Help with C# DependencyObject

Hi Everyone,

I have a custom control (WPF) that has a couple dependancy objects in it, when the value of any one of these DP objects are updated I need it to run a method.

However;

Because the object's DPs are databound in XAML when used the call to the method i want to run on DP value change isn't called as the DP is access directly and not through the obj property.

How can i trigger the same way from a XAML value assignment to a DP?

Thanks,

Xavier.



 public class CDNImage : Control
    {
        public enum CDNFetchModes
        {
            GetLatestFromMediaStorageLocation,
            GetSpecificMediaItemVersion
        }

        public void ReloadImage()
        {
            if (CDNFetchMode == CDNFetchModes.GetLatestFromMediaStorageLocation)
            {
                if (MediaStorageLocationID != null && MediaStorageLocationID != new Guid())
                {
                    var r = Epicentre.ContentDeliveryNetwork.CDNController.GetLatestVersionOfMedia(MediaStorageLocationID);
                    if (Epicentre.Types.IO.MIMEType.Parse(r.MediaItemVersionInfo.MIMEType).Type == "image")
                    {
                        MemoryStream byteStream = new MemoryStream(r.MediaItemVersionInfo.FileData);
                        BitmapImage image = new BitmapImage();
                        image.BeginInit();
                        image.StreamSource = byteStream;
                        image.EndInit();
                        ImageData = image;
                    }
                    else
                    {
                        ImageData = new BitmapImage(new Uri("/OSManager;component/Icons/64/Gnome-Document-New-64.png", UriKind.RelativeOrAbsolute));
                    }
                }
                else
                {
                    ImageData = new BitmapImage(new Uri("/OSManager;component/no-item-selected.png", UriKind.RelativeOrAbsolute));
                }
            }
            else
            {
                if (MediaStorageLocationID != null && MediaItemVersionID != null && MediaStorageLocationID != new Guid() && MediaItemVersionID != new Guid())
                {
                    var r = Epicentre.ContentDeliveryNetwork.CDNController.GetSpecificVersionOfMedia(MediaStorageLocationID, MediaItemVersionID);
                    if (Epicentre.Types.IO.MIMEType.Parse(r.MediaItemVersionInfo.MIMEType).Type == "image")
                    {
                        MemoryStream byteStream = new MemoryStream(r.MediaItemVersionInfo.FileData);
                        BitmapImage image = new BitmapImage();
                        image.BeginInit();
                        image.StreamSource = byteStream;
                        image.EndInit();
                        ImageData = image;
                    }
                    else
                    {
                        ImageData = new BitmapImage(new Uri("/OSManager;component/Icons/64/Gnome-Document-New-64.png", UriKind.RelativeOrAbsolute));
                    }
                }
                else
                {
                    ImageData = new BitmapImage(new Uri("/OSManager;component/no-item-selected.png", UriKind.RelativeOrAbsolute));
                }
            }
        }


        private static void vChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            
        }

        public Guid MediaStorageLocationID
        {
            get { return (Guid)GetValue(MediaStorageLocationIDProperty); }
            set { SetValue(MediaStorageLocationIDProperty, value); ReloadImage(); }
        }

        // Using a DependencyProperty as the backing store for MediaStorageLocationID.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty MediaStorageLocationIDProperty =
            DependencyProperty.Register("MediaStorageLocationID", typeof(Guid), typeof(CDNImage), new UIPropertyMetadata(null));



        public Guid MediaItemVersionID
        {
            get { return (Guid)GetValue(MediaItemVersionIDProperty); }
            set { SetValue(MediaItemVersionIDProperty, value); ReloadImage(); }
        }

        // Using a DependencyProperty as the backing store for MediaItemVersionID.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty MediaItemVersionIDProperty =
            DependencyProperty.Register("MediaItemVersionID", typeof(Guid), typeof(CDNImage), new UIPropertyMetadata(null));



        public CDNFetchModes CDNFetchMode
        {
            get { return (CDNFetchModes)GetValue(CDNFetchModeProperty); }
            set { SetValue(CDNFetchModeProperty, value); ReloadImage(); }
        }

        // Using a DependencyProperty as the backing store for CDNFetchMode.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty CDNFetchModeProperty =
            DependencyProperty.Register("CDNFetchMode", typeof(CDNFetchModes), typeof(CDNImage), new UIPropertyMetadata(CDNFetchModes.GetLatestFromMediaStorageLocation));



        public BitmapImage ImageData
        {
            get { return (BitmapImage)GetValue(ImageDataProperty); }
            set { SetValue(ImageDataProperty, value); }
        }

        // Using a DependencyProperty as the backing store for ImageData.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty ImageDataProperty =
            DependencyProperty.Register("ImageData", typeof(BitmapImage), typeof(CDNImage), new UIPropertyMetadata(null));


        public CDNImage()
        {
            ReloadImage();
        }

        static CDNImage()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(CDNImage), new FrameworkPropertyMetadata(typeof(CDNImage)));
        }
    }

Open in new window

LVL 1
locdangAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Gautham JanardhanCommented:
i didnt get u, even if the dependency property changes thru code or thru xaml the DependencyPropertyChanged methd shud fire. Am i missing something ?
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
locdangAuthor Commented:
The calls to ReloadImage on Lines 70, 82, 94 are not executed when the value is changed via a XAML binding, if you in the code behind change the value of these properties then the calls are fired.
0
locdangAuthor Commented:
Thanks, you actually solved the issue for me :)

I just needed to impliment the DependencyPropertyChanged event and boom im done.

Thank you!

Xavier.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
C#

From novice to tech pro — start learning today.