How to get zoom steps from diagram

GoJS
1

I am using zoom control with % for this I need to calculate zoom steps for that I can zoom in or out smoothly as expected.
Actually the issue is while I am using increaseZoom and decreaseZoom and looking into the difference, which is not constant.

2

Yes, the behavior of CommandHandler.increaseZoom and decreaseZoom changes the Diagram.scale by multiplication, not by addition. You can change that factor by setting CommandHandler | GoJS API.

If you don’t want the current implementation of those two methods, you can override them to do what you want.

Here’s what one command does:

CommandHandler.prototype.increaseZoom = function(factor) {
  if (factor === undefined) factor = this.zoomFactor;
  var diagram = this.diagram;
  if (diagram === null) return;
  if (diagram.autoScale !== go.Diagram.None) return;
  var newscale = diagram.scale * factor;
  if (newscale < diagram.minScale || newscale > diagram.maxScale) return;
  diagram.scale = newscale;
};