Function beginPick

Arm the next plot click to resolve to a price, a bar time, or both as a 'point' (PickPoint), and hand it to cb. Returns a cancel function; calling it (or arming another pick on the same chart) disarms without calling back. The chart emits pick:start ({ kind }) and pick:end ({ kind, value }, value null when cancelled) so a host can show its own cursor or hint while the pick is live.

A time is snapped to the bar the click landed on, because a time between two bars matches no bar and anything anchored to it would never line up. Clicking past the last bar keeps the projected time, which is what a pick in the empty right-hand space means.

Arm the next plot click to resolve to a price, a bar time, or both as a 'point' (PickPoint), and hand it to cb. Returns a cancel function; calling it (or arming another pick on the same chart) disarms without calling back. The chart emits pick:start ({ kind }) and pick:end ({ kind, value }, value null when cancelled) so a host can show its own cursor or hint while the pick is live.

A time is snapped to the bar the click landed on, because a time between two bars matches no bar and anything anchored to it would never line up. Clicking past the last bar keeps the projected time, which is what a pick in the empty right-hand space means.