Dragging and zooming in Plot.geo

[espinielli]

I used to zoom and drag maps using base d3…I wonder whether something like d3-versor-dragging is applicable to Plot.geo…or something else, BTW.

Thanks for any feedbacks

[Fil]

Hi Enrico,

here’s a port of the D3 notebook for Plot: Plot: Versor Zooming / Observable | Observable

I fixed several issues since yesterday's version:

• the behavior is now local to the mark
• a pointer-events: all style on the plot ensures that it works on mobile
• the behavior also covers a dot mark

You can disable the zooming part by specifying a zoomExtent [1, 1].

The centroid transform is not great for labels, because when a shape extends on both sides of the map, its centroid might be in the middle. See #2098 for a better alternative.

[Fil]

also the Bertin projection is not really meant to be rotated!

[espinielli]

I know but I like to start with that and then zoom and rotate...once users have tools they can harm themselves ;-)

[espinielli]

Strangely enough, in World FIRs with zoom and rotate if I rotate, say, 180 degrees I lose the Plot.text labels and have to re-run the chart to get them repainted...

[Fil]

Good observation. That's due to projection clipping. Points that are clipped initially (because they are on the other side of the globe) always are invisible, and conversely points that are visible initially always are visible (even if you rotate them out). We can use https://observablehq.com/@d3/testing-projection-visibility to solve this (I've updated the notebook accordingly).

[espinielli]

you are stratospheric!
Thanks!