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Initiate panel upon zoom level

BenKane

I am trying to generate a panel popup when the zoom level exceeds a certain scale. I have been able to use lods to switch from one map service to another at the specified scale, but I would like to have a popup that explains the reason for the switch.

Specifically, I am trying to figure out how to call a specific LOD from my lods array with com.esri.ags.Map.zoomEnd, only initiating the popup panel for a specified zoom level. Right now it will popup at any zoomEvent, but I only want it at one LOD.

I am using Flex API 2.4.

Any ideas?

Thanks

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BenKane

I've used a layerUpdateStartHandler() to create an alert panel when the map is zoomed to a certain scale...the next problem is how to prevent the function from firing on layer updates after the first event (e.g. I don't want the alert to show if the map is panned after reaching this zoom scale).

Any guidance would be appreciated.

RobertScheitlin__GISP

Ben,

Check and see if the map.scale is the same as when the panel was fired.

BenKane

Robert,
map.scale is the same each time the panel fires when panning after the initial zoom level is reached.

Perhaps a I could put a panEvent function that cancels the layerUpdate event? Do you think that would work, or do you have and idea for a different solution?

RobertScheitlin__GISP

Ben,

That's what I meant if it is the same (because you are just panning) then don't display the panel.

BenKane

Robert,

I've been trying to do that but have been unable to figure out the syntax for this...can you provide example code please?

Thanks

RobertScheitlin__GISP

Ben,

Share what you have and I will see if I can fix it.

BenKane

Robert,
The scale at the zoom level is 72223.819286.
Here is my code, I'm relatively new to Flex and I don't have much understanding of the interaction between elements:

   protected function _updateStartHandler(event:LayerEvent):void
   {
    
     var Layer:ArcGISDynamicMapServiceLayer = event.target as ArcGISDynamicMapServiceLayer;    
     Alert.show("You have reached the limit of the zoom level for this layer."); 
     
    }
   protected function myMap_panStartHandler(event:PanEvent):void
   {
    if (myMap.scale == 72223.819286)
    {
     _updateStartHandler(null)
    }
    
   }

And the code for map:

  <esri:Map id="myMap" logoVisible="false"
      load="addLODs() + onMapLoad()"
      level="3"
      extent="{initialExtent}"
      top="89"
      panStart="myMap_panStartHandler(event)"
      panEnd="myMap_panStartHandler(event)"
      panUpdate="myMap_panStartHandler(event)"
      >

Code for the layer the handler is attached to:

   <esri:ArcGISDynamicMapServiceLayer id="zoomMax" alpha="0" 
            url="http://*mylayer*/MapServer"
            minScale="72223.819286"
            updateStart="_updateStartHandler(event)"
            />

Thanks

RobertScheitlin__GISP

Ben,

I had to find time to write an sample:

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx"
               xmlns:esri="http://www.esri.com/2008/ags"
               minWidth="955" minHeight="600">
    <fx:Script>
        <![CDATA[
            import com.esri.ags.events.LayerEvent;
            import com.esri.ags.events.MapEvent;
            import com.esri.ags.layers.supportClasses.LOD;
            
            import mx.controls.Alert;
            
            private var LastMapExt:Extent;
            private var PanelShown:Boolean;
            
            protected function zoomMax_updateStartHandler(event:LayerEvent):void
            {
                if (myMap.scale == 72223.819286){
                    LastMapExt = myMap.extent;
                    if(LastMapExt && !PanelShown){
                        PanelShown = true;
                        Alert.show("You have reached the limit of the zoom level for this layer.");
                    }
                }else{
                    PanelShown = false;
                    LastMapExt = null;
                }
            }
            
            private function addLODs(event:MapEvent):void
            {                
                var lods:Array = myMap.lods;
                lods.push(new LOD(19, 0.149291071, 564.2485881));
                lods.push(new LOD(18, 0.29858214171376, 1128.4971762));
                lods.push(new LOD(17, 0.59716428342752, 2256.9943525));
                lods.push(new LOD(16, 1.19432856685505, 4513.988705));
                lods.push(new LOD(15, 2.38865713397468, 9027.977411));
                lods.push(new LOD(14, 4.77731426794937, 18055.954822));
                lods.push(new LOD(13, 9.55462853563415, 36111.909643));
                lods.push(new LOD(12, 19.1092570712683, 72223.819286));
                lods.push(new LOD(11, 38.2185141425366, 144447.638572));
                lods.push(new LOD(10, 76.4370282850732, 288895.277144));
                myMap.lods = lods;
            }

            
        ]]>
    </fx:Script>
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>
    
    <esri:Map id="myMap"
              logoVisible="false"
              load="addLODs(event)">
        <esri:extent>
            <esri:Extent xmin="-9598200" ymin="3968200" xmax="-9500400" ymax="4026200">
                <esri:SpatialReference wkid="102100"/>
            </esri:Extent>
        </esri:extent>
        
        <esri:ArcGISTiledMapServiceLayer url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"/>
        <esri:ArcGISDynamicMapServiceLayer id="zoomMax" alpha="1" 
                                           url="http://*mylayer*/MapServer"
                                           visible="true" minScale="72223.819286" 
                                           updateStart="zoomMax_updateStartHandler(event)"/>
    </esri:Map>
</s:Application>

BenKane

Robert, thank you so much, that works beautifully! Really appreciate your time and help.

Ben

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