topic Re: 4.2 goTo collection of graphics with buffer in ArcGIS JavaScript Maps SDK Questions

4.2 goTo collection of graphics with buffer

JasonRainwater — Wed, 25 Jan 2017 17:22:42 GMT

Hi, I have a client side only feature layer that I add graphics to based on external data. When I use mapView.goTo(featureLayer.source) it properly changes the zoom and panning to bring all graphics into view. However it does not take into account the sizing of the graphics themselves so while the points are all view some graphics will be cut off out of full view.

Is there a way to goTo a collection of graphics but give it a buffer so that it goes out far enough to ensure the graphics are fully in view? I can determine the buffer myself but cant find in the documentation how to do this.

Thanks

Re: 4.2 goTo collection of graphics with buffer

JasonRainwater — Wed, 25 Jan 2017 18:07:55 GMT

To clarify, I would like whatever the zoom level is determined from the goTo to be +1 of whatever it would calculate

Re: 4.2 goTo collection of graphics with buffer

RobertScheitlin__GISP — Thu, 26 Jan 2017 14:08:31 GMT

Jason,

I don't see a way to do this in one step (currently in the API) but you could do

mapView.goTo(featureLayer.source).then(function(){mapView.zoom = mapView.zoom + 1});‍

Re: 4.2 goTo collection of graphics with buffer

JasonRainwater — Thu, 26 Jan 2017 14:28:33 GMT

I actually tried that. mapView.zoom is -1 at this time and even if I hard code setting zoom to a value of 4 if I inspect the value after setting it its still -1 so its as if the setter is throwing the value away. maybe its "isInteracting" or something and you cant change the zoom while its interacting?

Re: 4.2 goTo collection of graphics with buffer

RobertScheitlin__GISP — Thu, 26 Jan 2017 14:42:59 GMT

Jason,

Well the first thing I would try is setTimeout in the then function then to see if it is a timing issue.

mapView.goTo(featureLayer.source).then(function(){setTimeout(function(){mapView.zoom = mapView.zoom + 1}, 50)});

Re: 4.2 goTo collection of graphics with buffer

thejuskambi — Thu, 26 Jan 2017 14:52:11 GMT

Jason,

Have you tried to get the extent of the featureLayer and then expanding/buffer the geometry by a factor. That way your target geometry will always be bigger then the featureLayer.

-Thejus

Re: 4.2 goTo collection of graphics with buffer

JasonRainwater — Thu, 26 Jan 2017 18:04:06 GMT

I don't see how that works. its a custom empty feature layer added on the fly. when I check the fullextent property of the feature layer its null

Re: 4.2 goTo collection of graphics with buffer

JasonRainwater — Thu, 26 Jan 2017 18:07:52 GMT

tried that. same issue. -1 before the goTo, -1 after the goTo, -1 after the setTimeout (I waited 1000ms), -1 after I try to set it to any value

Re: 4.2 goTo collection of graphics with buffer

RobertScheitlin__GISP — Thu, 26 Jan 2017 18:12:07 GMT

Jason,

So does your map have a basemap?

Re: 4.2 goTo collection of graphics with buffer

JasonRainwater — Thu, 26 Jan 2017 18:15:07 GMT

it does not. loading a mapserver using Layer.fromArcGisServerUrl then adding a dynamic feature layer on top of that that I then add points to manually based on external data

Re: 4.2 goTo collection of graphics with buffer

RobertScheitlin__GISP — Thu, 26 Jan 2017 18:18:54 GMT

Jason,

Now it makes sense that your zoom is -1 then. The zoom comes from the LODs of a basemap. So you need to sets the mapView.scale then instead.

Re: 4.2 goTo collection of graphics with buffer

JasonRainwater — Thu, 26 Jan 2017 18:41:26 GMT

That worked! I multiply the scale by 1.1 after the goTo and my visuals are fully in view. However now it kind of jumps around a little

Re: 4.2 goTo collection of graphics with buffer

RobertScheitlin__GISP — Thu, 26 Jan 2017 18:49:53 GMT

Jason,

That may have to be a side effect you have to deal with for now. In the 3.x API there was a graphicsUtils class that allowed to to get the extent of the of a FeatureLayers graphics (and thus handled the clientside FL not having a fullextent), but it has not been added to 4.x yet.

Re: 4.2 goTo collection of graphics with buffer

JasonRainwater — Thu, 26 Jan 2017 19:26:03 GMT

What I don't understand is that the calculations have to be in the sdk somewhere because goTo figures it out and scales/pans to it correct?

Re: 4.2 goTo collection of graphics with buffer

RobertScheitlin__GISP — Thu, 26 Jan 2017 19:29:16 GMT

Correct it is probably some private internal function of the view or the FeatureLayer.