navigation.zoomPresets

Zoom menu levels and button steps (1 = 100%), kept inside minZoom–maxZoom. The default applies when the option is left out (it is not a key of DEFAULT_CONFIG). Presets are sorted and de-duplicated; a level outside minZoom–maxZoom is left out with a console warning. When none is left, the default levels inside the range are used, and when none of those fits either, the range's two ends — the zoom menu never offers a level the viewer will not reach.

navigation: { zoomPresets: [0.5, 1, 1.5, 2] }