  We investigate the pion electromagnetic half off-shell form factors, which
parametrize the matrix element of the charged pion electromagnetic current with
one leg off-mass-shell and the other leg on-mass-shell, using an exactly
solvable manifestly covariant model of a $(3+1)$ dimensional fermion field
theory. The model provides a 3D imaging of the two off-shell pion form factors
$F_1$ and $F_2$ as a function of $(Q^2,t)$, which are related to each other
satisfying the Ward-Takahashi identity. The normalization of the renormalized
charge form factor $F_1$ is fixed by $F_1(Q^2=0, t=m^2_\pi)=1$ while the other
form factor $F_2$ vanishes, i.e. $F_2(Q^2, t=m^2_\pi)=0$ for any value of $Q^2$
due to the time-reversal invariance of the strong interaction. We define the
new form factor $g(Q^2,t)=F_2(Q^2,t)/(t-m^2_\pi)$ and find that $g(Q^2,t)$ can
be measurable in the on-mass-shell limit. In particular, $g(Q^2=0, t=m^2_\pi)$
is related with the pion charge radius. We also compare our form factors with
the data extracted from the pion electroproduction reaction for both the
off-shell region ($t<0$) and the on-shell limit ($t \rightarrow m_\pi^2$).
