Terrible performance of custom-drawn control

Question

I am making simple graph control in wpf. And I can\'t explain nor fix performance problem: it\'s too slow compared to winforms. Perhaps I am doing something wro

Answer 1

It's strange and nobody here mentioned, but it is possible to use gdi draw in wpf natively (without hosting container).

I found this question first, which become normal render-based graph (use InvalidateVisuals() to redraw).

protected override void OnRender(DrawingContext context)
{
    using (var bitmap = new GDI.Bitmap((int)RenderSize.Width, (int)RenderSize.Height))
    {
        using (var graphics = GDI.Graphics.FromImage(bitmap))
        {
            // use gdi functions here, to ex.: graphics.DrawLine(...)
        }
        var hbitmap = bitmap.GetHbitmap();
        var size = bitmap.Width * bitmap.Height * 4;
        GC.AddMemoryPressure(size);
        var image = Imaging.CreateBitmapSourceFromHBitmap(hbitmap, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
        image.Freeze();
        context.DrawImage(image, new Rect(RenderSize));
        DeleteObject(hbitmap);
        GC.RemoveMemoryPressure(size);
    }
}

This approach is capable to draw hundred thousands of lines. Very responsive.

Drawbacks:

• not as smooth, as pure gdi one graph, DrawImage occurs some times after, will flickers a bit.
• necessary to convert all wpf objects to gdi ones (sometimes is impossible): pens, brushes, points, rectangles, etc.
• no animations, graph itself can be animated (to example, transformed), but drawings are not.