Buffer a circle

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12-16-2014 09:08 AM
OliviaGill
New Contributor

What's the simplest way to create a buffer round a circle. The current application creates a square buffer and I want it to reflect the circle shape. I've tried using getExtent but it just draws a square:

if (geometry.type === "polygon") {

var searchExtent = geometry.getExtent();

        var biggerExtent = new esri.geometry.Extent(searchExtent.getExtent().expand(1));

        wkid : 27700;

I also tried getCenter:

if (geometry.type === "polygon") {

var searchExtent = geometry.getExtent();

var centerPoint = newGeometry.getCenter();

var radius = newGeometry.getExtent().getWidth()/2;

var circleGeometry = new Circle(center, {"radius": radius});

        wkid : 27700;

which returns an error. Can anyone help please?

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4 Replies
StevenGraf1
Regular Contributor

Have you checked out this sample?  Go down to the html and change LINE/POLYLINE/etc to CIRCLE.

<button data-dojo-type="dijit.form.Button" onclick="app.tb.activate(esri.toolbars.Draw.CIRCLE);app.map.hideZoomSlider();">Line</button>

This will allow you to draw a circle and apply a buffer.

Steven

ReneRubalcava
Frequent Contributor

I'm not sure why you're code errors out, but I modified this sample to work. It buffers or a point or the center of a polygon without using the geometry service.

JS Bin - Collaborative JavaScript Debugging

If you have some sample code of the issue, it may help.

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OliviaGill
New Contributor

Hi Rene

I've included the script here that I started with. I've tried the suggestions this morning but still finding it rather confusing - will stick at it and see what I can come up with - any help appreciated. Sample code here:

JS Bin - Collaborative JavaScript Debugging

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YungKaiChin
Occasional Contributor

If you just want to add a circle (instand of a 'real' buffer), you could:

var firstCircle = new Circle(center, {blah});

var secondCircle = new Circle(firstCircle.center, {"radius": (firstCircle.radius +/- whatever)});

If you want to create a buffer, I would recommend creating it via BufferParameters and GeometryService.

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