topic Re: How do i rotate a Polygon programmaticly? in ArcGIS JavaScript Maps SDK Questions

How do i rotate a Polygon programmaticly?

Anonymous User — Tue, 08 Apr 2014 21:18:03 GMT

Original User: mmoles

I know the toolbar has a rotate option, but how can i rotate polygons programmaticly.

There must be some rotate function like rotate(myPolygon, deg, centerPoint) somewhere in there. If not, i guess i will need to write one myself =(

Re: How do i rotate a Polygon programmaticly?

JianHuang — Sat, 11 Dec 2021 17:04:53 GMT

Unfortunately, we didn't make it as an API.
You need to check dojox/gfx/matrix library. Here is the short but essential code:

var tx = matrix.rotategAt(angle, anchor);
graphic.getDojoShape().setTransform(tx);

Re: How do i rotate a Polygon programmaticly?

Anonymous User — Sat, 11 Dec 2021 17:04:56 GMT

Original User: mmoles

Unfortunately, we didn't make it as an API.
You need to check dojox/gfx/matrix library. Here is the short but essential code:
var tx = matrix.rotategAt(angle, anchor);
graphic.getDojoShape().setTransform(tx);

Sadly this wont work for me. The command just modifies the svg and not the polygon ring. I also wanted to use the geographic mercator system to define the location, which is probably still possible to do by creating a point in that coordinate or some other command. The next issue that I run into is that, when i would zoom out, it then refreshes the layer which removes my changes because its just a graphical change and not the object itself.

I guess i will need to start doing some math =(

Re: How do i rotate a Polygon programmaticly?

JianHuang — Wed, 09 Apr 2014 19:16:34 GMT

That code snippet is what we are using in the API to rotate the shape. Once it's done, you need to call graphic.setGeometry() to make it permanent.
There are a lot math going on, but still gfx library can do a lot heavy lifting part.

Re: How do i rotate a Polygon programmaticly?

Anonymous User — Wed, 09 Apr 2014 20:42:01 GMT

Original User: mmoles

That code snippet is what we are using in the API to rotate the shape. Once it's done, you need to call graphic.setGeometry() to make it permanent.
There are a lot math going on, but still gfx library can do a lot heavy lifting part.

Is it better to do it this way, or to modify the object and having it redraw?

I was using the mercator system and i was trying var tx = dojox.gfx.matrix.rotategAt(45, -10372784, 3316853) which sadly doesnt work. So, how can i convert a geo point to a browser coordinate?

Aaaand, last question... setGeometry(geometry) .... whats geometry do i pass in? The tempGraphicsLayer.graphics[2].getDojoShape() object that i did the transformation says it has no getExtent method.

Re: How do i rotate a Polygon programmaticly?

JianHuang — Wed, 09 Apr 2014 20:58:10 GMT

Please take a look:
https://developers.arcgis.com/javascript/jsapi/map-amd.html#toscreen

Re: How do i rotate a Polygon programmaticly?

Anonymous User — Wed, 09 Apr 2014 21:19:33 GMT

Original User: mmoles

awesome, i knew that was in there somewhere. I also edited my post after your reply asking 1 last question.

setGeometry(geometry) .... whats geometry do i pass in? The tempGraphicsLayer.graphics[2].getDojoShape() object that i did the transformation says it has no getExtent method. Same goes with trying to pass in tempGraphicsLayer.graphics[2].geometry funny enough.