c# - 在线程执行过程中更新UI C# android

Question

我目前正在将 Android 应用程序的 Java 代码迁移到 C#。我想在线程执行过程中更新我的用户界面。

这是我的java代码:-

private Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
      if (msg.what == MSG_SURFACE_CREATED) {
        contentWidth = 0;
        contentHeight = 0;
        requestLayout();
        return true;
      } else {
        Log.w("Unknown msg.what: " + msg.what);
      }
      return false;
    }
  });

并且:-

void postChangedToView(final int indexInAdapter) {
    handler.post(new Runnable() {
        @Override
        public void run() {
            changedToView(indexInAdapter, true);
        }
    });
}

我在 C# 中尝试过类似的方法:-

private Android.OS.Handler handler = new Android.OS.Handler();

private class Callback : Android.OS.Handler.ICallback //inner class 
{

    ViewController fp;    //Create instance of outer class 
    public Callback(FViewController _fp) //pass the instance to constructor of inner class
    {
        fp = _fp;
    }
    #region ICallback implementation

    public bool HandleMessage (Message msg)
    {
        if (msg.What == MSG_SURFACE_CREATED)
        {
            contentWidth = 0;
            contentHeight = 0;

            fp.RequestLayout ();   

            return true;
        }
        else
        {
            Log.w("Unknown msg.what: " + msg.What);
        }
        return false;
        throw new NotImplementedException ();
    }
}

这里我无法创建 Handler.ICallBack 的内联类

并且:-

internal virtual void postChangedToView(int indexInAdapter) {
    handler.Post (Task.Run (()=> flippedToView (indexInAdapter,true)));
}

这里我收到一个错误:-

Error CS1503: Argument 1: cannot convert from 'System.Threading.Tasks.Task' to 'System.Action' 

Answer 1

Handler.Post 需要 System.Action 参数。您可以创建System.Action，如下所示:

internal virtual void postFlippedToView(int indexInAdapter)
{
    Action action = () => flippedToView(indexInAdapter, true);
    handler.Post (action );
}