Venugopal on WPF and Silverlight

Microsoft Certified Technology Specialist (MCTS) Silverlight 4 Development

noreply@blogger.com (Venugopal) — Mon, 10 Oct 2011 07:20:00 +0000

I am really happy to share my first experience on MCTS exam. Yes, I successfully completed my Microsoft Certified Technology Specialist (MCTS) Silverlight 4 Development certification today. Really it was nice experience since it is first certification exam in my career. I just want to share some technical information about this exam. Hope following information will be useful to you guys when you plan for silverlight certification exam.
Here is the info:
Total questions are 50 and given time was 2:20 hrs. Here are the section details.

10 questions from data model (MVVM)

5 questions from WCF service reference.

5 to 7 questions from templates and styles.

2 questions from out of browser

3 questions from Object tag in aspx file.

10 questions from typical xaml and code behind logic such as event handler, background thread, dependency properties, etc.

That’s all I could remember. However, people can pass this exam very easily if you have good experience on MVVM, control templates, styles, basic WCF configuration and deployment, dependency properties and custom controls.
My transcript link. (Transcript ID (982461) and the Access Code (12345678)
Enjoy!

Microsoft released free eBook for VS2010

noreply@blogger.com (Venugopal) — Thu, 02 Dec 2010 07:20:00 +0000

Hi All,

Good news. Microsoft released free eBook for VS2010.
Download from here.
http://blogs.msdn.com/b/microsoft_press/archive/2010/09/13/free-ebook-moving-to-microsoft-visual-studio-2010.aspx

Thanks,
Venugopal.

Solution for "The underlying provider failed on Open" exception.

noreply@blogger.com (Venugopal) — Fri, 12 Nov 2010 09:30:00 +0000

As you guys know that I am posting enterprise architecture design article in code project here. While preparing third part, I started to implement simple tier application for demo. After completing server side implementation, I started to implement simple client for demo purpose. Once completed with client, i tried to run my demo application. But unfortunately I got the strange exception called "The underlying provider failed on Open". I googled more than an hour and found that most of the folks facing the same issue when they try to call the service which contains database access in local sql server through IIS. But no one is providing proper solution for this issue. Everyone says that IIS uses network credentials when it contacts sql server authentication process. So we should grant access to "NT AUTHORITY\NETWORK SERVICE" to your database.
But this is not the right solution and no one is saying how to fix the issue. After spending some hours, found the solution and my app running without any issues.

Here is the solution.

As folks mentioned IIS user network service user credentials while trying to log in sql server. So just change the Application pool settings in your IIS.

Step 1: Open Internet Information Service Manager
Step 2: Click on Application Pools in left navigation tree.
Step 3: Select your version Pool. In my case, I am using ASP .Net v4.0. If you dont have this version, select DefaultAppPool.
Step 4: Right click on step 3, and select advanced settings.
Step 5: Select Identity in properties window and click the button to change the value.
Step 6: Select Local System in Built-in accounts combo box and click ok.
That's it. Now run your application. Everything works well.

Enjoy!!!.

Enterprise Application Architecture: Designing Applications and Services in .Net - Part I

noreply@blogger.com (Venugopal) — Tue, 05 Oct 2010 09:12:00 +0000

A guided tour of the distributed enterprise application design in .Net

Introduction

This article is an attempt to show how to implement distributed application in .Net framework from the scratch. Indeed I can share my experience which I hope will be useful for architects (Obviously beginners in architecture design) or a lead developer wants to become an architect to start with. The application will contain simple web client CustomerOrderManagement System with our own distributed application platform.

The application will cover the following parts,

Part 1 (Distributed Application Layers with project details): Learn about what is layered design in distributed environment and how we are going to name it while implementing the actual app.
Part 2 (Database and Library Design): Learn about database design and implementing library which interacts with Edmx container.
Part 3 (Engine and Service Managers design): Learn how to implement the engine which has core business logic and implementing the actual WCF service with service contracts. And also how to test the service using test client.
Part 4 (Client implementation): Learn how to implement the actual client with MVVM pattern which invokes services.

Follow my articles in codeproject

Thanks,
Venugopal.

Lazy(Of T) class in .Net Framework4.0

noreply@blogger.com (Venugopal) — Wed, 25 Aug 2010 15:27:00 +0000

.Net Framework provides us with a new class called Lazy<T> which is used to initialize the object in lazy pace. It includes the ability to initialize the value types and to use null values. Using this class, we could implement complex navigation related applications very effectively with less memory use. For instance, consider the situation like I have a property which holds array of user controls(Approx 50 User Controls) in Silverlight application. In this instance, need to display five user controls in main page, but need to initiate all these fifty user controls to get the actual references while application load since I need to bind some elements between user controls. At the same time, rest of the user controls will be displayed when user navigate explicitly.

If we implement such a application using typical .Net property declaration/initialization without using the Lazy class, all the user control will be initialized when we use new keyword while adding items in my array property. Below is the typical .Net initialization.

// Property declaration
private UserControl[] loadMyUserControl;
public UserControl[] LoadMyUserControl
{
get
{
return loadMyUserControl;
}
set
{
loadMyUserControl = value;
}
}

// Initializing property.
public MainPage()
{

InitializeComponent();
var userControls = new UserControl[]
{
new UserControl1(),
new UserControl2(),
new UserControl3()
};
}

In this approach, my application consumes unnecessary memory(Nearly 45 user control memory) when user open my application and closes without navigating into other pages.

But Lazy initialization occurs the first time the Lazy<T>.Value property is accessed or the Lazy<T>.ToString method is called. For my scenario, five user controls instance and memory only created while loading my application. Rest of the user controls will be created when user navigate to the corresponding page through navigation link from my main page. Below is the code snippet for lazy load.

// Property declaration
private Lazy<UserControl>[] loadMyUserControl;
public Lazy<UserControl>[] LoadMyUserControl
{
get
{
return loadMyUserControl;
}
set
{
loadMyUserControl = value;
}
}

// Initializing property.
public MainPage()
{
InitializeComponent();
LoadMyUserControl = new Lazy<UserControl>[]
{
new Lazy<UserControl>(() => {return new UserControl1();
}),
new Lazy<UserControl>(() => {return new UserControl2();
}),
new Lazy<UserControl>(() => {return new UserControl3();
})
};
}

Now I am going to load my user controls based on navigation at runtime as below mentioned.

// Loading my fifth user control on button click
private void Button_Click_1(object sender, RoutedEventArgs e)
{
if (!TopPanel.Children.Contains(LoadMyUserControl[5].Value))
TopPanel.Children.Add(LoadMyUserControl[5].Value);
}

Note : TopPanel is the stack panel which is in main page of the application. See the demo sample for more idea.

Run the demo app and click “Status” button. Check the status of user controls. Still all the user controls are not loaded as shown in below mentioned snap.

Click “Load UserControl1” button and check the status. Now you could see, first user control loaded in view and status has been changed as True. What a great feature in framework4.0. :)

You can refer this in msdn documentation for more idea about Lazy class.

Here is the simple real time Silverlight sample which illustrates the same.

Enjoy :)

Thanks,

Venugopal.

Silverlight Image download indicator with MVVM Pattern

noreply@blogger.com (Venugopal) — Wed, 04 Aug 2010 12:48:00 +0000

Introduction

Microsoft Silverlight provides a BitmapImage class, which supports a set of features for Image expression including some of the useful events such as DownloadProgress, ImageFailed and ImageOpened events. These events can be effectively used to have a UI with nice look and feel by displaying download progress in case the images are downloaded from the web dynamically.

Probably, some folks might already have solution for this scenario. But I hope many developers don’t think in the same way. So, have got something to share on this based on my experience. My approach involves simple SpinAnimation custom control implementation. Also there are chances that my solution may not be offering something of the expertise level but at least it can help to discover the approach :).

This post explores a number of concepts; first, it involves creating tiny custom SpinAnimation control with animation, next, implementing a View Model (To follow MVVM pattern) with necessary properties for indicating progress details to the View and finally, creating View to design the UI with Model property binding.

SpinAnimationControl - Custom Silverlight control

As there are more articles on how to create custom control in Silverlight, I am directly jumping on to the main code that is related to changing the visibility of the control based on download progress value. I know, you are asking now, why SpinAnimation control? J Can’t we change the visibility of the SpinAnimation Control based on model property value? Yes, we can change, but I want to do some operation when the visibility of animation element gets changed. Like stop and start the animation when element visibility value gets changed. Both WPF and SL do not provide the Visibility property changed callback by default. But you could achieve using property metadata override logic in WPF. Unfortunately Silverlight doesn’t have feature to override the property metadata like WPF does. So we can go ahead with generic solution which works both in SL and WPF. Let's start with SpinAnimation control constructor, which is pretty basic:

Setting default style key for custom control.

public class SpinAnimationControl : Control

{

public SpinAnimationControl ()

{

this.DefaultStyleKey = typeof(SpinAnimationControl);

}

Creating dependency property called Progress which receives the download progress value from application side. Note that I have mentioned property value changed callback OnProgressChanged in PropertyMetadata. In this call back, if new value is less then 100, I am assuming that image is still not downloaded. If value is equal to 100, image gets downloaded witout any issue. So, I can change the visibility of my SpinAnimation control based on the new value. And also I can stop and start the animation after I change the visibility. Please refer the property value changed callback method for more details below.

public int Progress

{

get { return (int)GetValue(ProgressProperty); }

set { SetValue(ProgressProperty, value); }

}

public static readonly DependencyProperty ProgressProperty = DependencyProperty.Register("Progress", typeof(int), typeof(SpinAnimationControl), new PropertyMetadata(0, OnProgressChanged));

Override OnApplyTemplate method for getting template child which has animation storyboard in resource section of root element. You can get template child using GetTemplateChild method. Grid is the root element in control template.

Grid spinGrid = null;

public override void OnApplyTemplate()

{

base.OnApplyTemplate();

spinGrid = GetTemplateChild("SpinGrid") as Grid;

}

Property value changed callback.

private bool isAnimationStarted = false;

private static void OnProgressChanged(object sender, DependencyPropertyChangedEventArgs args)

{

if (sender is SpinAnimationControl)

{

(sender as SpinAnimationControl).OnProgressChanged(args);

}

public void OnProgressChanged(DependencyPropertyChangedEventArgs args)

{

int newValue = (int)args.NewValue;

Storyboard storyBoard = null;

if (spinGrid != null)

{

// Storyboard from grid resource.

storyBoard = spinGrid.Resources["RetrievalCircleAnimation"] as Storyboard;

}

if (newValue < 100)

{

this.Visibility = Visibility.Visible;

if (!isAnimationStarted)

{

if (storyBoard != null)

{

// Start the animation

storyBoard.Begin();

isAnimationStarted = true;

}

else

{

this.Visibility = Visibility.Collapsed;

if (isAnimationStarted)

{

if (storyBoard != null)

{

// Stop the animation.

storyBoard.Stop();

isAnimationStarted = false;

}

SpinAnimation control template – generic.xaml

Here is the template of SpinAnimation control. I put some ellipses with storyboard for animating download progress indicator. Please refer the generic.xaml for complete template code.

<Grid.Resources>
<Storyboard x:Name="RetrievalCircleAnimation" RepeatBehavior="Forever" SpeedRatio="4">

<Ellipse.RenderTransform>

</TransformGroup>

</Ellipse.RenderTransform>

</Ellipse>

<!- More codes -->

</Grid>

</ControlTemplate>

SpinAnimation Control Snap.

Creating ViewModel and View to present the Image with download indicator.

If you are a SL or WPF developer, I believe that you prefer MVVM approach only, nevertheless I always prefer MVVM since it is the only powerful pattern for SL or WPF apps till now. So that is the reason I decided that implementing image Uri and Progress notification from View Model.

ImageAppViewModel class

ImageAppViewModel class has property called ImageList with the type of ObservableCollection. This is the property that we are going to bind as an ItemsSource of Listbox control in View.

public ImageAppViewModel()

{

ImagesList = new ObservableCollection<ImageExt>();

ImagesList.Add(new ImageExt() { Uri = "http://www.pdssb.com.my/images/stories/gallery/car.jpg" });

ImagesList.Add(new ImageExt() { Uri = "http://joshua.maruskadesign.com/blog/uploaded_images/Car-02-723748.png" });

ImagesList.Add(new ImageExt() { Uri = "http://www.carbodydesign.com/archive/2009/02/13-automotive-designers-show-program/Autodesk-Concept-Car-rendering-lg.jpg" });

ImagesList.Add(new ImageExt() { Uri = "http://www2.hiren.info/desktopwallpapers/other/car-silver-87c.jpg" });

ImagesList.Add(new ImageExt() { Uri = "http://brianhansford.com/wp-content/uploads/2010/02/red-sports-car.jpg" });

}

private ObservableCollection<ImageExt> m_ImagesList;

public ObservableCollection<ImageExt> ImagesList

{

get

{

return m_ImagesList;

}

set

{

m_ImagesList = value;

OnPropertyChanged("ImagesList");

}

ImageExt class

ImageExt class has property called Uri, ImageSource(Type of BitmapImage) and Progress property. Why two property for image source in view model?. Typically we will send Image uri as a string type. See the below

Uri="http://www.pdssb.com.my/images/stories/gallery/car.jpg"

But we need to construct the BitmapImage object using this uri and register the DownloadProgress event in property getter. In Download progress event handler, update the Progress property of ImageExt class which we are using for indicating how much percentage of bytes has been downloaded for particular image. Now bind only ImageSource property in ItemTemplate of ListBox in View.

public class ImageExt : INotifyPropertyChanged

{

private int m_Progress;

public int Progress

{

get

{

return m_Progress;

}

set

{

m_Progress = value;

OnPropertyChanged("Progress");

}

private string m_Uri;

public string Uri

{

get

{

return m_Uri;

}

set

{

m_Uri = value;

OnPropertyChanged("Uri");

}

BitmapImage image = null;

public BitmapImage ImageSource

{

get

{

image = new BitmapImage(new Uri(Uri, UriKind.Absolute));

image.DownloadProgress += new EventHandler<DownloadProgressEventArgs>(image_DownloadProgress);

return image;

}

DownloadProgress Event Handler

// Updating Progress property value based on DownloadProgressEventArgs value and un registering the event once its // gets downloaded.

void image_DownloadProgress(object sender, DownloadProgressEventArgs e)

{

Progress = e.Progress;

if (e.Progress == 100)

{

image.DownloadProgress -= new EventHandler<DownloadProgressEventArgs>(image_DownloadProgress);

}

ImageAppView and ImageAppView.xaml

Now, create the ImageAppView.xaml and put the simple list box control with ViewModel property binding. See the below code snippet, ListBox ItemsSource property bound with ImageList property which we declared in ViewModel.

</ListBox>

Set the ItemsPanelTemplate with StackPanel to display images in horizontal view.

<ListBox.ItemsPanel>

</ItemsPanelTemplate>

</ListBox.ItemsPanel>

Set the ItemTemplate to host our SpinAnimation and Image control to display the actual image once gets downloaded. And also I put some textboxes to show the download percentage details as well.

<ListBox.ItemTemplate>

<Grid>

</StackPanel>

<control:SpinAnimationControl Name="spinAnimationControl" Width="50" Height="50" VerticalAlignment="Center" HorizontalAlignment="Stretch" Progress="{Binding Progress}" Margin="1"/>

</Grid>

</DataTemplate>

</ListBox.ItemTemplate>

Finally assign the ViewModel in DataContext of View .

public partial class MainPage : UserControl

{

public MainPage()

{

InitializeComponent();

this.DataContext = new ImageAppViewModel();

}

Run the demo application and see the output. Here is some snaps.

Download initiated

Download completed

Download complete source code from here.

Enjoy!!!!.

ToolTip for Disabled Element in Silverlight

noreply@blogger.com (Venugopal) — Wed, 23 Jun 2010 12:03:00 +0000

I noticed that there are many conversations departing in Silverlight forums regarding tool tip support for disabled elements in Silverlight. Silverlight program manager also accepts here that having the ToolTip not show on a disabled element is by design. However some folks suggesting mouse enter and mouse leave, and some evoking style modification, etc... But these approach not applicable when you develop your Silverlight application in MVVM pattern. Here is the simple approach that helps you to set tooltip for disabled item.

Host a rectangle on top of your element in a grid and bind the visibility property of the Rectangle with IsEnabled property of target element (Make sure that you have BooleanToVisibilityConverter like one in WPF). And bind your business property with tooltip of the rectangle as well as for your target element if you want to display in enabled state also. And also don’t forget to bind Rectangle Width and Height property with ActualWidth and ActualHeight of Button.

Here is the code.

<Grid Margin="30,0,20,0”>
<Button x:Name="MyButton" Content="See My ToolTip when I am in Disabled" IsEnabled="{Binding Path=IsEnabled}"/>
<Rectangle x:Name="toolTipForDiabledButton" Visibility="{Binding Path=IsEnabled, ElementName=AddButton, Converter={StaticResource BoolToVisibilityConverter}}" ToolTipService.ToolTip="{Binding Path=MyToolTip, Mode=TwoWay}" Fill="Transparent"
Width="{Binding Path=ActualWidth, ElementName=AddButton}" Height="{Binding Path=ActualHeight, ElementName=AddButton}">
</Rectangle>
</Grid>

Hope this helps for MVVM folks.

Enjoy!!!.

The calling thread cannot access this object because a different thread owns it.

noreply@blogger.com (Venugopal) — Fri, 14 May 2010 12:39:00 +0000

Hi,

Today I faced an issue with my custom control which has my own DictionaryList with custom CustomKeyValuePair class as Value of dictionary list. Key is a string type, so nothing problem on it. I used this dictionary list for storing resources to provide different skin support in my control template. Note the point, my CustomKeyValuePair class inherited from DependencyObject. After implementing my control with effective skin mechanism, I tried to host my control in multi threaded WPF application. But unfortunately I got this error message {"The calling thread cannot access this object because a different thread owns it."} since calling thread uses my dictionary list Value(CustomKeyValuePair). As I said, this class inherited from DependencyObject, so WPF won't allow you to access dependency property in multi thread application.

Initially I tried to solve this issue with value cloning logic. But no use. Finally tried with INotifyPropertyChanged class. Yes, I just removed base class DependencyObject from CustomKeyValuePair class and implemented INotifyPropertyChanged interface with Value property notification when its value getting changed. Now my controls works in multithread WPF application perfectly J

public class CustomKeyValuePair : INotifyPropertyChanged //DependencyObject
{
//public static readonly DependencyProperty ValueProperty = DependencyProperty.Register("Value", typeof(object), typeof(PairKeyValue), new UIPropertyMetadata(null));

//public object Value
//{
// get
// {
// return (object)GetValue(ValueProperty);
// }
// set
// {
// SetValue(ValueProperty, value);
// }
//}

// Solution for "The calling thread cannot access this object because a different thread owns it."

object _value;

/// <summary>
/// Gets or sets the value in key-value pair.
/// </summary>
public object Value
{
get
{
return _value;
}
set
{
_value=value;
OnPropertyChanged("Value");
}
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}

Enjoy J

-Venugopal.

Shifting focus to the first available element in WPF

noreply@blogger.com (Venugopal) — Thu, 18 Mar 2010 11:10:00 +0000

Hi,

Nice article for this requirement.

http://www.julmar.com/blog/mark/2008/09/12/Part3ShiftingFocusToTheFirstAvailableElementInWPF.aspx

-Venugopal.

How to suppress the System.Windows.Data Error warning message

noreply@blogger.com (Venugopal) — Mon, 15 Mar 2010 04:38:00 +0000

Hi,

When we use FindAncesstor in custom control template for binding internal elements property into its ancestor element, visual studio displays data warning messages in output window when binding engine meets unmatched target type during visual tree traversal though it does the proper binding when it receives expected target type during visual tree traversal. To suppress this data error warning messages, you should mention level of warning message trace in your library class.

Here is the simple data error that I am getting when I bind some commands in rich text box.

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.RichTextBox', AncestorLevel='1''. BindingExpression:Path=Content; DataItem=null; target element is 'Button' (Name=''); target property is 'CommandTarget' (type 'IInputElement')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.RichTextBox', AncestorLevel='1''. BindingExpression:Path=Content; DataItem=null; target element is 'Button' (Name=''); target property is 'CommandTarget' (type 'IInputElement')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.RichTextBox', AncestorLevel='1''. BindingExpression:Path=Content; DataItem=null; target element is 'Button' (Name=''); target property is 'CommandTarget' (type 'IInputElement')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.RichTextBox', AncestorLevel='1''. BindingExpression:Path=Content; DataItem=null; target element is 'Button' (Name=''); target property is 'CommandTarget' (type 'IInputElement')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.RichTextBox', AncestorLevel='1''. BindingExpression:Path=Content; DataItem=null; target element is 'Button' (Name=''); target property is 'CommandTarget' (type 'IInputElement')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.RichTextBox', AncestorLevel='1''. BindingExpression:Path=Content; DataItem=null; target element is 'Button' (Name=''); target property is 'CommandTarget' (type 'IInputElement')

Solution, set data binding source switch level as critical in constructor of the class.

System.Diagnostics.PresentationTraceSources.DataBindingSource.Switch.Level = System.Diagnostics.SourceLevels.Critical;

Thanks,
Venugopal.

Binding AttachedProperty Based on SelectedItem in Xaml

noreply@blogger.com (Venugopal) — Thu, 11 Mar 2010 05:14:00 +0000

Hi,

Today one of our WPF product customer raised a question about how to bind an attached property in XAML. I was wondered like what is the problem in it, and I just replied him immediately with below code.

But after his detailed reply for my post, came to know that his question was valid :). Because he wants to bind the attached property of custom ItemsControl using its items object without mentioning specific child object name whenever active item gets changed.

I just tried following code and its working perfectly without any event handler or converter in View Modal application.

Here is the solution.

Note that, ActiveItem should get updated whenever you select any item in itemscontrol. Just like SelectedItem property.

Thanks to the WPF team for providing powerful binding stuffs.

-Venugopal.

Property Grid Editing Support for Collection Type Property - Custom Control

noreply@blogger.com (Venugopal) — Mon, 01 Mar 2010 07:31:00 +0000

Hi,

Last week I faced some problem while giving property grid editor support for collection type property. For instance my custom control(NavigationControl) inherited from ItemsControl and its item container is NavigationItem. Now when I try to add items through Items property in property grid(In both VS2008 and VS2010), Add button is in disabled state which is present in collection editor dialog box.

To activate this with custom type or collection of types, you can register this in attribute table builder of your designer projects.

For instance,

internal class Metadata : IRegisterMetadata
{

// Called by Cider to register any design-time metadata
public void Register()
{
AttributeTableBuilder builder = new AttributeTableBuilder();
builder.AddCustomAttributes(typeof(NavigationItem), new ToolboxBrowsableAttribute(false));
builder.AddCustomAttributes(typeof(NavigationControl), "Items", new NewItemTypesAttribute(typeof(NavigationItem)));
MetadataStore.AddAttributeTable(builder.CreateTable());
}
}

Thanks,
Venugopal.

How to set Enum type as ItemsSource?

noreply@blogger.com (Venugopal) — Wed, 10 Feb 2010 11:19:00 +0000

Hi,

Here is the simple way to bind the Enum types as ItemsSource in items control.

<Window x:Class="DoubleTextBoxSample.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:DoubleTextBoxSample"
xmlns:syncfusion="http://schemas.syncfusion.com/wpf"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
Title="Window1" Height="300" Width="300">
<Window.Resources>
<ObjectDataProvider x:Key="itemsFromEnum" MethodName="GetValues" ObjectType="{x:Type sys:Enum}">
<ObjectDataProvider.MethodParameters>
<x:Type TypeName="Orientation"/>
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
</Window.Resources>

<StackPanel>
<syncfusion:CheckListBox ItemsSource="{Binding Source={StaticResource itemsFromEnum}}">
</syncfusion:CheckListBox>
</StackPanel>
</Window>

Just bound object provider instance with Syncfusion's CheckListbox ItemsSource property and got cool result.

Thanks,
Venugopal.

Composite Application Library (Prism-CAL)

noreply@blogger.com (Venugopal) — Wed, 20 May 2009 04:27:00 +0000

Hi Guys,

Sorry for the long delay in post. I was quiet busy with my work. I will update some interesting posts about CAL library soon.

-Venugopal.

If you have comments or if you have any questions that are not answered by this post please put them as a comment. It will be great useful for me to cover in my next post.

Visual Level Programming vs Logical Level Programming

noreply@blogger.com (Venugopal) — Tue, 16 Dec 2008 09:07:00 +0000

Excelent Article about Visual child and tree maintenance.

http://shevaspace.blogspot.com/2007/02/visual-level-programming-vs-logical.html

Thanks Zhou Yong.

Thanks,
Venugopal.

Own Certificate Installer for XBAP deployment

noreply@blogger.com (Venugopal) — Mon, 25 Aug 2008 09:46:00 +0000

Very nice article for certificate installer.

Certificate installer

XBAP Clickonce Deployment

Thanks,
Venugopal

Converting EXE Projects to XBAPs

noreply@blogger.com (Venugopal) — Mon, 25 Aug 2008 09:11:00 +0000

Here is nice explaination about Converting EXE Projects to XBAPs.

Converting EXE Projects to XBAPs

Thanks,
Venugopal.

How can we Resign the satelitte assembly from command prompt.

noreply@blogger.com (Venugopal) — Fri, 11 Jul 2008 10:27:00 +0000

Here is the command to resign the satelitte assembly :

sn -R "YourAssemblyName.dll" "yourpublickey.snk"

Another way to listen to dependency property change.

noreply@blogger.com (Venugopal) — Sat, 05 Jul 2008 18:46:00 +0000

Ben Constable just blogs about another elegant way to listen to dependency property change, the trick here is using DependencyPropertyDescriptor, imagine that you have a Label called myLabel, and you want to get notified when it's ContentProperty is changed, then you can do something like the following:

DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(Label.ContentProperty, typeof(Label));
if (dpd != null)
{
dpd.AddValueChanged(myLabel, delegate
{
// Add your logic here to respond to value change.
});
}

The other ways in WPF that you can use to listen to property change is to subclass an existing Control, and override the metadata of a dependency property whose property change you want to listen to, when you do so, you need to specify a PropertyChangedCallback which a delegate to your property change event handler, or instead of using PropertyChangedCallback, you can override the OnPropertyChanged method, and place your logic there, as a bonus, you can get additional information things like which property is changed by examining the value of passed-in DependencyPropertyChangedEventArgs argument's Property property.

What is difference between Timer and Dispatcher

noreply@blogger.com (Venugopal) — Fri, 13 Jun 2008 19:08:00 +0000

Dispatcher things

The DispatcherTimer is reevaluated at the top of every Dispatcher loop.

Timers are not guaranteed to execute exactly when the time interval occurs, but are guaranteed to not execute before the time interval occurs. This is because DispatcherTimer operations are placed on the Dispatcher queue like other operations. When the DispatcherTimer operation executes is dependent on the other jobs in the queue and their priorities.

If a System.Timers.Timer is used in a WPF application, it is worth noting that the System.Timers.Timer runs on a different thread then the user interface (UI) thread. In order to access objects on the user interface (UI) thread, it is necessary to post the operation onto the Dispatcher of the user interface (UI) thread using Invoke or BeginInvoke. Reasons for using a DispatcherTimer opposed to a System.Timers.Timer are that the DispatcherTimer runs on the same thread as the Dispatcher and a DispatcherPriority can be set on the DispatcherTimer.

A DispatcherTimer will keep an object alive whenever the object’s methods are bound to the timer.

So, the right way to schedule things inside the WPF UI is something like this.

private DispatcherTimer _timer;
timer = new DispatcherTimer(DispatcherPriority.Background);
timer.Interval = TimeSpan.FromMinutes(5);
timer.Tick += delegate { ScheduleUpdate(); };
timer.Start();

Coordinate Systems in .Net

noreply@blogger.com (Venugopal) — Thu, 05 Jun 2008 13:23:00 +0000

Before we discuss transformations, we need to understand coordinate systems. GDI+ defines three types of coordinate spaces: world, page, and device. When we ask GDI+ to draw a line from point A (x1, y1) to point B (x2, y2), these points are in the world coordinate system.

Before GDI+ draws a graphics shape on a surface, the shape goes through a few transformation stages (conversions). The first stage converts world coordinates to page coordinates. Page coordinates may or may not be the same as world coordinates, depending on the transformation. The process of converting world coordinates to page coordinates is called world transformation.

The second stage converts page coordinates to device coordinates. Device coordinates represent how a graphics shape will be displayed on a device such as a monitor or printer. The process of converting page coordinates to device coordinates is called page transformation. Figure 10.2 shows the stages of conversion from world coordinates to device coordinates.

In GDI+, the default origin of all three coordinate systems is point (0, 0), which is at the upper left corner of the client area. When we draw a line from point A (0, 0) to point B (120, 80), the line starts 0 pixels from the upper left corner in the x-direction and 0 pixels from the upper left corner in the y-direction, and it will end 120 pixels over in the x-direction and 80 pixels down in the y-direction. The line from point A (0, 0) to point B (120, 80) is shown in Figure 10.3.

Figure 10.3. Drawing a line from point (0, 0) to point (120, 80)

Drawing this line programmatically is very simple. We must have a Graphics object associated with a surface (a form or a control). We can get a Graphics object in several ways. One way is to accept the implicit object provided by a form’s paint event handler; another is to use the CreateGraphics method. Once we have a Graphics object, we call its draw and fill methods to draw and fill graphics objects. Listing 10.1 draws a line from starting point A (0, 0) to ending point B (120, 80). You can add this code to a form’s paint event handler.

Listing 10.1 Drawing a line from point (0, 0) to point (120, 80)

Graphics g = e.Graphics;
Point A = new Point(0, 0);
Point B = new Point(120, 80);
g.DrawLine(Pens.Black, A, B);

Figure 10.3 shows the output from Listing 10.1. All three coordinate systems (world, page, and device) draw a line starting from point (0, 0) in the upper left corner of the client area to point (120, 80).

Now let’s change to the page coordinate system. We draw a line from point A (0, 0) to point B (120, 80), but this time our origin is point (50, 40) instead of the upper left corner. We shift the page coordinates from point (0, 0) to point (50, 40). The TranslateTransform method of the Graphics class does this for us. We will discuss this method in more detail in the discussion that follows. For now, let’s try the code in Listing 10.2.

Listing 10.2 Drawing a line from point (0, 0) to point (120, 80) with origin (50, 40)

Graphics g = e.Graphics;
g.TranslateTransform(50, 40);
Point A = new Point(0, 0);
Point B = new Point(120, 80);
g.DrawLine(Pens.Black, A, B);

Figure 10.4 shows the output from Listing 10.2. The page coordinate system now starts at point (50, 40), so the line starts at point (0, 0) and ends at point (120, 80). The world coordinates in this case are still (0, 0) and (120, 80), but the page and device coordinates are (50, 40) and (170, 120). The device coordinates in this case are the same as the page coordinates because the page unit is in the pixel (default) format.

Figure 10.4. Drawing a line from point (0, 0) to point (120, 80) with origin (50, 40)

What is the difference between page and device coordinates? Device coordinates determine what we actually see on the screen. They can be represented in many formats, including pixels, millimeters, and inches. If the device coordinates are in pixel format, the page coordinates and device coordinates will be the same (this is typically true for monitors, but not for printers).

The PageUnit property of the Graphics class is of type GraphicsUnit enumeration. In Listing 10.3 we set the PageUnit property to inches. Now graphics objects will be measured in inches, so we need to pass inches instead of pixels. If we draw a line from point (0, 0) to point (2, 1), the line ends 2 inches from the left side and 1 inch from the top of the client area in the page coordinate system. In this case the starting and ending points are (0, 0) and (2, 1) in both world and page coordinates, but the device coordinate system converts them to inches. Hence the starting and ending points in the device coordinate system are (0, 0) and (192, 96), assuming a resolution of 96 dots per inch.

Listing 10.3 Setting the device coordinate system to inches
g.PageUnit = GraphicsUnit.Inch;
g.DrawLine(Pens.Black, 0, 0, 2, 1);

Figure 10.5 shows the output from Listing 10.3. The default width of the pen is 1 page unit, which in this case gives us a pen 1 inch wide.

Figure 10.5. Drawing with the GraphicsUnit.Inch option

Now let’s create a new pen with a different width. Listing 10.4 creates a pen that’s 1 pixel wide (it does so by dividing the number of pixels we want—in this case 1—by the page resolution, which is given by DpiX). We draw the line again, this time specifying a red color.

Listing 10.4 Using the GraphicsUnit.Inch option with a pixel width
Pen redPen = new Pen(Color.Red, 1/g.DpiX);
g.PageUnit = GraphicsUnit.Inch;
g.DrawLine(Pens.Black, 0, 0, 2, 1);

Figure 10.6 shows the output from Listing 10.4.

Figure 10.6. Drawing with the GraphicsUnit.Inch option and a pixel width

We can also combine the use of page and device coordinates. In Listing 10.5 we transform page coordinates to 1 inch from the left and 0.5 inch from the top of the upper left corner of the client area. Our new page coordinate system has starting and ending points of (1, 0.5) and (3, 1.5), but the device coordinate system converts them to pixels. Hence the starting and ending points in device coordinates are (96, 48) and (288, 144), assuming a resolution of 96 dots per inch.

Listing 10.5 Combining page and device coordinates
Pen redPen = new Pen(Color.Red, 1/g.DpiX);
g.TranslateTransform(1, 0.5f);
g.PageUnit = GraphicsUnit.Inch;
g.DrawLine(redPen, 0, 0, 2, 1);

Figure 10.7 shows the output from Listing 10.5.

Figure 10.7. Combining page and device coordinates

Troubleshooting WPF Designer Load Failures

noreply@blogger.com (Venugopal) — Wed, 13 Feb 2008 09:56:00 +0000

Hi,

Now that people have been kicking the tires of the WPF Designer for Visual Studio 2008 (aka "Cider). Here's a preview of the topic that will ship in the docs. Hopefully this will help out before frustration and despair set in.

Thanks,
Venugopal.

How Can I Get ItemsPanelTemplate Obeject Reference In Custom Control Class Itself?.

noreply@blogger.com (Venugopal) — Tue, 05 Feb 2008 07:05:00 +0000

Hi,

I have faced complex problem during my ScrollPanel(I will post this ScrollPanel logic and advantage by shortly) CustomControl implementation. The actual problem is I couldn't get ItemsPanelTemplate object reference in control class itlsef. I found some solution in net, but those things are related to outside of control class only.

Then finally i found the soultion with the help of VisualTreeHelper class. Here is the code snippet.

private T FindItemsPanel(Visual visual)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(visual); i++)
{
Visual child = VisualTreeHelper.GetChild(visual, i) as Visual;
if (child != null)
{
if (child is T && VisualTreeHelper.GetParent(child) is ItemsPresenter)
{
object temp = child;
return (T)temp;
}

T panel = FindItemsPanel(child);
if (panel != null)
{
object temp = panel;
return (T)temp; // return the panel up the call stack
}
}
}
return default(T);
}
But here also I had one problem like getting object reference after initialized my control. I had tried with OnInitialized method, and tried in constructor of my control class, but not use. Then finally found the solution with the help of OnLoaded event of my control class.

Like Below :

public ReflectionGallery()
{
this.Loaded += new RoutedEventHandler(ReflectionGallery_Loaded);
}

void ReflectionGallery_Loaded(object sender, RoutedEventArgs e)
{
//ItemsPanelObject is my own dependency property
ItemsPanelObject = FindItemsPanel(this);
}

This is my control template(Style)

<Style TargetType="{x:Type local:ReflectionGallery}" x:Key="{x:Type local:ReflectionGallery}">
<Setter Property="Template" Value="{StaticResource ReflectionGalleryTemplateKey}"/>
<Setter Property="Margin" Value="2"/>
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<local:ReflectionPanel Name="PART_ReflectionPanel" />
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Style>

Now we can use ItemsPanelObject property to play with custom panel of my ScrollPanel control.

I hope this will help to Custom Control authors like me :) :).

Please feel free to post your comments on this.

I will meet you with my ScrollPanel post. This might be very cool like Carousel panel.

Thanks,
Venugopal.

How Can I Get System Brushes List in WPF?.

noreply@blogger.com (Venugopal) — Wed, 09 Jan 2008 09:30:00 +0000

For getting System brushes list, we need to use propertyinfo class.

Here i am creating ObservableCollection with object type as MyBrush.

public class ColorItemList: ObservableCollection
{
public ColorItemList() : base()
{
Type type = typeof( Brushes );
foreach( PropertyInfo propertyInfo in type.GetProperties( BindingFlags.Public BindingFlags.Static ) )
{
if( propertyInfo.PropertyType == typeof( SolidColorBrush ) )
Add( new MyBrush( propertyInfo.Name, ( SolidColorBrush )propertyInfo.GetValue( null, null ) ) );
}
}
}

MyBrush.CS class should be like this.

public class MyBrush
{
private string m_name;
private SolidColorBrush m_brush;
public string Name
{
get
{
return m_name;
}
set
{ m_name = value;
}
}
public SolidColorBrush Brush
{
get
{
return m_brush;
}
}
public MyBrush(string name, SolidColorBrush brush )
{
m_name = name;
m_brush = brush;
Color color = brush.Color;
}
}

Now you can get System brushes list using our IEnumerable class MyBrushList.

I hope you may got idea. if not Please don't hesitate to post your comments here.

How Can I Host WPF Controls In WinForms Application

noreply@blogger.com (Venugopal) — Sat, 05 Jan 2008 09:46:00 +0000

First add references to the WPF namespaces (PresentationCore, PresentationFramework, UIAutomationProvider, UIAutomationTypes, and WindowsBase). Next create an instance of the ElementHost control and the control you wish to embed in the Windows Forms application and then hook that control up to the ElementHost control. Then simply add the ElementHost control to your Forms control collection:

ElementHost host = new ElementHost();
System.Windows.Controls.ListBox wpfListBox =
new System.Windows.Controls.ListBox();

for (int i = 0; i < 10; i++)
{
wpfListBox.Items.Add("Item " + i.ToString());
}

host.Dock = DockStyle.Fill;
host.Controls.Add(wpfListBox);
this.panel1.Controls.Add(host);

However, if you want to use XAML to describe the WPF control that you want to use in the Windows Forms application, you would need to add an Avalon UserControl item to your project. This will create a UserControl1.xaml file and a UserControl1.xaml.cs file. You can then modify the UserControl1.xaml file to contain whatever XAML you wish to describe your control. Then you would simply create an instance of this control and add it to the ElementHost control as in the above example:

ElementHost host = new ElementHost();
UserControl1 uc1 = new UserControl1();
host.Controls.Add(uc1);
host.Dock = DockStyle.Fill;
this.panel1.Controls.Add(host);

In addition, you will need to modify the project file because the Windows Application does not what to do with the XAML file. You will need to open the project file (.csproj, .vbproj, etc.) in an editor like Notepad and then scroll to the bottom.
You will see the following line:

<Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
You will need to copy this line and paste it just below the above line and then change "CSharp" to "WinFX" so that the two lines look like:

<Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
<Import Project="$(MSBuildBinPath)\Microsoft.WinFx.targets" />
Now save this file and reload the project using VS and run the application.

Thanks,
Venugopal.