  We present a calculation of the vector-isovector timelike form-factors of the
pion and the kaon using lattice quantum chromodynamics. We calculate two-point
correlation functions with $m_\pi \sim 280$ MeV, extracting both the
finite-volume spectrum and matrix elements for these states created from the
vacuum by a vector current. After determining the coupled-channel $\pi\pi,
K\overline{K}$ scattering amplitudes, we perform the necessary correction for
the significant finite-volume effects present in the current matrix elements,
leading to the timelike form-factors. We find these to be dominated by the
presence of the $\rho$ resonance, and we extract its decay constant by an
analytic continuation of the amplitudes to the resonance pole. In addition, the
spacelike pion form-factor is determined on the same lattice configurations,
and a dispersive parameterization is used to simultaneously describe the
spacelike and elastic timelike regions.
