Lester's WPF blog

XAML 2009 Features: Named Object References

llester — Fri, 13 Nov 2009 15:07:00 GMT

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

llester — Thu, 12 Nov 2009 15:08:00 GMT

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

llester — Wed, 11 Nov 2009 15:14:00 GMT

[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

llester — Tue, 10 Nov 2009 16:25:00 GMT

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

llester — Mon, 09 Nov 2009 15:57:00 GMT

[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

llester — Fri, 06 Nov 2009 15:49:00 GMT

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

llester — Thu, 05 Nov 2009 15:52:00 GMT

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

llester — Wed, 04 Nov 2009 16:03:00 GMT

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

llester — Tue, 03 Nov 2009 15:53:00 GMT

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

llester — Mon, 02 Nov 2009 15:30:00 GMT

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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New WPF Features: LayoutRounding

llester — Fri, 30 Oct 2009 14:47:00 GMT

This is part of a series on New WPF Features

LayoutRounding - If you are familiar with Silverlight, this is nothing new. If you are unfamiliar with it, all it does is that it rounds up lengths..

Take for example the code below (hypothetical case)

The one on the left is a bit blurry due to the subpixel positioning and doesnt use LayoutRounding. The one on the left is rendered with LayoutRounding and has crisper lines.

The property to enable LayoutRounding is UseLayoutRounding="true" ... By default this is set to false (unlike SL)

You can also take a look at the MSDN documentation

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New WPF Features: Key\Gesture Binding

llester — Thu, 29 Oct 2009 14:51:00 GMT

This is part of a series on New WPF Features

We got a lot of feedback to improve the way a developer could set binding to the input keys and modifiers. Earlier, the command property on the inputbinding class was not a Dependency property - so binding to it was out of question. Also it didnt inherit the datacontext of the parent. There are workarounds and most likely you would be doing something like the below as is done in the CoreMVVM libraries.

<Window.Resources>

<c:CommandReference x:Key="ExitCommandReference" Command="{Binding ExitCommand}" />

</Window.Resources>

<Window.InputBindings>

</Window.InputBindings>

However, now we have baked this in the framework so the experience is a lot better. InputBindings inherits from Freezable for the DataContext and exposes the commands as Dependency Properties. Now the above looks something like

<Window.InputBindings>

</Window.InputBindings>

Aint that sweet.. You could also bind the Key and Modifiers as below.

<Window.InputBindings>

<KeyBinding Command="{Binding ExitCommand}"

Key="{Binding ExitCommand.GestureKey}"

Modifiers="{Binding ExitCommand.GestureModifier}"/>

</Window.InputBindings>

So whats the plumbing needed for this..

In your delegateCommand class, declare the following 3 properties:

public Key GestureKey { get; set; }

public ModifierKeys GestureModifier { get; set; }

public MouseAction MouseGesture { get; set; }

Now in the ViewModel, set these properties when you initialize the command

public ICommand ExitCommand

{

get

{

if (exitCommand == null)

{

exitCommand = new DelegateCommand(Exit);

exitCommand.GestureKey = Key.X;

exitCommand.GestureModifier = ModifierKeys.Control;

exitCommand.MouseGesture = MouseAction.LeftDoubleClick;

}

return exitCommand;

}

Thats it... the sample code is attached.

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New WPF Features: ClearTypeHint

llester — Wed, 28 Oct 2009 12:26:00 GMT

This is part of a series on New WPF Features

WPF enforces grayscale rendering when text is rendered on a transparent area. However, its possible that the background of a control is opaque even though its inside a transparent area. For example, popups have rounded edges and will have the allowstransparency property set. Same is the case with transparent windows.

Now in .NET 4, we provide the developer to decide whether to render with cleartype or not. The way to do this is to set the RenderOptions.ClearTypeHint property.

RenderOptions.ClearTypeHint="Enabled"

This forces the rendering engine to enable Cleartype for the subtree. Intermediate render targets, such as Effect, OpacityMask, VisualBrush, DrawingBrush, Clip, and Opacity, can introduce backgrounds that are not fully opaque. WPF disables ClearType when it detects that the buffer into which text is drawn could have a transparent background. However, you could easily enable it again.

To get a more clear picture, consider the XAML like

<TextBlock Name="Block1">This text will be rendered with ClearType.</TextBlock>

This text will be rendered with NO ClearType (note the opacity Prop).

</TextBlock>

<Grid.Clip>

</Grid.Clip>

<Grid.RowDefinitions><RowDefinition/><RowDefinition/></Grid.RowDefinitions>

<TextBlock Name="Block3" > This text will be rendered with NO ClearType.</TextBlock>

This text will be rendered with ClearType

</TextBlock>

</Grid>

<TextBlock Name="Block5">This text will be rendered with ClearType.</TextBlock>

</StackPanel>

</Window>

Here the values are set as per the hierarchy

Window à hint enabled

StackPanel à inherits Hint (cleartype)

Block1 à inherits Hint (cleartype)

Block2 à overrides Hint because of Opacity [intermediate render target]

Grid à overrides Hint because of Clip [intermediate render target]

Block3 à Inherits Grid’s hint (No cleartype)

Block4 à overrides Hint to enabled (Cleartype)

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New WPF Features: CaretBrush\SelectionBrush

llester — Tue, 27 Oct 2009 13:12:00 GMT

This is part of a series on New WPF Features

There have been quite a few asks for changing the selection color and the caret color. We have now provide 2 properties to make this possible

CaretBrush
SelectionBrush

An example usage would be like

SelectionBrush="RED"
SelectionOpacity="0.3" (Default value is 0.6)
CaretBrush="Red"

These properties are avaialble on controls that allow selection\caret.

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New WPF Features: Custom Speller Dictionary

llester — Mon, 26 Oct 2009 14:22:00 GMT

This is part of a series on New WPF Features

In previous versions, adding a custom dictionary was an unsupported scenario. You could still do it but it required writing a bunch of code.

In this release, we have provided suport for adding custom dictionaries.

<SpellCheck.CustomDictionaries>

<sys:Uri>Dictionary1.lex</sys:Uri>

<sys1:Uri>\\dictServer\Dictionary3.txt</sys1:Uri>

</SpellCheck.CustomDictionaries>

<Paragraph>Some Names: Zorig Lester </Paragraph>

<Paragraph>Misspelled: Zorg BlahBlah </Paragraph>

</FlowDocument>

</RichTextBox>

The dictionaries are plain text files and list the words to be updated.

For a non default locale (en-us) you can specify the locale ID at the top (#LID localeID). In the pic above, we are using the locale 2057 which corresponds to english-UK.

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