wpf - Rehosted WF4 Delete Activity scenario -

in order reach context of assign activity, hosted custom activity follows :

<sap:activitydesigner x:class="ariasquiblibrary.design.customasigndesigner" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:sap="clr-namespace:system.activities.presentation;assembly=system.activities.presentation" xmlns:sapv="clr-namespace:system.activities.presentation.view;assembly=system.activities.presentation" xmlns:statements="http://schemas.microsoft.com/netfx/2009/xaml/activities" collapsible="false"> <sap:activitydesigner.template>     <controltemplate targettype="sap:activitydesigner">         <grid>             <contentpresenter horizontalalignment="center"                                       verticalalignment="center"/>         </grid>     </controltemplate> </sap:activitydesigner.template> <dockpanel lastchildfill="true">     <sap:workflowitempresenter item="{binding path=modelitem.body, mode=twoway}"/> </dockpanel> 

and code library:

public sealed class customassign : nativeactivity, iactivitytemplatefactory {     [browsable(false)]     public activity body { get; set; }       protected override void execute(nativeactivitycontext context)     {         activityinstance res = context.scheduleactivity(body, new completioncallback(onexecutecomplete));     }      /// <summary>     /// called execute when condition evaluates true.     /// </summary>     /// <param name="context">the context.</param>     /// <param name="instance">the instance.</param>     public void onexecutecomplete(nativeactivitycontext context, activityinstance instance)     {         //to added     }      activity iactivitytemplatefactory.create(system.windows.dependencyobject target)     {         return new customassign         {             body = new assign()         };     } } 

when dragging activity on designer, looks default assign. issue appears when trying delete it. being hosted, parent remain on designer because, in fact, delete body if user doesn't see this.

is there way propagate parent in order delete entire activity designer?

ok need override onmodelchanged event on workflow designer.

        modelservice modelsvc = (modelservice)designer.context.services.getservice<system.activities.presentation.services.modelservice>();          if (modelsvc != null)         {             modelsvc.modelchanged += onmodelchanged;         } 

once have done can access activities have been removed designer.

            void modelsvc_modelchanged(object sender, modelchangedeventargs e)             {                 //we have deleted design surfaace                 if (e.modelchangeinfo.modelchangetype == modelchangetype.collectionitemremoved)                 {                    modelitem modelitem = (modelitem)e.modelchangeinfo.value;                 }             } 

based on model item deleted activity can traverse workflow tree find relevant activities wish remove.

this concept explained here.

you can remove activities using modeleditingscope following code.

 using (modeleditingscope editingscope = modelsvc.root.beginedit("activities"))  {     //to add activity     modelsvc.root.properties["activities"].collection.add(new sequence());     //to remove activity     modelsvc.root.properties["activities"].collection.remove(*a model item remove);      editingscope.complete();   } 

this not trivial task , there few funnies when doing this. have not implemented exact requirement in own applications, have done similar deletion of variables associated deleted activity , there various gotchas above code should give starting point.