topic Re: Controlling Layers in Legend Control in ArcGIS API for Silverlight Questions

Controlling Layers in Legend Control

PaulHuppé — Tue, 04 Jan 2011 12:02:16 GMT

Hi,

I am testing the new Legend Control in the 2.1 API. Is there a way to control what is shown or not shown in the Table OF Contents? In particular, I do not want to show the Graphics Layer used to display results. There does not seem to be any options directly on the <esri:GraphicsLayer> or the <esri:Legend> tags. What would be nice is to have a ShowInLegend="false" attribute on the <esri:GraphicsLayer> tag. Is there an easy way to remove the layer from the legend?

Thanks,
Paul

Re: Controlling Layers in Legend Control

ErikEngstrom — Tue, 04 Jan 2011 12:36:50 GMT

Set the LayerIDs property of the legend control.

So for instance, you only want to display your baselayer in the legend:
<esri:Map>
<esri:ArcGISTiledMapServiceLayer ID="baseLayer" Url="..." />
</esri:Map>

in legend:
<esri:legend Map="{Binding ElementName=MyMap}"
LayerItemsMode="Tree"
LayerIDs="baseLayer"
ShowOnlyVisibleLayers="True" />

To add layers to your legend, just separate them by a comma.

Re: Controlling Layers in Legend Control

PaulHuppé — Tue, 04 Jan 2011 12:48:14 GMT

Hi,

That might work, but if I have lots of layers, which I do, this list of IDs can become extremely long!!! Is there a limit to the length this string can be? I hope there is a better way than this because it may not be manageable for us.

Paul

Re: Controlling Layers in Legend Control

DominiqueBroux — Sun, 12 Dec 2021 08:17:49 GMT

Additionaly to the LayerIds property mentionned by Erike, you can dynamically remove legend items in the legend refreshed event.

For example if you don't want to see any GraphicsLayer, you can add this code:

private void Legend_Refreshed(object sender, Legend.RefreshedEventArgs e)
{
if (e.LayerItem.Layer is ESRI.ArcGIS.Client.GraphicsLayer)
    MyLegend.LayerItems.Remove(e.LayerItem);
}

You can obviously extend this sample by using another criteria than the layer type : for example a custom attached property.

Re: Controlling Layers in Legend Control

PaulHuppé — Tue, 04 Jan 2011 13:43:08 GMT

Hi,
I tried using the Remove in the Legend_Refreshed method as you suggested, and that does the trick.
Thanks,
Paul

Re: Controlling Layers in Legend Control

karenvolarich — Wed, 26 Jan 2011 23:50:00 GMT

Is there a way to remove the Bing basemap from the Legend? I tried using the same code as the GraphicsLayer, but it just doesn't see it.

if (e.LayerItem.Layer is ESRI.ArcGIS.Client.Bing.TileLayer)
MyLegend.LayerItems.Remove(e.LayerItem);

I also tried:

if (layerItemVM.Layer.ID == "BingLayer")
removeLayerItemVM = layerItemVM;

Any ideas?

Re: Controlling Layers in Legend Control

DominiqueBroux — Sun, 12 Dec 2021 08:17:51 GMT

Is there a way to remove the Bing basemap from the Legend? I tried using the same code as the GraphicsLayer, but it just doesn't see it.

You have to hookup the handler to the Refreshed event:

<esri:Legend x:Name="MyLegend" Map="{Binding ElementName=MyMap}" Height="400" Width="400" 
Refreshed="Legend_Refreshed" >

Then both versions of your code should work.

Re: Controlling Layers in Legend Control

karenvolarich — Thu, 27 Jan 2011 14:37:20 GMT

I already have that in my xaml:

<esri:Legend Map="{Binding ElementName=Map}"
                         Name="MyLegend"
                         LayerItemsMode="Tree"
                         ShowOnlyVisibleLayers="False"
                         Refreshed="Legend_Refreshed">

Any other ideas?

Thanks,
Karen

Re: Controlling Layers in Legend Control

DominiqueBroux — Sun, 12 Dec 2021 08:17:54 GMT

You are right there is an issue.The event is not fired with Bing layers (because this kind of layer doesn't return any legend).This is a bug that we'll try to fix for next version.For the moment, the workaround might be to remove the bing layers from the legend whatever the layer firing the event:

private void Legend_Refreshed(object sender, Client.Toolkit.Legend.RefreshedEventArgs e)
{
 foreach (var bingLayerItem in MyLegend.LayerItems.Where(item => item.Layer is TileLayer).ToList())
   MyLegend.LayerItems.Remove(bingLayerItem);
}

Not very elegant, but....

Re: Controlling Layers in Legend Control

karenvolarich — Thu, 03 Feb 2011 16:57:38 GMT

That works! Thanks.

Re: Controlling Layers in Legend Control

karenvolarich — Fri, 04 Feb 2011 01:16:06 GMT

I'm going to bounce one more question out there for you...

I have added the ability to dynamically add an ArcGISDynamicLayer Map Service to the map and to the TOC/Legend. But, it places it at the bottom of the legend, and I would like to place it at the top. There doesn't seem to be an "orderby" type method. I was looking at LegendUpdated but am not seeing anything that might assist in the ordering of the dynamically added data.

Re: Controlling Layers in Legend Control

DominiqueBroux — Sun, 12 Dec 2021 08:17:57 GMT

I have added the ability to dynamically add an ArcGISDynamicLayer Map Service to the map and to the TOC/Legend. But, it places it at the bottom of the legend, and I would like to place it at the top.

By default, the entries in the legend are in the same order than the layers in the map. So, if you add a layer at the bottom of the map, it will be at the bottom of the legend.

If you want to change this behavior, the easier way is to set the LayerIds property. The legend will be ordered as the LayerIds.

For some scenarios, it might also be useful to reorder dynamically by code on the event Legend.Refreshed.
A code like this one should do the job:

private void Legend_Refreshed(object sender, Legend.RefreshedEventArgs e)
{
  Legend legend = sender as Legend;
 if (e.LayerItem.Layer.ID == "MyTopLayerID")
  {
    legend.LayerItems.Remove(e.LayerItem); // Remove legend entry from its current location
    legend.LayerItems.Insert(0, e.LayerItem); //Add it at the top
  } 
}

Re: Controlling Layers in Legend Control

BrandonIves — Tue, 25 Nov 2014 15:49:56 GMT

Hey Dominique,

I can successfully remove a legend entry with your example above. How would I go about re-adding an item after removing it? Once I remove the LayerItem from the Legend l no longer have access to that layer to use the insert method.

Ex:

if(HPGasLegend == false){

if (layerItemVM.Layer.ID == "HP_Gas_Feeder_Layer")

{

Legend.LayerItems.Remove(e.LayerItem);

}

else

{

// here is where I would like to reinsert the layer above that I removed based on a checkbox checked/unchecked event

// when I hover over the legend object and look through the collection I no longer see my layer that with the ID of "HP_Gas_Feeder_Layer"

// in the collection

}

Thanks for any help!

Re: Controlling Layers in Legend Control

DominiqueBroux — Tue, 25 Nov 2014 16:24:46 GMT

The easiest way to get a layer out of the legend is to set the layer.ShowLegend property to false.

So by binding this layer property to your checkbox, you should directly get the expected behavior.

Else, if for any reason you'd rather using the Legend_Refreshed Handler, a couple of possible options:

- call Refresh on the Legend object (the drawback is that all legend layers will be refreshed)

- keep the legend item in a private field when you removed it, so you can readd it when needed.

Re: Controlling Layers in Legend Control

BrandonIves — Tue, 25 Nov 2014 20:45:07 GMT

I was attempting to keep a copy of the legend item and readd it but it seems like it will be overly complicated for multiple layers.

Could you give an example of the binding the layer property to the checkbox?

Thanks!

Re: Controlling Layers in Legend Control

BrandonIves — Tue, 25 Nov 2014 21:34:34 GMT

Nevermind Dominique,

I got it to work with this code. Thank you for your help in pointing me in the correct direction.

<CheckBox Content="CheckBox" Height="16" HorizontalAlignment="Left" Margin="331,261,0,0" VerticalAlignment="Top"

DataContext="{Binding Layers, ElementName=MyMap}"

IsChecked="{Binding [GasLayer].ShowLegend, Mode=TwoWay}" />