[BUG] CaptureAsync produces incorrect image on Android

[Pairoba]

Description

I'm creating a custom control using SKCanvasView. Putting this into a view and then using CaptureAsync on the view is producing a wrong image on android. Works on Windows.

The top view was captured and the bottom is the captured image:

Code

GitHub repository: https://github.com/Pairoba/CaptureAsyncSkiaSharp

CustomView.cs

internal class CustomView : SKCanvasView
{
    protected override void OnPaintSurface(SKPaintSurfaceEventArgs e)
    {
        base.OnPaintSurface(e);
        var canvas = e.Surface.Canvas;
        var info = e.Info;

        using var paint = new SKPaint();
        paint.Color = SKColors.Black;
        paint.StrokeWidth = 10;

        canvas.DrawLine(0, 0, info.Width, info.Height, paint);
        canvas.DrawLine(info.Width, 0, 0, info.Height, paint);
    }
}

MainPage.xaml.cs

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
    }

    private async void CaptureAsync(object sender, EventArgs e)
    {
        var snap = await CaptureTarget.CaptureAsync();
        if (snap != null)
        {
            var s = await snap.OpenReadAsync();
            CaptureImageView.Source = ImageSource.FromStream(() => s);
        }
    }
}

MainPage.xaml

<VerticalStackLayout>
    <Border x:Name="CaptureTarget"
            HeightRequest="250"
            WidthRequest="250"
            StrokeThickness="10"
            Stroke="Blue">
        <AbsoluteLayout BackgroundColor="Green">
            <local:CustomView AbsoluteLayout.LayoutBounds="40, 40, 100, 100"
                              AbsoluteLayout.LayoutFlags="None" />
        </AbsoluteLayout>
    </Border>
    <Button Text="Capture Async"
            Clicked="CaptureAsync"/>
    <Image x:Name="CaptureImageView"
           HeightRequest="250"
           WidthRequest="250"/>
</VerticalStackLayout>

Expected Behavior

Correct generated image

Actual Behavior

Incorrect generated image

Version of SkiaSharp

2.88.3 (Current)

Last Known Good Version of SkiaSharp

Other (Please indicate in the description)

IDE / Editor

Visual Studio (Windows)

Platform / Operating System

Android

Platform / Operating System Version

• Android 13
• Android 14

Devices

• Pixel 5 Emulator

Relevant Screenshots

No response

Relevant Log Output

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[Pairoba]

It seems like, that the canvas on the snapshot is scaled to the snapshot target's size. So I was able to create a Workaround by scaling the CustomView during the snapshot creation.

private async void CaptureAsync(object sender, EventArgs e)
{
    CustomViewInstance.AnchorX = 0;
    CustomViewInstance.AnchorY = 0;
    CustomViewInstance.ScaleX = CustomViewInstance.Width / CaptureTarget.Width;
    CustomViewInstance.ScaleY = CustomViewInstance.Height / CaptureTarget.Height;

    var snap = await CaptureTarget.CaptureAsync();
    if (snap != null)
    {
        var s = await snap.OpenReadAsync();
        CaptureImageView.Source = ImageSource.FromStream(() => s);
    }

    CustomViewInstance.ScaleX = 1;
    CustomViewInstance.ScaleY = 1;
}