private static void ResetLabels()
{
QueuedTask.Run(async() =>
{
//Get the line feature we want to clear labels for
var featureLayer = MapView.Active.Map.GetLayersAsFlattenedList().Where(f => f.Name == "U.S. Rivers (Generalized)").FirstOrDefault() as FeatureLayer;
if (featureLayer == null)
{
return;
}
// create an instance of the inspector class
var inspector = new ArcGIS.Desktop.Editing.Attributes.Inspector();
//Clear the previous "Yes" values for the LabelOn field.
//Create a QueryFilter to search for all features that have the LabelOn field value set at Yes.
var qf = new QueryFilter
{
WhereClause = "LabelOn = 'Yes'"
};
var selectionLabelOnYes = featureLayer.Select(qf);
var featuresToClear = selectionLabelOnYes.GetObjectIDs()?.ToList();
if (featuresToClear.Count > 0)
{
// load the features into the inspector using a list of object IDs
await inspector.LoadAsync(featureLayer, featuresToClear);
// assign the attribute value of "No" to the field "LabelOn"
// if more than one features are loaded, the change applies to all features
inspector["LabelOn"] = "No";
// apply the changes as an edit operation
await inspector.ApplyAsync();
}
});
}
/// <summary>
/// The features are labeled using a Field in the feature layer. The field LabelOn has values Yes or No.
/// If the value is "Yes", that feature will be labeled. If value is No, the feature will not be labeled.
/// </summary>
/// <param name="geometry"></param>
/// <returns></returns>
protected override Task <bool> OnSketchCompleteAsync(Geometry geometry)
{
QueuedTask.Run(async() =>
{
//select features that intersect the sketch geometry
var selection = MapView.Active.SelectFeatures(geometry, SelectionCombinationMethod.New);
//Get the line feature we want to label
var featureLayer = selection.Where(f => f.Key.Name == "U.S. Rivers (Generalized)").FirstOrDefault().Key as FeatureLayer;
if (featureLayer == null)
{
return;
}
//Get the list of line features that are selected
var oidsOfSelectedFeature = selection[featureLayer];
if (oidsOfSelectedFeature.Count == 0)
{
return;
}
//We want to only label the selected features. So..
//Clear the previous "Yes" values for the LabelOn field.
//Create a QueryFilter to search for all features that have the LabelOn field value set at Yes.
// create an instance of the inspector class
var inspector = new ArcGIS.Desktop.Editing.Attributes.Inspector();
var qf = new QueryFilter
{
WhereClause = "LabelOn = 'Yes'"
};
var selectionLabelOnYes = featureLayer.Select(qf);
var featuresToClear = selectionLabelOnYes.GetObjectIDs()?.ToList();
if (featuresToClear.Count > 0)
{
// load the features into the inspector using a list of object IDs
await inspector.LoadAsync(featureLayer, featuresToClear);
// assign the attribute value of "No" to the field "LabelOn"
// if more than one features are loaded, the change applies to all features
inspector["LabelOn"] = "No";
// apply the changes as an edit operation
await inspector.ApplyAsync();
}
//Now modify the features that are selected by the tool to have the value Yes
await inspector.LoadAsync(featureLayer, oidsOfSelectedFeature);
// assign the attribute value of "Yes" to the field "LabelOn" for the features selected
// if more than one features are loaded, the change applies to all features
inspector["LabelOn"] = "Yes";
// apply the changes as an edit operation
await inspector.ApplyAsync();
//Get the layer's definition
var lyrDefn = featureLayer.GetDefinition() as CIMFeatureLayer;
//Get the label classes - and check if the correct label class we need to label the line features with exists
var listLabelClasses = lyrDefn.LabelClasses.ToList();
var theLabelClass = listLabelClasses.Where(l => l.Name == "LabelSelectedManyFeaturesWithLength").FirstOrDefault();
if (theLabelClass == null) //create label class and add to the collection
{
theLabelClass = await CreateAndApplyLabelClassAsync(featureLayer);
listLabelClasses.Add(theLabelClass);
}
//Turn off all the label classes except this one
foreach (var lc in listLabelClasses)
{
lc.Visibility = lc.Name == "LabelSelectedManyFeaturesWithLength" ? true : false;
}
//Apply the label classes back to the layer definition
lyrDefn.LabelClasses = listLabelClasses.ToArray();
//Set the layer definition
featureLayer.SetDefinition(lyrDefn);
//set the label's visiblity
featureLayer.SetLabelVisibility(true);
});
return(base.OnSketchCompleteAsync(geometry));
}