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Silverlight 5 Essential Training
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Understanding event bubbling


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Silverlight 5 Essential Training

with Walt Ritscher

Video: Understanding event bubbling

You can define a routed EventHandler in any element in the Element tree. When an event fires, it starts on the original element and traverses the element tree looking for EventHandlers. Each handler encountered on the way to the root element is called in sequence. I am going to demonstrate that by using a project called EventBubbling. I am going to start by using this file, WatchTheBubbling. I will double-click on this file and show you my UI. I have a dice prototype here that is composed of a number of children elements.
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  1. 1m 41s
    1. Welcome
      53s
    2. Using the exercise files
      48s
  2. 35m 0s
    1. Overview of Silverlight
      3m 29s
    2. Setting up a developer computer
      2m 46s
    3. Installing the Silverlight Toolkit
      2m 21s
    4. Exploring the toolkit samples
      2m 35s
    5. Using Visual Studio 2010 to create a Silverlight project
      5m 10s
    6. Using Expression Blend to create a Silverlight project
      3m 13s
    7. Getting to know the Visual Studio interface
      8m 15s
    8. Working in the Expression Blend interface
      7m 11s
  3. 29m 46s
    1. Understanding the Visual Studio project structure
      3m 38s
    2. Creating a Silverlight page
      3m 17s
    3. Compiling your first application
      5m 0s
    4. Using other assemblies in an application
      5m 45s
    5. Deploying a Silverlight application
      3m 43s
    6. Understanding the startup process for an application
      3m 13s
    7. Understanding how users get Silverlight on their computers
      5m 10s
  4. 16m 59s
    1. Exploring the relationship between XAML and .NET
      3m 57s
    2. Using C#
      7m 16s
    3. Exploring the code-behind file
      5m 46s
  5. 43m 22s
    1. Working with XAML elements and Property attributes
      4m 56s
    2. Investigating XAML namespaces
      7m 31s
    3. Converting XAML properties with TypeConverters
      5m 1s
    4. Working with Property elements
      4m 24s
    5. Assigning runtime data with XAML markup extensions
      4m 21s
    6. Digging into the dependency property system
      6m 12s
    7. Creating a custom dependency property
      4m 42s
    8. Understanding attached properties
      6m 15s
  6. 9m 35s
    1. Debugging your code
      5m 17s
    2. Special Silverlight debugging techniques
      4m 18s
  7. 36m 0s
    1. Understanding layout
      4m 55s
    2. Using DockPanel and WrapPanel
      4m 2s
    3. Exploring sophisticated layouts with the Grid
      6m 40s
    4. Absolute positioning with the Canvas panel
      5m 20s
    5. Scrolling content with the ScrollViewer
      3m 28s
    6. Adjusting content alignment, margins, and sizing
      5m 6s
    7. Using the TabControl
      2m 17s
    8. Manipulating elements with transforms
      4m 12s
  8. 20m 32s
    1. Painting the user interface (UI) with SolidColorBrush
      6m 7s
    2. Getting colorful with gradient brushes
      3m 15s
    3. Decorating elements with ImageBrush
      4m 56s
    4. Creating effects with VideoBrush
      6m 14s
  9. 25m 42s
    1. Understanding routed events
      3m 12s
    2. Wiring up event handlers in Silverlight
      6m 4s
    3. Understanding event bubbling
      4m 39s
    4. Exploring mouse events
      7m 43s
    5. Exploring keyboard events
      4m 4s
  10. 32m 31s
    1. Displaying text on the screen
      3m 24s
    2. Gathering text input from the user
      5m 30s
    3. Showing complex text with RichTextBox
      6m 7s
    4. Understanding text overflow and text linking
      3m 14s
    5. Searching content with the AutoComplete type-ahead control
      6m 45s
    6. Using and embedding Silverlight fonts
      7m 31s
  11. 26m 47s
    1. Understanding content controls
      5m 7s
    2. Understanding button controls
      6m 16s
    3. Using the BusyIndicator
      4m 40s
    4. Showing tooltips
      4m 34s
    5. Changing content size with ViewBox
      1m 39s
    6. Exploring more controls
      4m 31s
  12. 55m 36s
    1. Connecting elements with binding
      9m 54s
    2. Using business data in a binding
      9m 21s
    3. Listing data with ItemsControls
      6m 39s
    4. Digging into the DataGrid
      8m 28s
    5. Using the DataForm
      3m 49s
    6. Storing data on the client
      7m 10s
    7. Debugging XAML bindings
      5m 41s
    8. Charting data
      4m 34s
  13. 24m 36s
    1. Creating an Out-of-Browser (OOB) application
      6m 16s
    2. Controlling aspects of an OOB application
      2m 49s
    3. Alerting the user with notification windows
      7m 13s
    4. Hosting HTML content in Silverlight applications
      8m 18s
  14. 30m 2s
    1. Exploring Silverlight trust levels
      3m 51s
    2. Creating an elevated trust application
      5m 57s
    3. Reaping the benefits of XAP signing
      6m 5s
    4. Making cross-domain calls
      5m 1s
    5. Getting started with COM Interop using the Speech API
      4m 21s
    6. Using COM Interop to interact with Microsoft Office
      4m 47s
  15. 16m 33s
    1. Showing child windows
      3m 48s
    2. Using a child window as a dialog window
      5m 7s
    3. Creating native windows
      2m 53s
    4. Maximizing a window with full screen mode
      4m 45s
  16. 13m 20s
    1. Dynamically loading UI content with user controls
      4m 46s
    2. Using the Navigation Framework
      8m 34s
  17. 9m 28s
    1. Using resource files
      3m 53s
    2. Using images in an application
      5m 35s
  18. 16m 32s
    1. Playing audio
      4m 27s
    2. Playing sound effects
      5m 4s
    3. Viewing video content with MediaElement
      4m 58s
    4. Changing video playback speed with TrickPlay
      2m 3s
  19. 14m 40s
    1. Capturing video with a web camera
      4m 16s
    2. Working with a microphone
      3m 47s
    3. Creating print output
      6m 37s
  20. 22m 35s
    1. Understanding Silverlight animations
      4m 35s
    2. Creating animations
      7m 52s
    3. Controlling animations
      4m 18s
    4. Simulating physics with animation easings
      5m 50s
  21. 27m 47s
    1. Placing XAML resources within a FrameworkElement
      6m 47s
    2. Centralizing settings in styles
      4m 8s
    3. Creating an alternate control UI with ControlTemplates
      6m 29s
    4. Dressing up your data with DataTemplates
      4m 33s
    5. Explaining the VisualStateManager: a simple way to manage control states
      5m 50s
  22. 10m 55s
    1. Handling global errors in a Silverlight application
      5m 46s
    2. Showing an application loading screen
      5m 9s
  23. 10m 48s
    1. Integrating with XNA
      7m 40s
    2. Exploring data analysis with PivotViewer
      3m 8s
  24. 1m 6s
    1. Goodbye
      1m 6s

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Silverlight 5 Essential Training
8h 51m Beginner Mar 27, 2012

Viewers: in countries Watching now:

Microsoft Silverlight 5 is a rich application framework for creating high-performance, cross-platform desktop and mobile applications. In this course, author Walt Ritscher demonstrates how to build a variety of applications in Silverlight, with particular focus on building compelling business applications and delivering premium video and audio content. Developers will work with the C# programming language and Visual Studio Professional, as well as Expression Blend, a tool that simplifies creation of the interactive user interfaces expected in modern-day applications.

Topics include:
  • Installing the toolkit and setting up the development environment
  • Using Expression Blend vs. Visual Studio 2010
  • Creating a Silverlight page
  • Compiling an application
  • Exploring the relationship between XAML and .NET
  • Using C#
  • Working with XAML
  • Digging into the Dependency Property System
  • Deploying and debugging code
  • Creating sophisticated layouts with panel elements
  • Managing Visual State with Visual State Manager
  • Transforming the user interface (UI) with templates
  • Understanding the event model
  • Working with text
  • Using business data in a binding
  • Creating an out-of-browser (OOB) application
  • Exploring trust levels
  • Playing audio and video
  • Handling errors
  • Exploring animations
  • Working with application windows
  • Integration with XNA
Subject:
Developer
Software:
Silverlight Visual Studio
Author:
Walt Ritscher

Understanding event bubbling

You can define a routed EventHandler in any element in the Element tree. When an event fires, it starts on the original element and traverses the element tree looking for EventHandlers. Each handler encountered on the way to the root element is called in sequence. I am going to demonstrate that by using a project called EventBubbling. I am going to start by using this file, WatchTheBubbling. I will double-click on this file and show you my UI. I have a dice prototype here that is composed of a number of children elements.

For instance, there is a Rectangle, the name of the rectangle is called diceBody. That is a child of a canvas and the canvas is called diceCanvas. There are also some ellipses and each one of these ellipses is called pip 1, pip 2 and so on. So the ellipse is a child of the canvas and the rectangle is the child of the canvas. Let's switch to the code view. Over here I wired up the MouseLeftButtonDown EventHandler to the root element which is my user control and then also to my diceCanvas, my diceBody and all of the pips.

What this allows me to do is watch the events as they bubble up the tree. I need to go to App.xaml.cs and change my startup root. I am going to uncomment line 26; Ctrl+K, Ctrl+U. We need to press F5 to run the application, I will click on this center pip and you see that I had the Sender pip sent an event and so did the diceCanvas. Now I am going to click on the Rectangle and you see that the diceBody fired an event and so did the dice canvas.

So they are both firing the event. While I am in this window, I might as well change to my next demo. So I am going to comment out this line and uncomment Line 27. Now I am going to move to this BubbleToRoot. This is the same dice UI I showed you in the last one, look at the events and the code behind. What I am doing here is I am going to get the diceCanvas and I am setting up a MouseLeftButtonDown handler and they are not setting up any handlers for any of the children.

Then inside this MouseLeftButtonDown handler, I am going to use the MouseButtonEventArgs to get some information about the original sender. I am doing that here on line 30. I declare a variable called original and I get the original source from the EventArg and I cast it to a FrameworkElement. Once I've done that, I can then call original.Name to get the name of the original element. I'm also going to output the sender. The sender is the root element that I am clicking on.

Let's watch this one and press F5. I will click on the center pip and you are going to see that it says the sender was the canvas, that's the parent, and the Original node was pip 3. Now I am going to click on this pip and you see it again, it's the original, this pip 1, and the sender is the canvas. Want to guess what's going to happen when I click on the rectangle? The sender is still the canvas, but now the original is the rectangle, which is called diceBody.

For my third demo, I am going to show you how you can suppress the event. As it's bubbling up the tree, any handler can say stop here, don't let it go any higher than this level. I'll switch to SuppressingEvents, switch to the code behind, and in here, I've set up a number of Event Handlers; one at the LayoutRoot level; each one of the pips have one; and so does the Body and the Canvas. On my UI, I have a checkbox down here that says Stop Bubbling at diceCanvas.

So my code is checking whether that's checked or not. So at the canvas level, when the canvas event fires, I check to see if the checkbox is checked and here's where I stop the bubbling. By setting e.Handled = true, it will never get to the root element of this user control. Let's try this. Go to App.xaml.cs and change my startup, press F5, click on this center pip, there are three events firing; Canvas, Grid level, and Pips. And then I am going to click on stop the bubbling at the canvas and I will click on the same pip again and this time, you see that it didn't make it up to the grid.

It only made it to the canvas, it was stopped at the canvas level. But I have shown you is that event bubbling allows you to capture events in a simple way at the parent level.

Find answers to the most frequently asked questions about Silverlight 5 Essential Training.


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Q: I'm trying to access a Silverlight 3D application template, [cid:image001.png@01CD0E7D.3E07ECA0]. I have already installed the Silverlight 5 SDK and my Visual Studio 2010 is professional. Could you please help me?
A: You must install XNA Studio in order to use the new Silverlight 3D templates. Otherwise the new templates will not show up. Download it at http://www.microsoft.com/download/en/details.aspx?id=23714.

For other Silverlight downloads (the toolkit, developer runtime, etc.), see http://www.silverlight.net/downloads.
 
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