I've been playing around with WPF animation, and ended up wanting to take a snapshot of an animation at a specific place.

Specifically, I have a canvas that has some pictures on it that are moving, and I want to be able to save a bitmap of what it looks like at a specific time.

Getting the bitmap is pretty easy, using a RenderTargetBitmap and a VisualBrush.

private BitmapSource CaptureScreen(Visual target)
{

    Rect bounds = VisualTreeHelper.GetDescendantBounds(target);

    RenderTargetBitmap renderBitmap = new RenderTargetBitmap(800, 600, 96, 96, PixelFormats.Pbgra32);

    DrawingVisual dv = new DrawingVisual();
    using (DrawingContext ctx = dv.RenderOpen())
    {
        VisualBrush vb = new VisualBrush(target);

        ctx.DrawRectangle(vb, null, new Rect(new Point(), bounds.Size));
    }
    renderBitmap.Render(dv);

    return renderBitmap;
}

That gives you the state of the objects pre-animation, but what I really wanted was the state of the objects during the animation. I had some code to move the image around:

    DoubleAnimation anim = new DoubleAnimation(50, 400, TimeSpan.FromSeconds(10), FillBehavior.HoldEnd);
    AnimationClock clock = anim.CreateClock();
    m_imageLeft.ApplyAnimationClock(Canvas.LeftProperty, clock);