An OpenSeadragon plugin to allow restricting the image zoom to specific levels.
Currently only works with single images!
http://picturae.github.io/openseadragonselection/#tabs-zoom-levels
This plugin requires a version of OpenSeadragon later than 2.0
Include dist/openseadragonzoomlevels.js after OpenSeadragon in your html. Then after you create a viewer:
var zoomLevels = viewer.zoomLevels({
levels: [0.1, 0.5, 1]
});
Zoom levels are specified as an array of Floats where 1 is 100%. Allows zooming only to specific levels.
When minZoomImageRatio, maxZoomPixelRatio, minZoomLevel and/or maxZoomLevel are in conflict with this, the most restrictive options are used. defaultZoomLevel is always respected, even if not in this list.
If zoomPerScroll is too big, some levels might be skipped, so a small value is recommended (e.g. 1.00001).