topic Re: Zooming through a Loop of Features in ArcGIS JavaScript Maps SDK Questions

Zooming through a Loop of Features

TomLeMahieu — Mon, 08 Feb 2016 14:58:43 GMT

I am trying to step through a set of selected features, zoom to the extent of the feature, do something with it and then go to the next feature and do the same. I can't seem to trap the end of the zoom no matter what I do. Does anybody have code that does this successfully. It works fine for one. It just doesn't work when I loop through a set of features. Here's what I've tried:

printSingleParcelFeature: function (feature, callback) {
     var self = this;
     self.zoomSelectedOne(feature, function() {
          callback();
      });
},

zoomSelectedOne: function(feature, callback) {

var gExt;

var selectedExt;

//Also tried 'zoom-end'. That never works.

var mapZoomChange = this.map.on('extent-change', zoomHandler);

function zoomHandler() {

console.info("Extent Change");

setTimeout(lang.hitch(this, function () {

mapZoomChange.remove();

callback();

}), 1000);

}

gExt = feature.geometry.getExtent();

if (gExt) {

selectedExt = gExt.expand(this.zoomSelectExpand,true);

this.map.setExtent(selectedExt);

console.info("Set Extent: " + feature.attributes["PIN"]);

}

My console results are basically this:

I also tried this, but again the extent only changes for the last one:

zoomSelectedOne: function (feature, callback) {

var gExt;
var selectedExt;
gExt = feature.geometry.getExtent();
if (gExt) {
selectedExt = gExt.expand(this.zoomSelectExpand,true);
this.map.setExtent(selectedExt).then(callback());
}
},

Re: Zooming through a Loop of Features

TimWitt2 — Mon, 08 Feb 2016 15:27:21 GMT

Hey Tom,

Instead of waiting for the "extent-change" event to finish, use the featurelayer "update-end" event?

FeatureLayer | API Reference | ArcGIS API for JavaScript

Even though the extent is changed, i think your feature layer isn't ready yet?

Tim

Re: Zooming through a Loop of Features

KellyHutchins — Tue, 09 Feb 2016 18:57:59 GMT

Tom LeMahieu

One option would be to wait until setExtent is complete then do what you need to do then navigate to the next features extent. Here's a jsbin that shows zooming to a feature, generating a printout, then zooming to the next feature.

JS Bin - Collaborative JavaScript Debugging

Re: Zooming through a Loop of Features

TomLeMahieu — Wed, 10 Feb 2016 14:06:49 GMT

Kelly & Tim,

Thanks for your responses. Both helped get me on the right track. It ended up that my problem was how I was stepping through the selected features. It wasn't getting to the callback until it had stepped through all the features.

Not working:

Working:

for (var i = 0; i < numSelected; i++) {

feature = features;

self.printSoilErosionFeature(feature, function() {

//nothing

});

}

callback();

count = 0;

function processFeatures() {

if (features.length > count) {

var feature = features[count];

self.printSingleParcelFeature(feature, processFeatures)

count++;

} else {

callback();

}

processFeatures();