Programmatically rotate/zoom?

[Jianan-Li]

Is it possible to programmatically rotate/zoom alongside user interactions?

[vasturiano]

@Jianan-Li to set the rotation/scale programmatically you don't need this module. You can do it directly on the D3 projection itself, with https://github.com/d3/d3-geo#projection_rotate and https://github.com/d3/d3-geo#projection_scale.

This module is simply aconvenience layer to control those projection parameters by means of user interaction.

[antonytrupe]

I think this is the same thing I am experiencing...
After a user zoom and then a programmatic change of the scale via projection.scale, the next user interaction reverts the scale to the pre-programmatic value, if that makes sense. My hunch is something is storing the scale internally somewhere and ignoring the projection's current scale.

[antonytrupe]

I'm not sure what all ev.transform.k on https://github.com/vasturiano/d3-geo-zoom/blob/master/src/geoZoom.js#L51 is based on. It seems to be 'remembering' previous zooms, which I think it needs to in order to know the change, but I don't know how to influence it so it "sees" programmatic changes to zoom/scale.

[antonytrupe]

Found a solution. My specific case was programmatically resetting to the original orientation/scale as when zoom was added, so returning to the zoomIdentity makes geozoom aware of that.
d3.select(canvas).call(d3.zoom().transform,d3.zoomIdentity);