在 Xamarin android 9 版本以下，使用捏合来放大和缩小一些不需要的背景应该出现复制的颜色并且像素质量低 android

Question

每当我用两根手指捏合来放大和缩小一些不需要的背景应该复制颜色出现我的 camerapagerenderer 如果我单触摸或触摸它似乎不 apppear 当我用两根手指捏合来放大它出现在我的屏幕上

    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

您可以查看下面的代码。它适用于 Android 10.0，没有色差。

 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();
    }       
}

更新： Android 6.0

上的结果

在 Xamarin android 9 版本以下，使用捏合来放大和缩小一些不需要的背景应该出现复制的颜色并且像素质量低 android

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