In these days I needed to increase the value of a “frequency” attribute contained into a certain XML file. Unfortunately this attribute appears several times into several XML files, so I wrote a simple WPF application that does this job for me ūüėČ

Click here to download the application.
Click here to download the sample XML File.

The following picture show the Application. Once you digit the number you want to add to all frequency attributes you should press Ok button and after that an Open File Dialog appears allowing you to choose the XML file. After choosing the file, all frequency attributes will be updated according to the delta value and a backup of the original file will be stored as “yourXMLfile.back_0” ūüėČ

How does it works?
The file is opened using the .Net XmlDocument , after that the the application selects all nodes containing the “frequency” attribute via XmlNodeList. Finally all “frequency” attribute value is updated and the XML file is saved.

Here the code:

                    // Open document
                    filename = dlg.FileName;

                     if (!File.Exists(filename))
                        throw new Exception("Satellites file not found!");

                    // Create a backup copy of source file
                    int counter = 0;
                    while (File.Exists(filename + ".bak_" + counter))

                    backupFileName = filename + ".bak_" + counter;
                    File.Copy(filename, filename + ".bak_" + counter);

                    XmlDocument doc = new XmlDocument();

                    XmlNodeList nodeList = doc.SelectNodes("satellites/sat/transponder");                      

                    foreach (XmlNode transponderNode in nodeList)
                        foreach (XmlAttribute transponderAttribute in transponderNode.Attributes)
                            if (transponderAttribute.Name.Equals("frequency", StringComparison.InvariantCultureIgnoreCase))
                                long currentValue = long.Parse(transponderAttribute.Value);
                                long newValue = currentValue + delta;
                                transponderAttribute.Value = newValue.ToString();


Here how the XML file looks like:

  <sat name="37.5W NSS 10/Telstar 11N" flags="0" position="-375">
    <transponder frequency="12651000" symbol_rate="4280000" polarization="0" fec_inner="3" system="0" modulation="1" onid="235" tsid="17185" />
    <transponder frequency="12665264" symbol_rate="4280383" polarization="0" fec_inner="3" system="0" modulation="1" onid="65535" tsid="1" />
    <transponder frequency="12697500" symbol_rate="3214359" polarization="0" fec_inner="3" system="0" modulation="1" onid="1" tsid="1" />

WPF provides two main ways for implementing data validation: ValidationRule and IDataErrorInfo. In this post is focused on IDataErrorInfo.

The demo project is available here and the below images displays the result from an UI point of view:

Using ValidationRule you are able to validate user inputs directly into UI (View). This way consists in implementing a class that extends .Net ValidationRule and using your class into Binding. You can check an example here.

Using IDataErrorInfo you are able to validate user inputs in both UI and Business Logic too (ViewModel). This way is more MVVM oriented and allow performing validation in different layers (View and ViewModel) sharing a common validation code.

The first step consists into implementing IDataErrorInfo interface into the class that contains a Property that will be involved in UI binding. IDataErrorInfo consists into two properties: the Error property that tells what is wrong with this object, and the Item property that gets the error message of the specified property. Regardless of your object you can implement IDataErrorInfo interface in the following way:

        #region IDataErrorInfo Members

        string IDataErrorInfo.Error { get { return null; } }

        string IDataErrorInfo.this[string propertyName]
            get { return this.GetValidationError(propertyName); }

        #endregion // IDataErrorInfo Members

You might ask “why”? The answer is easier you can imagine: the GetValidationError method we are going to implement will be also used by IsValid property into other layers (typically ViewModel).
In other words the IDataErrorInfo is used by .Net into binding expressions, while IsValid property can be used into code behind layers.

Here below the rest of the code:

        public bool IsValid
                foreach (string property in ValidatedProperties)
                    if (GetValidationError(property) != null)
                        return false;

                return true;

        static readonly string[] ValidatedProperties = 

        private string GetValidationError(string propertyName)
            string error = null;

            switch (propertyName)

                case "ServerIPAddress":
                    error = ValidateIPAddress();


            return error;

        private string ValidateIPAddress()

            if (String.IsNullOrEmpty(ServerIPAddress))
                return "Please enter an IP Address.";

            if (ServerIPAddress.Contains(" "))
                return "Blank characters are not allowed in IP Address.";

            string[] parts = ServerIPAddress.Split('.');
            if (parts.Length != 4)
                return "IP Address should be four octets, seperated by decimals.";

            foreach (string p in parts)
                int intPart;

                if (!int.TryParse(p, out intPart))
                    return "Each octet of an IP Address should be a number.";

                if (intPart < 0 || intPart > 255)
                    return "Each octet of an IP Address should be between 0 and 255.";

            return null;

Finally the following XAML Code is used for validating data into the View:

        <Style TargetType="{x:Type TextBox}">
            <Setter Property="Validation.ErrorTemplate">
                        <DockPanel LastChildFill="True">
                            <TextBlock Text="*" 
                                       Width="16" Height="16" 
                                       Margin="4,0,0,0" />
                            <Border BorderBrush="Red" BorderThickness="1">
                                <AdornedElementPlaceholder />
                <Trigger Property="Validation.HasError" Value="true">
                    <Setter Property="ToolTip" 
                            Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}"/>
        <TextBox MaxLength="15"
                    Text="{Binding Path=MyDummyItem.ServerIPAddress, ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}" />

Stay tuned and happy coding!

today I want to share with you the fast way for creating a dropdown menu on WPF.
You can download sample code here.

The following image display the result (remark that you can customize the Button look&feel as you need):

The idea is to use the WPF ContextMenu modifying the way to open it.
The first step consist in creating a Button with a ContextMenu and disabling the ContextMenuService for this Button object. In this way the right click does not show the ContextMenu. Here the code:

        <Button Content="Click Me" 
                <ContextMenu >
                    <MenuItem Header="Menu 1"/>
                    <MenuItem Header="Menu 1"/>
                    <MenuItem Header="Menu 1"/>
                    <MenuItem Header="Menu 1"/>

The second step consist in displaying the ContextMenu when the button is clicked. This is achieved by few lines of code:

        private void Button_Click(object sender, RoutedEventArgs e)
            (sender as Button).ContextMenu.IsEnabled = true;
            (sender as Button).ContextMenu.PlacementTarget = (sender as Button);
            (sender as Button).ContextMenu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
            (sender as Button).ContextMenu.IsOpen = true;

Stay tuned and happy coding ūüėČ

in this posts I am going to present a nice control I developed for asynchronously loading image using WPF.
This control is implemented into the PhotoLoader DLL and all the available functionalities are tested into a test client that is included into the solution. You can download PhotoLoder and Test client here.

If you try to load a lot of big images directly via Image’s Source property you will notice that your application will stuck. Performances became better when you load images via BitmapFrame and using the Thumbnail property, however not all images have embedded Thumbnail and, even if your images have it, your application will not responsive during loading.

I developed an additional attached property to be used with WPF Image and that allows Images to be loaded asynchronously by a background Thread. I put this property and others into the PhotoLoader DLL that can be used for free into your applications ūüôā

The attached property performing asynchronous loading is the Loader.Source and it must be used in replace of Image.Source property.

PhotoLoader DLL provides also others Attached Properties that allows developers displaying and customizing the ‘waiting animation’ as well as managing errors.

Example of usage

                    <Image PhotoLoader:Loader.DisplayOption="FullResolution"
                           PhotoLoader:Loader.Source="{Binding Path=FirstFileInCollection}"
                           PhotoLoader:Loader.DisplayWaitingAnimationDuringLoading="{Binding Path=DisplayAnimationDuringLoading}"
                           PhotoLoader:Loader.DisplayErrorThumbnailOnError="{Binding Path=DisplayErrorImageOnError}">

The following screenshots give you an idea about PhotoLoader Attached Properties functionalities.

Documentation – Loader Attached Properties
PhotoLoader exposes the following Attached Properties via the static Loader class:

  • Source: string representing the path of the image to display. Right now it is possible to specify only file names of images stored into a disk. Once set, the PhotoLoader automatically performs the asynchronous loading displaying a nice loading animation.
  • SourceType: it is an enum indicating the way used to specify the Source. Right now the only source type allowed is LocalDisk.
  • DisplayOption: it is an enum indicating the image resolution to be used for displaying the image. Supported resolutions: Preview and FullResolution. Notice that using FullResolution requires more memory than Preview modality. Avoid to display a large number of huge images using FullResolution for all, othxerwise an OutOfMemoryException can happen. Normally in an application only few images at time are displayed in full resolution and does not make sens displaying thumbnails using full resolution.
  • DisplayWaitingAnimationDuringLoading: boolean value used for displaying (or not) the default waiting animation during loading.
  • DisplayErrorThumbnailOnError: boolean value used for displaying (or not) a default thumbnail error in case the image cannot be loaded (wrong path, unknown image format…)
  • IsLoading: boolean value set by PhotoLoader indicating if the loading of the specified image is in progress or it is finished. It can be used for customizing loading animation.
  • ErrorDetected: boolean value set by PhotoLoader indicating if an error happened during loading. It can be used for managing the failed loading.

in these days I needed to override the default highlight color used for marking selected items in GridView of WPF Application running on Windows 7.
First of all I noticed that the well known strategy that consist in overriding the SystemColors.HighlightBrushKey didn’t work for ListView that contains GridView on Windows 7 even if the same strategy works fine in ListBox and ListView (that does not have GridView inside) on both Windows XP and 7. This strange behavior is also described in the following msdn post: http://social.msdn.microsoft.com/Forums/en/wpf/thread/1f62b66f-bdcb-4092-8568-a8fa4d39ea9b.

In order to solve that problem, my idea was to define a global style for ListViewItem, but ListViewItem Style  must be different for ListView that contains GridView and ListView without GridView.
In fact when a ListView contains a GridView, the ListViewItem Style must display items via GridViewRowPresenter.
Instead when ListView does not contains the GridView, the ListViewItem Style must display item via ContentPresenter.
This implies to implement a Trigger into ListViewItem Style in order to hide\show the GridViewRowPresenter or the ContentPresenter.

Below a screenshot of ListView and ListView + GridView using a common ListViewItem Style! The solution is downloadable here.

Highlighted item in ListView via ListViewItem Style

And here you are the final working solution for defining a common ListViewItem Style. Notice the Triggers in lines 36-38 that shows/hides the ContentPresenter.

        <Style TargetType="{x:Type ListViewItem}" x:Key="{x:Type ListViewItem}" >
            <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
            <Setter Property="Foreground" Value="Black"/>
            <Setter Property="UIElement.SnapsToDevicePixels" Value="True"/>
            <Setter Property="Template">
                    <ControlTemplate TargetType="{x:Type ListViewItem}">

                        <Border SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" 
                            BorderThickness="{TemplateBinding BorderThickness}" 
                            BorderBrush="{TemplateBinding BorderBrush}"
                            Background="{TemplateBinding Background}">


                                <!-- This is used when GridView is put inside the ListView -->
                                <GridViewRowPresenter Content="{TemplateBinding ContentControl.Content}"
                                                  HorizontalAlignment="{TemplateBinding Control.HorizontalContentAlignment}" 
                                                  VerticalAlignment="{TemplateBinding Control.VerticalContentAlignment}" 
                                                  SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}"/>

                                <!-- This is used for ListView that does not use GridView -->
                                <ContentPresenter x:Name="contentPresenter"
                                              Content="{TemplateBinding ContentControl.Content}" 
                                              ContentTemplate="{TemplateBinding ContentControl.ContentTemplate}" 
                                              ContentStringFormat="{TemplateBinding ContentControl.ContentStringFormat}" 
                                              HorizontalAlignment="{TemplateBinding Control.HorizontalContentAlignment}" 
                                              VerticalAlignment="{TemplateBinding Control.VerticalContentAlignment}" 
                                              SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}"/>


                            <Trigger Property="GridView.ColumnCollection" Value="{x:Null}">
                                <Setter TargetName="contentPresenter" Property="Visibility" Value="Visible"/>

                            <Trigger Property="IsSelected" Value="True">
                                <Setter Property="Background" Value="#FFB3D0E5" />

                            <Trigger Property="IsEnabled" Value="False">
                                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />


Stay tuned!

Today I want to share with you some videos about application prototyping in Sketchflow with Expression Blend 4.
One of the new amazing feature of Blend 4.0 is the SharePoint support. In fact, Expression Blend 4 is able to publish your Sketchflow prototypes into SharePoint and in this way you can also collect and combine feedbacks coming from different SharePoint users.

I think Sketchflow is an important and useful mock-up application since allows you to share and discus prototypes in an effectively.

If you want to learn how to use Sketchflow I suggest you to download the following Sketchflow PDF GUIDE: http://www.dynamic-prototyping.com

Remember: prototyping’s activity is not time wasting. It helps in pointing out software requirement and specification allowing to better plan development activities!


Hi guys,
today I wanna share with you a MultiSelectionTreeView control that I coded by myself a couple of day ago.
The source code can be downloaded here.
Feel free to reply at this post with any question or comments you have.

The controller provide the following functionalities:

  • three different selection modalities can be specified setting SelectionMode property. Supported Selection Modalities are:¬†
    • SingleSelectionOnly: same behaviors of ¬†classic WPF TreeView,
    • MultipleSelectionOnly: every click select/unselect the clicked item,¬†
    • KeyboardModifiersMode: multiple select ¬†items when CTRL key is pressed
  • retrieving selected nodes using SelectedItems property
  • data binding support, including HierarchicalDataTemplate
  • tree navigation using arrows keyboards up, down and left, right for expanding and collapsing nodes
  • helpful TreeItem nodes methods like:
    • SelectAllExpandedChildren/UnselectAllChildren,
    • GetDepth,
    • GetNextNodeAtSameLevel, GetPreviousNodeAtSameLevel
  • look and feel can be¬†overridden

The default look and feel is shown in the picture below:

Happy Coding,