What's new in XAML of .NET 4.0

Easy Object References with {x:Reference}

Built-in Types

Generics in XAML with x:TypeArguments

Support for Arbitrary Dictionary Keys

Use of Non-Default Constructors with x:Arguments

Use of Static Factory Methods with x:FactoryMethod

With .NET 4.0 Microsoft will bring up a improved version of XAML. This arcitle shows you the language enhancements they made.

If you want to create an object reference today you need to do a databinding and declare the source with an ElementName. In XAML 2009 you can use the new {x:Reference} markup extension

 
<!-- XAML 2006 -->
<Label Target="{Binding ElementName=firstName}">FirstName</Label>
<TextBox x:Name="firstName" />
 
<!-- XAML 2009 -->
<Label Target="{x:Reference firstName}">FirstName</Label>
<TextBox x:Name="firstName" />
 
 

If you want to add objects of simple types like string or double to a resource dictionary today you need to map the needed clr-namespaces to an XML namespaces. In XAML 2009 we a lot of simple types that are included in the XAML language.

 
<!-- XAML 2006 -->
<sys:String xmlns:sys="clr-namespace:System;assembly=mscorlib >Test</sys:String>
 
<!-- XAML 2009 -->
<x:String>Test</x:String>
 
 

The following types are included into the XAML language:

• <x:Object/>
• <x:Boolean/>
• <x:Char/>
• <x:String/>
• <x:Decimal/>
• <x:Single/>
• <x:Double/>
• <x:Int16/>
• <x:Int32/>
• <x:Int64/>
• <x:TimeSpan/>
• <x:Uri/>
• <x:Byte/>
• <x:Array/>
• <x:List/>
• <x:Dictionary/>

If you want to use an ObservableCollection<Employee> in XAML you need to create a type that derives from ObservableCollection because you cannot declare it in XAML. With XAML 2009 you can use the x:TypeArguments attribute to define the type of a generic type.

 
<!-- XAML 2006 -->
class EmployeeCollection : ObservableCollection<Employee>
{
}
 
<l:EmployeeCollection>
    <l:Employee FirstName="John" Name="Doe" />
    <l:Employee FirstName="Tim" Name="Smith" />
</lEmployeeCollection>
 
<!-- XAML 2009 -->
<ObservableCollection x:TypeArguments="Employee">
    <l:Employee FirstName="John" Name="Doe" />
    <l:Employee FirstName="Tim" Name="Smith" />
</ObservableCollection />
 
 

In XAML 2006 all explicit x:Key value were threated as strings. In XAML 2009 you can define any type of key you like by writing the key in ElementSyntax.

 
<!-- XAML 2006 -->
<StreamGeometry x:Key="CheckGeometry">M 0 0 L 12 8 l 9 12 z</StreamGeometry>
 
<!-- XAML 2009 -->
<StreamGeometry>M 0 0 L 12 8 l 9 12 z
    <x:Key><x:Double>10.0</x:Double></x:Key>
</StreamGeometry>
 
 

In XAML 2006 objects must have a public default constructor to use them. In XAML 2009 you can pass constructor arguments by using the x:Arguments syntax.

 
<!-- XAML 2006 -->
<DateTime>00:00:00.0000100</DateTime>
 
<!-- XAML 2009 -->
<DateTime>
    <x:Arguments>
        <x:Int64>100</x:Int64>
    </x:Arguments>
</DateTime>
 
 

When you have a type that has no public constructor but a static factory method you had to create that type in code in XAML 2006. With XAML 2009 you can use the x:FactoryMethodx:Arguments attribute to pass the argument values.

 
<!-- XAML 2006 -->
Guid id = Guid.NewGuid();
 
<!-- XAML 2009 -->
<Guid x:FactoryMethod="Guid.NewGuid" />
 
 

 Comments on this article

Tore Aurstad	Commented on 9.May 2009 Can I make use of these new features in Visual Studio 2008? When will the new .NET 4.0 features of WPF be available for developers outside Microsoft?
Christian Moser	Commented on 10.May 2009 They are all part of .NET 4.0. You need Visual Studio 2010 to use it. You can download a CTP version from here: http://www.microsoft.com/downloads/details.aspx?FamilyId=922B4655-93D0-4476-BDA4-94CF5F8D4814&displaylang=en. It's a virtual PC image. The beta version that will be released soon will be an installable version.
Jan Kučera	Commented on 16.May 2009 Do the non-default constructor arguments has to be in order of the consctructor signature? Or how do I specify which arguments are which? (And how does it work together with optional arguments?)
Theo Zographos	Commented on 19.May 2009 Nice changes, especially the added namespaces, but overall I wouldn't call them earth-shattering. Would be nicer to see simple arithmetic in XAML for example.
Christian Moser	Commented on 19.May 2009 Hi Theo, you are right. I often missed arithmetic functions in XAML too. Maybe there is another clever way to do such things - for example with a MarkupExtension.
Prashant	Commented on 4.June 2009 Great article .. thanks for all that info
xeonix	Commented on 20.June 2009 cool, all XAML improvements in single article. that's interesting, i'll try them...
San	Commented on 29.June 2009 Cool.. really informative..
Ajay	Commented on 27.August 2009 Brilliant!!
Muthu	Commented on 28.August 2009 If you add Previous and Next buttons in all the pages it will be more user fiendly
Christian Moser	Commented on 28.August 2009 Hi Muthu, thanks for the excellent idea. I will do this as soon as I find time.
Grammar Nazi	Commented on 4.September 2009 Couple of wierd spelling mistakes. Nice and informative though!
nayak14	Commented on 31.October 2009 I have VS2008. I wanna use XAML 2009. how can install it?
nayak14	Commented on 31.October 2009 I have VS2008. I wanna use XAML 2009. how can install it?
Christian Moser	Commented on 1.November 2009 Hi Nayak14, unfortunately it is not possible. The new XAML features are part of .NET 4.0 and this is only included in VS2010. You can download the free Beta 2 Bits and get startet. http://www.microsoft.com/downloads/details.aspx?FamilyID=a80dfb5d-51c6-4778-8656-a9ff29d3a132&displaylang=en Greetings Christian
Nayak14	Commented on 2.November 2009 Thanks a Bunch!!!
Nayak14	Commented on 2.November 2009 Thanks a Bunch!!!
Don Wingate	Commented on 27.November 2009 What about defining a DataTemplate with a DataType that is a generic type? Is this still not possible in 4.0?
John D	Commented on 28.November 2009 How do you enable xaml 2009 in vs2010 beta 2? From the list of schemas I am only seeing http://schemas.microsoft.com/netfx/2009/xaml/presentation but no http://schemas.microsoft.com/netfx/2009/xaml I read somewhere that using the /winfx/2006/xaml ns should just work but that doesn't seem to be the case.
neeraj	Commented on 8.February 2010 Is there a need of learning XAML..before i push my hand to a WPF application?? Or it can be learned side by side!!
JamesT	Commented on 10.March 2010 neeraj, wtf does "push my hand to a WPF application" mean?
Sergey	Commented on 19.May 2010 How can I use XAML 4 feature in regular WPF application? If I create workflow console application everything works, but not in WPF. Am I doing anything wrong?
Sergey	Commented on 19.May 2010 How can I use XAML 4 feature in regular WPF application? If I create workflow console application everything works, but not in WPF. Am I doing anything wrong?
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Chatur	Commented on 7.July 2010 Blog likhnese kuch nahi hota he.. validation karna bhi ana chahiye... :)
Rajni Padhiyar	Commented on 12.July 2010 I like these new features, Thanks Rajni Padhiyar rajnicby.si@gmail.com
shreyas	Commented on 28.July 2010 Nice man.......
	Commented on 29.July 2010
Veni	Commented on 3.August 2010 Nice Ram.
bindu	Commented on 5.August 2010 hi very interesting features...but pls provide explanation with working examples apart from syntax..it will be more easy to understand for newbees like me...
Vimal	Commented on 13.August 2010 Hi That is very nice features
Vimal	Commented on 13.August 2010 Hi That is very nice features
this is nice...	Commented on 14.August 2010 explain with example
Mamta	Commented on 18.August 2010 This page is not detailed.
Jared	Commented on 5.September 2010 I like the conciseness here (not too many examples), which makes for a nice quick reference/overview.
sailaja	Commented on 18.September 2010 Hi the features you explained are nice; but plz provide examples. Frankly speaking i didnt understand full concept
	Commented on 22.September 2010
Asif	Commented on 5.October 2010 I also Didn't got the topic !!!! for what it is
pallavi	Commented on 20.October 2010 Nice Article
lll	Commented on 20.October 2010 se
rahul	Commented on 20.October 2010 yak................dirty
sp	Commented on 9.November 2010 uper kiye gye sare comment bakwaas hain
Kiran	Commented on 10.November 2010 Hi Very nice article, i am using VS2010 C# expression Edition When i am using this markup <Label Target="{x:Reference firstName}">FirstName</Label> <TextBox x:Name="firstName" /> i got warning "Service Provider is Missing the INameResolver Service" Any idea how to resolve this???
John	Commented on 18.November 2010 Here is the explanation from Adam Nathan's WPF 4 unleashed book: "The x:Reference markup extension is often mistakenly associated with the XAML2009 features that can only be used from loose XAML at the time of this writing. Although x:Reference is a new feature in WPF 4, it can be used from XAML2006 just fine as long as your project is targeting version 4 or later of the .NET Framework. One glitch is that the XAML designer in Visual Studio 2010 doesn�t properly handle x:Reference, so it gives the following design-time error that you can safely ignore: Service provider is missing the INameResolver service"
Harish	Commented on 15.December 2010 nice features...nice explanation
vishal	Commented on 22.December 2010 Above Example and Definition is very good & sort and sweet.
basavaprasad	Commented on 14.January 2011 Really nice Explanations.....
sohan	Commented on 1.February 2011 didnt understand any thing.please explain in detail with examples..
orhor	Commented on 25.February 2011 thank you for mentioning, but VS2010 doesnt offer a namespace url like "http://schemas.microsoft.com/winfx/2009/xaml" or where should I set the version?
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DNM	Commented on 14.March 2011 This still does not work in WPF and VS 2010 !
DNM	Commented on 14.March 2011 This still does not work with WPF and VS 2010 !!!
kkk	Commented on 14.March 2011 mmmm
Anup	Commented on 1.April 2011 Good for beginer...
kamlendra	Commented on 11.April 2011 please provide the examples along with the syntax.you can provide the link to the example.
Mohit Jethva	Commented on 20.June 2011 It's very nice feature.. Keep it up...It's very useful for beginer.
Deepthi	Commented on 8.July 2011 Good one
Tim Valentine	Commented on 10.July 2011 http://msdn.microsoft.com/en-us/library/ee792002.aspx
Raj	Commented on 4.August 2011 Hi I think this site is useful, but it will be more useful if there are more examples to explain the concepts,as we are beginners. Thanks in advance.
Rajeev Kumar	Commented on 19.September 2011 I did not get the topic.Can you please explain it little bit more.
anand	Commented on 21.September 2011 hai... i need eg.,