  We develop a resource theory for continuous-variable systems grounded on
operations routinely available within current quantum technologies. In
particular, the set of free operations is convex and includes quadratic
transformations and conditional coarse-grained measurements. The present theory
lends itself to quantify both quantum non-Gaussianity and Wigner negativity as
resources, depending on the choice of the free-state set --- i.e., the convex
hull of Gaussian states or the states with positive Wigner function,
respectively. After showing that the theory admits no maximally resourceful
state, we define a computable resource monotone --- the Wigner logarithmic
negativity. We use the latter to assess the resource content of experimentally
relevant states --- e.g., photon-added, photon-subtracted, cubic-phase, and cat
states --- and to find optimal working points of some resource concentration
protocols. We envisage applications of this framework to sub-universal and
universal quantum information processing over continuous variables.
