  We write down some relevant matrix elements for the scattering and decay
processes of the pion by considering a quark-meson vertex function. The pion
charge and transition form factors $F_\pi$, $F_{\pi\gamma}$, and
$F_{\pi\gamma^*}$ are extracted from these matrix elements using a relativistic
quark model on the light-front. We found that, the form factors $F_\pi$ and
$F_{\pi\gamma}$ in the space-like region agree well with experiment.
Furthermore, the branching ratios of all observed decay modes of the neutral
pion, that are related to the form factors $F_{\pi\gamma}$ and
$F_{\pi\gamma^*}$ in the time-like region, are all consistent with the data as
well. Additionally, $F_\pi$ in the time-like region, which deals with the
nonvalence contribution, is also discussed.
