CODEWITHSUNDEEP
c#winforms.net-2.0
Jason Sundram
Jason Sundram

Reputation: 12554

PropertyGrid: getting PropertyValueChanged notifications from a CollectionEditor

The PropertyGrid control is very useful for editing objects at run-time. I'm using it as follows:

Form form = new Form();
form.Parent = this;
form.Text = "Editing MyMemberVariable";

PropertyGrid p = new PropertyGrid();
p.Parent = form;
p.Dock = DockStyle.Fill;
p.SelectedObject = _MyMemberVariable;
p.PropertyValueChanged += delegate(object s, PropertyValueChangedEventArgs args) 
{ 
    _MyMemberVariable.Invalidate(); 
};

form.Show();

As you can see, I'm using the PropertyValueChanged notification to figure out when to update _MyMemberVariable. However, _MyMemberVariable is a class that I didn't write, and one of its members is a Collection type. The PropertyGrid calls the Collection Editor to edit this type. However, when the Collection Editor is closed, I do not get a PropertyValueChanged notification.

Obviously, I could work around this problem by using ShowDialog() and invalidating _MyMemberVariable after the dialog is closed.

But I'd like to actually get PropertyValueChanged events to fire when collections have been edited. Is there a way to do that without modifying _MyMemberVariable (I don't have access to its source code)?

Upvotes: 1

Views: 4495

Answers (2)

mkaj
mkaj

Reputation: 3489

This isn't very elegant, but it solved the issue I was having when someone updates / changes the order of a collection from a property grid:

propertyGrid1.PropertyValueChanged += (o, args) => PropertyGridValueChanged();
propertyGrid1.LostFocus += (sender, args) => PropertyGridValueChanged();

I listen to the LostFocus event when they click on something else. For my particular use case this solution is sufficient. Thought I'd mention it in case someone else finds this useful.

Upvotes: 2

Jeremy
Jeremy

Reputation:

I did some research and even reproduced the problem, however the solution I found won't help you, but I'm hoping the information may help another person help you.

Here goes

The problem is easily reproducable by creating a new windows form project, adding a property grid and a listbox to the form and setting the listbox as the property grid's selected object.

//designer code excluded
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        propertyGrid1.SelectedObject = listBox1;

        propertyGrid1.PropertyValueChanged += delegate(object s, PropertyValueChangedEventArgs args)
        {
            MessageBox.Show("Invalidate Me!");
        };

    }
}

When editing the items collection of the listbox, the event will never fire, the reason is because the Items property returns a reference to the collection. Since adding items to the collection doesn't actually change the reference when the property never appears to change so the property grid.

The solution I tried would be to extend property grid, and update the logic that compares the two and checks if the data in the collection has changed and call the event. I tried this but the PropertyGrid had an internal class PropertyGridView that caused problems for me.

I hope this helps someone else figure out your problem.

-jeremy

Upvotes: 0

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