Const
How much of a pane (or the whole chart) must be repainted this frame.
Readonly
Repaint only the top (overlay) canvas — crosshair, hover, dragging primitives.
Recompute scales/ticks then repaint everything.
Repaint the base canvas at the current scales — series moved/changed, no rescale.
Nothing to do.
How much of a pane (or the whole chart) must be repainted this frame.