Markers are text annotations embedded at certain points in a media file. They help you in several cases. For example, you might use markers to set captions or subtitles for a video file, or maybe you use it to identify particular points in a media file so you can play the media starting at particular points.
Marker Support
Silverlight has native support for video markers, you can subscribe to the MarkerReached event of MediaElement control to get notified whenever you reach a marker. However, in order to use video markers you need to encode them in the video file. The best application that you can use to encode markers in a video file for Silverlight is Microsoft Expression Encoder.
Marker Encoding
After you have your video file added to Expression Encoder, you can use the timeline to set the markers at the desired locations. You can add a marker by moving to the position where you want to set the marker at, then right-clicking the timeline and selecting Add Marker to add a new marker.
You then go to the Markers window where you can set marker text (value) and manage existing markers.
Notice that every marker is identified on the timeline by a symbol like diamond (♦). You can change marker position by moving this symbol, and you can remove it by right-clicking it and choosing Remove (you can also use the Markers window.)
Now encode the video and prepare it to be used in Silverlight.
Code
After you have created your MediaElement and prepared it with the video, you can then subscribe to the MarkerReached event and handle the marker when the video reaches it. An example of handling markers is to display the marker text on the screen if, for example, it is a caption/subtitle for the video:
And you can also load the markers to a list box (for example) and let the user moves to the position of the markers he chooses (worth mentioning that markers are only available after MediaOpened event is raised):
In this article, we’ll have a brief discussion of the new features in elevated-trust applications in Silverlight 5.
Overview
Elevated-trust applications have undergone few changes in Silverlight 5:
In-Browser Support
Multiple Windows Support
File System Access
Platform Invocation
Let’s see those changes in details.
In-Browser Support
Unlike previous versions, in Silverlight 5 you don’t have to run your application as OOB to get elevated-trust features, you can now run elevated-trust applications in the browser and get all the features you need.
There’re two security considerations to be taken in order to run your elevated-trust application in browser:
You must enable running your application in browser via either the Client Access Policy file or the Windows Registry. Using the policy file allows your application to run in a private network. Using the Windows Registry approach allows your application to run on a single machine. In either approaches, you cannot deploy in-browser elevated-trust applications to everyone on the web.
In addition, your XAP must be signed with a trusted certificate e.g. X.509 certificate) available in the Trusted Publisher Certificate store.
Without any of those requirements, you won’t be able to run your elevated-trust application in browser. But wait, there’s a catch!
In your development machine you can run elevated-trust applications in browser only on whitelisted domains. For example, by default, localhost is whitelisted, so you can easily run an elevated-trust application in the browser in localhost. If you change to another domain, ensure that you add this name to the whitelist, or you won’t be able to run the application. More comes about this later.
The last thing to keep in mind is that in the Beta version, in-browser elevated-trust applications are supported in Windows only. Other platforms are going to be available in the final version.
Client Access Policy Approach
If you want your application to be available in a private network, you need to do some changes to the client access policy file in order to allow it to run in browser as elevated-trust. The changes are as the following; just set the ElevatedPermissions property of SecuritySettings to Required:
The other approach you have is to use the Windows Registry to enable in-browser elevated-trust applications to run on a particular machine. To do this, go to HKEY_LOCAL_MACHINESOFTWAREMicrosoftSilverlight. In this registry key, you have several values related to elevated-trust applications:
AllowElevatedTrustAppsInBrowser: Set to TRUE (0x00000001) to enable running elevated-trust applications in browser.
AllowInstallOfElevatedTrustApps: Set to TRUE to enable installation of elevated-trust applications to the PC (i.e. OOB.)
AllowLaunchOfElevatedTrustApps:
Set to TRUE to enable launching elevated-trust applications (in-browser or OOB.)
Example
To run an elevated-trust application in browser you need first to enable OOB and elevated-trust features from project properties. After that, create a Web application and link it to the Silverlight application to host it. If you didn’t do this, your Silverlight application will run as OOB. Your application is able now to run as elevated-trust in browser. To ensure this, you can check for the Application.HasElevatedPermissions property:
As you see, the application works as expected, and has all the elevated-trust features as OOB applications.
Now let’s try changing the domain from localhost to another domain. Go to Web application project properties, switch to the Web tab, then go to Server settings and change the server from Visual Studio Development Server to Local IIS Web Server and use your machine name as the domain and save the settings. (You might be asked to confirm virtual directory creation, it’s because you have changed to another domain and used another virtual directory.)
Now try to run the application. The application won’t be able to run and you’ll get a security exception, that’s because the new domain is not whitelisted like localhost.
Multiple Windows Support
Multiple Windows Support or Ad-hoc Windows is a feature that enables elevated-trust OOB applications in Silverlight 5 to have windows other than the main window. The feature is available through the Window class which is now instantiable. You use the Window class to create another window and set its contents through the Content property and show it using the Visibility property.
The following code creates a Window that’s 400 pixels wide and 300 pixels long, and has just a button in the interface:
Notice that you can end the application by closing the main window; it doesn’t matter if you close any other window.
You’re not limited to just a button or a single object in the window contents. You can create another page (i.e. user control) and set it to be the content of the window:
Window wnd = new Window();
wnd.Width = 400;
wnd.Height = 300;
wnd.Content = new MyOtherPage();
wnd.Visibility = System.Windows.Visibility.Visible;
And you can also create windows with custom chrome by removing the toolbar and borders and create them yourself via code:
Notice that if you don’t have elevated-trust features, you won’t be able to spawn other windows. And if you tried to, you’ll get a security exception.
File System Access
Unlike elevated-trust applications in Silverlight 4 which have access to only My Documents folder, Silverlight 5 elevated-trust applications (in-browser and out-of-browser) have full access to the file system. But keep in mind that although you have full access to the file system, you still restricted by the rights of the user running your application. If the user doesn’t have access to a specific file or folder, then you don’t have access to that file or folder.
To test this feature, try reading contents from a file in the system folder (for instance):
By default, if you’re running Windows Vista or Windows 7, your user wouldn’t have administrator privileges as long as he doesn’t launch Visual Studio (or your application) in elevated mode. So if you don’t have admin privileges and tries to gain the write access to the same file your application would fail, that’s because your application is restricted by user rights and the user don’t have write access to that file:
Same results when trying to write to the system drive without elevated permissions for the user:
File.WriteAllText(@"C:test.txt", "Foo");
Platform Invocation
Silverlight 4 has introduced support for automation and COM components. Silverlight 5 has added support for Platform Invocation (or P/Invoke.) Platform Invocation allows you to call native code (e.g. DLLs and Windows API) from your Silverlight application. This is a great improvement of course. It uses the same mechanism as other WinForms applications. Unfortunately, this feature is currently not available in the Beta.
Summary
The following changes have been happened to elevated-trust applications in Silverlight 5:
In-Browser Support:
You can now run elevated-trust applications in Silverlight 5 in browser. Must be enabled via client access policy file or Windows Registry, and XAP must be signed with a trusted certificate.
Multiple Windows Support:
Allows elevated-trust OOB applications to span windows other than the main window.
File System Access:
Allows you to have full access to the file system with the rights of the current user.
Platform Invocation:
Allows you to call native code like DLLs and Windows API from your Silverlight application. Not available in Beta.
In this article, we’ll have a brief discussion of the new features in media stack in Silverlight 5.
Overview
Silverlight 5 has undergone few changes in the media stack:
Better Battery Management:
Less battery when playing media. Plus, no screensaver in the full-screen mode.
Remote Control Support:
Now you can control the media being played in Silverlight 5 using a remote control. This feature is currently not available in the Beta.
Hardware Decoding; More GPU Support:
For better performance, Silverlight 5 depends more on the GPU for media decoding especially for the high definition H.264 formats. In Beta, no DRM or Mac support.
1080p Support:
Combined with hardware decoding, user can now watch high definition 1080p media on a Netbook or Tablet.
IIS Media Services 4:
Support for media streaming using IIS Media Services 4 has been added.
And two more features require more details:
Speed Control; Trick Play:
Allows you to control playing speed, and to play the media forward or backward.
Low-Latency Sounds:
Silverlight 5 has added native support for raw wave files.
Speed Control; Trick Play
This feature allows you to control playing speed, to speed-up or slow-down the media. The ability to change playing speed is called, Trick Play. This feature is available in the MediaElement control through a new property called PlaybackRate. This property takes a decimal value ranges from -8, -4, -2, … to …, 0.5, 1.2, 1.4, 2, 4, 8, and the default is 1. The downside of the Beta version is that it doesn’t have a pitch correction, means that when you change the rate to a value other than the default (1) you wouldn’t have any sound. And because of a bug found in the Beta version, you must set this property in code, if you set it in XAML will reset at application start to the default value.
The following are three examples of changing the playing speed of a media element:
// Normal Speed
media.PlaybackRate = 1.0;
// Fast
media.PlaybackRate = 4.0;
// Slow
media.PlaybackRate = -2.0;
Low-Latency Sounds
In the past, you had to create a wave file parser that reads file headers to determine if this is a wave file, and after recognizing a wave file, the parser reads file contents and encode them in order for your application to be able to play it. That changed completely in Silverlight 5. Today, you have native support for raw sounds data (i.e. low-latency sounds.) You can now play wave files and wave data directly in your application without the need to encode them.
This feature is available through a new API based on the XNA Framework. It uses the same classes and functions available in XNA. The main class you have is SoundEffect (Microsoft.Xna.Framework.Audio) that you can use it to play wave files and raw data. You have all the control over the media played; you can set volume, pitch, and stereo space. And you can create a more sophisticated class of SoundEffect called SoundEffectInstance that represents an instance of that sound file. This instance can be played repeatedly, and allows you to have all the control like SoundEffect and more, as we’ll see in the examples.
Finally, keep in mind that Silverlight 5 has the same limitations as XNA; it allows only for 8/16bit PCM, mono/stereo, 22.5/44.1/48khz wave files.
The following code loads the SoundEffect class with a wave file available in application resources:
var resource = Application.GetResourceStream(
new Uri("MediaLowLatency;component/tada.wav",
UriKind.RelativeOrAbsolute));
SoundEffect effect = SoundEffect.FromStream(resource.Stream);
After you have the SoundEffect at your hands, you can call the Play() method to play it. This method have two overrides, one can accept no parameters in which it plays the media normally with the default volume and no changes in the pitch or the stereo space. The other override accepts three values:
volume:
Ranges from 0.0f to 1.0f.
pitch:
Ranges from -1.0f to 1.0f. Default is 0f.
pan:
Controls the stereo space. Ranges from -1.0f to 1.0f. Default is 0f.
The following are some examples of playing sound files using SoundEffect:
// Normal
effect.Play();
// Normal (default values)
effect.Play(1.0f, 0f, 0f);
// Faster
effect.Play(1.0f, 1.0f, 0f);
// Slower
effect.Play(1.0f, -1.0f, 0f);
And finally you can use the SoundEffectInstance to create multiple instances of the same audio, or to play it repeatedly (Volume, Pitch, and Pan values are available through properties):
While Silverlight 5 manages battery better, it also has improved media performance by depending more on the GPU for media decoding. And it allows now for high definition 1080p and H.264 videos. In addition, Silverlight 5 has introduced remote control support. And finally, the greatest features are its support for raw wave files and the ability to control playing speed.
In this article, we’ll have a brief discussion of the new features in graphics stack in Silverlight 5.
Overview
Silverlight 5 has undergone few changes in the graphics stack:
Improved Performance and Rendering:
Performance has been improved dramatically by using lessons learned from Windows Phone 7. More comes later in this article.
Hardware Acceleration:
Silverlight 5 now depends more on GPU for graphics processing. This frees CPU from much work, and as a result, improves performance.
New 3D API:
The most exciting feature yet. Silverlight 5 now supports native 3D API. More comes later.
Vector Printing:
Very useful for certain cases, not available in the Beta.
Print Preview:
The long-waited printing feature. Silverlight 5 now allows you to show the user a preview of what he is going to print. Yet not available in the Beta.
Now let’s look at the currently available features in details.
Performance Improvements
To improve rendering performance, Silverlight 5 uses the composition model available in Windows Phone 7. This model implies using a separate, dedicated thread for graphics rendering instead of using the UI thread. This helps freeing the UI thread from graphics work, and thus improves the performance of rendering UI elements and reduces flickers and glitchy animations happen when UI thread was interrupted.
In addition, moving the graphics rendering to another thread adds support for independent animations and helps with immediate-mode rendering on the GPU (in which graphics are sent directly and being rendered on the display.)
3D API
Silverlight 5 now supports natively a 3D API. This API is based on the XNA API; you have the same classes and the same code, however, the 3D API is Silverlight is not game-loop based.
While it’s so amazing to have a 3D API natively supported in Silverlight, things are not as good as they seem. The 3D API of Silverlight 5 is very low-level, means that you have access to the GPU, vertex shaders, and other 3D primitives. It’s not as easy as it should be; it requires that you have a solid understanding of low-level graphics and game development to be able to interact with this API. However, the good news is that community will likely wrap this low-level API into simpler components.
Technically, to draw graphics on the screen you need to use the new control DrawingSurface where all the rendering and graphics go on. This control offers a Draw event that you can use to supply your drawing calls. The calls are carried to a GraphicsDevice object and then be processed and carried to the display.
Because of the complexities in this low-level API, and because we assume that you are a business developer, we won’t discuss the 3D API. Instead, we’ll have a brief look at two of the great samples of this API.
Cube Sample
The cube sample (download from http://bit.ly/sl5-cubesample, colored, non-textured) demonstrates how to create and rotate a 3D cube in Silverlight 5. Here’s a screenshot of this sample:
Looking at the Solution Explorer at project files, we can see that the project contains some pixel shader (PS) and vertex shader (VS) files. Those files besides the HLSL files contain the code (in the HLSL language) for the effects required to render the cube.
Moving to MainPage.xaml you can see the DrawingSurface object used to display the graphics and drawings.
Looking at the code behind at the Draw event handler, we can see that the sample has encapsulated all the code required for drawing the cube and rotating it into a new class called Scene. The Draw event passes the GraphicsDevice object to the Scene to have it draw the cube and other graphics into the device:
// init the 3D scene
Scene scene = new Scene();
public MainPage()
{
InitializeComponent();
}
void OnDraw(object sender, DrawEventArgs args)
{
// draw 3D scene
scene.Draw(args.GraphicsDevice, args.TotalTime);
// invalidate to get a callback next frame
args.InvalidateSurface();
}
Moving to the Scene class, we can see that it creates another class that handles drawing the Cube, and has configured the view and camera position and completes the drawing in the Draw() function by clearing the screen and calling the Draw() function of the cube.
public class Scene
{
Matrix view; // The view or camera transform
Matrix projection;
// The single Cube at the root of the scene
Cube Cube = new Cube();
public Scene()
{
// the camera's position
Vector3 cameraPosition = new Vector3(0, 0, 5.0f);
// the place the camera is looking (towards world origin)
Vector3 cameraTarget = Vector3.Zero;
// the transform representing a camera at a position looking at a target
view = Matrix.CreateLookAt(cameraPosition, cameraTarget, Vector3.Up);
}
...
public void Draw(GraphicsDevice graphicsDevice, TimeSpan totalTime)
{
// clear the existing render target
graphicsDevice.Clear(ClearOptions.Target | ClearOptions.DepthBuffer,
Color.Transparent, 1.0f, 0);
// draw the Cube
Cube.Draw(graphicsDevice, totalTime, view * projection);
}
}
Finally, the Cube class completes all the drawing by loading the vertex and pixel shaders in its constructor, configuring cube surfaces and surface colors in the CreateCube() function, and then performs the drawing and handling the animation in the Draw() function.
public class Cube
{
// the device to use when creating resources
static readonly GraphicsDevice resourceDevice
= GraphicsDeviceManager.Current.GraphicsDevice;
// resources
VertexShader vertexShader;
PixelShader pixelShader;
public Cube()
{
// Initialize resources required to draw the Cube
vertexBuffer = CreateCube();
Stream shaderStream = Application.GetResourceStream(
new Uri(@"CubeSample;component/Cube.vs", UriKind.Relative)).Stream;
vertexShader = VertexShader.FromStream(resourceDevice, shaderStream);
shaderStream = Application.GetResourceStream(...);
,,,
}
VertexBuffer CreateCube()
{
// cube vertices
var cube = new VertexPositionColor[36];
// face coordinates
Vector3 topLeftFront = new Vector3(-1.0f, 1.0f, 1.0f);
Vector3 bottomLeftFront = new Vector3(-1.0f, -1.0f, 1.0f);
...
return vb;
}
public void Draw(GraphicsDevice graphicsDevice, ...)
{
// update cube transform
Matrix position = Matrix.Identity; // origin
Matrix scale = Matrix.CreateScale(1.0f); // no scale modifier
...
// setup pixel pipeline
graphicsDevice.SetPixelShader(pixelShader);
// draw using the configured pipeline
graphicsDevice.DrawPrimitives(PrimitiveType.TriangleList, 0, 12);
}
}
Lengthy, isn’t it? Now, let’s have a look at another example.
Solar Wind
The Solar Wind 3D sample (download from http://bit.ly/sl5-solarwind) uses the new 3D features of Silverlight 5 to draw the Earth with day and night transitions, atmosphere layers, and population density overlays. It demonstrates advanced concepts and it’s very cool that you’ll like to run and play with it.
Babylon3D
The most amazing sample yet (download from http://bit.ly/sl5-babylon3d), it shows a full 3D realtime engine with some advanced features and an integrated collisions system.
Summary
Silverlight 5 has got few improvements in the graphics stack:
Improved performance:
Uses the composition model of Windows Phone 7; a separate, dedicated thread for graphics and drawing.
Hardware Acceleration:
Depending more on GPU for graphics processing. Frees CPU from much work, and as a result, improves performance.
New 3D API:
A low-level 3D API based on XNA Framework. Difficult to work with. Community will likely wrap to simplify use.
Vector Printing:
Very useful for certain cases, not available in the Beta.
Print Preview:
Allows for print previews. Not in Beta.
In this article, we’ll have a brief discussion of the new features of controls and text in Silverlight 5.
Overview
Silverlight 5 has undergone few improvements in controls and text; new added features for controls, and rendering and performance enhancements for text.
The following are the new features of controls in Silverlight 5:
Text tracking and leading control
Text overflow
Multi-click support
Type-ahead text searching
SaveFileDialog DefaultFilename
DataContextChanged event (not in Beta)
And text has been improved in in a few ways:
Rendering is now better
Performance of text layout has been improved
Text clarity is improved with Pixel Snapping
OpenType support has been enhanced
As improvements in text were all about rendering and performance, we won’t talk more about the text improvements. Instead, we’ll focus in this article on control stack and cover the changes that happened to it in details.
Text Tracking and Leading Control
Silverlight 5 has added three features to text controls (TextBlock, TextBox, and RichTextBox) to allow you to control precisely text tracking and leading space for characters and lines:
Character Spacing
Line Height
Line Stacking Strategy
Character Spacing
This feature allows you to precisely set how far apart each character is. This feature is available in all text controls through a property called CharacterSpacing that specifies the distance between characters. This distance is measured by 1000th of the current font size, means that for instance if you set the font size to 20px and character spacing to 500, then the distance will be 10px between each character (since 20 * 500 / 1000 = 10px.)
Here’s an example of a TextBlock that uses the character spacing feature to put 10px between each character:
<TextBlock FontSize="20" CharacterSpacing="500">
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
</TextBlock>
Line Height
This feature allows you to set precisely the height of each line of the content in a text controls. It’s available in all text controls through a property called LineHeight and, unlike CharacterSpacing, it’s measured in pixels.
The following code sets the height of each line in the text to 50px:
<TextBlock Margin="5" LineHeight="50">
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
<LineBreak />
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
<LineBreak />
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
</TextBlock>
Line Stacking Strategy
This feature allows you to specify how each line box is determined. For example, if you’re in a scenario like the following where you have some text larger than other text, what will you do? Would you increase the height for each line to accommodate the size for the larger text and allow the text to be readable? Or would you leave the text as it as if there wasn’t any text with different font size? That’s what the stacking strategy is all about.
<TextBlock Margin="25" FontSize="12">
Lorem ipsum <Span FontSize="20">dolor sit amet</Span>, ...
<LineBreak />
Proin aliquam augue quis ipsum <Span FontSize="38">rhoncus</Span> ...
<LineBreak />
Quisque eleifend ante vitae velit vehicula luctus. ...
</TextBlock>
The stacking strategy is available to your code through a new property called LineStackingStrategy. This property takes one value of three:
MaxHeight (default):
Increases the size of each line’s box enough to hold its content. If LineHeight is set, adds the value of LineHeight to the determined value of the height of line’s box.
BlockLineHeight:
Uses value from LineHeight if specified. Otherwise, increases the size for each line’s box to hold its various font sizes content.
BaselineToBaseline:
Uses value from LineHeight if sepified. Otherwise, uses the default line height that doesn’t care about whether the content has larger text or not.
The following figure compares between the three stacking strategies while setting LineHeight and while not setting it.
Makes sense?
Text Overflow
This feature allows for multi-column and free-form text layouts. It’s available for RichTextBoxes only. You set a RichTextBox as the master element, and link it to the new RichTextBoxOverflow to capture extra text that doesn’t fit in the master RichTextBox. You can also continue the chain and link another RichTextBoxOverflow to the previous one to capture extra text that doesn’t fit there and so on. To link an overflow control to another one, you use the new OverflowContentTarget property available in the previous control to bind to the next overflow control.
The following figure shows how you can use overflow controls to create multi-column text:
And the following shows an example of a free-form text where the text wraps around an object in the center:
The following example creates a multi-column text:
Silverlight 5 now allows you to capture multi-clicks in controls. It can capture any n-clicks, but most of the time you’ll capture double-clicks and sometimes triple clicks. This feature is available through a property called ClickCount available in MouseButtonEventArgs. While MouseButtonEventArgs is available in ButtonDown and ButtonUp events, ClickCount is only valid on MouseLeftButtonDown and MouseRightButtonDown, it always return 1 from ButtonUp events.
The following code shows how you can capture multiple clicks in a TextBlock, it updates the TextBlock for each click:
Type-ahead text searching capability in Silverlight 5 allows you to search in a collection control (e.g. ComboBox, ListBox, etc.) using keyboard; you reach the desired item by typing the first letters of its content.
The content that the control searches in must be specified in DisplayMemberPath. For example, in our books scenario to search in book titles you must set DisplayMemberPath to the Title field. This leads up to another problem, if you have set a data template, you cannot set DisplayMemberPath along with it. This problem can be solved by using the new Silverlight 5 XAML feature, implicit data templates, which has been covered earlier in the previous article.
In our books scenario, we have the following ComboBox that has an implicit data template applied:
<ComboBox x:Name="books" />
And we have also the following code that populates the ComboBox and sets the DisplayMemberPath to allow searching using keyboard:
books.ItemsSource = new BookData().OrderBy(b => b.Title);
books.DisplayMemberPath = "Title";
The application works perfectly now. But if you convert the data template to an explicit data template like the following:
You receive the following error, because DisplayMemberPath cannot be set while setting an ItemTemplate:
SaveFileDialog DefaultFilename
Now in Silverlight 5 you can set the default filename in SaveFileDialog (using the new DefaultFileName property) that will show in the file name box when you launch the dialog:
SaveFileDialog dialog = new SaveFileDialog();
dialog.DefaultFileName = "Foo";
dialog.ShowDialog();
DataContextChanged Event
This feature is currently not available in Beta; it should be available in the final version. It occurs when the DataContext object for a control changes.
Summary
For controls in Silverlight 5, we have the following improvements:
Text tracking and leading control:
Allows you to set character spacing, line height, and line stacking strategy for a text control.
Text overflow:
Available for RichTextBoxes. Allows for multi-column and free-form text layouts.
Multi-click support:
Allows you to capture any n-clicks.
Type-ahead text searching:
Allows searching in a collection control using keyboard.
SaveFileDialog DefaultFilename:
Allows you to set the default file name for SaveFileDialog.
DataContextChanged event:
Not in beta. Occurs when the DataContext object for a control changes.
And in the text stack, there were some improvements related to performance and rendering:
In this article, we’ll have a brief discussion of the new XAML features of Silverlight 5.
Overview
Silverlight 5 has the following changes in the XAML stack:
Implicit Data Templates
Ancestor RelativeSource
Binding in Styles
Markup Extensions
XAML Debugging
Let’s see them in action one after one.
Model
Our demos in this section are based on a very simple model consists of just a collection of paper books and audio books. We have the following business model:
public class Book
{
public string Title { get; set; }
public string Author { get; set; }
public decimal Price { get; set; }
}
public class PaperBook : Book
{
public string Isbn { get; set; }
public int Pages { get; set; }
}
public class AudioBook : Book
{
public TimeSpan Duration { get; set; }
}
And here’s our collection:
public class BookData : List
{
public List PaperBooks
{
get
{
return (from b in this where b is PaperBook
select (PaperBook)b).ToList();
}
}
public List AudioBooks
{
get
{
return (from b in this where b is AudioBook
select (AudioBook)b).ToList();
}
}
public BookData()
{
this.Add(new PaperBook()
{
Title = "The Sixth Man",
Author = "David Baldacci",
Isbn = "9780446573108",
Pages = 432,
Price = 14.28m,
});
...
this.Add(new AudioBook()
{
Title = "Water for Elephants",
Author = "Sara Gruen",
Duration = new TimeSpan(11, 29, 00),
Price = 21.56m,
});
}
}
Implicit Data Templates
Silverlight 5 has got one of the great features of data templates in WPF, Implicit Data Templates. Instead of explicitly attaching the data template to every control, you can set a data type (through the DataType property) that the data template will apply to and then the data template will be applied automatically to any control that’s trying to display that data type.
Keep in mind that an implicit data template applies only to controls that…
Trying to display the data type specified
Have a templatable content (e.g. collection controls)
Defined in the scope of the template
So the implicit data template won’t apply to any other control doesn’t meet those requirements.
Implementation:
Let’s see implicit data templates in action. In the following scenario we have a list box that uses a data template to display some books and it gets populated through the code:
We could refactor this code by making the data template implicit, and this can be done by moving the data template from the list box to application resources (for instance) and specifying the data type, and then the data template will be applied automatically to each templatable-content control trying to display the data type specified:
Now let’s do something more interesting to see the real power of implicit data templates. Instead of having a simple data template, we’ll have two templates for the two types of books, once for the paper books, and the other for the audio books:
As you see, each data template will be applied to a templatable-content control that tries to display the data type it specifies. In addition, both the data templates would be applied to a collection control that tries to display a collection of both PaperBook and AudioBook.
Ancestor RelativeSource
This is another feature of XAML that Silverlight 5 has got from WPF. It allows you to bind to a property in a parent control. This is especially useful in situation where you are in a data template and wish to bind to a property in a control outside the template higher in the render tree.
Implementation:
You use {Binding.RelativeSource} to specify the source in the tree.
Use the AncestorType property to specify the type of the parent control that you wish to bind to.
Use AncestorLevel to specify how far is the parent control of the type specified from the current control.
The following TextBlock controls all bind to the same Tag property found in the root StackPanel:
And here’s a more complex example. In the following example we change the color of a control inside an item template based on whether the item is selected or not. For this to work we bind to the IsSelected property of the ListBoxItem control (that represents an item on the list box) and we use a type converter to return a color based on a Boolean value:
This is another feature of XAML that Silverlight 5 has got from WPF. It allows you to bind directly in style setters, and that would allow changing styles automatically at runtime by changing source objects.
Implementation:
In the following scenario, we have a class that contains brushes used in the application:
public class MyBrushes
{
public SolidColorBrush MainBrush { get; set; }
public MyBrushes()
{
MainBrush = new SolidColorBrush(Colors.Red);
}
}
And we have a style that binds to that class and gets the main brush from there (as you can see, all binding features are available now in style setters):
Finally, we can change the style automatically at runtime by changing the source brush using code like this:
MyBrushes brshes = Application.Current.Resources["brushes"] as MyBrushes;
brshes.MainBrush.Color = Colors.Red;
Markup Extensions
Markup extensions allow you to execute code at XAML parsing time, they are like {Binding}, {StaticResource}, {RelativeSource}, etc. The new feature of XAML in Silverlight 5 is the ability to create custom markup extensions. They provide more concise syntax, and they are easier and simpler than attached properties.
Implementation:
An example of a very simple markup extension is an extension that sums two numbers and returns the result to the control (the following TextBlock would have the text ‘3’ at runtime):
So how to create such an extension? You can create markup extensions by implementing the generic IMarkupExtenstion interface (in System.Xaml namespace) that accepts a type parameter specifies the return type from the extension (must be a reference type.) After that, you provide extension parameters as properties, and you implement ProvideValue() to do the work and return the results to the XAML.
The following code defines our summation extension:
public class SumExtension : IMarkupExtension<object>
{
public int FirstNumber { get; set; }
public int SecondNumber { get; set; }
public object ProvideValue(IServiceProvider serviceProvider)
{
return (FirstNumber + SecondNumber).ToString();
}
}
And here’s a more complex example. In the books scenario, we have defined a markup extension that returns a collection of books based on the book type (paper/audio):
public class BookLocatorExtension : IMarkupExtension<object>
{
public BookType Type { get; set; }
public object ProvideValue(IServiceProvider serviceProvider)
{
if (Type == BookType.Paper)
return BookData.PaperBooks;
else
return BookData.AudioBooks;
}
}
public enum BookType { Paper, Audio }
The last new XAML feature introduced in Silverlight 5 is the ability to debug data bindings. It is very useful when watching for binding errors and it works by placing a breakpoint inside the binding in XAML and watching the Locals window and other Visual Studio windows for binding details.
Keep in mind that XAML debugging works only in Internet Explorer 9.
Implementation:
In our books scenario, we have the following data form:
Now, put a breakpoint inside the binding in the list box and run the application to see what happens.
When you run the application, Visual Studio stops on the breakpoint while it loads the list box with data. Looking at the Locals window we can see binding details:
Here we have the details encapsulated in a BindingState, and the current state is UpdatingTarget means that it’s a Pull operation where list box gets loaded with data.
We can see that we have 5 items in the list referred by FinalSource. In addition, we don’t have any errors or validation errors yet.
Now stop the application, and let’s try something else. Try inserting the breakpoint into the Price text box instead and run the application.
As you can see, Visual Studio stops on both Push and Pull operations. The Pull operation happens when the text box get loaded by the data, and the Push operation happens when the value in the text box changes and gets updated to the source.
Now try writing some invalid data in the price text box (e.g. some letters) and watch the Locals Window:
Now you watch out any error that might happen in binding.
The last thing to mention is that conditions and filters can be used in the breakpoints. As an example, you can use the following condition to tell Visual Studio to stop only on binding errors and not in every operation:
The first thing to know about Silverlight 5 is that it’s currently in beta, means that it definitely has bugs, and it also not yet feature-complete; some features are going to be shipped later in the final version. In addition, being in beta means that no go-live license available, this is for internal use and testing only so do not install on user’s machine.
Worth mentioning that Silverlight 5 was first announced at PDC 2010 conference (October 2010) and the beta version was shipped later at MIX11 (April 2011,) and the final version will be released soon this year.
Goal
Goals of the version 5 include:
Improving performance
Getting closer to WPF
Enabling line-of-business scenarios
Better development experience
Improvements
Silverlight 5 has come with lots of improvements and changes, and those improvements can be divided into several areas:
In this article we’ll have a brief introduction to Microsoft Silverlight, see how it fits with other technologies today, and watch it in action. Get ready!
What is Silverlight
Definition
Silverlight is a Microsoft technology aimed to help developers create rich interactive Web applications with the best user interface features and functionalities. It’s available as a plugin for almost all famous browsers available today, and it’s used to deliver the next generation media and Web applications.
Figure 1 - Silverlight Logo
When we say rich applications we don’t mean those with amazing interfaces and lots of graphics. Indeed, we mean by “rich” those have lots of functionalities not available for standard Web applications. Common examples of rich applications are online document editors and image processors; both are very interactive and offer lots of functionalities that are usually not available for standard Web applications. And that actually what Silverlight is devoted for, its main goal is to allow for developing rich interactive applications for the Web.
Platform Support
Unlike many other Microsoft technologies, Silverlight applications can run everywhere. It’s said to be cross-platform, cross-browser, and cross-device. It can run on Windows, Linux, and even Mac, it can run on Internet Explorer, Mozilla Firefox, Google Chrome, and many others, and it also can run on PCs, mobile devices, and handhelds. Really it can run everywhere without any code changes!
One more interesting thing is that Silverlight Web applications can be hosted on any server. You can host your Silverlight application on a Windows, Linux, or Mac server without any additional code changes or configuration.
Rich Interactive Applications
We have been talking about rich interactive applications for a while; now let’s see what a rich interactive application really means.
A Rich Interactive/Internet Application (RIA) is a Web application that’s very interactive with the user and has lots of functionalities. It’s very similar to desktop applications comparing interactivity and features; however, it’s a Web application that runs on the browser not the desktop. So we can say that RIA applications have the best functionalities and user interface features of desktop applications and Web applications.
Figure 2 - RIA
Today, there’re lots of technologies available for creating RIA applications. The most famous platforms are Adobe Flash, Microsoft Silverlight, and Sun Java. Worth mentioning that every platform of the above mentioned (that includes Silverlight of course) is available through a plugin for the browser, and therefore its runtime must be installed on user’s machine in order to be able to run the application.
RIA Stats
Now someone asks: Who wins the race? What’s the best RIA platform that one can spend his time and effort to learn?
First of all, let’s have a look at the following diagrams that represent penetration rates of Adobe Flash, Microsoft Silverlight, and Sun Java. The first diagram we have comes from http://riastats.com and it shows that Adobe Flash is installed on almost 96% of internet-connected machines. Microsoft Silverlight comes in the second place with about 74% of total internet-connected machines. And Sun Java comes third with about 73% of internet-connected machines.
Figure 3 - RIA Stats
StatOWL shows a bit different data with more details:
Figure 4 - Stats from StatOWL
Looking at the above diagrams we can see that Microsoft Silverlight did a great job in a very short time (first release was on 2007.) However, we can’t depend much on this data since, as you know, Microsoft Silverlight is installed automatically on Windows machines via Windows Update.
Now, let’s have a look at Microsoft Silverlight features and see what makes it the best RIA platform yet.
Why Silverlight
Other than being delivered by Microsoft, some features of Silverlight are:
It’s FREE.
It runs on all popular browsers, platforms, and devices.
It can be run in browser and as a desktop application.
Easy to create excellent UIs that looks “WOW”.
Enables business application development.
Supports 2D/3D animations/graphics.
Natively supports CLR and .NET Framework.
Can be automated using JavaScript.
Supports a variety of media (audio/video) formats with streaming capabilities.
Supports a variety of rich controls including the DataGrid.
Supports a variety of enterprise technologies including WCF.
In addition, Silverlight is considered to be the main development framework for Windows Phone.
Figure 5 - Windows Phone
Silverlight vs. Flash
Silverlight and Flash are very similar, so which is better, Silverlight or Flash? Since I’m a Microsoft developer and since you are reading now in a .NET blog, and although I haven’t ever developed for Flash, I can say that Silverlight is the best RIA platform ever!!! However, we need to be more serious.
InfoWorld did a review and compared between Silverlight and Flash, and the results were so great, Silverlight passed Flash and scored 8.3 points, while Flash got 7.8 points only.
Figure 6 - Silverlight vs. Flash, InfoWorld
Silverlight vs. WPF
Windows Presentation Foundation (WPF) is a graphical subsystem utilizing DirectX for rendering UI in Windows-based application, developed by Microsoft and introduced as part of Microsoft .NET Framework 3.0 and Windows Vista. WPF is considered to be the replacement for WinForms (that considered now Feature-Complete,) while WinForms relies on the older GDI subsystem, WPF relies on DirectX.
On the other hand, Silverlight is actually a subset of WPF, and formerly Silverlight was codenamed WPF/E (WPF/Everywhere) because it’s considered to be the cross-platform version of WPF. And while WPF focuses on desktop development, Silverlight focuses on Web development.
Figure 7 - Silverlight vs. WPF
Rich vs. Reach
The following diagram compares some of the available Web development technologies in terms of richness (i.e. UI functionalities) and reach (platform and browser support.)
Figure 8 - Rich vs. Reach
From the above diagram we can see that WPF has the best UI features today. However, it’s devoted primarily for desktop development, and it can run only on Windows platforms.
On the other hand, ASP.NET can run everywhere, but unfortunately it doesn’t support the UI functionalities required for today’s Web.
And finally, Silverlight has the best of UI functionalities, and it also supports a wide range of platforms and browsers (its platform/browser support is expanded each release.)
Showcase
To get a solid understanding of what Silverlight can do, check out some of the Silverlight applications from around the world:
Deep Earth (http://deepearth.codeplex.com)
A project utilized Bing Maps allows you to check maps and get directions.
And another great feature of Silverlight is the DeepZoom technology that was introduced by Microsoft as part of Silverlight. DeepZoom allows you to view very large high resolution images. It reduces the time of initial load by downloading only the region being viewed at the resolution it’s displayed at. Subsequent regions are downloaded as the user pans to (or zooms into) them.
Figure 9 - Deep Zoom, Microsoft Silverlight
Deep Inside
Silverlight and XAML
Like WPF, user interface in Silverlight is declared in a specific language called Extensible Markup Language (or XAML, pronounced ‘Zammel’.) XAML is an XML-based language created by Microsoft which is used to initialize structured values and objects. XAML elements are mapped directly to CLR objects (e.g. a <Button> element maps to a Button object.)
Figure 10 - XAML Logo
Former ASP.NET developers are somewhat familiar with the nature of XAML. You have a WYSIWYG XAML designer that you use to design the interface of your application. The code for this interface is available through a code-behind file, where you can write in your preferred .NET language.
The concept of two files for the same page (e.g. a XAML file for the interface and a CS file for the C# code) separates two main roles in application development, design and development. The designer can work in the XAML file, and the developer can work in the code file, and both files are linked together. This also leads to a loosely-coupled design that separates user interface code from the business logic.
Figure 11 - Designer vs. Developer
Deployment Process
What steps you would follow to deploy your Silverlight application to your users? That’s what this section is devoted for.
When you build your Silverlight application, the XAML markup, as well as the code and all other resources, is compiled into .NET assemblies which are then compressed using ZIP and stored in a XAP (.xap) file.
Figure 12 - XAP Files
The XAP file can then be hosted in a Web server and referenced by Web pages declaring the Silverlight plugin object. And when the user navigates to the page, the XAP file is downloaded to his PC and executed on the Web page by the Silverlight runtime.
Figure 13 - Silverlight Application Deployment Process
So all you need is just to develop your application, get the XAP file, insert the plugin into a Web page, and then publish the page and the XAP file to the Web.
Silverlight Architecture
The following illustration shows the essential architecture and components of Microsoft Silverlight. It shows how the presentation (interface) core components fit together with other .NET and Silverlight components, and what services does the provider offer.
Figure 14 - Silverlight Architecture
Silverlight 5
The current stable version of Silverlight is Silverlight 4. Back to PDC 2010 the 5th version of Silverlight was introduced, it’s still in Beta but it’s supposed to be released soon.
Figure 15 - Silverlight 5 Logo
Here’s a brief overview of the forthcoming Silverlight 5 features:
In the following example, we’ll create the Hello World application in Silverlight. Follow those steps:
First, ensure that Silverlight SDK is installed on your PC, and launch Visual Studio 2010 and select New Project.
Figure 18 - Creating a New Silverlight Application
From the New Project dialog, select your desired language from the left and select Silverlight as project type. From the middle pane, select Silverlight Application to start.
Now another dialog appears asks you to specify whether to create another Web application to host the Silverlight application or not. As you know, Silverlight applications run inside a plugin defined in a Web page, and that dialog asks if to create a new Web Application project for you to host the Silverlight application or to create just a simple HTML page to host it. Leave the dialog with no changes and ensure that you have selected Silverlight 4 from the Silverlight Version combo box and click OK to proceed.
Figure 19 - New Silverlight Application Settings
Now let’s have a look at what Visual Studio has created for us. Looking at the Solution Explorer we can see that Visual Studio has created two projects, one is the Silverlight project, and the other is a Web project that’s going to host this Silverlight application.
Figure 20 - Silverlight Project in Solution Explorer
Looking at the Web project we can see that VS has included two test pages in that project, the first is an ASPX page and the second is a simple HTML page, both define the Silverlight plugin and both are ready to show you your Silverlight application when you browse to them. The difference is that ASPX pages can define ASP.NET elements and code, while the simple static HTML cannot.
Back to the Silverlight application, we can see that it define 4 files:
App.xaml.cs (C# code file, linked to App.xaml):
Define the startup logic and any other application-wide code.
MainPage.xaml:
The main application page; contains the interface elements.
MainPage.xaml.cs (C# code file, linked to MainPage.cs):
The business logic and code for the main application page.
Then we have two pages, the first is App.xaml that defines the application-wide elements and code (inside App.xaml.cs,) and the second is MainPage.xaml that defines the main page of your application where you can define your interface elements and code them (inside MainPage.xaml.cs.)
Now let’s design our interface. Go to MainPage.xaml and inside the <Grid> element define a Button (you can also drag the button from the Toolbox to the designer to define it):
From the previous line of code we can see that we have defined a Button control using a <Button> element, and we have also set the control’s characteristics and properties using the element attributes. And to have our button respond to user clicks, we have wired up the Click event into the function Button_Click() that we’re going to define it in the code file.
Now go to MainPage.xaml.cs and define the Click event handler for the button:
Before we leave this section, let’s have a look over the plugin required for Silverlight. Go to and of the test pages on the Web project and step down until you reach the <object> element that defines the plugin. Simply, the Silverlight application requires only the following HTML code to define its plugin:
As you see, we have references the XAP file in the page by using the source parameter. When you build your application in Visual Studio, it will create a new folder besides the test page called ClientBin and put the XAP file inside it so you can reference it in the page.
Clear, aih?
Summary
Silverlight is a cross-platform application framework for writing and running rich Internet applications (RIA.)
Its runtime is available as a cross-browser, cross-platform, and cross-device plug-in.
It’s the main development framework for Windows Phone.
It’s a subset of WPF so it depends on XAML for UI design.
You define the interface using XAML, and write the code using your preferred .NET language.
The XAML markup, as well as the code, is compiled into .NET assemblies and compressed into a XAP file.
The XAP file is then referenced by a prepared Web page and then downloaded to client’s PC when he navigates to the page.
Version 4 is the current stable version of Silverlight.
Silverlight 5 is currently in beta and it will be released soon.
You use Visual Studio 2010 and Microsoft Expression Studio for developing and designing your Silverlight application.
Microsoft Expression Studio is preferred for you if you are a designer.
Wiki-OS is the only open-source web OS (online operating system) where anyone can contribute right away like a wiki.
It lets you:
Launch applications without installation (in a secure sandbox)
See how applications work by clicking their Edit Source button
Develop new applications right away from the browser
Start developing an application and let the community finish it
Copy/paste source code from other apps or quickly reuse components
Share applications by embedding them into web pages
Mac OS users can write C# / .NET / Silverlight applications without a PC
What’s unique about it is that it is completely user-generated and developed like Wikipedia! Every application has an “Edit” button that allow to immediately see the source code of the application (this is very useful for beginners to learn Silverlight!) and people can also modify the code by using the build-in online IDE! When someone makes a change, the changes are automatically reflected in real-time to all users! (like wikipedia)
Just Like [a] Magic 