How to Share Resources between diffrent GRContexts?

[AhmedEssoubai]

We're trying to use multiple GRContexts for rendering on diffrent threads. But, we're struglling with sharing resources between them.

A simple example with 2 GRContexts; GRC1 and GRC2:

• On a diffrent thread createa a surface S1 using GRC1.
• Draw shapes on S1.
• Take snapshot of S1 and save it on S1Img.
• On main thread create a surface S2 using GRC2.
• Draw S1Img into S2.

This code is a bit diffrent where GRC2 and S2 are created internaly inside of SKGLElement:

SKImage S1Img = null;

SKGLElement GLElement1 = new SKGLElement();
GRContext GRC1 = GRContext.CreateGl();

SKGLElement GLElement2 = new SKGLElement((IGLFWGraphicsContext)GLElement1.Context);

GLElement1.Context.MakeNoneCurrent();
GLElement2.Context.MakeNoneCurrent();

Task.Run(() =>
{
    GLElement1.Context.MakeCurrent();
    using SKSurface S1 = SKSurface.Create(GRC1, true, new SKImageInfo(800, 800));

    SKPaint paint = new()
    {
        Color = SKColors.Red
    };

    S1.Canvas.DrawRect(new SKRect(10, 10, 200, 200), paint);

    S1Img = S1.Snapshot();

    //S1Img = S1Img.ToRasterImage();

}).Wait();

Content = GLElement2;
GLElement2.Context.MakeCurrent();
GLElement2.PaintSurface += (s, e) =>
{
    e.Surface.Canvas.DrawImage(S1Img, new SKPoint(20, 20));
};

After modifing SkiaSharp.Views.WPF.SKGLElement class to use the latest GLWpfControl from OpenTK, we used SharedContext on GLWpfControlSettings to share resources between diffrent GLContexts.
The issue is that the sharing is happening on GLContext not GRContext.

The result of drawing S1Img into S2 that we get is nothing (just like drawing a transparent image). But, we do have a workaround by rasterising the image before drawing:

S1Img = S1Img.ToRasterImage();

But, this is slow, especially with large images. We wan't something that skips the rasterisation step. Is there away to share resources between GRContexts just like GLContext?