How to get the control that has the focus in Silverlight?

22. November 2011 01:51 by Mrojas in General  //  Tags:   //   Comments (0)

Is very simple. To get the control with the focus do something just use the FocusManager.GetFocusedElement()



You can also add an extension method like:

public static class FocusExtensionMethods

public static bool HasFocus(this Control c)
     return FocusManager.GetFocusedElement() == c;


Catastrophic failure with Bitmap.setSource

2. November 2011 10:06 by Mrojas in General  //  Tags: , , , , ,   //   Comments (0)


My friend Jesus has been working on an interesting task. We has been implementing some code so we can connect
a WIA compatible scanner with a Silverlight App.

Once he got the scanner to work, he had to send that data to the Silverlight app.
Something like:

var stream = new MemoryStream(data);
BitmapImage bmp = new BitmapImage();

During this interesting test the infamous Catastrophic failure was raised. This exception
is caused if the data is in an invalid or unsupported format. You can see about this issue in
these links:

However, Jesus found a interesting solution. Use an appropriate encoder. He found this page:

With references of Encoder for: .ICO, BMP and GIF

With this code you can do something beautiful like this:

Stream    file = …

// Decode
Texture texture = Silverlight.Samples.BMPDecoder.Decode(file); 
//Texture is another class in this sample that will return a writeable Bitmap //And with that texture object you just load the image like this: WriteableBitmap wb = texture.GetWriteableBitmap(); wb.Invalidate(); img.Source = wb; Nice!!!!

Can I FTP to my Azure account?

18. October 2011 17:20 by Mrojas in General  //  Tags: , ,   //   Comments (0)

Azure Storage easily gives you 10TB of storage.

So a common question, is how can you upload information to your Storage Account.
FTP is a standard way of uploading files but is usually not available in Azure.
However is it possible to implement something that mimics an FTP but allows you to save data to the
FTP server?

Well I thought on trying on implementing something like that but luckily several guys have already
done that.

Richard Parker has a post on his blog and has also posted the source code in
codeplex FTP2Azure. This implementation works with clients like FileZile. It only does
Active connections.


 Maarten Balliauw also did some similar work. He did not provided the source code but
he does active and passive connections so a mix with Richard’s post can be interesting.

Silverlight ObservableCollection with AddRange

Silverlight is when you have to add a lot of items.
I know, I know maybe you should choose another way to show that data,
but leaving philosophical-ui design discussions, the real problem is that
usually those components are bind  to ObservableCollections.

ObservableCollections are a bit of an exhibitionist.
Each time you add an item it will yell

Hey!! Yoo-hoo! HEY!!! YOU!!
Look at me!! Look at Me!!! Look Mom No Hands!!! Look Dad no Feet!!! HEY!!!!!!!!

So if you have some code like:

for(int i=0;i<10000;i++)
    comboItems.Add("item" + i);

A nice thing will be to be able to do something like:

var items = new String[10000] 
for(int i=0;i<10000;i++) 
    items[i]="item" + i; 

And then provide just ONE notification of Collection Changed instead of a lot of
little cries for attention.

Well that is the reason for this new version of ObservableCollection that I call

using System;
using System.Collections.ObjectModel;
using System.Collections.Generic;

namespace Utils
    public class RangeObservableCollection<T> : ObservableCollection<T>
        private bool _suppressNotification = false;

        public RangeObservableCollection() : base() { }

        public RangeObservableCollection(IEnumerable<T> collection) : base(collection) { }

        protected override void OnPropertyChanged(System.ComponentModel.PropertyChangedEventArgs e)
            if (!_suppressNotification) base.OnPropertyChanged(e);

        protected override void OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
            if (!_suppressNotification)

        /// <summary>
        /// Adds a collection suppressing notification per item and just raising a notification
        /// for the whole collection
        /// </summary>
        /// <param name="list"></param>
        public void AddRange(IEnumerable<T> list)
            if (list == null) throw new ArgumentNullException("list");
            _suppressNotification = true;
            foreach (T item in list)
            _suppressNotification = false;
            OnCollectionChanged(new System.Collections.Specialized.NotifyCollectionChangedEventArgs(System.Collections.Specialized.NotifyCollectionChangedAction.Reset));


Free Alternatives for .NET Reflector

6. October 2011 06:26 by Mrojas in C#  //  Tags: , ,   //   Comments (0)

As I use to start stories to my kids when they go to bed:

“A long long time ago when I was a kid there existed a tool called
.NET Reflector, by a great wizard called Lutz Roeder. This wizard created
a magical tool that allowed you to discover what where the dark forces of the
Framework that produced weird behavior. And he provided it to the code warrior so
they could find their path”

Well .NET Reflector still exists and is a great tool, but is no longer free. You can no longer
just download it and enjoy its bliss : S

But is everything loss. Should I sell my sword and horse to be able to use the .NET reflector Oracle jQuery15203662828153464943_1359277348820?

No. There are now good free alternatives.

First one is call ILSpy( It looks almost the same as .NET reflector. Is not the same but is very good

And recently JetBrains a clan of powerful code warlocks, has just release another magical jewel,
they called it dotPeek (

Profiling Silverlight Applications with Visual Studio 2010

5. October 2011 11:11 by Mrojas in Silverlight  //  Tags: , , , , ,   //   Comments (0)

The VS Profiler Team has an excellent post teaching how to use the VS2010 profiler with Silverlight Applications.

The steps are simple.

Run the A Visual Studio Command Prompt

And follow these steps:

  1. VSPerfClrEnv /sampleon
  2. "c:\Program Files (x86)\Internet Explorer\iexplore.exe" C:\Breakout\Breakout\Bin\Release\TestPage.html
  3. VSPerfCmd /start:sample /output:MyFile /attach:<PID of iexplore.exe process>
  4. Run your scenario
  5. VSPerfCmd /detach
  6. VSPerfCmd /shutdown
  7. VSPerfClrEnv /off

NOTE: information reposted from

When the finish you will have a file called MyFile.vsp and just open that with VS2010.

Running Object Table and .NET

30. September 2011 10:27 by Mrojas in General  //  Tags: , , , , , , , , ,   //   Comments (0)

What is the ROT?

“Using ROT (Running Object Table) is a great way to establish interprocess communication between two windows applications. From a purely logical aspect, one application registers a pointer to an instance of a class in the ROT, the other one gets a pointer pointing to the same instance of the registered class and therefore can use the same instance of the class via this pointer. The class that is registered has to be a COM class, otherwise it can be written in any language. The application that will retrieve the pointer from the ROT can be written in any language that can use COM, as ROT gives a pointer to a COM interface.”

Can it be implemented in .NET?

Sure a .NET application can be exposed thru COM and then its pointer can be gotten and consumed by other applications querying the ROT.

And excelent example can be found here:

As always it has its caveats. Be careful.

Obvious replacement?

Well if what you want is (Interprocess Communication) IPC,there are several options in .NET :

* Classical .NET remoting which is very simple and stable to

* Named Pipes see an example here

* or WCF with Named Pipes, an example here

WCF can be an interesting option specially if we were doing things like DCOM and Remote monikers.

Put an application in FullScreen Mode

28. September 2011 03:55 by Mrojas in General  //  Tags: , , ,   //   Comments (0)


In Silverlight you can put an application in FullScreen mode using code like the one exposed here:

However that does not allows you to start the application in FullScreen, because the application
can only enter in FullScreen with an user event.

So, one possible approach is to use javascript. So you can do something like this:


<script LANGUAGE="JavaScript"> 
    closeTime = "2000";
    function closeTimer() {
        setTimeout("newURL()", closeTime);
    function newURL() {
        newURLWindow ="FullScreenModeTestPage.html", "redirect", "fullscreen=yes");
<BODY onLoad="closeTimer()"> 

Ohhh Glorious Silverlight Theming!!

27. September 2011 03:14 by Mrojas in General  //  Tags: , , , , ,   //   Comments (0)

I’m very fond of one of our newest products Smile

It provides a way to refresh your applications to take full advantage of XAML,
solves deployment issues, runs in Windows, Mac OSX and in some Linux with

And we are event tuning it up for the next jump: Windows 8… keep tuned for that.

One of the things a like most about this solution is XAML theming.

In general there are good themes but today I would like to recommend the SystemColors theme

You can download it from here.
This theme allows you to style all core, sdk and toolkit controls so they will use the theme that
you currently have in Windows. These might be very useful for some LOB applications,
so the applications can see more like native applications, and with the advent of Silverlight 5 and more
native integration, better Out-of-Browser execution I think it is just fine.

See some screen shots:


21. September 2011 09:06 by Mrojas in General  //  Tags: , , ,   //   Comments (0)

Out of the blue, I just started getting this obnoxious exception. Why?? Why meeeeeee!!

Another weird thing is that is was only from my test server. Again Why?>>> Why Meeee!!!

In general when I executed some stored procedures or performed select staments againts the
Oracle database I just got that exception.

ORA-01843: not a valid month


The source of the problem is that when a table has a date stored in a format that the client is not able
to understand due to format differentes it will throw this message.

For example, if the table is storing dates like ‘DD-MM-YY’, (that is day-month-year european format)
and the client tries to read the date as ‘MM-DD-YY’ or viceversa. In this case we can see that the
month number is confused with the day and it is very likely that there will be dates with a month value
bigger that 12.


The solution to this problem is to tell the client the right format to use for dates. This is part of the session values
in oralce. Part of those values can be queries with the following statement:

select * from nls_session_parameters

In the query results, we can see the value of the NLS_DATE_FORMAT that is being used by the client.

You can take several actions.

1. If you are just performing a query on SQL PLUS and is just an isolated query you can just change that value for
your current session by executing:

alter session set NLS_DATE_FORMAT=’DD-MM-RR’

This will take effect ONLY for the actual session. In this example we can see that the format is being changed to
‘day-month-year’. The RR, indicates the year.

2. If you want a more permanent change or at least something that applies to all your session. You can:

2.1. Create an After Logon Trigger something like:



2.2. Option 2. Go to the Registry and locate


For example in my case it was


And create an String Key called NLS_DATE_FORMAT and set it to DD-MM-RR