What's the correct way to render a bitmap while panning and zooming using Sharp DX Direct 2D?

Question

I'm attempting to display dxf files using sharp DX. It's running too slow while panning so I'm trying to use a cached bitmap during this but I can't get the bitmap to show in the correct location on the render target. I've a link below for the class in question. I've tried handling the transforms in many different ways but it doesn't seem to affect it. What am I missing here?

git