Zoom and Pan events

[Kampii]

How do I monitor these events? The inspector demo did not have that info.

[asturur]

there is not event for those actions. you get the the zoomToPoint, setZoom, and absolutePan ( if i remember good). If you want to use them with interaction you will bind them to some events. (mouse move, mouse click... )

[Kampii]

Thanks! The pan part could be tracked by some "key down" event together with "mouse move" event. However, how would I track the mouse scroll event which zooms in/out?

[StephanBijzitter]

@asturur Is there any reason why these property changes do not trigger events?

I can imagine there will be enormous performance issues when the event handlers are unnecessarily big, but that should not be a concern for fabric as a library.

[asturur]

there is no particular reason.
We can add event for setZoom.
We can send the newZoom as parameter considering that zoom can be fired in anyway, so there is no event to send. For panning we have 2 functions ( absolute and relative ) and they can fire event also... But what can they bring as parameter?
Do we send a reference to the canvas that is firing the event?

[asturur]

We have events mainly for things we do with mouse or keyboard ( object:added and removed are exceptions).
We do not have a standard way of triggering a zoom or a pan, that is why we do not generate any event.

[asturur]

Before adding this event i should be sure we do not use setZoom and other stuff internally for processing. i think we do in dataUrl but i can still change that.
Some event like onZoom and onPan would be nice but those would not fire when people change viewport transform manually.