如何从Xamarin.forms侧SkiaSharp请求重绘？

using SkiaSharp.Views.Forms;

public class MyCanvasView : SKCanvasView
{
    protected override void OnPaintSurface(SKPaintSurfaceEventArgs e)
    {
        base.OnPaintSurface(e);

        // 在此处进行绘制操作
        SKCanvas canvas = e.Surface.Canvas;
        // 绘制代码...
    }
}

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace"
             x:Class="YourNamespace.YourPage">
    <local:MyCanvasView />
</ContentPage>

private void RedrawButton_Clicked(object sender, EventArgs e)
{
    MyCanvasView.InvalidateSurface();
}