Handle rect with zero arguments.

[fryguybob]

Right now rect is implemented by scaling a unitSquare, but if given zero as an argument that scaling will not have a valid inverse. This shows up later as a NaN with doubles. Semantically a rect with zero is fine, however, as a line or four lines, depending on how we want to go about it.

Ryan

Sönke Hahn wrote:

Hi!

Is this wanted behaviour?

Prelude> import Diagrams.Prelude
Prelude Diagrams.Prelude> import Diagrams.Backend.Cairo
Prelude Diagrams.Prelude Diagrams.Backend.Cairo> size2D (rect 0 10 ::
QDiagram Cairo R2 Any)
[snip]
Loading package diagrams-cairo-0.5.0.2 ... linking ... done.
(NaN,NaN)

I would have expected (0, 10).

Thanks,
Sönke

[byorgey]

Note that this works as expected:

Diagrams.Prelude> size2D (rect 0 10 :: Path R2)
(0.0,10.0)

Perhaps instead of scaling unitSquare we could call pathLike directly?