Lập trình .net 4.0 và visual studio 2010 part 59 pptx

CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 387 • Many changes to API and refactoring of XamlSchemaContext for performance improvements • System.Xaml.dll no longer has a dependency on WindowsBase.dll • The same XAML stack is utilized by WCF, WF, and WPF • Performance optimizations in Baml2006Reader class • New class XamlXmlReader • Improved localization support • Baml2006Writer class might be available with this release, which could potentially allow the obfuscation of BAML Silverlight 3.0 Silverlight developers are in for a treat with the latest version of Silverlight which offers the ability to run your applications offline, deep linking for content and much more.  NOTE This chapter assumes a basic knowledge of Silverlight and WPF. If you haven’t used Silverlight before you might want to take a look at Chapter 14 where I introduce Silverlight. Upgrading from Silverlight 2 Before you look at the new changes in Silverlight 3.0, note that upgrading can potentially break existing applications. This URL lists breaking changes: http://msdn.microsoft.com/en- us/library/cc645049(VS.95).aspx. And this URL provides guidance on how to upgrade your Silverlight 2.0 applications: http://msdn.microsoft.com/en-us/library/cc645049(VS.95).aspx. Offline Applications Probably the best feature of Silverlight 3.0 is the ability it offers to run your applications offline. Offline Silverlight applications run with the same permissions as their web counterparts, so they do not require additional permissions to install. Offline applications also work on both PC and Mac platforms, providing a very easy way to create cross-platform .NET applications. Creating an Offline Application To enable your Silverlight applications to run offline is very easy and involves making a simple change to the AppManifest file. Try it now: 1. Create a new Silverlight application called Chapter15.Offline. 2. Add some content (e.g., an image). CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 388 3. Open the project properties (see Figure 15-22). Figure 15-22. Enabling offline application in project properties 4. Check the box marked “Enable running application outside of browser”. 5. Click the Out-of-Browser Settings button and note that you can set properties such as images, window size, and application title. 6. Press F5 to run your Silverlight project and then right-click the Silverlight app. The Silverlight menu will open up. 7. Select the “Install Chapter15.Offline Application onto this computer” option (see Figure 15-23). CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 389 Figure 15-23. Installing a Silverlight application onto the computer 8. Silverlight will then ask you to confirm where you want to place shortcuts to your application: Start menu and/or Desktop (see Figure 15-24). Figure 15-24. Offline Silverlight application 9. Check both the Start menu and Desktop options. 10. Close the browser. 11. Now click one of the short cuts that has been created, and your application will load up running offline (see Figure 15-25): CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 390 Figure 15-25. Running a silverlight app offline Uninstalling Offline Silverlight Applications If you want to uninstall an offline Silverlight application, simply right-click the window when it is running locally and select the “Remove this application” option. Detaching Manually You probably don’t want to explain these steps to end users, so the Silverlight API contains an Application.Current.Install()method that performs the same functionality. Application.Current.Install() method returns a Boolean value indicating whether the detachment was possible or not. Retrieving Attachment State To query whether your application is running online in a browser or detached, use the Application.Current.IsRunningOutOfBrowser method. CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 391 Detecting Connection Status Now that you have the ability to run applications offline, it is very useful to be able to determine whether the user is connected to the Internet. This can be accomplished through the GetIsNetworkAvailable method that returns true if the user is connected: System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable()  CAUTION If the user has chosen to work in offline mode, this method will still return true. You also have the ability to monitor network address changes through the NetworkAddressChanged event: System.Net.NetworkInformation.NetworkChange.NetworkAddressChanged() Autoupdate When offline applications are run, Silverlight automatically checks to see whether a later version is available. If it is, it is downloaded. Deep Linking and Browser History A major problem with Silverlight applications is that you cannot directly link to content within the application in the same way you can with web pages. This makes it difficult for users to share or bookmark content and makes search engine indexing impossible. Silverlight 3.0 attempts to solve this issue by making use of HTML bookmark syntax in your application's URL. Navigation Application Navigation Application is a new type of project in Silverlight 3.0. If you say Navigation Application quickly it sounds like gangsta rap, argued Silverlight MVP Chris Hay, and he was right. But that doesn’t have much to do with anything, so let’s take a look at Navigation Application now: 1. Create a new Silverlight Navigation Application project called Chapter15.NavigationApplication. 2. Press F5 to run the application and you will see the default Navigation Application project (see Figure 15-26). 3. Click the about button and notice how the URL changes to something similar to this: http://localhost:51951/Chapter15.NavigationApplicationTestPage.aspx#/About You can use this URL to refer directly to the about pagetry navigating to a different page and then pasting the URL into the address bar. This new URL format allows the browser to maintain a history of pages the user navigated through, which means the back and forward browser buttons can be used to move around your applications. CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 392 Figure 15-26. Default Navigation Application Local Connections Some page designs utilize two separate Silverlight controls and need a way to pass information between them. Previously, this could only be accomplished using the HTML DOM methods. Silverlight 3.0 makes this much easier with the local connection API. Let’s create a simple example and send some text from one Silverlight control to another: 1. Open Visual Studio and create a new Silverlight application called Chapter15.Sender. 2. Add another Silverlight application to the solution called Chapter15.Receiver (opt not to create another web hosting project). 3. Open Chapter15.SenderTestPage.aspx. 4. You want to display the Chapter15.Receiver project on the same page, so add another Silverlight control beneath the existing one by copying the object block and modifying the source parameter to display the Chapter15.Receiver project.xap file: <object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%"> <param name="source" value="ClientBin/Chapter15.Receiver.xap"/> <param name="onError" value="onSilverlightError" /> <param name="background" value="white" /> CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 393 <param name="minRuntimeVersion" value="3.0.40818.0" /> <param name="autoUpgrade" value="true" /> <a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=3.0.40818.0" style="text-decoration:none"> <img "http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style:none"/> </a> </object> 5. Open MainPage.xaml in the sender project and add a button with the following XAML: <Button x:Name="cmdSendMessage" Content="Send Message" Width="200" Height="200"></Button> 6. Open MainPage.xaml.cs in the sender project and import the following namespace: using System.Windows.Messaging; 7. Amend the code in MainMenu.xaml.cs to the following: public partial class MainPage : UserControl { LocalMessageSender Channel1 = new LocalMessageSender("Channel1"); public MainPage() { this.Loaded += new RoutedEventHandler(MainPage_Loaded); Channel1.SendCompleted += new EventHandler<SendCompletedEventArgs>(Channel1_SendCompleted); InitializeComponent(); } void Channel1_SendCompleted(object sender, SendCompletedEventArgs e) { //Code to run after message is sent } void MainPage_Loaded(object sender, RoutedEventArgs e) { this.cmdSendMessage.Click += new RoutedEventHandler(cmdSendMessage_Click); } void cmdSendMessage_Click(object sender, RoutedEventArgs e) { Channel1.SendAsync("Hello from sender project"); } } 8. Open the receiver project MainPage.xaml and add a text box to display the received messages: <TextBlock>Received messages:</TextBlock> <TextBox x:Name="txtMessage"></TextBox> CHAPTER 15  WPF 4.0 AND SILVERLIGHT 3.0 394 9. You now need to add code to receive the messages and update the text box with the messages you have received. To receive messages, handle the MessageReceived event on an instance of LocalMessageReceiver. Open MainPage.xaml.cs in the receiver project and import the following namespace: using System.Windows.Messaging; 10. Amend MainPage.xaml.cs to the following: public partial class MainPage : UserControl { LocalMessageReceiver Channel1Receiver = new LocalMessageReceiver("Channel1"); public MainPage() { Channel1Receiver.MessageReceived += new EventHandler<MessageReceivedEventArgs>(Channel1Receiver_MessageReceived); Channel1Receiver.Listen(); InitializeComponent(); } void Channel1Receiver_MessageReceived(object sender, MessageReceivedEventArgs e) { txtMessage.Text="" + e.Message.ToString(); } }  NOTE The LocalMessageReceiver constructor sets the parameter to Channel1 (the same channel that messages are being sent on). 11. Press F5 to run the project. 12. Click the Send Message button. A message should then be sent using the local connection API and the results displayed in the text box in the receive project. Styles Styles in Silverlight 3.0 can now be modified at runtime and support inheritance. Applying Styles Dynamically The following code shows how to apply a style to a button at runtime: myButton.Style=(Style)Application.Current.Resources["MyHorridFuciaStyle"]; . http://msdn.microsoft.com/en- us/library/cc 645 04 9 (VS.95).aspx. And this URL provides guidance on how to upgrade your Silverlight 2 .0 applications: http://msdn.microsoft.com/en-us/library/cc 645 04 9 (VS.95).aspx. Offline. value="white" /> CHAPTER 15  WPF 4. 0 AND SILVERLIGHT 3 .0 393 <param name="minRuntimeVersion" value="3 .0 . 40 818 .0& quot; /> <param name="autoUpgrade". true. You also have the ability to monitor network address changes through the NetworkAddressChanged event: System .Net. NetworkInformation.NetworkChange.NetworkAddressChanged() Autoupdate When