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BCIS 4650 Visual Programming for Business Applications

BCIS 4650 Visual Programming for Business Applications

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BCIS 4650 Visual Programming for Business Applications

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  1. BCIS 4650 Visual Programming for Business Applications More Data Binding The University of North Texas, ITDS Dept., Dr. Vedder

  2. Brief Review

  3. What is the Binding Source Object? • Any object whose properties contain the value(s) that you want, or • A collection of objects The University of North Texas, ITDS Dept., Dr. Vedder

  4. Sometimes a static list • Often can be an ObservableCollection<T> • Must support INotifyPropertyChanged to update UI • Must have a Dependency Property • DP name format is always nnnProperty • Often “shortcut syntax” used • Use Path= to retrieve just a property from the source object The University of North Texas, ITDS Dept., Dr. Vedder

  5. What is the Binding Target Object? • Must be a class that have one or more dependent properties • Often children of ItemsControl class • TextBox and other textual controls The University of North Texas, ITDS Dept., Dr. Vedder

  6. Children of ItemsControl Class include • Most popular: ListView, GridView, ListBox • FlipView • ComboBox • MenuFlyoutPresenter, Selector • (Could use IC directly, but children have more custom features) The University of North Texas, ITDS Dept., Dr. Vedder

  7. Simple Binding

  8. Simple Binding Example in XAML • Source object = MyData • Source property = ColorName • Target object = Button • Target DP = Background(.Property) (Button inherits DataContext value) The University of North Texas, ITDS Dept., Dr. Vedder

  9. Different Syntaxes; Same Result • Explicitly calls path binding property • Exploits ButtonTextas Button’s default property • Uses “fully qualified” binding syntax The University of North Texas, ITDS Dept., Dr. Vedder

  10. The Path Attribute/Prop. of Bindingcommon syntax; not for XML-formatted data files • Simplest: Path=propertyname • Attached: Path=(object.property) • Indexed: Path=propertyname[n] • If source object has only one value, not necessary to use Path The University of North Texas, ITDS Dept., Dr. Vedder

  11. The XPath Attribute/Property • Use for binding to XML data files • http://msdn.microsoft.com/en-us/library/system.windows.data.binding.xpath%28v=vs.110%29.aspx The University of North Texas, ITDS Dept., Dr. Vedder

  12. FYI:Sample XML Data File ~ .JSONData File(human-formatted)

  13. List<T>ObservableCollection<T>

  14. List<T> Class (T = element type) • Is a strongly typed list of objects • Accessed by index value • Has methods to search, sort, manipulate • Is read-only; does not update UI The University of North Texas, ITDS Dept., Dr. Vedder

  15. ObservableCollection<T> (T=type) a special version of the more generic Collection<T> • Is a generic, dynamic data collection • Supports additions, deletions, updates • To use effectively in XAML, create in C# a custom collection class that inherits from ObservableCollection<T>, and then reference it in XAML The University of North Texas, ITDS Dept., Dr. Vedder

  16. Example: Data for a ListBox

  17. Displaying Data in a ListBox • Populate with XAML elements • Populate using Binding class and Path= or XPath= • Populate by setting ItemsSource dep. property to a collection of data and, if needed, setting DisplayMemberPath to the field you want retrieved The University of North Texas, ITDS Dept., Dr. Vedder

  18. 1. C#: Create a NameList Collection Class & PersonName Type NameList collection class, inherits from OC of type PersonName Defines the type as a class Constructor for the type Exposed variable Exposed variable

  19. 2. XAML: Instantiate Collection; Then Specify It as a Resource SDKSample is a custom CLR namespace defined in C# Partial class directive Use the NameList class found in the SDKSample namespace and give it the key NameListData The University of North Texas, ITDS Dept., Dr. Vedder

  20. 3. XAML: Bind the Collection • Add “Path=” above if you want just FirstName or LastName • (path example with different collection) The University of North Texas, ITDS Dept., Dr. Vedder

  21. 1. Using ItemsSource & DisplayMemberPathCustomer type class, Customers collection class Defines the type as a class with 3 exposed variables Constructor for the type Customers collection class, inherits from OC of type Customer

  22. 2. Using ItemsSource & DisplayMemberPath(retrieves Anderberg, Ashton, Hicks, Pica) ListBoxSnippetEx is a custom CLR namespace defined in C# Use the Customers class inside ListBoxSnippetExnamespace and give it the key customers The University of North Texas, ITDS Dept., Dr. Vedder

  23. Monitoring Collection Changes • The ObservableCollection<T> class implements INotifyCollectionChangedinterface. • This exposes a CollectionChanged event that you can use when the custom collection class values change. The University of North Texas, ITDS Dept., Dr. Vedder

  24. Data Templates

  25. Data Templates • Specify the presentation or visual structure of associated data objects • Used often when binding items, ex., a ListBox to a collection of data objects • Can be written individually, or as a shared resource • Use data binding to adapt a data template to the needs of each element The University of North Texas, ITDS Dept., Dr. Vedder

  26. Data Templates ≠ Control Templates • Control template: defines look and some behavior of a control, including control state behavior (focus, hover, …) • Data template: defines look for a specific property of a control; far more atomic The University of North Texas, ITDS Dept., Dr. Vedder

  27. ListBox Without a Data Templateabbreviated example; see http://msdn.microsoft.com/en-us/library/ms742521%28v=vs.110%29.aspx The University of North Texas, ITDS Dept., Dr. Vedder

  28. ListBox with a DataTemplateabbreviated example; see http://msdn.microsoft.com/en-us/library/ms742521%28v=vs.110%29.aspx

  29. Some Other Data Template Examples(same source as before) The University of North Texas, ITDS Dept., Dr. Vedder

  30. ITDS Logo / Mood Slide The University of North Texas, ITDS Dept., Dr. Vedder