Huy's Blog

WPF Expanding Menu

2011-07-21T09:47:00.000-07:00

This is just a nice simple demo using toggle buttons to display an accordion style menu.

Expanding Menu

Please let me know if this helps you.

WPF Loading Panel

2011-07-20T21:26:00.001-07:00

Having a nice loading panel with a progress bar showing that some work is in progress is a very cool feature to any application.

With this control you can show a loading panel as you are going and fetching data from the database, it will update your window with up to date progress messages.

<ctr:LoadingPanel x:Name="loadingPanel"
                  IsLoading="{Binding PanelLoading}"
                  Message="{Binding PanelMainMessage}"
                  SubMessage="{Binding PanelSubMessage}" 
                  ClosePanelCommand="{Binding PanelCloseCommand}" />

Loading Panel

Please let me know if this helps you.

Rx Lazy Loading Text Box

2010-10-27T07:55:00.000-07:00

I started using .Net Reactive (Rx) extensions for work recently.
As a WPF UI developer, one of the nice way of handling a users input is not to do anything until the user have complete his/her action.

In this example; I have a text box, which will auto filter a data grid when the user stop typing in the text box and the text changed event is fired.
This will improve the UI responsiveness, instead of firing after every key is entered.

// Method OnSearchTextChanged is called .5s after Text Box text changed
Observable.FromEvent<TextChangedEventArgs>(textbox, "TextChanged")
          .Throttle(TimeSpan.FromSeconds(.5))
          .ObserveOnDispatcher()
          .Subscribe(OnSearchTextChanged);

This was only possible in the past throught the use of Timers and Thread.Sleep, Rx makes this easier to do.

Lazy Loading Text Box

Please let me know if this helps you.

WPF Value Type Text Box

2010-08-15T15:05:00.000-07:00

I wrote a WPF numeric text box control that can support currency, integer and numeric values.
It can prevent invalid input such as letters, spaces, etc. and can be constrained to a max length value.

For example, with the currency text box; when the text box is in focused the formatting is removed allowing the user to enter the value.
When the text box loses focus, formatting is reapplied and display in the text box.

Value Type Text Box

Please let me know if this helps you.

WPF Filter Combo Box

2010-05-05T15:11:00.000-07:00

I was asked to write a prototype for a project that I am currently working on.
They wanted to be able to selected for a master combo box and filter the selection of the sub-child combo boxes.

I read an article on stackoverflow, which I base my code sample on.

To do this Master-Child Hierarchy, I have implemented it through the use of the attribute property, by creating a custom attribute (PriorityLevel).

public class Football
{
    [PriorityLevel(1)]
    public League League { get; set; }

    [PriorityLevel(2)]
    public string Team { get; set; }
}

I have created the custom attribute with the use of an interface (IAttribute).

public class PriorityLevelAttribute : Attribute, EnumHelper.IAttribute<int>
{
    private readonly int _value;

    public PriorityLevelAttribute(int value)
    {
        _value = value;
    }

    public int Value
    {
        get { return _value; }
    }
}

Another think that I thought would be quite good was to have a strong type attribute for enums.
This extension method will allow you to return a strong type value of your attribute enum value.

/// <summary>
/// Returns the attribute value for a given Enum value.
/// </summary>
public static TR GetAttributeValue<T, TR>(this Enum value)
{
    var attributeValue = default(TR);

    if (value != null)
    {
        var fi = value.GetType().GetField(value.ToString());

        if (fi != null)
        {
            var attributes = fi.GetCustomAttributes(typeof(T), false) as T[];

            if (attributes != null && attributes.Length > 0)
            {
                var attribute = attributes[0] as IAttribute<TR>;

                if (attribute != null)
                {
                    attributeValue = attribute.Value;
                }
            }
        }
    }

    return attributeValue;
}

Imagine you have a enum class, and you wanted to have addition information to the enum.
This is a elegant way to implement a strong type value for your enum, throught attribute.

public enum League
{
    [DisplayDescription("Argentine Primera Division")]
    PrimeraDivision = 1,
    
    [DisplayDescription("English Premier League")]
    PremierLeague = 2,

    [DisplayDescription("Spanish La Liga")]
    LaLiga = 3
}

public class DisplayDescriptionAttribute : Attribute, EnumHelper.IAttribute<string>
{
    private readonly string _value;

    public DisplayDescriptionAttribute(string value)
    {
        _value = value;
    }

    public string Value
    {
        get { return _value; }
    }
}

/// <summary>
/// This is the implementation.
/// </summary>
var displayValue = league.GetAttributeValue<DisplayDescriptionAttribute, string>();

Filter Combo Box

Please let me know if this helps you.

Reading and Writing XML with Linq

2010-02-12T16:43:00.001-08:00

In this sample, I am using Linq to construct my objects into XML, then being able to read the XML with Linq and construct it back into my class objects.

Writing (Linq to XML):

var xmlFile = 
    new XElement("Movies",
    from m in movies
    select new XElement("Movie",
        new XElement("Title", m.Title),
        new XElement("Director", m.Director),
        new XElement("ReleaseDate", m.ReleaseDate),
        new XElement("Casts",
            from c in m.Casts
            select new XElement("Cast",
                new XElement("Name", c.Name),
                new XElement("Dob", c.Dob),
                new XElement("Roles",
                    from r in c.Roles
                    select new XElement("Role",
                        new XElement("MovieName", r.Movie),
                        new XElement("RoleName", r.RoleName)))))));

Reading (XML to Linq):

var movies = 
    from m in xmlFile.Descendants("Movie")
    select new Movie
    {
        Title = (string)m.Element("Title"),
        Director = (string)m.Element("Director"),
        ReleaseDate = (DateTime)m.Element("ReleaseDate"),
        Casts = (from c in m.Elements("Casts").Descendants("Cast")
                 select new Cast
                 {
                    Name = (string)c.Element("Name"),
                    Dob = (DateTime)c.Element("Dob"),
                    Roles = (from r in c.Elements("Roles").Descendants("Role")
                             select new Role
                             {
                                Movie = (string)r.Element("MovieName"),
                                RoleName = (string)r.Element("RoleName")
                             }).ToList()
                 }).ToList()
    };

Reading and Writing Xml Files

Please let me know if this helps you.

IEnumerable Extension

2009-10-20T22:04:00.000-07:00

This is an IEnumerable extension method, that create a generic ObservableCollection from a generic IEnumerable.

public static class CollectionExtensions
{
    public static ObservableCollection<T> ToObservableCollection<T>(this IEnumerable<T> ienum)
    {
        ObservableCollection<T> oc = new ObservableCollection<T>();

        foreach (T i in ienum)
        {
            oc.Add(i);
        }
                
        return oc;
    }
}

Have the extension method residing in a namespace that can be common accessible by all.

Please let me know if this helps you.

WPF Memory Leaks

2009-09-30T22:34:00.000-07:00

Using of Event Handlers

Event handlers are a very common source of non-obvious memory leaks. For example, you think an event handler on an object is getting disposed when the object is destroyed, unaware that the object is not being released from memory, because the event handler is continued to be used elsewhere.

If you subscribe to an event on object1 from object2, then dispose of object2 and assume it no longer exists (and drop out all references from your code); there is an implicit reference in object1's event that will prevent object2 from being garbage collected.

Code:

SomeObject object1 = new SomeObject();
OtherObject object2 = new OtherObject();

object1.SomeEvent += object2.myEventHandler;
object2 = null;

The Fix/Work around:

object1.SomeEvent -= object2.myEventHandler;

This is a common case of a leak; forgetting to unsubscribe from events. If you create an object that attaches an event handler, then this object must remove that event handler again (at an appropriate time).

Using of Static Variables

This is an example of creating a reference which is allocated to static variable, and by nature, static variables are not destroyed. By not setting the static variable back to null; this will cause the object to reference the static variable, and stop the garbage collector from disposing of the object.

The static staticObject reference is always reachable from code; the garbage collector would not be able to destroy the allocated object.

Code:

static SomeStaticClass staticObject;

static void SomeStaticMethod()
{
    staticObject = new SomeStaticClass();
}

The Fix/Work around:

staticObject = null;

This is a common case of a leaking; forgetting to set an allocated object to null.

Using of DynamicResource

It seems that using a DynamicResource to refer to a global resource can cause memory leaks to occur.

• StaticResource - "look up the resource once, then just keep using the same value."
• DynamicResource - "look up the resource each time it's needed, in case the value has changed."

Code:

Background="{DynamicResource Style}"

The Fix/Work around:

Background="{StaticResource Style}"

Avoid using DynamicResource, use StaticResource to access resources unless you absolutely have to use a DynamicResource.

Using of RegisterClassCommandBinding/RegisterClassInputBinding

You can register a class command binding for a command, using CommandManager.RegisterClassCommandBinding or you can register a class input binding for an input, using CommandManager.RegisterClassInputBinding.

However there is an internal bug with these two methods on the CommandManager class, which can cause memory leaks to occur - the garbage collector cannot unregister the binding.

Code:

CommandManager.RegisterClassCommandBinding(type, command binding);

The Fix/Work around:

this.CommandBindings.Add(command binding);

Avoid using CommandManager and class command bindings; instead bind the command to the current instance object. As the object is destroyed the command will now be destroyed with it.

Using of BitmapEffects

Up until .Net 3.5 SP1, all BitmapEffects were rendered in software, which causes memory leak.

New Effects (now called BlurEffect, DropShadowEffect) are introduced as of .Net 3.5 SP1, which are hardware accelerated and rendered by the GPU, which will stop the memory leak (as claimed by Microsoft).

Code:

<Border.BitmapEffect>
    <DropShadowBitmapEffect ShadowDepth="10" Softness="1" />
</Border.BitmapEffect>

The Fix/Work around (from .NET 3.5 SP1):

<Border.Effect>
    <DropShadowBitmapEffect ShadowDepth="10" Softness="1" />
</Border.Effect>

As of .Net 3.5 SP1, you can use the new Effects classes instead. You must avoid using old Effects, i.e. BevelBitmapEffect, BlurBitmapEffect, DropShadowBitmapEffect, BevelBitmapEffect, EmbossBitmapEffect, OuterGlowBitmapEffect as these are now obsolete classes.

Using of DataBinding

Extract from Microsoft Bug Report:

Data binding operation that is not marked as OneTime must listen for property change notifications from the source object. WPF uses the built-in notifications of the DependencyProperties class or the notifications from the INotifyPropertyChanged interface.

If the DependencyProperties class and the INotifyPropertyChanged interface are unavailable, WPF uses the ValueChanged event. This behavior involves calling the PropertyDescriptor.AddValueChanged method on the PropertyDescriptor object that corresponds to property.
Unfortunately, this action causes the CLR to create a strong reference from this PropertyDescriptor object to source object. The CLR also keeps a reference to the PropertyDescriptor object in a global table. This behavior causes a reference chain to occur.

As long as the data binding target is used, the binding must continue to listen for changes. This behavior keeps the reference alive between the PropertyDescriptor object and source object, and the target remains in use. This behavior causes a memory leak in source object and in every object to which source object refers. These objects include the data binding target.

Code:

View:
<CollectionViewSource x:Key="Results"
    Source="{Binding Path=Data.SomeEntity}">

Entity:
public class SomeEntity
{
    // Entity properties
}

The Fix/Work around:

View:
<CollectionViewSource x:Key="Results"
    Source="{Binding Path=Data.SomeEntity}">

Entity:
public class SomeEntity : INotifyPropertyChanged
{
    // Entity properties
}

You must implement the INotifyPropertyChanged interface on the entity that you are binding to in the view. By inheriting the from the BusinessBase class, you will implement the INotifyPropertyChanged interface.

Using of Generic List to Data Bind

The use of generic list on an entity, then data binding the generic list to the view; it cause a memory leak.
Same problem as the previous example, as the generic list doesn’t implement the INotifyPropertyChanged interface.

Code:

public class SomeEntity : INotifyPropertyChanged
{
    // Entity properties
    List<User> Users { get; set; }
}

The Fix/Work around:

public class UserCollection : ObservableCollection<User>
{
}

public class SomeEntity : INotifyPropertyChanged
{
    // Entity properties
    UserCollection Users { get; set; }
}

It is recommended that you use ObservableCollection class instead of the generic list class as it implements the INotifyPropertyChanged interface, and provides many additional benefits. You can then bind the collection to the view without causing a memory leak.

Please let me know if this helps you.

Money Validator

2009-05-01T11:55:00.000-07:00

I wrote this money (whole dollar) validation method.
It use a regular expression to validate a whole dollar.

public class MoneyValidator
{
    /// <summary>
    /// Regular expression, which is used to validate an whole dollar (money).
    /// </summary>
    private const string PATTERN = @"^\$?(((\d{1,3},*)+\d{3})|\d+)$";

    /// <summary>
    /// Checks whether the given dollar value is valid.
    /// </summary>
    /// <param name="money">String that contains an dollar.</param>
    /// <returns>True, if valid dollar; otherwise false.</returns>
    public static bool IsValidDollar(string money)
    {
        if (!string.IsNullOrEmpty(money))
            return Regex.IsMatch(money, PATTERN, RegexOptions.IgnoreCase);

        return false;
    }
}

I've been doing alot of unit testing @ work recently. The theory is that everything that you write must be unit tested.
So, I've written this unit test to validate that the function will pass for all whole dollar that I think should be valid and invalid.

/// <summary>
/// Summary description for UnitTest
/// </summary>
[TestClass]
public class UnitTest
{
    string _money;
    bool _result;

    [TestMethod]
    public void ValidMoneyNormal()
    {
        _money = "$1";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "1";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$10";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "10";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$100";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "100";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$1000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "1000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$1,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "1,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$10000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "10000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$10,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "10,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$100000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "100000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$100,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "100,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$1000000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "1000000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "$1,000,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);

        _money = "1,000,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsTrue(result, _money);
    }

    [TestMethod]
    public void InValidMoneyNormal()
    {
        _money = "$1.99";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "1.99";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "$90,999.99";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "90,999.99";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "$2..0";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "2..0";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "2,8";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "2,00,0";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "2,00";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "$20,00";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "1,0$00,000,000";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "$$3";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "2,,,0";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "$200$";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "$2d";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "$2,,0";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);

        _money = "2$3";
        result = MoneyValidator.IsValidDollar(_money);
        Assert.IsFalse(result, _money);
    }
}

Money Validator

Please let me know if this helps you.

WPF Animated Sliding Adorner

2009-01-07T17:08:00.000-08:00

I wanted to create a custom control that would have the ability to have an animated part sliding out of it. My first through was to have this control have the ability to slide out in any direction (left, right, up or down), and that it had to be an adorner (to be able on slide on top of other objects etc).
And second to that was the thing that was created, was also a custom control, letting the user define what the control would content.

Animated Sliding Adorner

Please let me know if this helps you.

WPF Fisheye Control

2008-12-10T07:53:00.001-08:00

If you are a big fan of Apple - Mac OS X Leopard, you will love this WPF animated dashboard that I've created.

I was inspired to build a control (Fish Eye effect) that would mimic the dashboard of the Mac's.

This is a simple implementation of the Fish Eye control:

<Controls:FishEyeControl VerticalAlignment="Bottom">
    <Image Source="{Binding Source={x:Static Images:ImageConstants.MESSAGES}}" 
           Width="32" 
           Height="32" />
    <Image Source="{Binding Source={x:Static Images:ImageConstants.CONTACTS}}" 
           Width="32" 
           Height="32" />
    <Image Source="{Binding Source={x:Static Images:ImageConstants.CALENDAR}}" 
           Width="32" 
           Height="32" />
</Controls:FishEyeControl>

This is a dynamic implementation (ItemsControl) of the Fish Eye control:

<ItemsControl ItemsSource="{Binding Path=DashBoardApps}" VerticalAlignment="Bottom" HorizontalAlignment="Center">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Controls:FishEyeControl />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Vertical">
                <TextBlock x:Name="txtAppName" 
                           Text="{Binding Path=ApplicationName}" 
                           TextAlignment="Center" 
                           Visibility="Hidden" 
                           FontSize="7px" 
                           Foreground="#eff7ff" />
                <Button Width="32" Height="32">
                    <Image Source="{Binding Path=ApplicationImage}" />
                </Button>
            </StackPanel>
            <DataTemplate.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter TargetName="txtAppName" Property="Visibility" Value="Visible" />
                </Trigger>
            </DataTemplate.Triggers>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

Animated Dashboard

Please let me know if this helps you.

Can Parallel Programming Improve Performance

2008-11-24T18:08:00.000-08:00

I love to optimize my code for performance, whenever I can.
So I wrote a simple speed test to see what works best.

I've use the new System.Threading, provided in the Parallel Extensions June 08 CTP from Microsoft and I have to said it is bloody awesome.

For example a simple for / foreach loop:

for (var item = 0; item < list.Length; item++)
{
    DoSomeWork();
}

foreach (var item in list)
{
    DoSomeWork();
}

This is the same example, but using a parallel for / foreach loop:

Parallel.For(0, list.Length, item => { DoSomeWork(); });

Parallel.ForEach(list, DoSomeWork);

Coding it is as easy as pie, it makes use of all the cores that your CPU has to offer.

Speed Test

Please let me know if this helps you.

Using WPF ListView to display Complex Data Structure

2008-11-13T08:24:00.000-08:00

I was ask @ work today, to display in a WPF List View, a list of items and within each item there are other list of items (subclass within a class).

There are lots of examples on the net to display to simple class.
But in the real world there is no simple data structure, only complex data structure.

I wrote is example to demonstrate the point.
Imagine that you have a list of movies, and each movie has a movie id, a title, a list (subclass) of images and descriptions for the movie, a list (subclass) of cast in the movie and a list (subclass) of movie recommendations.

Code:
A list of Movies

public List<Movie> MovieData

And each Movie has

public class Movie
{
       public int MovieId { get; set; }
       public string Title { get; set; }
       public IList<MovieInfos> Infos { get; set; }
       public IList<Cast> Cast { get; set; }
       public IList<string> Recommendations { get; set; }
}

MovieInfos is a subclass in the Movie class

public class MovieInfos
{
       public string Description { get; set; }
       public ImageSource MovieImage { get; set; }
}

Xaml:
Bind the list of movies to the WPF List View

<ListView ItemsSource="{Binding Path=MovieData}">
   <ListView.View>
       <GridView>
           <GridViewColumn DisplayMemberBinding="{Binding Path=MovieId}" Header="Movie Id" />
           <GridViewColumn DisplayMemberBinding="{Binding Path=Title}" Header="Title" />
           <!-- Can Bind to complex subclass -->
           <GridViewColumn Header="Movie(s)">
               <GridViewColumn.CellTemplate>
                   <DataTemplate>
                       <StackPanel>
                           <ItemsControl ItemsSource="{Binding Path=Infos}">
                               <ItemsControl.ItemsPanel>
                                   <ItemsPanelTemplate>
                                       <WrapPanel Orientation="Horizontal"/>
                                   </ItemsPanelTemplate>
                               </ItemsControl.ItemsPanel>
                               <ItemsControl.ItemTemplate>
                                   <DataTemplate>
                                       <StackPanel>
                                           <Image ToolTip="{Binding Path=Description}"
                                                          Source="{Binding Path=MovieImage}"
                                                          Margin="3,0,3,0"
                                                          Height="125" Width="75" />
                                       </StackPanel>
                                   </DataTemplate>
                               </ItemsControl.ItemTemplate>
                           </ItemsControl>
                       </StackPanel>
                   </DataTemplate>
               </GridViewColumn.CellTemplate>
           </GridViewColumn>
           <!-- Binding with data triggers -->
           <GridViewColumn Header="Cast">
               <GridViewColumn.CellTemplate>
                   <DataTemplate>
                       <StackPanel>
                           <ItemsControl ItemsSource="{Binding Path=Cast}">
                               <ItemsControl.ItemsPanel>
                                   <ItemsPanelTemplate>
                                       <WrapPanel Orientation="Vertical" />
                                   </ItemsPanelTemplate>
                               </ItemsControl.ItemsPanel>
                               <ItemsControl.ItemTemplate>
                                   <DataTemplate>
                                       <StackPanel Orientation="Horizontal">
                                           <TextBlock x:Name="tbName" Text="{Binding Path=Name}"/>
                                                   <Image x:Name="imgStar"
                                                          Visibility="Collapsed"
                                                          Source="{Binding Source={x:Static constants:ImageConstants.STAR}}"
                                                          Height="16" Width="16" Margin="3,0,0,0" />
                                       </StackPanel>
                                       <DataTemplate.Triggers>
                                           <DataTrigger Binding="{Binding Path=MainCharacter}" Value="True">
                                               <Setter TargetName="tbName" Property="Foreground" Value="Red" />
                                               <Setter TargetName="imgStar" Property="Visibility" Value="Visible" />
                                           </DataTrigger>
                                       </DataTemplate.Triggers>
                                   </DataTemplate>
                               </ItemsControl.ItemTemplate>
                           </ItemsControl>
                       </StackPanel>
                   </DataTemplate>
               </GridViewColumn.CellTemplate>
           </GridViewColumn>
           <!-- Simple binding -->
           <GridViewColumn Header="Recommendations">
               <GridViewColumn.CellTemplate>
                   <DataTemplate>
                       <StackPanel>
                           <ItemsControl ItemsSource="{Binding Path=Recommendations}">
                               <ItemsControl.ItemsPanel>
                                   <ItemsPanelTemplate>
                                       <WrapPanel Orientation="Vertical"/>
                                   </ItemsPanelTemplate>
                               </ItemsControl.ItemsPanel>
                               <ItemsControl.ItemTemplate>
                                   <DataTemplate>
                                       <StackPanel>
                                           <TextBlock Text="{Binding}"/>
                                       </StackPanel>
                                   </DataTemplate>
                               </ItemsControl.ItemTemplate>
                           </ItemsControl>
                       </StackPanel>
                   </DataTemplate>
               </GridViewColumn.CellTemplate>
           </GridViewColumn>
       </GridView>
   </ListView.View>
</ListView>

This sample demonstrates the power of WPF List View.

Using Items Control in WPF List View

Please let me know if this helps you.

Use LINQ to count items in a List

2008-10-29T08:18:00.000-07:00

I wanted a way to go through a list of items and get a count for each distinct item in the list.
To do this nice and easy, I just use LINQ.

class Program
{
        static void Main()
        {
            var cities = new List<string>
                             {
                                 "Sydney", 
                                 "Perth", 
                                 "Sydney", 
                                 "Melbourne", 
                                 "Brisbane", 
                                 "Melbourne",
                                 "Sydney"
                             };

            var result = (from c in cities
                          group c by c into grouping
                          orderby grouping.Key ascending
                          select new {grouping.Key, Count = grouping.Count()});

            foreach (var item in result)
            {
                 Console.WriteLine(string.Format("City={0}, Count={1}", item.Key, item.Count));
            }

            Console.ReadLine();
        }
}

Count items in a List using LINQ

Please let me know if this helps you.

Email Address Validator

2008-09-16T19:33:00.000-07:00

I wrote this email address validation method a few months ago.
It use a regular expression to validate an email address.

public class EmailAddressValidator
{
        /// <summary>
        /// Regular expression, which is used to validate an email address.
        /// </summary>
        private const string PATTERN = @"^[a-z|0-9][a-z|0-9]*([_'-][a-z|0-9]+)*" +
                                       @"(([.][a-z|0-9]+)+([_'-][a-z|0-9]+)*)?@" +
                                       @"[a-z|0-9][a-z|0-9]*([-][a-z|0-9]+)*" +
                                       @"(([.][a-z|0-9]+)+([-][a-z|0-9]+)*)$";

        /// <summary>
        /// Checks whether the given email address is valid.
        /// </summary>
        /// <param name="emailAddress">String that contains an email address.</param>
        /// <returns>True, if valid email address; otherwise false.</returns>
        public static bool IsValidEmailAddress(string emailAddress)
        {
            if (!string.IsNullOrEmpty(emailAddress))
                return Regex.IsMatch(emailAddress, PATTERN, RegexOptions.IgnoreCase);
            else
                return false;
        }
}

I wrote this unit test to validate that the function will pass for all email that I think should be valid and invalid.

/// <summary>
/// Summary description for UnitTest
/// </summary>
[TestClass]
public class UnitTest
{
        string _emailAddress;
        bool _result;

        [TestMethod]
        public void ValidEmailAddressNormal()
        {
            _emailAddress = "a@b.c";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "joe@home.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "joe.bob123@home.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "123joe@home.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "joe.bob@home.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "joe.bob@his.home.place";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "duke_me.baby@hotmail.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "o'reilly@there.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "uat-test.me@hotmail123.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "joe_bob@jb-test.com.au";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "duty.it.sit.dev.prog@test.com.au";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "joe.bob@google.it.com.au";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);

            _emailAddress = "joe.bob@123.test.me.co.uk";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsTrue(result, _emailAddress);
        }

        [TestMethod]
        public void InValidEmailAddressNormal()
        {
            _emailAddress = "joe";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe@home";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe-bob[at]home.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe.@bob.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = ".joe@bob.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe@.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe..bob@bob.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe<>bob@bob.come";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe~bob@bob.come";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe&bob@bob.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "~joe@bob.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe$bob@bob.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe+bob@bob.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe_bob@hotmail..com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "joe_bob@hotmail...com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "email withspace@hotmail.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "test@hot_mail.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);

            _emailAddress = "test@o'reilly.com";
            result = EmailAddressValidator.IsValidEmailAddress(_emailAddress);
            Assert.IsFalse(result, _emailAddress);
        }
}

Email Address Validator

Please let me know if this helps you.

WPF drop down and split button

2008-09-11T09:57:00.001-07:00

I've been trying to create a drop down button and a split button in WPF.
It has been very frustrating, but I think I finally got it.

Drop Down and Split Button ver 1.2

I have updated the split button control to use command binding.

Please let me know if this helps you.