Lester's WPF blog

XAML 2009 Features: FactoryMethod\Arguments

2009-11-20T15:54:00Z

This is part of a series on New WPF\XAML Features

Another new feature in XAML 2009 is the possibility of creating objects using the non-default constructors. The keyword here is x:Arguments

So creating a person object with a constructor requiring Name\Age could be written in XAML as

<local:Person>

<x:Arguments>

<x:String>Tom</x:String>

<x:Int32>21</x:Int32>

</x:Arguments>

</local:Person>

Next interesting feature is using FactoryMethods… the keyword here is x:FactoryMethod

<p:Guid x:FactoryMethod='NewGuid'/>

You could also combine x:Arguments with FactoryMethod

<coll:List x:Key='list' x:TypeArguments='x:String' x:FactoryMethod='local:Factory.CreateStringList'>

<x:Arguments>

<x:String>Mickey,Donald</x:String>

</x:Arguments>

</coll:List>

Sample app showing usage is attached

Note that XAML 2009 features work only for loose XAML in WPF.

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XAML 2009 Features: Generics Support

2009-11-19T13:34:00Z

This is part of a series on New WPF\XAML Features

XAML 2009 supports generics J .. In previous releases, if you needed to have an observableCollection for databinding you would probably have written code like

class PersonCollection:ObservableCollection<Person>{}

<l:PersonCollection>

</l:PersonCollection>

In this release, you can now write this as

<local:Person Name='Tom' Age='21' />

</ObservableCollection>

…

Notice the use of TypeArguments to specify the collection type (Person in this case). It is used to pass the required constraints for a generic type

Lets go for some more examples. Simple Dictionary with the key\value pair being strings

<StackPanel.DataContext>

<coll:Dictionary x:TypeArguments='x:String, x:String' xmlns:coll='clr-namespace:System.Collections.Generic;assembly=mscorlib'>

<x:String x:Key='One'>1</x:String>

<x:String x:Key='Two'>2</x:String>

</coll:Dictionary>

</StackPanel.DataContext>

Next we have a slightly more complicated dictionary with an object as the key\value pair. Interesting to note here is that Key

<StackPanel.DataContext>

<coll:Dictionary x:TypeArguments='p:Object, p:Object' xmlns:p='clr-namespace:System;assembly=mscorlib'>

<x:Key>

</x:Key>

</Point>

<x:Null x:Key='three' />

</coll:Dictionary>

</StackPanel.DataContext>

And finally a nested dictionary sample

<StackPanel.Resources>

<coll:Dictionary x:TypeArguments='p:Object, coll:Dictionary(p:Object, p:Object)' x:Key='NestedItems'>

<coll:Dictionary x:Key='Dictionary1' x:TypeArguments='x:Object, x:Object'>

<x:String x:Key='One'>1</x:String>

<x:Key>

</x:Key>

</Point>

</coll:Dictionary>

</StackPanel.Resources>

Sample app showing the usage is attached.

Note that XAML 2009 features work only for loose XAML in WPF.

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New WPF Features: SynchronizedInputPattern

2009-11-18T15:05:00Z

This is part of a series on New WPF Features

In previous releases, sending input through automation was tricky mainly because the app and the automation processes were separate. The app state could change between the time the input was sent and received. As an example, suppose you need to click something but before the click happens, the elements move (maybe due to resize …). In this case, some other element could get the mouse input.

To overcome this problem, we have introduced the SynchronizedInputPattern. Now the framework sees where the input is going and if its not the intended target, the input is cancelled. The sender is notified whether the input operation was successful or not and based on it can make a decision to try again.

So coming to the API, to determine if an element supports the pattern we get the property value

buttonElement.GetCurrentPropertyValue(AutomationElement.IsSynchronizedInputPatternAvailableProperty);

Next, you need to hook the events to the element so that we are notified of the operations success

InputReachedTargetEvent	Identifies the event raised when the input was received by the element currently listening for the input.
InputReachedOtherElementEvent	Identifies the event raised when the input was received by an element other than the one currently listening for the input.
InputDiscardedEvent	Identifies the event raised when the input was discarded by WPF.

Once the events are hooked, you can start listening to the specific SynchronizedInputType

SynchronizedInputType.KeyUp,

SynchronizedInputType.KeyDown,

SynchronizedInputType.LeftMouseUp,

SynchronizedInputType.LeftMouseDown,

SynchronizedInputType.RightMouseUp,

SynchronizedInputType.RightMouseDown

syncInputPattern.StartListening(SynchronizedInputType.MouseLeftButtonDown);

One thing to note is that the event fires only once. So if you need to send the input again, you will need to call the StartListening API again.

You can cancel listening by calling the Cancel() API

Sample app which shows the usage is attached. The app clicks on different controls simulating incorrect input received. The console output describes the operations being performed.

******Goal is to Click the Button******

-- Click on the List

---- Input was Discarded - Try Again clicking On TextBox nested in Button

-- Click on the Textbox inside Button

---- Input Reached Element other than Target - Try Again clicking on Button

-- Click on the Button

---- SUCCESS: Input Reached Target

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New WPF Features: PixelShader3 Support

2009-11-17T15:28:00Z

This is part of a series on New WPF Features

Previously WPF only supported Pixel Shader 2.0 (PS 2.0). For this release, we added PS 3.0 support providing the benefits of more instructions, registers ....

The usage is similar as before. However, we have provided an API to determine if the shader can be run on the machine. The API’s are self-explanatory

· RenderCapability.IsPixelShaderVersionSupported(majorversion,minorVersion)

· RenderCapability. IsPixelShaderVersionSupportedInSoftware (majorversion,minorVersion)

· RenderCapability. MaxPixelShaderInstructionSlots(majorversion,minorVersion)

(snapshot of app on a PS2.0 supported machine)

Sample project attached.

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New WPF Features: UIA Virtualization

2009-11-16T16:06:00Z

Pre .NET 4, from a UI automation perspective, virtualization was not a good story. There wasn’t a standard way of dealing with virtualized controls, since some would expose only the visual elements while the others would create an automation tree that had every element. To fix this problem, in .NET 4, we have introduced 2 new UIA patterns: ItemContainerPattern\VirtualizedItemPattern

ItemContainerPattern enables searching the whole tree irrespective of it being virtualized.

testObject.GetCurrentPattern(ItemContainerPattern.Pattern)

Search is done using the FindItemByProperty function which has 3 parameters

- AutomationElement startAfter: element to start search from. Setting to null would mean start from beginning

- AutomationProperty: Property to be used for search. Setting to null corresponds to match all properties

- Object value: Property value

Once you find the element, you can then determine if it’s virtualized by querying the IsVirtualizedItemPatternAvailable.

(bool)item.GetCurrentPropertyValue(AutomationElementIdentifiers.IsVirtualizedItemPatternAvailableProperty);

So you have the virtualized item and would like to de-virtualize it.

VirtualizedItemPattern vpattern = item.GetCurrentPattern(VirtualizedItemPattern.Pattern) as VirtualizedItemPattern;

vpattern.Realize(); // de-virtualize the object

You can also query if the ItemContainerPattern is available using the property IsItemContainerPatternAvailable.

Sample project showing usage is attached.

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XAML 2009 Features: Named Object References

2009-11-13T15:07:00Z

This is part of a series on New WPF\XAML Features

In previous releases, if you needed to reference a named object, your XAML would look something like

<Label Target='{Binding ElementName=firstNameBox}' >_Target</Label>

<TextBox Name='firstNameBox'>Uses Binding</TextBox>

In the current release (.NET 4), we introduced a built in markup extension x:Reference. This would enable referencing a named object. The above XAML can now be written as

<Label Target= '{x:Reference secondNameBox}'>_Second Target</Label>

<Label Target= 'thirdNameBox' >_Third Target</Label>

The references look both forward as well as backwards

Another possibility working with named objects is to create a markupextension that calls into IXamlNameResolver to resolve a name. One scenario is having method calls in XAML like the below. We covered this is a previous post written by Shree.

<School.Class>

</Students>

</School.Class>

<!--<School.Topper>

</School.Topper>-->

</School>

A simple project showing the usage of x:Reference is attached

Note that XAML 2009 features work only for loose XAML in WPF.

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New WPF Features: Updated File Dialogs

2009-11-12T15:08:00Z

This is part of a series on New WPF Features

In previous releases, WPF open\Save dilogs had the XP style even on Vista. Some workarounds were to use the Vista bridge library or use the winforms dialogs. For this release we fixed this issue. You now get the OS style dialogs :) ... Usage wise its the same, you get the updated behavior for free ... The pic below shows the difference.

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XAML 2009 Features: XAML Event handling

2009-11-11T15:14:00Z

[This is part of a series on New WPF\XAML Features]

In previous releases, when loose XAML had events in it and was loaded it would crash. In V4, there are 2 options to avoid this crash.

à On loading events are searched on the root object of the XAML file. Suppose you had the loose XAML like the below

<local:MyStackPanel

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:local ="clr-namespace:DemoApp;assembly=DemoApp">

<Button Click="Button_Click" >Date (Event on Root)</Button>

As long as the root object (in this case MyStackPanel) can be found, the event will be hooked and will work fine without a crash

à The second approach is to define a MarkupExtension that returns a delegate and assign this to the event. So you could have XAML like the below

The sample project using the CoreMVVM library is attached.

Note that XAML 2009 features work only for loose XAML in WPF.

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New WPF Features: Cached Composition

2009-11-10T16:25:00Z

This is part of a series on New WPF Features

One of the big improvements in 4.0 is the Cached Composition feature in graphics. This feature enables caching a live UIElement as a bitmap, which enables quick rendering of the element as a bitmap. The UIElement is user interactive and hence will respond to keyboard input, mouse clicks,… Also, transforms, effects,.. which operate on top will not cause the cache to regenerated resulting in better performance. Previously, it was common to use RenderTargetBitmap for this purpose. However, this would be at the cost of interactivity.

Lets jump into usage. You have the BitmapCache and the BitmapCacheBrush classes. The former is useful in rendering a complex UIElement while the latter facilitates better reuse of a cached element.

Usage of BitmapCache is shown below. RenderAtScale is helpful for zoom scenarios since it a cache which is multiple of the original bitmap size. Note that changing the UIElement subtree or these properties (EnableClearType\RenderAtScale) will cause the cache to be regenerated.

<Canvas.CacheMode>

</Canvas.CacheMode>

BitmapCacheBrush is useful when you need to paint the same content on multiple elements. A sample usage is below.

<Grid.Resources>

<Image.CacheMode>

</Image.CacheMode>

</Image>

</Grid.Resources>

...

Got a couple of apps in place to show the usage. The one on the left shows the zoom in action while the second app applies the cacheMode on Viewport2dVisual3D.

The code is attached. Have fun

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XAML 2009 Features: Node Loop flexibility

2009-11-09T15:57:00Z

[This is part of a series on New WPF\XAML Features]

So by now most of you must have noticed the System.Xaml dll as part of your .NET 4 WPF projects. It’s a well componentized XAML stack that provides a lot of flexibility working with XAML. So at the core we a System.Xaml.XamlReader and XamlWriter which provide the base implementation and definition for a reader and writer. XamlXmlReader is a reader that reads in XAML and produces a XAML node stream. This stream is then consumed by a ~~XamlXmlWriter~~ XamlObjectWriter to produce the object graph. Similarly for the Save path, you have the XamlObjectReader and XamlXmlWriter.

So the Load Path looks like

XAML à XXR à Node Stream à XOW à Object Graph

The Save path would look like

Object Graph à XOR à Node Stream à XXW à XAML

Prior to .NET 4, you didn’t have access to the internals; the access points were XamlReader.Load and XamlWriter.Save in PresentationFramework. In .NET 4, we provide access to the node stream and you could manipulate this node loop. There are 7 XamlNodeType’s that you need to look out for in this node loop.

An example of a node loop could be filtering out events and unknown elements. Wouldn’t that make a nice feature in XamlPadX J..

The code below shows how we could replace the Window in the Xaml passed with a Page.

XmlReader xmlReader = XmlReader.Create(input);

XamlXmlReader reader = new XamlXmlReader(xmlReader, System.Windows.Markup.XamlReader.GetWpfSchemaContext());

XamlObjectWriter writer = new XamlObjectWriter(reader.SchemaContext);

while (reader.Read())

{

switch (reader.NodeType)

{

case XamlNodeType.StartObject:

if (!reader.Type.Name.Equals("Window"))

writer.WriteNode(reader);

else

writer.WriteStartObject(new XamlType(typeof(Page), reader.SchemaContext));

break;

case XamlNodeType.EndObject:

case XamlNodeType.StartMember:

case XamlNodeType.EndMember:

case XamlNodeType.Value:

case XamlNodeType.GetObject:

case XamlNodeType.NamespaceDeclaration:

writer.WriteNode(reader);

break;

}

Attached is a project that shows how events\unknown elements could be filtered.

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New WPF Features: Full Trust Xbap Deployment

2009-11-06T15:49:00Z

This is part of a series on New WPF Features

In earlier versions, on trying to deploy a Full Trust Xbap, you would get a "Trust Not Granted" error. Its possible to workaround this issue by installing an assembly in the GAC that has the AllowPartiallyTrustedCallersAttribute. Another option is to install a certificate on the user machine and sign the Xbap with the certificate. Yeah, its painful and we worked on this issue for this release

Now on deployment, you would get a clickonce dialog so that the user can determine if s\he want to run the Xbap. This is really beneficial in the case of Intranet deployment. Do I hear a WOW.. :)

Below is the pictorial difference..

In addition, clicking on the More Information link open up a dialog with additional information that would enable the user to make a more knowledgeable decision about installation

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Xaml 2009 Features: Built in Types

2009-11-05T15:52:00Z

In Xaml2009, we have built-in support for common CLR types which simplifies authoring. So rather than specifying something like

<s:String xmlns:s="clr-namespace:System;assembly=mscorlib"> Foo </s:String>

We can use the notation <x:String > Foo </s:String>

The list of types supported is below:

• <x:String>

• <x:Char>

• <x:Single>

• <x:Double>

• <x:Boolean>

• <x:Byte>

• <x:Int16>

• <x:Int32>

• <x:Int64>

• <x:Decimal>

• <x:Object>

• <x:Uri>

• <x:TimeSpan>

• <x:Array>

One thing to note is wrt WPF this will work only in loose Xaml. This means that these features cannot be used within Cider\Blend. Rob has a post clarifying the absence of tooling support.

Now you get the slight change in title J

[This is part of a series on New WPF\XAML Features]

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New WPF Features: Bindable Run

2009-11-04T16:03:00Z

This is part of a series on New WPF Features

Bindable run - yeah its possible currently but you would require a custom implementation. if you didnt like to create your own implementation, likely you would be using textblock. Problem here is that its likely you would have issues in copy paste scenarios, layout and what not. Now its a lot easier as the framework supports it.

<WrapPanel xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:sys="clr-namespace:System;assembly=System"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >

<WrapPanel.Resources>

<sys:String x:Key="string1">Hello world!! .NET 4 Coming Soon!! New features in WPF!!</sys:String>

</WrapPanel.Resources>

<Run>Sample Text Beginning:</Run>

<Run>End of sample text.</Run>

</Paragraph>

</FlowDocument>

</FlowDocumentReader>

<Run>Sample Text Beginning:</Run>

<Run>End of sample text.</Run>

</Paragraph>

</FlowDocument>

</FlowDocumentReader>

</WrapPanel>

Difference is obvious.. in the textblock case you have wider separations, text is clipped.... look to the right.. its perfect :)

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New WPF Features: Script Interop in Xbap

2009-11-03T15:53:00Z

This is part of a series on New WPF Features

Often times you have Xbap hosted in a Html page and its pretty common to have some kind of interaction between the host and Xbap. In this release, we have enabled these scenarios.

Operation	Changes In	Code Sample
Invoking a function	Xbap	dynamic script = BrowserInteropHelper.HostScript; script.ReportProgress(progressValue.ToString());
Passing an object to a function	Script	function ReportDate(dateTime) { date = new Date(dateTime); var dateBox = document.getElementById("displayDate"); dateBox.value = date.getFullYear(); }
	Xbap	DateTime date1 = (DateTime)date.SelectedDate; script.ReportDate(date1);
Fetching custom data from the script	Script	function ComplexData() { var res = { FirstName: "John", LastName:"Foo", Age:20 }; return res; }
	Xbap	var result = script.ComplexData(); var resultName = result.FirstName; var resultAge = result.Age; tbData.Text = "FirstName: " + resultName + " Age: " + resultAge;
Fetch Function from the script	Script	function ReturnFunction() { return TestAdd; } function TestAdd(arg1, arg2) { return arg1 + arg2; }
	Xbap	var AddFunction = script.ReturnFunction(); var value = AddFunction.call(null, 5, 6); tbData1.Text = "Total: " + value;
Setting up a default callback	Script	function SetClickHandler(handler) { btn1.onclick = handler; }
	Xbap	OnClickHandler handler1 = new OnClickHandler(); script.SetClickHandler(handler1); [ComVisible(true)] public class OnClickHandler { [DispId(0)] // This makes it the object’s default member. public void Invoke() { MessageBox.Show("Default Invoke"); } }
Setting up a custom callback	Script	var XBAPCallback; function SetCallback(callbackObj) { XBAPCallback = callbackObj; btn2.onclick = OnViewReportButtonClick; } function OnViewReportButtonClick() { date = new Date(); XBAPCallback.Callback(date.getFullYear()); }
	Xbap	OnClickHandler handler = new OnClickHandler(); handler.mainViewModel = this.DataContext; script.SetCallback(handler); [ComVisible(true)] public class OnClickHandler { public object mainViewModel; public void Callback(object arg) { ((MainViewModel)mainViewModel).MyText = "CallBack:" + arg.ToString(); } };

A simple sample (love the simple part..) is attached to show the above in action.. Note that you'll need to enable scripts in the browser to get the sample working.

Also, you could look at the publish folder in order to play with the sample without building it.

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New WPF Features: Binding to Dynamic Objects

2009-11-02T15:30:00Z

This is part of a series on New WPF Features

C# 4.0 allows creation of dynamic objects which is useful when you are interacting with dynamic languages. If you are unfamiliar with the dynamic concept take a quick look at this blog entry

So back to WPF. We support binding to dynamic objects.. woohoo... To begin with you need to create the dynamic object (see attached proj)

<Window.Resources>

<local:DynamicObjectClass x:Key="MyDynamicObject" />

</Window.Resources>

In the loaded event , we can then set values

dynamic dynamicObj = BindPanel.DataContext ;

dynamicObj.A = "Simple Binding";

dynamicObj.B = new DynamicObjectClass();

dynamicObj.B.C = "Nested Prop Binding";

dynamicObj.AddItem("item 0");

dynamicObj[0] = "Indexer Binding";

Project Code attached

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