CODEWITHSUNDEEP
c#.netpropertygridcollectioneditor
Kosmo零
Kosmo零

Reputation: 4151

How to make CollectionEditor to fire CollectionChanged event when items added or removed?

I have this custom control that I grabbed from somewehere long ago:

public class NotifyingCollectionEditor : CollectionEditor
{
    // Define a static event to expose the inner PropertyGrid's PropertyValueChanged event args...
    public delegate void MyPropertyValueChangedEventHandler(object sender, PropertyValueChangedEventArgs e);
    public static event MyPropertyValueChangedEventHandler ElementChanged;

    // Inherit the default constructor from the standard Collection Editor...
    public NotifyingCollectionEditor(Type type) : base(type) { }

    // Override this method in order to access the containing user controls from the default Collection Editor form or to add new ones...
    protected override CollectionForm CreateCollectionForm()
    {
        // Getting the default layout of the Collection Editor...
        CollectionForm collectionForm = base.CreateCollectionForm();
        Form frmCollectionEditorForm = collectionForm as Form;
        TableLayoutPanel tlpLayout = frmCollectionEditorForm.Controls[0] as TableLayoutPanel;

        if (tlpLayout != null)
        {
            // Get a reference to the inner PropertyGrid and hook an event handler to it.
            if (tlpLayout.Controls[5] is PropertyGrid)
            {
                PropertyGrid propertyGrid = tlpLayout.Controls[5] as PropertyGrid;
                propertyGrid.PropertyValueChanged += new PropertyValueChangedEventHandler(propertyGrid_PropertyValueChanged);
            }
        }

        return collectionForm;
    }

    void propertyGrid_PropertyValueChanged(object sender, PropertyValueChangedEventArgs e)
    {
        // Fire our customized collection event...
        var evt = NotifyingCollectionEditor.ElementChanged;

        if (evt != null)
            evt(this, e);
    }
}

It used to fire event when one of edited items in collection has changed, but I need it to fire even when some items were added or removed into this collection.

For now, I don't have other idea than compare amount of elements at creation of the form and at it's close.

But how I can access that edited collection to get it's Count value?

I tried to access propertyGrid.SelectedObject but it's null and even if it wasn't, I think there are collection items, instead of collection.

Upvotes: 2

Views: 3521

Answers (2)

Kosmo零
Kosmo零

Reputation: 4151

public class NotifyingCollectionEditor : CollectionEditor
{
    // Define a static event to expose the inner PropertyGrid's PropertyValueChanged event args...
    public static event EventHandler<PropertyValueChangedEventArgs> ElementChanged;

    // Inherit the default constructor from the standard Collection Editor...
    public NotifyingCollectionEditor(Type type) : base(type) { }

    // Override this method in order to access the containing user controls from the default Collection Editor form or to add new ones...
    protected override CollectionForm CreateCollectionForm()
    {
        // Getting the default layout of the Collection Editor...
        CollectionForm collectionForm = base.CreateCollectionForm();
        Form frmCollectionEditorForm = collectionForm as Form;
        TableLayoutPanel tlpLayout = frmCollectionEditorForm.Controls[0] as TableLayoutPanel;

        if (tlpLayout != null)
        {
            // Get a reference to the inner PropertyGrid and hook an event handler to it.
            if (tlpLayout.Controls[5] is PropertyGrid)
            {
                PropertyGrid propertyGrid = tlpLayout.Controls[5] as PropertyGrid;
                propertyGrid.PropertyValueChanged += new PropertyValueChangedEventHandler(propertyGrid_PropertyValueChanged);
            }
        }

        return collectionForm;
    }

    protected override object SetItems(object editValue, object[] value)
    {
        object ret_val = base.SetItems(editValue, value);

        // Fire our customized collection event...
        var evt = NotifyingCollectionEditor.ElementChanged;

        if (evt != null)
            evt(this, null);

        return ret_val;
    }

    void propertyGrid_PropertyValueChanged(object sender, PropertyValueChangedEventArgs e)
    {
        // Fire our customized collection event...
        var evt = NotifyingCollectionEditor.ElementChanged;

        if (evt != null)
            evt(this, e);
    }
}

Can do this.

Upvotes: 1

simon at rcl
simon at rcl

Reputation: 7344

Best bet is to use the ObservableCollection defined in System.Collections.ObjectModel. This will raise events when the collection is added to or removed from. This class is part of the framework and so should work pretty well, now and in the future.

If you wish to monitor the type in the collection (the T) then that type will have to implement INotifyPropertyChanged.

Upvotes: 1

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