Using pinch to zoomin and zoomout some unwanted background should copied color appeared and pixel quality low android below 9 version Xamarin android

Question

Whenever i using wo fingers pinch to zoomin and zoomout some unwanted background should copied color appeared my camerapagerenderer if i single touch or touch it not seems to be apppear when i pinch to zoomin using two fingers it appears on my screen

    public override bool OnTouchEvent(MotionEvent e)
            {
                
                switch (e.Action & MotionEventActions.Mask)
                {
                    case MotionEventActions.Down:
                        oldDist = getFingerSpacing(e);
                        break;
                    case MotionEventActions.Move:
                        float newDist = getFingerSpacing(e);
                        if (newDist > oldDist)
                        {
                            //mCamera is your Camera which used to take picture, it should already exit in your custom Camera
                            handleZoom(true, camera);
                        }
                        else if (newDist < oldDist)
                        {
                            handleZoom(false, camera);
                        }
                        oldDist = newDist;
                        break;
                }
                return true;
            }
    
    private void handleZoom(bool isZoomIn, global::Android.Hardware.Camera camera)
            {
                global::Android.Hardware.Camera.Parameters parameters = camera.GetParameters();
                if (parameters.IsZoomSupported)
                {
                    int maxZoom = parameters.MaxZoom;
                    int zoom = parameters.Zoom;
                    
                    if (isZoomIn && zoom < maxZoom)
                    {
                        zoom++;
                    }
                    else if(zoom > 0)
                    {
                        zoom--;
                    }
                    parameters.Zoom = zoom;
                    camera.SetParameters(parameters);
                }
                else
                {
                    Android.Util.Log.Error("lv", "zoom not supported");
                }
            }
        private static float getFingerSpacing(MotionEvent e)
            {
         if(e.PointerCount==2)
    {
               int pointerIndex = e.FindPointerIndex(_activePointerId);
                float x = e.GetX(pointerIndex);
                float y = e.GetY(pointerIndex);
        return (float)Math.Sqrt(x * x + y * y);
    }
        }

Answer 1

You could check the code below. It works on Android 10.0 with no color shades.

 class CameraPageRenderer : PageRenderer, TextureView.ISurfaceTextureListener
{
    global::Android.Hardware.Camera camera;
    global::Android.Widget.Button takePhotoButton;
    global::Android.Widget.Button toggleFlashButton;
    global::Android.Widget.Button switchCameraButton;
    global::Android.Views.View view;

    Activity activity;
    CameraFacing cameraType;
    TextureView textureView;
    SurfaceTexture surfaceTexture;

    bool flashOn;

    public CameraPageRenderer(Context context) : base(context)
    {
    }

    float oldDist = 1f;
    public override bool OnTouchEvent(MotionEvent e)
    {

        switch (e.Action & MotionEventActions.Mask)
        {
            case MotionEventActions.Down:
                oldDist = getFingerSpacing(e);
                break;
            case MotionEventActions.Move:
                float newDist = getFingerSpacing(e);
                if (newDist > oldDist)
                {
                    //mCamera is your Camera which used to take picture, it should already exit in your custom Camera
                    handleZoom(true, camera);
                }
                else if (newDist < oldDist)
                {
                    handleZoom(false, camera);
                }
                oldDist = newDist;
                break;
        }
        return true;
    }
    private static float getFingerSpacing(MotionEvent e)
    {
        if (e.PointerCount == 2)
        {
            float x = e.GetX(0) - e.GetX(1);
            float y = e.GetY(0) - e.GetY(1);
            return (float)Math.Sqrt(x*x + y*y);
        }

        return 0;
    }

    private void handleZoom(bool isZoomIn, global::Android.Hardware.Camera camera)
    {
        //camera.StopPreview();
        //  camera.Release();
        // camera = global::Android.Hardware.Camera.Open((int)cameraType);
        global::Android.Hardware.Camera.Parameters parameters = camera.GetParameters();
        if (parameters.IsZoomSupported)
        {
            int maxZoom = parameters.MaxZoom;
            int zoom = parameters.Zoom;

            if (isZoomIn && zoom < maxZoom)
            {
                zoom++;
            }
            else if (zoom > 0)
            {
                zoom--;
            }
            parameters.Zoom = zoom;
            camera.SetParameters(parameters);
            camera.SetPreviewTexture(surfaceTexture);
            PrepareAndStartCamera();
        }
        else
        {
            Android.Util.Log.Error("lv", "zoom not supported");
        }
    }


    protected override void OnElementChanged(ElementChangedEventArgs<Page> e)
    {
        base.OnElementChanged(e);
        if (e.OldElement != null || Element == null)
        {
            return;
        }

        try
        {
            SetupUserInterface();
            //SetupEventHandlers();
            AddView(view);
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine(@"           ERROR: ", ex.Message);
        }
    }

    void SetupUserInterface()
    {
        activity = this.Context as Activity;
        view = activity.LayoutInflater.Inflate(Resource.Layout.CameraLayout, this, false);
        cameraType = CameraFacing.Back;

        textureView = view.FindViewById<TextureView>(Resource.Id.textureView);
        textureView.SurfaceTextureListener = this;
    }

   
    protected override void OnLayout(bool changed, int l, int t, int r, int b)
    {
        base.OnLayout(changed, l, t, r, b);
        var msw = MeasureSpec.MakeMeasureSpec(r - l, MeasureSpecMode.Exactly);
        var msh = MeasureSpec.MakeMeasureSpec(b - t, MeasureSpecMode.Exactly);

        view.Measure(msw, msh);
        view.Layout(0, 0, r - l, b - t);
    }

    public void OnSurfaceTextureAvailable(SurfaceTexture surface, int width, int height)
    {
        camera = global::Android.Hardware.Camera.Open((int)cameraType);
        textureView.LayoutParameters = new FrameLayout.LayoutParams(width, height);
        surfaceTexture = surface;

        camera.SetPreviewTexture(surface);
        PrepareAndStartCamera();
    }

    public bool OnSurfaceTextureDestroyed(SurfaceTexture surface)
    {
        camera.StopPreview();
        camera.Release();
        return true;
    }

    public void OnSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height)
    {
        PrepareAndStartCamera();
    }

    public void OnSurfaceTextureUpdated(SurfaceTexture surface)
    {

    }

    void PrepareAndStartCamera()
    {
        camera.StopPreview();

        var display = activity.WindowManager.DefaultDisplay;
        if (display.Rotation == SurfaceOrientation.Rotation0)
        {
            camera.SetDisplayOrientation(90);
        }

        if (display.Rotation == SurfaceOrientation.Rotation270)
        {
            camera.SetDisplayOrientation(180);
        }

        camera.StartPreview();
    }       
}

Update: The result on Android 6.0