For now, when we creating the diagram node and trying to apply the clip area by override the 'Draw' method - this clipping area is not applying when we trying to export the diagram by SvgExporter.

The code:
In this context the 'node' variable - it is another diagram node that exists under the mask (under the clipping area). We are just trying to apply the clipping area over another diagram node. That works good, but not with svg exporter.

public override void Draw(DrawingContext graphics, MindFusion.Diagramming.Wpf.RenderOptions options)
    {
        var maskBounds = mask.Rectangle.GetBoundingBox();
        var maskRect = DomainUtilities.CreateDomainRectangle(maskBounds);
        var clip = new RectangleGeometry(maskRect);

        graphics.PushClip(clip);
        node.Draw(graphics, options);
        graphics.Pop();
    }
 

1) The diagram node without the 'clipping area'
2) The diagram node with applied 'clipping area'
3) Check the 'output.pdf' where the exported svg is located.

Please, let me know, are you still working on it?
If so, could you please let me know ETA of this feature?

Its not working as expected with code above. Could you provide any sample how it works with SetClipPaths property?
Also, sometimes when i was trying to export diagram as svg - it cut off parts of some diagram items (without applied mask).

Thanks for sample, but for now SVG node doesn't support clipping area. See the code and attachments.

Light blue background displays the clipping area in 'testSvg.svg' file, the area around this background must be clipped, but it doesn't.

Also you can see the bounds of SVG node and clipping area (see the text in attached testSvg.svg file)

public override void Draw(DrawingContext graphics, MindFusion.Diagramming.Wpf.RenderOptions options)
        {
            // Just a SVG node with loaded svg content.
            svgNode.Text = $"Svg node bounds: {svgNode.Bounds} \n Clip area bounds: {clip.Bounds}";

            // 'Clip' bounds is lesser than SVG node bounds.
            // But it doesn't clip the resulting SVG node.
            graphics.PushClip(clip);

            // The clip area doesn't apply without 'push transform' call, even for shape node.
            graphics.PushTransform(new TranslateTransform(0, 0));

            // Here we are draw the SVG node under the clipping area (but it doesn't apply).
            svgNode.Draw(graphics, options);

            graphics.Pop();
        } 

New build here should clip embedded SvgNode too -
https://mindfusion.eu/_beta/wpfdiag39.zip

diagram.Nodes.Add(
    new ClipNode
    {
        Node = new ShapeNode
        {
            Bounds = new Rect(0, 0, 160, 160),
            Shape = Shapes.Star16Pointed
        },
        Bounds = new Rect(20, 20, 120, 120)
    });

diagram.Nodes.Add(
    new ClipNode
    {
        Node = new SvgNode
        {
            Bounds = new Rect(0, 0, 200, 200),
            Content = SvgContent.FromFile("img.svg"),
            Transparent = true
        },
        Bounds = new Rect(160, 60, 120, 120)
    });

var svgEx = new SvgExporter();
svgEx.SetClipPaths = true;
svgEx.Export(diagram, "test.svg");

class ClipNode : DiagramNode
{
    public ClipNode() {}

    public override void Draw(
        DrawingContext graphics, MindFusion.Diagramming.Wpf.RenderOptions options)
    {
        if (Node != null)
        {
            var maskRect = this.GetLocalBounds();
            var clip = new RectangleGeometry(maskRect);

            graphics.PushClip(clip);
            graphics.PushTransform(new TranslateTransform(0, 0));
            Node.Draw(graphics, options);
            graphics.Pop();
            graphics.Pop();
        }
    }

    public DiagramNode Node { get; set; }
} 

Please attach your source SVG drawing if it's still not working for you.

Regards,
Slavcho
Mindfusion