SilverlightShow: Behaviors and Triggers in Silverlight Comments

Re: Behaviors and Triggers in Silverlight

Ezra — Tue, 02 Aug 2011 13:27:17 GMT

Thx for your article.Much helpful to me.

Re: Behaviors and Triggers in Silverlight

Philip — Thu, 23 Jun 2011 23:01:04 GMT

Thanks! Got my trigger written!

public class DatePickerDefaultContextMenuBehavior : WeakBehavior<DatePicker> 
    {
        protected override void OnAttached()
        {
            base.OnAttached();
            this.AssociatedObject.MouseRightButtonUp += AssociatedObject_MouseRightButtonUp;
            this.AssociatedObject.MouseRightButtonDown += AssociatedObject_MouseRightButtonDown;         
        }
        protected override void OnDetaching()
        {
            base.OnDetaching();
            this.AssociatedObject.MouseRightButtonUp -= AssociatedObject_MouseRightButtonUp;
            this.AssociatedObject.MouseRightButtonDown -= AssociatedObject_MouseRightButtonDown;            
        }
        
        void AssociatedObject_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
        {
            e.Handled = true;
        }
        ContextMenu contextmenu;
        void AssociatedObject_MouseRightButtonUp(object sender, MouseButtonEventArgs e)
        {
            if (contextmenu == null)
            {
                Action<string> Add = delegate(string header)
                {
                    if (header == "-")
                    {
                        contextmenu.Items.Add(new Separator());
                    }
                    else
                    {
                        var item = new MenuItem();
                        item.Header = header;
                        item.Click += menuItem_Click;
                        contextmenu.Items.Add(item);
                    }
                };
                contextmenu = new ContextMenu();
                Add("Clear Value");
                Add("-");
                Add("Today's Date");
            }
            var layoutRoot = AssociatedObject.GetBaseParent();
            contextmenu.IsOpen = true;
            contextmenu.HorizontalOffset = e.GetPosition(layoutRoot).X;
            contextmenu.VerticalOffset = e.GetPosition(layoutRoot).Y;
        }
        private void menuItem_Click(object sender, RoutedEventArgs e)
        {
            switch ((sender as MenuItem).Header.ToString())
            {
                case "Clear Value":
                    this.AssociatedObject.SelectedDate = null;
                    break;
                default:
                    this.AssociatedObject.SelectedDate = DateTime.Today;
                    break;
            }
        }
    }

Re: Behaviors and Triggers in Silverlight

blacklight — Mon, 20 Jun 2011 18:58:01 GMT

I very much liked your article on behaviors. However, I have found that they can cause memory leaks unless you explicitly remove the behaviours. I did some investigation and found that the Unloaded event of a control is called when you navigate away from a page in Silverlight or WP7. This releases the reference to the AssociatedObject and frees up memory which is a big problem in WP7.

public abstract class WeakBehavior : Behavior where T : FrameworkElement
{
    protected virtual void OnAssociatedObjectUnloaded(object sender, RoutedEventArgs e)
    {
        Interaction.GetBehaviors(this.AssociatedObject).Remove(this);
    }

    protected override void OnAttached()
    {
        base.OnAttached();

        this.AssociatedObject.Unloaded += this.OnAssociatedObjectUnloaded;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        this.AssociatedObject.Unloaded -= this.OnAssociatedObjectUnloaded;
    }
}

RE: Behaviors and Triggers in Silverlight

Nam Cao — Wed, 27 Apr 2011 21:26:59 GMT

Very good articale. Thanks

RE: Behaviors and Triggers in Silverlight

ppopadiyn — Fri, 25 Feb 2011 18:42:50 GMT

Hi Sae1962,

"local" is an alias for the namespace where the behavior (or generally, the target element you want to use in xaml) resides. For example I use "local" always when I want to import the namespace for the current project. Take a look at the declaration of UserControl with the examples in xaml:

xmlns:local="clr-namespace:Behaviors".

Sorry for the double entries!

Sae1962 — Fri, 25 Feb 2011 18:30:37 GMT

I pressed twice F5 (refresh) on the Microsoft Internet Explorer 8 and clicked OK on the message that warned that it would not be a good idea to refresh, if I am shopping. Interestingly, the last entered message appears a second time with a new timestamp.

ad Question on local

Sae1962 — Fri, 25 Feb 2011 18:25:55 GMT

I forgot to write you the error message MVS2010 gives for local. It reads "'local' is an undefined prefix. Line 24, position 7."

RE: Behaviors and Triggers in Silverlight

Sae1962 — Fri, 25 Feb 2011 18:15:40 GMT

All the demos run very well. Also, I can see on this page the animations.

I have only one question about the code. In the MainPage.xaml code, you use for the first click behaviour in the block

<interactivity:Interaction.Behaviors>

<local:InverseColorClickBehavior/>

interactivity:Interaction.Behaviors>

From where does the system find this local element? I created in another test project for my own a , but the local element remains unknown. The underlined part in italic is underlined with a blue waved line in my MVS2010. From where does the system "knows" the "local" in your project?

Thank you for your information!

public class DeleteOnRightMouseButtonDownBehavior : Behavior<FrameworkElement>

...

<interactivity:Interaction.Behaviors>

<local:DeleteOnRightMouseButtonDownBehavior/>

interactivity:Interaction.Behaviors>

RE: Behaviors and Triggers in Silverlight

Sae1962 — Fri, 25 Feb 2011 17:29:15 GMT

Thank you verrry much! :-> That was the reason. Now, the first one runs properly. If other problems arise, I will let you know.

Have a nice weekend!

RE: Behaviors and Triggers in Silverlight

ppopadiyn — Fri, 25 Feb 2011 17:20:32 GMT

Hi Sae1962,

I think, you should set the Behaviors.Web project as a start up project. It seems that after the conversion of the demo to SL4, the start up project get changed. Sorry for the inconvenience caused.

RE: Behaviors and Triggers in Silverlight

Sae1962 — Fri, 25 Feb 2011 17:09:17 GMT

Hi!

Behaviours and triggers are new to me. I tried the first and second example under Silverlight 4 with Microsoft Visual Studio 2010. Interestingly, the program runs, but there is no action: no colour change, no magnification. Can you help me?

Thanks!

RE: Behaviors and Triggers in Silverlight

Cathleen — Sun, 02 Jan 2011 23:47:18 GMT

excellent resource

RE: Behaviors and Triggers in Silverlight

lnikolov — Wed, 22 Dec 2010 18:11:51 GMT

The article has been updated to the latest version of Silverlight and Visual Studio.

RE: Behaviors and Triggers in Silverlight 3

ppopadiyn — Tue, 12 Oct 2010 12:59:52 GMT

Thanks Braulio ;)

RE: Behaviors and Triggers in Silverlight 3

Braulio Diez — Mon, 11 Oct 2010 23:46:06 GMT

Great article, nice to learn, but the best... nice to use as reference material ;-).

RE: Behaviors and Triggers in Silverlight 3

ppopadiyn — Thu, 08 Jul 2010 17:12:11 GMT

Hi Ray,

As far as I know, there are no differences with SL 4. Everything that is written in this article is valid also for SL4. Probably there are some predefined behaviors which are part of the new version of Expression Blend, but I am not familiar with them.

RE: Behaviors and Triggers in Silverlight 3

Ray Akkanson — Thu, 08 Jul 2010 17:08:41 GMT

Any differences in Behaviors in Silverlight 4

Ray Akkanson

RE: Behaviors and Triggers in Silverlight 3

SuperMan — Thu, 20 May 2010 02:52:59 GMT

it's nice

RE: Behaviors and Triggers in Silverlight 3

Samiha — Tue, 13 Apr 2010 14:12:29 GMT

excellent

RE: Behaviors and Triggers in Silverlight 3

Harish Kumar — Sun, 04 Apr 2010 08:46:21 GMT

Great Post. Can you please provide some info regarding the project "SharedEffectsLibrary" in the solution?

RE: Behaviors and Triggers in Silverlight 3

Adam Kinney — Fri, 08 Jan 2010 02:05:26 GMT

This is a great resource on Behaviors, nicely done. Definitely worth sharing.

RE: Behaviors and Triggers in Silverlight 3

roboblob — Wed, 23 Sep 2009 10:02:25 GMT

Thanks for the tutorial this is maybe the best resource on subject i found so far!

RE: Behaviors and Triggers in Silverlight 3

ppopadiyn — Fri, 18 Sep 2009 07:31:42 GMT

Hi qotsa

Did you try to open the whole solution? It must include 3 projects.

RE: Behaviors and Triggers in Silverlight 3

qotsa — Fri, 18 Sep 2009 01:05:43 GMT

when i try to run the first proyect i got an error because it doesnt find the inverseColor method, and i dont have the code,

tnks

RE: Behaviors and Triggers in Silverlight 3

Fallon Massey — Thu, 20 Aug 2009 21:18:34 GMT

The TargetedTriggerAction can be used to effectively implement the isolation between the view and the model, because it's essentially commanding without having binding(it's done manually).

I love this addition for all the reasons you listed, and see a lot of use in our development.

Thanks for making these concepts clearer.