tailieunhanh - Flash Builder 4 and Flex 4 Bible- P11

Flash Builder 4 and Flex 4 Bible- P11: When Macromedia first released Flash MX in 2002, the product was branded as the new way to build Rich Internet Applications (known by the acronym RIA). The term was invented at Macromedia to describe a new class of applications that would offer the benefits of being connected to the Internet, including access to various types of Web-based services, but would solve many of the nagging issues that had been inherent in browser-based applications since the mid-1990s | Chapter 16 Managing Application Navigation recalculated and rendered anew on each visit to the page. The browser offers caching of image and other assets to speed up this process but graphical presentation in a Web page is necessarily limited. HTML and JavaScript aren t interpreted identically by every Web browser. In fact one of the most costly and time-consuming aspects of classic Web application development is testing because you must test your application on each combination of operating system browser and version that you want to support. Some Web application vendors handle this issue by limiting the platforms on which an application is supported. For example Intuit s QuickBooks Online while a powerful and reliable Web application is supported only on Microsoft Internet Explorer on Windows and Safari on Mac no Firefox users allowed Understanding Flex Navigation Navigation in Flex applications is handled at two levels with navigator containers and view states. The difference between these strategies can be described as one of the amount of visual change during a move from one presentation to another Navigator containers. Use these when you want to replace a rectangular region of a Flex application a view with a completely different visual presentation. View states. Use these when you want to modify an existing view by adding or removing visual components or by changing components properties styles or event listeners. In some cases either a navigator container or a view state can get the job done but for the most part the choice is clear Use a navigator container to move from one view to another and use a view state to change an existing view. Cross-Reference Detailed information about view states is available in Chapter 13. Using Navigator Containers You create a stack of views using one of the navigator containers provided in the Flex framework. The ViewStack class is the simplest of these navigator containers. You declare the ViewStack container as a parent .