Xamarin OpenGL GLSurfaceView构造函数抛出null引用异常

Question

我正在尝试用Xamarin opengl实现android LiveWallpaper。 但是当我激活LiveWallpaper时，GLSurfaceView会在构造函数中抛出null引用异常。

错误行：  调用GLSurfaceView的基础构造函数时的base（context）。

错误详情：  Java.Lang.NullPointerException：尝试调用接口方法 'void android.view.SurfaceHolder.addCallback（android.view.SurfaceHolder $ Callback）' 在空对象引用上

[Service(Label = "@string/ApplicationName", Permission = "android.permission.BIND_WALLPAPER")]
[IntentFilter(new[] { "android.service.wallpaper.WallpaperService" })]
[MetaData("android.service.wallpaper", Resource = "@layout/MyLiveWallpaper")]
public class OpenGLWallpaperService : WallpaperService
{
    public override Engine OnCreateEngine()
    {
        return new OpenGLWallpaperEngine(this);
    }

    public class OpenGLWallpaperEngine : Engine
    {
        private readonly OpenGLWallpaperService _serviceInstance;

        public OpenGLWallpaperView GLWallpaperView { get; set; }

        public OpenGLWallpaperEngine(OpenGLWallpaperService serviceInstance)
            : base(serviceInstance)
        {
            _serviceInstance = serviceInstance;
        }

        public override void OnCreate(ISurfaceHolder surfaceHolder)
        {
            base.OnCreate(surfaceHolder);
            GLWallpaperView = new OpenGLWallpaperView(this, _serviceInstance, surfaceHolder);
        }
    }
}

public class OpenGLWallpaperView : GLSurfaceView
{
    private readonly OpenGLWallpaperService.OpenGLWallpaperEngine _engineInstance;

    public override ISurfaceHolder Holder { get; }

    public OpenGLWallpaperView(OpenGLWallpaperService.OpenGLWallpaperEngine engineInstance, 
        Context context, ISurfaceHolder surfaceHolder) 
        : base(context)
    {
        _engineInstance = engineInstance;
        Holder = surfaceHolder;
    }
}

Answer 1

我对覆盖Holder做错了。持有人不应被覆盖。

取消此行及相关事项：
公开覆盖ISurfaceHolder Holder {get; }