Silverlight 4 – Using the webcam

Yesterday the beta release of Silverlight 4 was announced. Of course I couldn’t resist to get started with one of the items on my personal wish list (and on lots of other peoples wish list as well).

 

Using the webcam in Silverlight 4 turned out to be a quite easy process. I only needed about 8 lines to get it started. A few lines more and I have an application which starts and stops the webcam with the click of a button.

 

Create the controls

First thing I did was create the controls in xaml using the new designer in Visual Studio 2010. I created a Grid to show the video in (I’ll explain later on why I used a Grid instead of the expected MediaElement) and a button for starting and stopping it.

 

Huh?! No Stream?

As I mentioned before we’ll be using a Grid to display the video in. Why wouldn’t you use a MediaElement? The reason for that is that, as far as I have found out until now, no Stream output for the videocapturing devices available.

This probably has something to do with the difficulty to control the videocapturing devices and with the different formats of the streams. Note that this isn’t based on anything, it’s just my assumption.

What is available then? Good question. It took me a while to figure out, so finally I gave up and goo.. euhm binged for the webcam support in Silverlight 4 and came up with an article describing how to get the video from the capturing device.

 

The code

First we need a field to save the CaptureSource in and we need to hook up the Click event of the button:

private CaptureSource _cs = new CaptureSource(); 

public MainPage() 
{ 
    InitializeComponent(); 
    myButton.Click += new RoutedEventHandler(myButton_Click); 
}

 

Next we will dive into the code required for getting the video from the capturing device.

Before we’re able to show the video from the CaptureSource we need to do some checks and verfications.

First of all, we’re going to check if the state of the CaptureSource is stopped. It would cause an exception if we would start it when it is already started.

if (_cs.State == CaptureState.Stopped)if (_cs.State == CaptureState.Stopped)

 

Next we’ll need to check if the user has granted us permission to use the webcam. We can do this by using the CaptureDeviceConfiguration class as follows:

 

if (!CaptureDeviceConfiguration.AllowedDeviceAccess) 
{ 
    CaptureDeviceConfiguration.RequestDeviceAccess(); 
}

 

So what will happen here is that the Silverlight plug-in will show a pop-up with the question if you want allow camera and microphone access:

If the user responds with “Yes” we’ll continue to the next step. The code for this is:

if (!CaptureDeviceConfiguration.AllowedDeviceAccess) 
{ 
    CaptureDeviceConfiguration.RequestDeviceAccess(); 
} 
if (CaptureDeviceConfiguration.AllowedDeviceAccess) 
{

}

The reason for the duplicate if is that I need to be sure my sure clicked on the yes button after showing the dialogbox. If I would use an else statement the user would have to click on the start button again and if I would use no if and the user would click on the “No” button an exception will be thrown when starting the CaptureSource without permission.

 

The following code needs to be placed inside the last curly braces of the previously added code:

 

System.Windows.Media.VideoCaptureDevice videodev; 
videodev = CaptureDeviceConfiguration.GetDefaultVideoCaptureDevice(); 
if (videodev != null) 
{ 
    _cs.VideoCaptureDevice = videodev; 

    VideoBrush vb = new VideoBrush(); 
    vb.SetSource(_cs); 
    _cs.Start(); 

    grid1.Background = vb; 
    myButton.Content = "Stop webcam"; 
}

As you can see from the fifth line of the code above, the CaptureSource (_cs) needs a VideoCaptureDevice to start the capturing. We can create a VideoCaptureDevice and get the default one by using the GetDefaultVideoCaptureDevice.

We need to be sure there is a default capture device otherwise the app would crash and burn again when starting the CaptureSource.

 

In the two lines of code that follow the VideoCaptureDevice setting we created a VideoBrush and set the source to the CaptureSource. After this, most of the work is done and all we need to do now is start the capturing, set the background of my Grid to the VideoBrush and change the content of the button to “Stop webcam”.

 

In the final piece of code, which goes right after the if in the previous piece of code, we’ll create the functionality to stop the capturing and return to the state where we can start the capturing all over again:

else 
{ 
    if (_cs.State == CaptureState.Started) 
    { 
        _cs.Stop(); 
        myButton.Content = "Start webcam"; 
    } 
}

 

You can find the source of the application here

 

Cheers!

 

Rob

Silverlight & Expression Usergroup in the Netherlands

I'm pretty proud to announce that Silverlight & Expression Insiders, the first Silverlight & Expression user group in the Netherlands, is starting it's activities.

Together with a number of other enthousiastic professionals we created a website. In the near future we will start more activities like organizing events and publishing articles.

If you want us to keep you posted, register on the homepage of the new website:
http://sixin.nl


Cheers!

Rob

TextBox with automatically resizing of the fontsize

View the demo 

Download the source

 

A while back I ran into this textbox that automatically made the font smaller when the text was larger than the size of the textbox.

I wanted to recreate one in Silverlight.

 

The textbox had to have a property for the minimum size of the font. We don’t want our users to see a textbox with a font of 0.25 pixels. That wouldn’t be a good user experience :)

The rest of the stuff has to go pretty much automatically. When the user types, the fontsize automatically adjust. It gets smaller when the text is getting larger than the available space in the textbox and the fontsize gets larger when there’s enough available space.

 

Create a control

In Visual Studio, add a class and make it inherit the default TextBox:

public class TextBoxAutoResizingText : TextBox 

I am going to use a TextBlock to get the width of the text so that we can compare it to the ActualWidth property of the TextBox. If anyone has a different suggestion of how to achieve this, please let me know!

First of all, we need to create a field to keep the value of the original FontSize in. We create this field as a nullable double so we can check if it’s set, and only set it once:

private readonly TextBlock _textBlock = new TextBlock();  
private double? _originalFontSize;

Besides these private fields we have a few properties we can use to set the values of the: MinFontSize, Offset and Step. The Offset is required to prevent the text from dissapearing on the left side of the TextBox. The Step property is used as the amount in which the font needs to be scaled up or down. By default this is set to .25:

private double _minFontSize = 7;
public double MinFontSize
{
     get { return _minFontSize; }
     set { _minFontSize = value; }
} 
private double _step = .25;
public double Step
{
     get { return _step; }
     set { _step = value; }
} 
private double _offset = 12;
public double Offset
{
     get { return _offset; }
     set { _offset = value; }
}

Hooking up the events

We have a couple of events we’re going to use for this control. First of all we’re using the LayoutUpdated event to retrieve the original value of the fontsize and create our TextBlock so that it has almost the same properties as the TextBox.

In the constructor, we hook up the two events we’re using. That leaves us with the following code:

public TextBoxAutoResizingText()
{
     TextChanged += TextBoxAutoResizingTextTextChanged;
     LayoutUpdated += TextBoxAutoResizingTextLayoutUpdated;
}

private void TextBoxAutoResizingTextLayoutUpdated(object sender, EventArgs e)
{
     _textBlock.FontFamily = FontFamily;
     _textBlock.FontSize = FontSize;
     _textBlock.Padding = Padding;
     if(_originalFontSize == null)
     {
         _originalFontSize = FontSize;
     }
}

As you can see, we check if the _originalFontSize is set so it won’t be set every time the event is triggered.

The TextChanged event

This is the event where the actual work is done.
We can separate the event in two parts, one piece occurs when the text is larger than the available space in the TextBox and the other part when text is smaller than the available space:

private void TextBoxAutoResizingTextTextChanged(object sender, TextChangedEventArgs e)
{
     _textBlock.Text = Text;
     if (_textBlock.ActualWidth > ActualWidth - BorderThickness.Left - BorderThickness.Right - _offset)
     {
         while (_textBlock.ActualWidth > ActualWidth - BorderThickness.Left - BorderThickness.Right - _offset && FontSize > MinFontSize)
         {
             if (FontSize - _step <= MinFontSize)
                 break;
             FontSize -= _step;
             _textBlock.FontSize = FontSize;
         }
     }
     else
     {
         while (_textBlock.ActualWidth < ActualWidth - BorderThickness.Left - BorderThickness.Right - _offset && FontSize < _originalFontSize)
         {
             if (FontSize + _step <= MinFontSize)
                 break;
             FontSize += _step;
             _textBlock.FontSize = FontSize;
         }
     }
}

And that’s all there is to it. Pretty simple solution, but it can enhance the user experience without much effort.

This control can also be used from within Expression Blend. Because we used properties for the MinFontSize, it is easily adjustable in the Blend toolbox “Miscellaneous”.

View the demo 

Download the source

Open in Expression Blend - switch between 2 and 3

Since Silverlight 3 is available, Blend 3 Preview was also released. When installing Silverlight 3 tools it is no longer available to create Silverlight 2 applications. Thanks to Amy Dullard who created an awesome batch file/deinstaller/installer script it makes life a lot easier.

The only thing that was bugging me was Expression Blend 2 and 3. Although the Silverlight 2 tools are installed, once installed, Blend 3 is the preferred application when using the "Open in Expression Blend" option in the context menu in VS2008.
After some searching in the registry I found out that it was the following key that did the mapping:
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Expression\Blend\VS]

I created 2 registry files, 1 for going from Blend 2 to Blend 3 and one for going from Blend 3 back to Blend 2. It doesn't install/uninstall anything, it just changes the value in the registry.

So after I created the registry files and copied them to the folder of the batch file that Amy created, I added the following command(s) to the corresponding batch files:
reg import Blend3-to-2.reg
reg import Blend2-to-3.reg

Now, when switching between Silverlight 2 and 3 the "Open in Expression Blend" option also switches to Blend 2 for Silverlight 2 and Blend 3 Preview to Silverlight 3.

NOTE: I created this and only tested it on a 64 bit machine. I did include x86 version of the registry keys but these are untested!

Sometimes being lazy is a good thing, right? :)

Download the registry key files

Automatically translate your Silverlight Application

Get the source now (58Kb)

UPDATE: Thanks to my colleague Emile van Ewijk who pointed out the the is keyword in C# does the same as the extension method that was used, I could refactor and optimize the code. So the source is updated. Thanks, Emile! (and shame on me for not knowing that...)

Let me start by saying that I’m no great fan of automatic translations. I rarely come across an automatically translated text that makes sense :)

As most of you know, I’m Dutch. That’s why my English sux ;). When I was at MIX09, where I met all of these great people, I also received a flyer in my goodie bag of Microsoft Live Translator. Since we, at Amercom, work for some international clients and create multilingual sites this attracted my attention.

And since everyone seems to be blogging on the new features of Silverlight 3B1 I figured, why not do it in plain old Silverlight 2 :P

Preparing your website for multilanguage in Silverlight

First thing I noticed when working with the Cultures in Silverlight (which most of you probably already know) was that the culture did NOT respond to the language settings of the browser. After some research I came across an article on MSDN library that said:

“The .NET Framework for Silverlight provides data for the invariant culture, but it retrieves information about all other cultures from the operating system. This means that the information that is available to a specific culture may differ across operating systems or even across versions of the same operating system.”

IMHO it is a mistake not to read the browser settings by default, but using the OS settings. There must be a pretty good reason for this, but I can’t think of it.

Anyway, to make sure your Silverlight 2 application responds to the settings of the browser, 2 configuration steps are necessary:

1. If you’re using an ASP.NET website/web application, set the following tag in the system.web section of the web.config:

2. Set the following parameters in the object tag of the silverlight control in the ASPX page (ASPX is needed for this functionality):

<param value="<%=System.Threading.Thread.CurrentThread.CurrentCulture.Name %>" name="Culture" />
<param value="<%=System.Threading.Thread.CurrentThread.CurrentUICulture.Name %>" name="UICulture" />

Once you’ve done that, you’ll be able to use the System.Globalization.CultureInfo.CurrentCulture and System.Globalization.CultureInfo.CurrentUICulture properties to retrieve the language set in the browser’s language settings.

What I wanted to achieve with my application is that I wanted to do nothing more then call a single method which takes a Panel control and goes through the children. It should be able to identify the type of control and should check the content for strings that can be translated. One thing that is not working in the sample application is controls that are contained in other controls than those that are derived of a Panel. So controls added to a Button.Content won’t be translated, but I doubt it will be difficult to add that functionality as well.

Adding the Live Translator

To add the Live translator to our application we only need to add a reference to the webservice they created. However, to use the webservice you also need to request an App_Id. You can create an app_id on the following website: http://search.live.com/developers/appids.aspx

On the previously mentioned site there is also more information available on the Live Translator service (API documentation, etc.). I created a constant which contains my app_id so I can easily reuse it through my entire class.

For the webservice, app_id and the source language I created the following fields/const:

private readonly LanguageServiceClient _languageServiceClient = new LanguageServiceClient();
private const string APP_ID = "7BAAE0482B3EA27295D38DA669A42E0F57B56B57";
private const string SOURCE_LANGUAGE = "en";

NOTE: the SOURCE_LANGUAGE should contain the TwoLetterISOLanguageName of the culture you want to use as the source for the translation. I chose English which means that all of the text I use in my Application should be added as English text. Translator should, in some cases be able to detect the language, but since we’re using single words in our application like “Upload” or “Download” I won’t rely on the automatic detection.

In my Page constructor I created a few basic Eventhandlers and a call to the translate method we will create in a moment:

_languageServiceClient.TranslateCompleted += _languageServiceClient_TranslateCompleted;
if(System.Globalization.CultureInfo.CurrentCulture.TwoLetterISOLanguageName != SOURCE_LANGUAGE)
{
 DoTranslateElements(TranslateGrid);
}
ReTranslate.Click += ReTranslate_Click;

Create the DoTranslateElements method

We can use: if (element is TextBox) to check if the element is a TextBox or derived from the type.

Now for the DoTranslateElements method, the most imprtant thing that is done here is the following:

foreach (var element in parent.Children)
{
 //contentcontrol elements (button, etc)
 if (element is ContentControl)
 {
  ContentControl contentControl = element as ContentControl;
  if (contentControl != null)
   if (contentControl.Content is string)
   {
    _languageServiceClient.TranslateAsync(
     APP_ID, 
     contentControl.Content.ToString(), 
     SOURCE_LANGUAGE, 
     System.Globalization.CultureInfo.CurrentCulture.TwoLetterISOLanguageName, 
     contentControl);
   }
 }

 //elements which contain children
 if (element is Panel)
 {
  //recursive call
  DoTranslateElements(element as Panel);
 }

 if (element is TextBlock)
 {
  TextBlock textBlock = element as TextBlock;
  if (textBlock != null)
   _languageServiceClient.TranslateAsync(
    APP_ID,
    textBlock.Text,
    SOURCE_LANGUAGE,
    System.Globalization.CultureInfo.CurrentCulture.TwoLetterISOLanguageName,
    textBlock);
 }

 if (element is TextBox)
 {
  TextBox textBox = element as TextBox;
  if (textBox != null)
   _languageServiceClient.TranslateAsync(
    APP_ID,
    textBox.Text,
    SOURCE_LANGUAGE,
    System.Globalization.CultureInfo.CurrentCulture.TwoLetterISOLanguageName,
    textBox);
 }
}

What is actually done here is loop through all of the elements in a Panel and:

1. If the element is a button, check if content is a string, than translate 2. If the element is a textblock or textbox, translate the text property value 3. If the element is a Panel, call the method itself again (recursive call)

What needs to be noticed is that I use the UserState property to send the object that is translated (button, textblock, etc) to the webservice. This object is returned in the TranslateCompleted event as you will see in the next section.

That is basically it. Now all of the (async) calls to the webservice are made and we only have to catch the TranslateCompleted event and set the correct content in the correct control property.

The TranslateCompleted event

In this event we need to retrieve the data which is returned from the webservice and set it in the corresponding property.

var element = e.UserState;
 if (element is ContentControl)
 {
  ContentControl contentControl = e.UserState as ContentControl;
  if (contentControl != null)
  {
   contentControl.Content = e.Result;
  }
 }

 if (element is TextBlock)
 {
  TextBlock textBlock = e.UserState as TextBlock;
  if (textBlock != null)
  {
   textBlock.Text = e.Result;
  }
 }

 if (element is TextBox)
 {
  TextBox textBox = e.UserState as TextBox;
  if (textBox != null)
  {
   textBox.Text = e.Result;
  }
 }

That's it! Now we get an automatically translated version of our application. I created a couple of buttons and a textblock - and box to test it. I also nested a few controls in a Grid and a Canvas which also worked fine. I have no more space on my personal site, so I can't get a demo online right now, but the source is available: Get the source now (58Kb) Hope this helps!

Dag 2 op MIX09

De 2e dag op MIX begint met een, voor ons, wat minder interessante keynote. De eerste helft is prima, daar wordt namelijk de nieuwste versie van Internet Explorer officieel gereleased (versie 8).

Het 2e gedeelte is een keynote van Deborah Adler. Zij is een designer die, nadat haar oma bijna overleed door het nemen van verkeerde medicijnen (die van haar man), een verbeteringsslag heeft gemaakt voor medicijnlabels en verpakkingen zodat de informatie over de medicatie eenvoudiger en duidelijker wordt. Op zich wel interessant, maar het had niets met internet te maken. Wel een erg mooi verhaal want haar ideeën zijn opgepikt door Target en zij hebben haar geholpen het product te verfijnen en hebben het daadwerkelijk op de markt gebracht.

Verder hebben we sessies gezien van Blend 3, ASP.NET vs MVC framework en The Best Video and Photography on the Web in Silverlight. De 2e sessie was minder interessant dan de andere 2. Maar in die periode waren er niet veel andere interessante sessies, dus de keuze was wat beperkt.

Tussen de middag hebben we gelunched met Martin Tirion en een collega van hem van Microsoft. Ik liep vandaag nog een aantal andere mensen tegen het lijf: Page Brooks van o.a. SilverlightContrib, Koen Zwikstra, Dave Campbell.

 

‘s Avonds de party @ Lavo gehad. De party zelf was niet echt een succes, maar we hebben wel de hele avond leuk en constructief kunnen spreken met Martin Tirion van Microsoft. Al met al dus weer een geslaagde dag geworden.

De laatste dag, dag 3 beloofd weer een aantal leuke sessies. Na de sessies gaan we waarschijnlijk lekker bij het zwembad zitten, want het weer is vrijdag nog goed. Vrijdagavond gaan we waarschijnlijk naar Freemont street, zaterdag is het weer wat minder dus dan gaan we de stad in.

Dag 1 op MIX09

Dag 1 was erg verassend, interessant en erg gezellig.

We hebben bij de keynote een aantal aankondigingen gehoord, waaronder Silverlight 3 beta 1 wat wel de verwachting was.
Andere releases die gisteren plaatsvonden zijn:

Commerce Server 2009

Expression Blend 3 preview

Superpreview

 

SuperPreview

Superpreview is een applicatie die in de nieuwe versie (3) van Expression Web zit. Het is ook een losse applicatie, dus Expression Web is niet nodig om deze tool te gebruiken. De tool kan worden gebruikt om geknipte HTML in meerdere browser te testen. Hierbij kun je vensters waarin de schermen worden weergegeven als bijvoorbeeld IE6 en FF3 over elkaar heenleggen (semi transparant) zodat je makkelijk de verschillen kunt zien.

Het lijkt op het eerste gezicht een erg mooi hulpmiddel om de HTML in diverse browser er hetzelfde uit te laten zien. Zelfs testen van browsers op de MAC is hiermee mogelijk doordat er gebruik wordt gemaakt van servers op het internet. Hoe dit exact werkt weten we nog niet, maar we hebben de tool meegekregen op een memorystick, dus thuis kunnen we het uitproberen.

De versie die nu is gereleased geeft alleen nog de mogelijkheid voor IE 6 t/m 8. De andere browsers en platformen zullen snel volgen.

Expression Blend 3 preview

Waar ik zeer verrast door was, was de nieuwe features in Expression Blend. Ze hebben een mogelijkheid toegevoegd om te sketchen in Blend en om een flow op te zetten van je applicatie waardoor je in no-time een prototype kunt bouwen die eruit ziet als een geschetste applicatie. Maar met clickable buttons en animaties. Erg krachtig, dus ook daar moeten we goed induiken. Helaas hoorde ik net (donderdag, de 2e dag) bij een andere sessie dat de sketch functionaliteit nog niet in deze preview zitten. Da’s wel een teleurstelling.

Daarnaast is er een enorme verbetering gemaakt voor de Photoshop/Illustrator workflow met Expression Blend. Het is mogelijk om direct in Blend Photoshop files te importeren waarbij vectoren die gemaakt zijn in Photoshop bewaard blijven zodat deze nog te wijzigen zijn in Blend. Alle lagen, inclusief effecten (masks, etc) worden 1 op 1 overgenomen. Zelf fonts en alle fontsettings zoals line-height, etc. worden overgenomen in Blend.

 

Silverlight 3 beta 1

Weinig verrassingen voor wat mij betreft, op 1 na. Met Silverlight 3 wordt het mogelijk om de applicaties uit de browser te halen en offline te gebruiken. Dat geeft hele mooie mogelijkheden vooral omdat er geen los framework voor nodig is, zoals wel bij bijvoorbeeld Adobe Air het geval is. Ook de offline applicatie zit in de nieuwe plug-in.

Verder zijn toegevoegd:

• 3D support (basis, alleen plaatsen in 3D space)
• Pixel plaatsen
• Genereren van Bitmaps van je objecten
• Bitmap Shaders (dropshadow en blur worden meegeleverd, verder moeten we ze zelf schrijven)
• Support voor chroma key (dus geen alpha channel, maar een aardig alternatief)

Commerce Server 2009

Helaas hebben ze hier niets van laten zien, maar daar kan ik me iets bij voorstellen. Commerce Server, tenminste de voorgaande versie was niet voorzien van een front-end voor zover ik begreep, dus dat is wellicht bij deze versie hetzelfde.

 

Even een kort videootje genomen van net buiten de Venetian.