在Windows Phone中删除枢纽项目

Question

I have around 30 images which i want to keep as items in pivot control.But if i do all those i have encountered OutOfMemoryException. SO i was adding pivots dynamically.Now if i exceed some limit i want to remove pivot items, but if i remove on pivot selection changed i am getting InvalidException. In the snippet pivotshow is the pivot control.

    void PivotShow_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        AddItems();
    }

    private void AddItems()
    {
        PivotItem toadd = PivotGen(images[i]);
        i = (i + 1) % (images.Length);
        PivotShow.Items.Add(toadd);
        try
        {
            if (PivotShow.Items.Count > 3)
                PivotShow.Items.RemoveAt(0);
        }
        catch (InvalidOperationException)
        {
            MessageBox.Show("Operation not allowed");
        }
    }

    private PivotItem PivotGen(string urlimage)
    {
        PivotItem p = new PivotItem();
        p.Margin = new Thickness(0, -90, 0, 0);

        Image img = new Image();
        BitmapImage bmp = new BitmapImage(new Uri(urlimage, UriKind.Relative));
        img.Stretch = Stretch.Fill;
        img.Source = bmp;
        p.Content = img;

        return p;
        //PivotShow.Items.Add(p);
    }

thanks in advance

Answer 1

This is most likely occuring because you are trying to change a collection that is currently being modified. You could defer your code as follows:

        EventHandler handler = null;
        handler = (s, e) =>
        {
            element.LayoutUpdated -= handler;

            AddItems();
        };
        element.LayoutUpdated += handler;

The above code will invoke AddItems on the next layout pass. Give this a go and see if it helps!