topic Re: Setting map extent to a group of graphics in ArcGIS JavaScript Maps SDK Questions

Setting map extent to a group of graphics

SamirGambhir — Wed, 23 Feb 2011 02:51:50 GMT

Hi,
I am running a query to select a number of polygons based on an intersecting polygon. The selected polygons are contiguous and are highlighted when the query is complete. I am trying to set the map extent to the extent of all these polygons combined together but have been unsuccessful. I have tried suggestions posted on these forums and using samples provided by ESRI but am still unable to get the map to zoom to this area. I have tried creating an array to push graphics inside it. I have also tried creating a polygon feature, a feature set and a graphicsLayer as a container to hold all the selected graphics, but it didn't work. I am using ArcGIS Server 9.3 with JavaScript API. Please help.
(Note: The code below has been extracted from a longer version. It might be missing some braces)

function findPolygonsInExtent(extent) {

var graphics = map.graphics.graphics;
var attr =[];
var items = [];
        var graphic;
var len=0;

for (var i=0, il=graphics.length; i<il; i++) {
          graphic = graphics;
          if (extent.intersects(graphic.geometry)) {
   len = len + 1;
   var results = [];

   graphic.setSymbol(highlightSymbol);
   var featureAttributes = graphic.attributes;
   for (att in featureAttributes) {
             var s = featureAttributes[att];
    results.push(s);
   }

   attr = results.slice(0,10);
   for(var j=0, jl=10; j<jl; j++)
   {
    items.push(attr);
   }

    } //if

          else if (graphic.symbol == highlightSymbol) {
            graphic.setSymbol(symbol);
          }

        } //for
map.setExtent(//some polygon feature//.geometry.getExtent());
}

Re: Setting map extent to a group of graphics

HemingZhu — Wed, 23 Feb 2011 12:50:25 GMT

Hi,
I am running a query to select a number of polygons based on an intersecting polygon. The selected polygons are contiguous and are highlighted when the query is complete. I am trying to set the map extent to the extent of all these polygons combined together but have been unsuccessful. I have tried suggestions posted on these forums and using samples provided by ESRI but am still unable to get the map to zoom to this area. I have tried creating an array to push graphics inside it. I have also tried creating a polygon feature, a feature set and a graphicsLayer as a container to hold all the selected graphics, but it didn't work. I am using ArcGIS Server 9.3 with JavaScript API. Please help.
(Note: The code below has been extracted from a longer version. It might be missing some braces)

function findPolygonsInExtent(extent) {

var graphics = map.graphics.graphics;
var attr =[];
var items = [];
        var graphic;
var len=0;

for (var i=0, il=graphics.length; i<il; i++) {
          graphic = graphics;
          if (extent.intersects(graphic.geometry)) {
   len = len + 1;
   var results = [];

   graphic.setSymbol(highlightSymbol);
   var featureAttributes = graphic.attributes;
   for (att in featureAttributes) {
             var s = featureAttributes[att];
    results.push(s);
   }

   attr = results.slice(0,10);
   for(var j=0, jl=10; j<jl; j++)
   {
    items.push(attr);
   }

    } //if

          else if (graphic.symbol == highlightSymbol) {
            graphic.setSymbol(symbol);
          }

        } //for
map.setExtent(//some polygon feature//.geometry.getExtent());
}

the utility function esri.graphicsExtent(graphics) returns the extent of graphics. It included in javascript api 1.6. So it should wok on ArcGIS server 9.3. If not, you just have to create a logic in you for loop for (var i=0, il=graphics.length; i<il; i++) to calculate an extent that contains all your graphics. let me know if you need more help on how.

Re: Setting map extent to a group of graphics

SamirGambhir — Wed, 23 Feb 2011 13:19:37 GMT

Thanks Heming,
I looked up ARcGIS resource Center but could not find any example to use esri.graphicsExtent function. I'll really appreciate it if you can guide me a bit more.
Thanks
Samir

Re: Setting map extent to a group of graphics

HemingZhu — Wed, 23 Feb 2011 14:01:29 GMT

Thanks Heming,
I looked up ARcGIS resource Center but could not find any example to use esri.graphicsExtent function. I'll really appreciate it if you can guide me a bit more.
Thanks
Samir

Here is link: http://help.arcgis.com/en/webapi/javascript/arcgis/help/jsapi/namespace_esri.htm#esri.graphicsExtent . could use this method like this. var extent =esri.graphicsExtent(map.graphics.graphics)... map.setExtent(extent).

Re: Setting map extent to a group of graphics

SamirGambhir — Wed, 23 Feb 2011 14:20:48 GMT

Thanks Heming,
I am not sure where to put his piece of code in my code. If you notice, I am selecting a subset of graphics from the overall set of graphics based on the intersecting criteria. I need to set the extent to the selected subset of graphics only.
Thanks again,
Samir

Re: Setting map extent to a group of graphics

HemingZhu — Wed, 23 Feb 2011 14:42:59 GMT

Hi,
I am running a query to select a number of polygons based on an intersecting polygon. The selected polygons are contiguous and are highlighted when the query is complete. I am trying to set the map extent to the extent of all these polygons combined together but have been unsuccessful. I have tried suggestions posted on these forums and using samples provided by ESRI but am still unable to get the map to zoom to this area. I have tried creating an array to push graphics inside it. I have also tried creating a polygon feature, a feature set and a graphicsLayer as a container to hold all the selected graphics, but it didn't work. I am using ArcGIS Server 9.3 with JavaScript API. Please help.
(Note: The code below has been extracted from a longer version. It might be missing some braces)

function findPolygonsInExtent(extent) {

var graphics = map.graphics.graphics;
var attr =[];
var items = [];
var graphic;
var len=0;
   var intersectedGraphics =[];

for (var i=0, il=graphics.length; i<il; i++) {
graphic = graphics;
if (extent.intersects(graphic.geometry)) {
   intersectedGraphics.push(graphic);
len = len + 1;
var results = [];

graphic.setSymbol(highlightSymbol);
var featureAttributes = graphic.attributes;
for (att in featureAttributes) {
var s = featureAttributes[att];
results.push(s);
}

attr = results.slice(0,10);
for(var j=0, jl=10; j<jl; j++)
{
items.push(attr);
}

} //if

else if (graphic.symbol == highlightSymbol) {
graphic.setSymbol(symbol);
}

} //for
   var extent =esri.graphicsExtent(intersectedGraphics);
map.setExtent(extent);
}

Re: Setting map extent to a group of graphics

SamirGambhir — Wed, 23 Feb 2011 15:28:40 GMT

Hi Heming,
This works great! Thanks for all your help.
Samir

Re: Setting map extent to a group of graphics

JasonMiller1 — Thu, 10 Mar 2011 18:10:30 GMT

I'm doing this same thing, using the same method. It works for me some of the time. I have a map that puts a route on there, similar to driving directions you'd get from Google maps and whatnot. Sometimes, it zooms in perfectly. Sometimes it zooms in too far, so it cuts the part of the route off. Any idea what would cause this?

Re: Setting map extent to a group of graphics

HemingZhu — Thu, 10 Mar 2011 18:16:49 GMT

I'm doing this same thing, using the same method. It works for me some of the time. I have a map that puts a route on there, similar to driving directions you'd get from Google maps and whatnot. Sometimes, it zooms in perfectly. Sometimes it zooms in too far, so it cuts the part of the route off. Any idea what would cause this?

Use the map.setExtent(yourExtent, true) instead of map.setExtent(yourextent). It will garantee that your extent will fully show.

Re: Setting map extent to a group of graphics

JasonMiller1 — Fri, 11 Mar 2011 11:22:18 GMT

So simple, but that works like a champ. Thanks for your help!