition = condition, StackTrace = stackTrace, LogType = type });
            });
        }

        return subject.AsObservable();
    }
}

// method is separatable and composable
LogHelper.LogCallbackAsObservable()
    .Where(x => x.LogType == LogType.Warning)
    .Subscribe();

LogHelper.LogCallbackAsObservable()
    .Where(x => x.LogType == LogType.Error)
    .Subscribe();

Unity5中,Application.RegisterLogCallback被移除了,转而提供Application.logMessageReceived的支持,因此,我们现在可以简单的使用Observable.FromEvent.

public static IObservable<LogCallback> LogCallbackAsObservable()
{
    return Observable.FromEvent<Application.LogCallback, LogCallback>(
        h => (condition, stackTrace, type) => h(new LogCallback { Condition = condition, StackTrace = stackTrace, LogType = type }),
        h => Application.logMessageReceived += h, h => Application.logMessageReceived -= h);
}

Stream Logger


// using UniRx.Diagnostics;

// logger is threadsafe, define per class with name.
static readonly Logger logger = new Logger("Sample11");

// call once at applicationinit
public static void ApplicationInitialize()
{
    // Log as Stream, UniRx.Diagnostics.ObservableLogger.Listener is IObservable<LogEntry>
    // You can subscribe and output to any place.
    ObservableLogger.Listener.LogToUnityDebug();

    // for example, filter only Exception and upload to web.
    // (make custom sink(IObserver<EventEntry>) is better to use)
    ObservableLogger.Listener
        .Where(x => x.LogType == LogType.Exception)
        .Subscribe(x =>
        {
            // ObservableWWW.Post("", null).Subscribe();
        });
}

// Debug is write only DebugBuild.
logger.Debug("Debug Message");

// or other logging methods
logger.Log("Message");
logger.Exception(new Exception("test exception"));

Debugging


UniRx.Diagnostics命名空间下的Debug运算符便于用于调试。

// needs Diagnostics using
using UniRx.Diagnostics;

---

// [DebugDump, Normal]OnSubscribe
// [DebugDump, Normal]OnNext(1)
// [DebugDump, Normal]OnNext(10)
// [DebugDump, Normal]OnCompleted()
{
    var subject = new Subject<int>();

    subject.Debug("DebugDump, Normal").Subscribe();

    subject.OnNext(1);
    subject.OnNext(10);
    subject.OnCompleted();
}

// [DebugDump, Cancel]OnSubscribe
// [DebugDump, Cancel]OnNext(1)
// [DebugDump, Cancel]OnCancel
{
    var subject = new Subject<int>();

    var d = subject.Debug("DebugDump, Cancel").Subscribe();

    subject.OnNext(1);
    d.Dispose();
}

// [DebugDump, Error]OnSubscribe
// [DebugDump, Error]OnNext(1)
// [DebugDump, Error]OnError(System.Exception)
{
    var subject = new Subject<int>();

    subject.Debug("DebugDump, Error").Subscribe();

    subject.OnNext(1);
    subject.OnError(new Exception());
}

在在OnNext,OnError,OnCompleted,OnCancel,OnSubscribe时序上显示序列元素以进行Debug.Log,仅当#if DEBUG时才被启用。

Unity-specific Extra Gems

// Unity's singleton UiThread Queue Scheduler
Scheduler.MainThreadScheduler 
ObserveOnMainThread()/SubscribeOnMainThread()

// Global StartCoroutine runner
MainThreadDispatcher.StartCoroutine(enumerator)

// convert Coroutine to IObservable
Observable.FromCoroutine((observer, token) => enumerator(observer, token)); 

// convert IObservable to Coroutine
yield return Observable.Range(1, 10).ToYieldInstruction(); // after Unity 5.3, before can use StartAsCoroutine()

// Lifetime hooks
Observable.EveryApplicationPause();
Observable.EveryApplicationFocus();
Observable.OnceApplicationQuit();

FrameCount-based timeoperators


UniRx 提供了一些继续帧数的时间运算符

Method
EveryUpdate
EevryFixedUpdate
EveryEndOfFrame
EveryGameObjectUpdate
EveryLateUpdate
ObserveOnMainThread
NextFrame
IntervalFrame
TimerFrame
DelayFrame
SampleFrame
ThrottleFrame
ThrottleFirstFrame
TimeoutFrame
DelayFrameSubscription
FrameInterval
FrameTimeInterval
BatchFrame

例如,一次延时调用:

Observable.TimerFrame(100).Subscribe(_ => Debug.Log("after 100 frame"));

Every* 方法的执行顺序如下:

EveryGameObjectUpdate(in MainThreadDispatcher's Execution Order) ->
EveryUpdate -> 
EveryLateUpdate -> 
EveryEndOfFrame

如果在MainThreadDispatcher之前调用了调用者,则从同一帧调用EveryGameObjectUpdate.(我建议对MainThreadDispatcher的调用在同一帧中优先于EveryLateUpdate、EveryEndOfFrame),EveryUpdate在下一帧中调用。

MicroCoroutine(微协程)

微协程的优点在于内存高效和执行快速。它的实现是基于Unity blog’s 10000 UPDATE() CALLS,避免了托管内存-非托管内存的开销,以致迭代速度提升了10倍。微协程自动用于基于帧数的时间运算符和ObserveEveryValueChanged.

如果你想使用微协程替代Unity自带的协程(Coroutine),使用MainThreadDispatcher.StartUpdateMicroCoroutine 或者Observable.FromMicroCoroutine.

int counter;

IEnumerator Worker()
{
    while(true)
    {
        counter++;
        yield return null;
    }
}

void Start()
{
    for(var i = 0; i < 10000; i++)
    {
        // fast, memory efficient
        MainThreadDispatcher.StartUpdateMicroCoroutine(Worker());

        // slow...
        // StartCoroutine(Worker());
    }
}

Unity Coroutine

当然微协程存在一些限制,经支持yield return null 迭代,并且其更新时间取决于启动微协程的方法(StartUpdateMicroCoroutine,StartFixedUpdateMicroCoroutine,StartEndOfFrameMicroCoroutine)。

如果和其它IObservable结合起来,你可以检测已完成的属性,比如:isDone.

IEnumerator MicroCoroutineWithToYieldInstruction()
{
    var www = ObservableWWW.Get("http://aaa").ToYieldInstruction();
    while (!www.IsDone)
    {
        yield return null;
    }

    if (www.HasResult)
    {
        UnityEngine.Debug.Log(www.Result);
    }
}

UGUI 集成


UniRx可以很容易的处理UnityEvent,使用UnityEvent.AsObservable 订阅事件:

public Button MyButton;
// ---
MyButton.onClick.AsObservable().Subscribe(_ => Debug.Log("clicked"));

将事件视为可观察对象可启用声明式UI编程。

public Toggle MyToggle;
public InputField MyInput;
public Text MyText;
public Slider MySlider;

// On Start, you can write reactive rules for declaretive/reactive ui programming
void Start()
{
    // Toggle, Input etc as Observable (OnValueChangedAsObservable is a helper providing isOn value on subscribe)
    // SubscribeToInteractable is an Extension Method, same as .interactable = x)
    MyToggle.OnValueChangedAsObservable().SubscribeToInteractable(MyButton);
    
    // Input is displayed after a 1 second delay
    MyInput.OnValueChangedAsObservable()
        .Where(x => x != null)
        .Delay(TimeSpan.FromSeconds(1))
        .SubscribeToText(MyText); // SubscribeToText is helper for subscribe to text
    
    // Converting for human readability
    MySlider.OnValueChangedAsObservable()
        .SubscribeToText(MyText, x => Math.Round(x, 2).ToString());
}

更多响应式UI编程,请参考Sample12,Sample13和下面的ReactiveProperty部分。

ReactiveProperty,ReactiveCollection


游戏数据通常需要通知,我们应该使用属性和事件回调吗?这样的话,简直太麻烦了,还好UniRx为我们提供了ReactiveProperty,轻量级的属性代理人。

// Reactive Notification Model
public class Enemy
{
    public ReactiveProperty<long> CurrentHp { get; private set; }

    public ReactiveProperty<bool> IsDead { get; private set; }

    public Enemy(int initialHp)
    {
        // Declarative Property
        CurrentHp = new ReactiveProperty<long>(initialHp);
        IsDead = CurrentHp.Select(x => x <= 0).ToReactiveProperty();
    }
}

// ---
// onclick, HP decrement
MyButton.OnClickAsObservable().Subscribe(_ => enemy.CurrentHp.Value -= 99);
// subscribe from notification model.
enemy.CurrentHp.SubscribeToText(MyText);
enemy.IsDead.Where(isDead => isDead == true)
    .Subscribe(_ =>
    {
        MyButton.interactable = false;
    });

你可以组合使用UnityEvent.AsObservable返回的ReactiveProperties、ReactuveCollections和Observables.所有的UI元素都可作为可观察对象(Observable).

泛型ReactiveProperties不能被序列化或者在Unity的Inspecatble中显示。但是UniRx为ReactivePropery提供了专门的子类,诸如 int/LongReactiveProperty,Float/DoubleReactiveProperty,StringReactiveProperty,BoolReactiveProperty 等等。(在这查看:(InspectableReactiveProperty.cs),这些属性都可以在Inspector中编辑,对于你自定义的Enum ReactiveProperty,编写一个自定义的inspectable ReactiveProperty[T]是很容易的。如果你需要为ReactiveProperty增加[Myltiline]或者[Range]之类的属性,你可以使用MultilineReactivePropertyAttribute和RangeReactivePropertyAttribute 替换Unity的Multiline和Range。

所提供的派生自InspecetableReactiveProperty显示在Inspector中,在值发生更改时发出通知,在Inspector中更改值时也会发出通知。
inspector
这个功能由 InspectorDisplayDrawer提供,通过继承你可以应用你自己自定义的ReactiveProperty:

public enum Fruit
{
    Apple, Grape
}

[Serializable]
public class FruitReactiveProperty : ReactiveProperty<Fruit>
{
    public FruitReactiveProperty()
    {
    }

    public FruitReactiveProperty(Fruit initialValue)
        :base(initialValue)
    {
    }
}

[UnityEditor.CustomPropertyDrawer(typeof(FruitReactiveProperty))]
[UnityEditor.CustomPropertyDrawer(typeof(YourSpecializedReactiveProperty2))] // and others...
public class ExtendInspectorDisplayDrawer : InspectorDisplayDrawer
{
}

 

如果ReactiveProperty仅在流中被更新,通过使用ReadOnlyReactiveProperty你可以将属性变为只读的。

public class Person
{
    public ReactiveProperty<string> GivenName { get; private set; }
    public ReactiveProperty<string> FamilyName { get; private set; }
    public ReadOnlyReactiveProperty<string> FullName { get; private set; }

    public Person(string givenName, string familyName)
    {
        GivenName = new ReactiveProperty<string>(givenName);
        FamilyName = new ReactiveProperty<string>(familyName);
        // If change the givenName or familyName, notify with fullName!
        FullName = GivenName.CombineLatest(FamilyName, (x, y) => x + " " + y).ToReadOnlyReactiveProperty();
    }
}

Model-View-(Reactive)Presenter Pattern


UniRx使得MVP(MVRP)模式的实现成为可能。
MVRP

为什么我们需要使用MVP模式替换MVVM模式。Unity中没有提供UI绑定机制,创建绑定层太过于复杂且会影响性能。尽管如此,视图任然需要更新。Presenter持有视图的组件并能更新视图。虽然不是真正的绑定,但Observables 启用了对通知的订阅,它看起来更真实,这个模式被称为Reactive Presenter.

// Presenter for scene(canvas) root.
public class ReactivePresenter : MonoBehaviour
{
    // Presenter is aware of its View (binded in the inspector)
    public Button MyButton;
    public Toggle MyToggle;
    
    // State-Change-Events from Model by ReactiveProperty
    Enemy enemy = new Enemy(1000);

    void Start()
    {
        // Rx supplies user events from Views and Models in a reactive manner 
        MyButton.OnClickAsObservable().Subscribe(_ => enemy.CurrentHp.Value -= 99);
        MyToggle.OnValueChangedAsObservable().SubscribeToInteractable(MyButton);

        // Models notify Presenters via Rx, and Presenters update their views
        enemy.CurrentHp.SubscribeToText(MyText);
        enemy.IsDead.Where(isDead => isDead == true)
            .Subscribe(_ =>
            {
                MyToggle.interactable = MyButton.interactable = false;
            });
    }
}

// The Model. All property notify when their values change
public class Enemy
{
    public ReactiveProperty<long> CurrentHp { get; private set; }

    public ReactiveProperty<bool> IsDead { get; private set; }

    public Enemy(int initialHp)
    {
        // Declarative Property
        CurrentHp = new ReactiveProperty<long>(initialHp);
        IsDead = CurrentHp.Select(x => x <= 0).ToReactiveProperty();
    }
}

在Unity的Hierarchy中,视图就是一个场景。视图在初始化时有UnityEngine和Presenters关联。xxxAsObservable方法使得创建事件信号变得简单,没有任何开销。SubscribeToText和SubscribeToInteractable是类似绑定的简单的工具。虽然简单,但是非常强大。他们很符合Unity的编程环境,并提供了高性能和简洁的体系结构。
Presenter View

V->RP->M->RP->V以响应式的方式完成的连接起来,UniRx提供了适配的方法和类。当然你也可以使用其它的MVVM(或者MV*) 框架代替,UniRx/ReactiveProperty仅仅是一个简单的工具集。

GUI编程也受益于ObservableTriggers.ObservableTriggers转化Unity事件为Observables(可观察对象),因此可以使用它们来组成MV®P模式。例如:ObservableEventTrigger 转化UGUI事件为Observable(可观察对象):

var eventTrigger = this.gameObject.AddComponent<ObservableEventTrigger>();
eventTrigger.OnBeginDragAsObservable()
    .SelectMany(_ => eventTrigger.OnDragAsObservable(), (start, current) => UniRx.Tuple.Create(start, current))
    .TakeUntil(eventTrigger.OnEndDragAsObservable())
    .RepeatUntilDestroy(this)
    .Subscribe(x => Debug.Log(x));

ReactiveCommand,AsyncReactiveCommand


ReactiveCommand作为可交互按钮命令的抽象。

public class Player
{		
   public ReactiveProperty<int> Hp;		
   public ReactiveCommand Resurrect;		
		
   public Player()
   {		
        Hp = new ReactiveProperty<int>(1000);		
        		
        // If dead, can not execute.		
        Resurrect = Hp.Select(x => x <= 0).ToReactiveCommand();		
        // Execute when clicked		
        Resurrect.Subscribe(_ =>		
        {		
             Hp.Value = 1000;		
        }); 		
    }		
}		
		
public class Presenter : MonoBehaviour		
{		
    public Button resurrectButton;		
		
    Player player;		
		
    void Start()
    {		
      player = new Player();		
		
      // If Hp <= 0, can't press button.		
      player.Resurrect.BindTo(resurrectButton);		
    }		
}

AsyncReactiveCommand 是ReactiveCommand的异步形式,将CanExecute(大多数情况下绑定到按钮的interactable)更改为false,直到异步操作执行完成。

public class Presenter:MonoBehaviour{
    public UnityEngine.UI.Button button;
    void Start(){
        var command=new AsyncReactiveCommand();

        command.Subscribe(_=>{
            return Observable.Timer(TimeSpan.FromSeconds(3)).asUnitObservable();
        });

        command.BindTo(button);

        button.BindToOnClick(_=>{
            return Observable.Timer(TimeSpan.FromSeconds(3)).AsUnitObservable();
        });
    }
}

AsyncReactiveCommand 有三个构造函数。

  • ()CanExecute默认为false,直到异步执行完成
  • (IObservable canExecuteSource) 当canExecuteSource发送true并且不在执行时,与empty混合,CanExecute变为true.
  • (IReactiveProperty sharedCanExecute) 在多个AsyncReactiveCommands之间共享执行状态,如果其中一个AsyncReactiveCommand正在执行,其它AsyncReactiveCommands(拥有一个sharedCanExecute属性)的CanExecute变为false,直到这个AsyncCommand异步执行完成.
public class Presenter : MonoBehaviour
{
    public UnityEngine.UI.Button button1;
    public UnityEngine.UI.Button button2;

    void Start()
    {
        // share canExecute status.
        // when clicked button1, button1 and button2 was disabled for 3 seconds.

        var sharedCanExecute = new ReactiveProperty<bool>();

        button1.BindToOnClick(sharedCanExecute, _ =>
        {
            return Observable.Timer(TimeSpan.FromSeconds(3)).AsUnitObservable();
        });

        button2.BindToOnClick(sharedCanExecute, _ =>
        {
            return Observable.Timer(TimeSpan.FromSeconds(3)).AsUnitObservable();
        });
    }
}

MessageBroker, AsyncMessageBroker


MessageBroker基于Rx的内存的pubsub系统的按类型过滤的。

public class TestArgs
{
    public int Value { get; set; }
}

---

// Subscribe message on global-scope.
MessageBroker.Default.Receive<TestArgs>().Subscribe(x => UnityEngine.Debug.Log(x));

// Publish message
MessageBroker.Default.Publish(new TestArgs { Value = 1000 });

AsyncMessageBroker是MessageBroker的异步形式,可以await发布调用

AsyncMessageBroker.Default.Subscribe<TestArgs>(x =>
{
    // show after 3 seconds.
    return Observable.Timer(TimeSpan.FromSeconds(3))
        .ForEachAsync(_ =>
        {
            UnityEngine.Debug.Log(x);
        });
});

AsyncMessageBroker.Default.PublishAsync(new TestArgs { Value = 3000 })
    .Subscribe(_ =>
    {
        UnityEngine.Debug.Log("called all subscriber completed");
    });

UniRx.ToolKit

UniRx.ToolKit 中包含一些Rx-ish工具。当前版本中包含 ObjectPool(对象池)和AsyncObjectPool(异步对象池),这个池子在租赁前可以租、回收和异步预加载。

// sample class
public class Foobar : MonoBehaviour
{
    public IObservable<Unit> ActionAsync()
    {
        // heavy, heavy, action...
        return Observable.Timer(TimeSpan.FromSeconds(3)).AsUnitObservable();
    }
}

public class FoobarPool : ObjectPool<Foobar>
{
    readonly Foobar prefab;
    readonly Transform hierarchyParent;

    public FoobarPool(Foobar prefab, Transform hierarchyParent)
    {
        this.prefab = prefab;
        this.hierarchyParent = hierarchyParent;
    }

    protected override Foobar CreateInstance()
    {
        var foobar = GameObject.Instantiate<Foobar>(prefab);
        foobar.transform.SetParent(hierarchyParent);

        return foobar;
    }

    // You can overload OnBeforeRent, OnBeforeReturn, OnClear for customize action.
    // In default, OnBeforeRent = SetActive(true), OnBeforeReturn = SetActive(false)

    // protected override void OnBeforeRent(Foobar instance)
    // protected override void OnBeforeReturn(Foobar instance)
    // protected override void OnClear(Foobar instance)
}

public class Presenter : MonoBehaviour
{
    FoobarPool pool = null;

    public Foobar prefab;
    public Button rentButton;

    void Start()
    {
        pool = new FoobarPool(prefab, this.transform);

        rentButton.OnClickAsObservable().Subscribe(_ =>
        {
            var foobar = pool.Rent();
            foobar.ActionAsync().Subscribe(__ =>
            {
                // if action completed, return to pool
                pool.Return(foobar);
            });
        });
    }
}

Visual Studio Analyzer


对Visual Studio 2015的用户来说,UniRx提供了一个自定义的分析工具————UniRxAnalyzer。例如:检测流什么时候没有被订阅。


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ObservableWWW 在订阅前不会被触发,分析器抛出使用不当的警告,你可以通过NuGet下载它。

  • Install-Package UniRxAnalyzer

请在github的Issuse中提交你的关于Analyzer的新想法。

案例

UniRx/Examples

Windows Store/Phone App (NETFX_CORE)


一些接口,例如UniRx.IObservable和System.IObservable ,当提交应用到Windows Store App时会引起冲突,因此,当时用NETFX_CORE时,请不要使用诸如UniRx.IObservable这样的结构,使用其简短的形式,不要添加命名空间,冲突就解决了。

分离DLL


如果你想使用预构建的UniRx,你可以构建自己的dll,克隆这个项目并打开UniRx.sln,你会看到这是一个完全分离的项目。你需要像这样定义编译宏定义UNITY;UNITY_5_4_OR_NEWER;UNITY_5_4_0;UNITY_5_4;UNITY_5; + UNITY_EDITOR, UNITY_IPHONE或者其它平台宏定义,在发布页面我们不提供预编译二进制文件,因为在asset store 中的编译符号各不相同。

posted @ 2020-03-31 15:13  小y  阅读(...)  评论(...编辑  收藏