topic Move Polygon by centroid in ArcGIS JavaScript Maps SDK Questions

Move Polygon by centroid

RodrigoFelga — Fri, 20 Oct 2017 13:15:04 GMT

Is there a easy way to move a polygon by its centroid on js API 4.x? I'm trying to implement a function where the user can drag a polygon of a graphicslayer on the screen

Re: Move Polygon by centroid

ThomasSolow — Fri, 20 Oct 2017 14:17:55 GMT

There's no built-in way to do this. In general, you need to clone a graphic, change the geometry on the clone, add clone to the layer, and then remove the old graphic. You can't just change the geometry. This will hopefully change in the future.

In terms of how you'd implement this, I would approach this by determining the difference in X and Y between "the handle" ie the centroid in your case, but possibly any point inside the polygon, and the current location of the mouse. Then you'll want to translate every vertex in every ring of the polygon by that amount in X and Y. I'll see if I can put together a simple example of this.

Re: Move Polygon by centroid

ThomasSolow — Fri, 20 Oct 2017 14:52:15 GMT

Here's a sample showing how you might allow points, polylines, and polygons to be dragged. In this example I'm using wherever the user clicked inside the polygon as the handle. You could easily use the centroid of the polygon as the origin/handle if you like: https://codepen.io/solowt/pen/QqoaeK?editors=1000#0

Re: Move Polygon by centroid

RodrigoFelga — Fri, 20 Oct 2017 15:13:57 GMT

That's exact what I need, thank you