Setting the Default Printer in .NET

The following C# code shows how to use WMI to query printers information, set and get default printer.
public bool SetDefaultPrinter()
    System.Management.ManagementObjectSearcher search = 
default(System.Management.ManagementObjectSearcher); System.Management.ManagementObjectCollection results =
default(System.Management.ManagementObjectCollection); System.Management.ManagementObject printer =
default(System.Management.ManagementObject); search =
new System.Management.ManagementObjectSearcher("select * from win32_printer"); results = search.Get(); //Get Default Printer System.Management.ManagementObject defaultPrinter = null; foreach (System.Management.ManagementObject foundPrinter in results) { System.Management.PropertyDataCollection
propertyDataCollection = foundPrinter.Properties; if ((bool)foundPrinter["Default"]) // DEFAULT PRINTER { System.Diagnostics.Debug.WriteLine(foundPrinter["Name"]); System.Diagnostics.Debug.WriteLine(foundPrinter["Location"]); } } //Sets new default Printer foreach (System.Management.ManagementObject foundPrinter in results) { System.Diagnostics.Debug.Print(foundPrinter["Name"].ToString()); if (foundPrinter["Name"].Equals("PDFCreator")) { System.Management.ManagementBaseObject outParams =
foundPrinter.InvokeMethod("SetDefaultPrinter", null, null); if (outParams == null) System.Diagnostics.Debug.WriteLine("Unable to set default printer"); Int32 retVal = (int)(uint)outParams.Properties["ReturnValue"].Value; if (retVal == 0) return true; else return false; } } return false; }

Converting from VB6 or Winforms to Context-Sensitive Help in Silverlight

If you were in VB6 HelpContextID will be familiar for you ( In those sweet VB6 days all you had to do was:

Private Sub Form_Load ()
   App.HelpFile = "VB.HLP"
   Frame1.HelpContextID = 21004   
   Text1.HelpContextID = 21001
   Form1.HelpContextID = 21005
End Sub

And each time you pressed the F1 button your application will have opened the .hlp file and show you the Help Topic corresponding to that ID. After migration from VB6 to WinForms Help you now have the HelpProvider.SetHelpKeyword And you had to do something like:

internal System.Windows.Forms.HelpProvider HelpProvider1;
HelpProvider1.HelpNamespace = "sample.chm";
HelpProvider1.SetHelpKeyword(TextBox1, "1007.html");
HelpProvider1.SetHelpNavigator(TextBox1, HelpNavigator.Topic);
HelpProvider1.SetHelpKeyword(ListBox1, "1006.html");
HelpProvider1.SetHelpNavigator(ListBox1, HelpNavigator.Topic);

And all that seems nice. But, what can you do when you cross over to SilverlightjQuery15205164761650376022_1357918518660? Well, in general there are several systems that allow you to author your help files in html or convert your .hlp or .chm files to html, but how do you link your components to that help system in order to provide context-sensitive help???? Ok. So one of the possible solutions is very very simple. In general, the solution that I will show in this post is this: 1) First implement an attached property for adding a HelpKeyword to Silverlight components 2) Set the helpkeyword in the desired components 3) Provide logic that will open the appropiate help file. Ok. So let's implement a Silverlight Attached property. An attached propery is like adding a new property to your controls. This new attached property will be called Helpkeyword

using System;
using System.Windows.Shapes;
namespace System.Windows.Controls
    public class HelpProvider
        public static readonly DependencyProperty HelpKeyword = 
            DependencyProperty.RegisterAttached("HelpKeyword", typeof(string), typeof(HelpProvider), new PropertyMetadata(null));
        public static void SetHelpKeyword(UIElement element, string keyword)
            element.SetValue(HelpKeyword, keyword);

        public static string GetHelpKeyword(UIElement element)
            return (string)element.GetValue(HelpKeyword);

Ok. So once we have the attached property we have to use it, and set it on the code: To set it on the code we must add a namespace:

<UserControl x:Class="SilverlightApplication.MainPage"

And apply the attribute to components

<Button help:HelpProvider.HelpKeyword="helpforbutton1" Content="Button" ...  />
<TextBox help:HelpProvider.HelpKeyword="helpfortext1" Height="47" ... />

So that almost everything, now we just need to trigger the appropiate logic, to do that we will add a KeyUp handler to the top most element, in this example a grid. NOTE: if Silverlight is running on the browser F1 is not an option. I just used F2 here as an example.

<Grid x:Name="LayoutRoot" Background="White" Height="205" KeyUp="LayoutRoot_KeyUp">
<Button help:HelpProvider.HelpKeyword="helpforbutton1" ...  />
<TextBox help:HelpProvider.HelpKeyword="helpfortext1" ... />
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Browser;

namespace SilverlightApplication
    public partial class MainPage : UserControl
        public MainPage()

        private void LayoutRoot_KeyUp(object sender, KeyEventArgs e)
            //check for the specific key. For now use F2 as the Help Shortcut
            if (e.Key==Key.F2) { 
                    var uielement = FocusManager.GetFocusedElement() as UIElement;
                    if (uielement!=null)
                        var keyword = HelpProvider.GetHelpKeyword(uielement);
                        var host = HtmlPage.Document.DocumentUri.Host;
                        var port = HtmlPage.Document.DocumentUri.Port;
                        var url = string.Format("http://{0}:{1}/help/{2}.html", host,port,keyword);
                        HtmlPage.Window.Navigate(new Uri(url),"_blank");
            } // else ignore the keystroke
This property can be used on the IDE:

On code
var uielement = FocusManager.GetFocusedElement() as UIElement; 
if (uielement!=null) { 
var keyword = HelpProvider.GetHelpKeyword(uielement); 
This is an image of the application running.

And you can download the code from: CODE

If you have any questions or would like more info on Silverlight migration check

Control Property Serialization in .NET

While solving a bug with a custom class that extended the System.Data.DataSet class, I found a situation where the class implemented, the ISerializable interface, but for some reason, during the call to the base.GetObjectData in my serialization code it was trying to get the value of some properties that caused an exception.

The reason was that those properties were not “ready” because my serialization code had not finish initializing the object. But why was the Dataset.GetObjectData trying to get or set those values.

It seems that there is some code in the dataset that used reflection to get the object properties and try to serialize them. I did not want that.
How could I stop the framework from doing that?

I thought of the NonSerializable attribute but that works only on fields and what I have is a property.

I thought of the XmlIgnore attribute but it had no effect.


Well I finally found that you can add a couple of (not attributes) methods to your component.

They should be named Reset<Property>() and ShouldSerialize<Property>() and returning a boolean value
from these functions will control if the properties are serialized or not.

For more info see MSDN page for ShouldSerialize

Migration from .NET Framework 1.1

13. August 2009 18:07 by Mrojas in General  //  Tags: , , , , , ,   //   Comments (0)

.NET has been around for quite a while. According Wikipedia it has been around since on 3 April 2003
So now there exist applications developed for .NET Framework 1.0 or 1.1 and people
need to migrate them to Framework 2.0 or Framework 3.5.

It is the general impression that there is not a direct path to 3.5.
As Zain Naboulsi explains in his blog you can go from 1.1 to 2.0 then from 2.0 to 3.5.
And From 2.0 to 3.5 the migration is a no-brainer because, both, 3.0 and 3.5 are based on 2.0.

A good reference also is the post of Peter Laudati on migration from 1.1 to 2.0.
Note: Peter’s post seem to have a broken link to the microsoft document about breaking changes in 2.0.
The correct link is this.

A more recent post by The Moth provides more links to breaking changes documents:

- Design time Breaking Changes in .NET Framework 2.0
- Runtime Breaking Changes in .NET Framework 2.0
- Microsoft .NET Framework 1.1 and 2.0 Compatibility
- Compatibility Testing Scenarios

Going from 1.1 to 2.0 or 3.5 can be just as simple as opening the solution in VS and compile
or it can take a lot of effort. Web Projects then to be more difficult due to several changes in ASP.NET.

So good luck.


Well there a lot of static analyisis tools we have used
(some internal, some from Third Parties. I particulary like Understand and NDepend)