ViewStateAttachedPropertyFeature.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx40 / Tools / System.Activities.Presentation / System / Activities / Presentation / ViewStateAttachedPropertyFeature.cs / 1305376 / ViewStateAttachedPropertyFeature.cs
                        

                        
                            //---------------------------------------------------------------- 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//---------------------------------------------------------------

namespace System.Activities.Presentation 
{
    using System.Activities.Presentation.Model; 
    using System.Activities.Presentation.View; 
    using System.Collections.Generic;
    using System.Runtime; 

    abstract class ViewStateAttachedPropertyFeature : Feature
    {
        Type modelType; 
        ViewStateService viewStateService;
        AttachedPropertiesService attachedPropertiesService; 
        Dictionary attachedProperties = new Dictionary(); 

        public sealed override void Initialize(EditingContext context, Type modelType) 
        {
            this.modelType = modelType;

            context.Services.Subscribe(delegate(ViewStateService viewStateService) 
            {
                this.viewStateService = viewStateService; 
                viewStateService.ViewStateChanged += this.OnViewStateChanged; 
                if (this.attachedPropertiesService != null)
                { 
                    RegisterAttachedProperties();
                }
            });
            context.Services.Subscribe(delegate(AttachedPropertiesService attachedPropertiesService) 
            {
                this.attachedPropertiesService = attachedPropertiesService; 
                if (this.viewStateService != null) 
                {
                    RegisterAttachedProperties(); 
                }
            });
        }
 
        protected abstract IEnumerable AttachedProperties
        { 
            get; 
        }
 
        internal void RegisterAttachedProperty(string propertyName, bool isBrowsable, T defaultValue)
        {
            AttachedProperty attachedProperty = new AttachedProperty
            { 
                IsBrowsable = isBrowsable,
                Name = propertyName, 
                OwnerType = modelType, 
                Getter = (modelItem) =>
                { 
                    T result = (T)viewStateService.RetrieveViewState(modelItem, propertyName);
                    return result == null ? defaultValue : result;
                },
                Setter = (modelItem, value) => 
                {
                    if (value == null || value.Equals(defaultValue)) 
                    { 
                        viewStateService.StoreViewStateWithUndo(modelItem, propertyName, null);
                    } 
                    else
                    {
                        viewStateService.StoreViewStateWithUndo(modelItem, propertyName, value);
                    } 
                }
            }; 
            attachedPropertiesService.AddProperty(attachedProperty); 
            attachedProperties.Add(propertyName, attachedProperty);
        } 

        void OnViewStateChanged(object sender, ViewStateChangedEventArgs e)
        {
            if (attachedProperties.ContainsKey(e.Key)) 
            {
                // Checking is required to avoid infinite loop of ViewState -> AttachedProperty -> ... 
                if ((e.NewValue == null && e.OldValue != null) || !e.NewValue.Equals(e.OldValue)) 
                {
                    attachedProperties[e.Key].SetValue(e.ParentModelItem, e.NewValue); 
                }
            }
        }
 
        void RegisterAttachedProperties()
        { 
            foreach (AttachedPropertyInfo attachedPropertyInfo in this.AttachedProperties) 
            {
                attachedPropertyInfo.Register(this); 
            }
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//---------------------------------------------------------------- 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//---------------------------------------------------------------

namespace System.Activities.Presentation 
{
    using System.Activities.Presentation.Model; 
    using System.Activities.Presentation.View; 
    using System.Collections.Generic;
    using System.Runtime; 

    abstract class ViewStateAttachedPropertyFeature : Feature
    {
        Type modelType; 
        ViewStateService viewStateService;
        AttachedPropertiesService attachedPropertiesService; 
        Dictionary attachedProperties = new Dictionary(); 

        public sealed override void Initialize(EditingContext context, Type modelType) 
        {
            this.modelType = modelType;

            context.Services.Subscribe(delegate(ViewStateService viewStateService) 
            {
                this.viewStateService = viewStateService; 
                viewStateService.ViewStateChanged += this.OnViewStateChanged; 
                if (this.attachedPropertiesService != null)
                { 
                    RegisterAttachedProperties();
                }
            });
            context.Services.Subscribe(delegate(AttachedPropertiesService attachedPropertiesService) 
            {
                this.attachedPropertiesService = attachedPropertiesService; 
                if (this.viewStateService != null) 
                {
                    RegisterAttachedProperties(); 
                }
            });
        }
 
        protected abstract IEnumerable AttachedProperties
        { 
            get; 
        }
 
        internal void RegisterAttachedProperty(string propertyName, bool isBrowsable, T defaultValue)
        {
            AttachedProperty attachedProperty = new AttachedProperty
            { 
                IsBrowsable = isBrowsable,
                Name = propertyName, 
                OwnerType = modelType, 
                Getter = (modelItem) =>
                { 
                    T result = (T)viewStateService.RetrieveViewState(modelItem, propertyName);
                    return result == null ? defaultValue : result;
                },
                Setter = (modelItem, value) => 
                {
                    if (value == null || value.Equals(defaultValue)) 
                    { 
                        viewStateService.StoreViewStateWithUndo(modelItem, propertyName, null);
                    } 
                    else
                    {
                        viewStateService.StoreViewStateWithUndo(modelItem, propertyName, value);
                    } 
                }
            }; 
            attachedPropertiesService.AddProperty(attachedProperty); 
            attachedProperties.Add(propertyName, attachedProperty);
        } 

        void OnViewStateChanged(object sender, ViewStateChangedEventArgs e)
        {
            if (attachedProperties.ContainsKey(e.Key)) 
            {
                // Checking is required to avoid infinite loop of ViewState -> AttachedProperty -> ... 
                if ((e.NewValue == null && e.OldValue != null) || !e.NewValue.Equals(e.OldValue)) 
                {
                    attachedProperties[e.Key].SetValue(e.ParentModelItem, e.NewValue); 
                }
            }
        }
 
        void RegisterAttachedProperties()
        { 
            foreach (AttachedPropertyInfo attachedPropertyInfo in this.AttachedProperties) 
            {
                attachedPropertyInfo.Register(this); 
            }
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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