  We generalise the celebrated semiclassical wavepacket approach from the
adiabatic to the non-adiabatic regime. A unified description covering both of
these regimes is particularly desired for systems with spatially varying band
structures where band gaps of various sizes are simultaneously present, e.g. in
moir\'{e} patterns. For a single wavepacket, alternative to the previous
derivation by Lagrangian variational approach, we show that the same
semiclassical equations of motion can be obtained by introducing a
spatial-texture-induced force operator similar to the Ehrenfest theorem. For
semiclassically computing the current, the ensemble of wavepackets based on
adiabatic dynamics is shown to well correspond to a phase-space fluid for which
the fluid's mass and velocity are two distinguishable properties. This
distinction is not inherited to the ensemble of wavepackets with the
non-adiabatic dynamics. We extend the adiabatic kinetic theory to the
non-adiabatic regime by taking into account decoherence, whose joint action
with electric field favours certain form of inter-band coherence. The
steady-state density matrix as a function of the phase-space variables is then
phenomenologically obtained for calculating the transport current. The result,
applicable with a finite electric field, expectedly reproduces the known
adiabatic limit by taking the electric field to be infinitesimal, and therefore
attains a unified description from the adiabatic to the non-adiabatic
situations.
