Question

我有一个面部检测应用程序，因此我需要在应用程序启动时打开相机，我已经查看了类似的问题但我找不到解决我现在遇到的问题。问题是没有调用函数 SurfaceCreated（ISurfaceHolder holder），因此没有启动摄像头。感谢您的回复

CameraLayout.axml

<AppName.Droid.CameraControls.CameraLiveStream
      android:id="@+id/cameraPreview"
      android:layout_width="match_parent"
      android:layout_height="match_parent" >
</App2.Droid.CameraControls.CameraLiveStream>

CameraLiveStream.cs继承 ViewGroup，ISurfaceHolderCallback2

CameraLiveStream.cs

    private Context mContext;
    private SurfaceView mSurfaceView;
    private bool mStartRequested;
    private bool mSurfaceAvailable;
    private CameraSource mCameraSource;

    public CameraLiveStream(Context context, IAttributeSet attrs) : base(context, attrs)
    {
        mContext = context;
        mStartRequested = false;
        mSurfaceAvailable = false;

        mSurfaceView = new SurfaceView(context);
        mSurfaceView.Holder.AddCallback(this);

        AddView(mSurfaceView);
    }
    #region camera-surface
    public void SurfaceChanged(ISurfaceHolder holder, [GeneratedEnum] Format format, int width, int height)
    {
        throw new NotImplementedException();
    }

    public void SurfaceCreated(ISurfaceHolder holder)
    {
        mSurfaceAvailable = true;

        try
        {
            StartCameraIfReady();
        }
        catch
        {
            Log.Error("CameraLiveStream", "Error when starting camera");
        }
    }

这是我的 MainActivity.cs OnCreate()

    protected override void OnCreate(Bundle bundle)
    {

        base.OnCreate(bundle);

        SetContentView(Resource.Layout.CameraLayout);

        mPreview = FindViewById<CameraLiveStream>(Resource.Id.cameraPreview);

        if (ActivityCompat.CheckSelfPermission(this, Manifest.Permission.Camera) == Permission.Granted)
        {
            CreateCameraSource();
        }
        else
        {
            RequestCameraPermissions();
        }

    }

CreateCameraSource 功能

private void CreateCameraSource()
    {
        var context = Application.Context;
        FaceDetector detector = new FaceDetector.Builder(context)
                .SetClassificationType(ClassificationType.All)
                .Build();

        if (!detector.IsOperational)
        {
            Log.Warn("MainActivity", "Face detector dependencies are not yet available.");
        }

        mCameraSource = new CameraSource.Builder(context, detector)
                .SetRequestedPreviewSize(200, 200)
                                        .SetFacing(CameraFacing.Back)
                .SetRequestedFps(30.0f)
                .Build();

    }

StartCameraSource 功能

private void StartCameraSource()
    {
        int code = GoogleApiAvailability.Instance.IsGooglePlayServicesAvailable(
                this.ApplicationContext);
        if (code != ConnectionResult.Success)
        {
            Dialog dlg =
                    GoogleApiAvailability.Instance.GetErrorDialog(this, code, RC_HANDLE_GMS);
            dlg.Show();
        }

        if (mCameraSource != null)
        {
            try
            {
                mPreview.StartCamera(mCameraSource);
            }
            catch (System.Exception e)
            {
                Log.Error("MainActivity-StartCameraSource", "Unable to start camera source.", e);
                mCameraSource.Release();
                mCameraSource = null;
            }

Answer 1

您正在创建一个没有布局参数的SurfaceView，因此它的大小为0,0因此永远不需要创建表面。

全屏：

var layoutParams = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MatchParent, ViewGroup.LayoutParams.MatchParent);
var view = new SurfaceView(someContext)
{
    LayoutParameters = layoutParams
};

或将SurfaceView加载到布局

中的容器

var aViewGroup = FindViewById<ViewGroup>(Resource.Id.SomeContainer);
aViewGroup.AddView(yourSurfaceView, new LayoutParams(MATCH_PARENT, WRAP_CONTENT));

Answer 2

修正了问题：

我在我的下面创建了另一种类型的视图的 AppName.Droid.CameraControls.CameraLiveStream

所以它就像这样

<AppName.Droid.Camera.Controls.CameraLiveStream> <AppName.Droid.Camera.Controls.Overlay> </AppName.Droid.Camera.Controls.Overlay> </AppName.Droid.Camera.Controls.CameraLiveStream>

其中，覆盖层继承了实现视图宽度/高度的View。

public int mPrevWidth { get => mWidth; set => mWidth = value; } public int mPrevHeight { get => mHeight; set => mHeight = value; } public float mPrevWidthScaleFactor { get => mWidthScaleFactor; set => mWidthScaleFactor = value; } public float mPrevHeightScaleFactor { get => mHeightScaleFactor; set => mHeightScaleFactor = value; } public CameraFacing mCameraFacing { get => mFacing; set => mFacing = value; }

Xamarin - Droid（SurfaceView）

2 个答案:

全屏：

或将SurfaceView加载到布局