为什么SkiaSharp“OnCanvasView_PaintSurface”不会自动Xamarin.Form应用程序重新绘制

Question

我在Xamarin.Form应用程序的StackLayout中有一个SkiaCanvasView和一个Label，试图频繁更新屏幕上的位图，但它只能绘制一次。 XAML文件和CS代码如下所示，

<StackLayout 
    x:Name="stackMonitors"
    VerticalOptions="FillAndExpand"
    HorizontalOptions="FillAndExpand">
    <Label x:Name="numCounter"
           Text="counter"
           VerticalOptions="Start"/>
    <skia:SKCanvasView x:Name="canvasView"
                       PaintSurface="OnCanvasView_PaintSurface"
                       VerticalOptions ="FillAndExpand"
                       Margin="10,10,0,10"/>

</StackLayout>


SKBitmap skiBMP = new SKBitmap();
SKSurface skiSurface;
SKCanvas skiCanvas;
SKPaint skiPaint = new SKPaint();
SKRect skiRect = new SKRect();
int temp = 0;
private void OnCanvasView_PaintSurface(object sender, SKPaintSurfaceEventArgs e)
{
    numCounter.Text = (++temp).ToString();    //if the PaintSurface is called more than once automatically, the numCounter should not be "1" all the time
    skiSurface = e.Surface;
    skiCanvas = skiSurface.Canvas;
    skiRect.Top = 0;
    skiRect.Left = 0;
    skiRect.Right = e.Info.Width;
    skiRect.Bottom = e.Info.Width * 0.5625f;

    skiBMP = SKBitmap.Decode(myOperator.PCImageMemoryStream);  //Bitmap stream updates 30 times per second
    skiCanvas.DrawBitmap(skiBMP, skiRect, skiPaint);
}

预期结果

myOperator.PCImageMemoryStream的值不断更新，我预计OnCanvasView_PaintSurface事件将每秒自动触发60次，因此CanvasView可以非常频繁地在MainPage上绘制myOperator.PCImageMemoryStream。

实际结果

但是，它只绘制一次，标签“ numCounter”在运行该应用程序后始终显示为“ 1”。

摘要

我不知道如何在OnCanvasView_PaintSurface每次可以称为设备屏幕刷新。微软Skia网络研讨会表示，Skia CanvasView每秒可涂漆60次...

（什么是坏的是，在该项目采取SkiaSharp的参考之后，XAML文件无法正常预览...）

非常感谢。