Is it possible to get ahold of the Drawing?

[kindaro]

So there is this issue elsewhere Twinside/Rasterific#53 and I need to provide some debug output which in turn requires me to feed in a Drawing type thing. I am not sure how to go about rendering my diagram to that type. It seems that renderDia can only give me an Image, which is a later stage of the diagram's lifeline.

[byorgey]

So unfortunately there is no really easy way to do this. The definition of renderRTree for the Backend Rasterific instance compiles the diagram to a Drawing and then immediately renders it without ever giving access to the intermediate result. You can see the code here:

https://github.com/diagrams/diagrams-rasterific/blob/master/src/Diagrams/Backend/Rasterific.hs#L182

One solution would be to manually call the part of the definition up to the Drawing, but this is a bit complicated by the fact that you would have to manually compose it with the other things the generic renderDia is doing (rescaling, centering, etc. --- see https://github.com/diagrams/diagrams-core/blob/master/src/Diagrams/Core/Compile.hs#L188) to get all the coordinates to come out right . Another option, but also annoying, would be to copy the entirety of Diagrams.Backend.Rasterific and modify the Backend instance to have type Result Rasterific V2 n = (Image PixelRGBA8, Drawing) or something like that. Then modify the renderRTree method to return a pair, like (R.renderDrawing (round w) (round h) bgColor r, r).