Xamarin SkiaSharp 缩放裁剪画布

如何解决Xamarin SkiaSharp 缩放裁剪画布

我尝试从我在 Xamarin Foms 中的应用程序中捕获的照片中获得多边形裁剪。 我使用 SkiaSharp 。所以第一步是好的，我像这样从我的 EdgeCroppingView 得到一个画布

所以现在我想在全屏中裁剪选择并“调整大小”，只有选择（围绕猫），我有这个：

The selected skpath (the borders) are correctly "resizing" but not the inside content(the cat's area) : i would like to strech this area ...

有什么想法吗？

 private void OnCanvasViewPaintSurface(object sender,SKPaintSurfaceEventArgs e)
    {
        SKImageInfo info = e.Info;
        SKSurface surface = e.Surface;
        SKCanvas canvas = surface.Canvas;
        
        canvas.Clear();

        if (_pathToClip != null)
        {
             SKRect rectSource;
            _pathToClip.GetTightBounds(out rectSource);

            e.Surface.Canvas.Clear();
            SKRect canvasRect = SKRect.Create(e.Info.Size);

            //I need to find the size of the path
            SKRect pathRect = _pathToClip.TightBounds;

            //I want to find the largest rectangle that can fit on my canvas maintaining the path's aspect ratio
            //SkiaSharp added a builtin method for this based on code from me

            SKRect drawPathRect = canvasRect.AspectFit(pathRect.Size);
            //Now I need to transform the path to draw within the drawPathRect
            //First translate original path to its own origin
            SKMatrix firstTranslateM = SKMatrix.CreateTranslation(-pathRect.Left,-pathRect.Top);
            //Next handle scaling.  Since I maintained aspect ratio,I should be able to use either
            //width or height to figure out scaling factor
            float scalingFactor = drawPathRect.Width / pathRect.Width;
            SKMatrix scaleM = SKMatrix.CreateScale(scalingFactor,scalingFactor);
            //Last I need to handle translation so path is centered on canvas
            SKMatrix secondTranslateM = SKMatrix.CreateTranslation(drawPathRect.Left,drawPathRect.Top);
            //Now combine the translation,scaling,and translation into a single matrix by matrix multiplication/concatentation
            SKMatrix transformM = SKMatrix.CreateIdentity();
            SKMatrix.PostConcat(ref transformM,firstTranslateM);
            SKMatrix.PostConcat(ref transformM,scaleM);
            SKMatrix.PostConcat(ref transformM,secondTranslateM);
            
            //Now apply the transform to the path
            _pathToClip.Transform(transformM);
            

            canvas.ClipPath(_pathToClip);

           using (var paint = new SKPaint())
            {
                paint.Style = SKPaintStyle.stroke;
                paint.Color = SKColors.magenta;
                paint.strokeWidth = 5;

                canvas.DrawPath(_pathToClip,paint);
                canvas.DrawBitmap(Bitmap,info.Rect,BitmapStretch.UniformToFill );
            }

          
        }