IEditableCollectionViewAddNewItem Interface
Definição
Importante
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Define os métodos e propriedades que um CollectionView implementa para habilitar a especificação de adição de itens de um tipo específico.
public interface class IEditableCollectionViewAddNewItem : System::ComponentModel::IEditableCollectionViewpublic interface IEditableCollectionViewAddNewItem : System.ComponentModel.IEditableCollectionViewtype IEditableCollectionViewAddNewItem = interface
interface IEditableCollectionViewPublic Interface IEditableCollectionViewAddNewItem
Implements IEditableCollectionView- Derivado
- Implementações
Exemplos
O exemplo a seguir permite que um usuário adicione vários tipos de itens a uma coleção. O usuário pode inserir um novo item e enviar a entrada ou cancelar a transação. O exemplo obtém um IEditableCollectionViewAddNewItem da Items propriedade de um ListBox e cria um objeto , cujo tipo é determinado pelo usuário. Em seguida, o exemplo chama o AddNewItem método para adicionar o objeto à coleção.
using System;
using System.ComponentModel;
using System.Windows;
namespace IEditableCollectionViewAddItemExample
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
IEditableCollectionViewAddNewItem viewToAddDisparateItems =
catalogList.Items as IEditableCollectionViewAddNewItem;
if (!viewToAddDisparateItems.CanAddNewItem)
{
MessageBox.Show("You cannot add items to the list.");
return;
}
// Create a window that prompts the user to enter a new
// item to sell.
AddItemWindow win = new AddItemWindow();
// Create an item, depending on which RadioButton is selected.
// Radio buttons correspond to book, cd, dvd, or other.
LibraryItem newItem;
if ((bool)book.IsChecked)
{
newItem = new Book("Enter the book title", "Enter an Author", "Enter a Genre",
"Enter a call number", DateTime.Now + new TimeSpan(21, 0, 0, 0));
}
else if ((bool)cd.IsChecked)
{
newItem = new MusicCD("Enter the Album", "Enter the artist", 0, "CD.******",
DateTime.Now + new TimeSpan(14, 0, 0, 0));
}
else if ((bool)dvd.IsChecked)
{
newItem = new MovieDVD("Enter the movie title", "Enter the director",
"Enter the genre", new TimeSpan(), "DVD.******",
DateTime.Now + new TimeSpan(7, 0, 0, 0));
}
else
{
newItem = new LibraryItem("Enter the title", "Enter the call number",
DateTime.Now + new TimeSpan(14, 0, 0, 0));
}
// Add the new item to the collection by calling
// IEditableCollectionViewAddNewItem.AddNewItem.
// Set the DataContext of the AddItemWindow to the
// returned item.
win.DataContext = viewToAddDisparateItems.AddNewItem(newItem);
// If the user submits the new item, commit the new
// object to the collection. If the user cancels
// adding the new item, discard the new item.
if ((bool)win.ShowDialog())
{
viewToAddDisparateItems.CommitNew();
}
else
{
viewToAddDisparateItems.CancelNew();
}
}
}
}
Imports System.ComponentModel
Imports System.Windows
Partial Class Window1
Public Sub New()
InitializeComponent()
End Sub
Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
Dim viewToAddDisparateItems As IEditableCollectionViewAddNewItem =
TryCast(catalogList.Items, IEditableCollectionViewAddNewItem)
If Not viewToAddDisparateItems.CanAddNewItem Then
MessageBox.Show("You cannot add items to the list.")
Exit Sub
End If
' Create a window that prompts the user to enter a new
' item to sell.
Dim win As New AddItemWindow()
' Create an item, depending on which RadioButton is selected.
' Radio buttons correspond to book, cd, dvd, or other.
Dim newItem As LibraryItem
If CBool(Book.IsChecked) Then
newItem = New Book("Enter the book title", "Enter an Author",
"Enter a Genre", "Enter a call number",
DateTime.Now + New TimeSpan(21, 0, 0, 0))
ElseIf CBool(cd.IsChecked) Then
newItem = New MusicCD("Enter the Album", "Enter the artist",
0, "CD.******", DateTime.Now + New TimeSpan(14, 0, 0, 0))
ElseIf CBool(dvd.IsChecked) Then
newItem = New MovieDVD("Enter the movie title",
"Enter the director", "Enter the genre", New TimeSpan(),
"DVD.******", DateTime.Now + New TimeSpan(7, 0, 0, 0))
Else
newItem = New LibraryItem("Enter the title",
"Enter the call number",
DateTime.Now + New TimeSpan(14, 0, 0, 0))
End If
' Add the new item to the collection by calling
' IEditableCollectionViewAddNewItem.AddNewItem.
' Set the DataContext of the AddItemWindow to the
' returned item.
win.DataContext = viewToAddDisparateItems.AddNewItem(newItem)
' If the user submits the new item, commit the new
' object to the collection. If the user cancels
' adding the new item, discard the new item.
If CBool(win.ShowDialog()) Then
viewToAddDisparateItems.CommitNew()
Else
viewToAddDisparateItems.CancelNew()
End If
End Sub
End Class
O exemplo a seguir cria a interface do usuário para o exemplo anterior.
<StackPanel xmlns:src="clr-namespace:IEditableCollectionViewAddItemExample">
<StackPanel.Resources>
<src:LibraryCatalog x:Key="catalog"/>
<!--Use AlternationConverter to create alternating background brushes
to better distinguish each item. See AlternationConverter
for more information.-->
<AlternationConverter x:Key="BackgroundConverter">
<SolidColorBrush>LightBlue</SolidColorBrush>
<SolidColorBrush>LightGray</SolidColorBrush>
</AlternationConverter>
<!--The DataTemplate for LibraryItem, which is the base class
of the other data types.-->
<DataTemplate DataType="{x:Type src:LibraryItem}">
<StackPanel>
<TextBlock FontWeight="Bold">Item:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
<!--The DataTemplate for Book.-->
<DataTemplate DataType="{x:Type src:Book}">
<StackPanel>
<TextBlock FontWeight="Bold">Book:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Author: {0} Genre: {1}">
<Binding Path="Author"/>
<Binding Path="Genre"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
<!--The DataTemplate for MusicCD.-->
<DataTemplate DataType="{x:Type src:MusicCD}">
<StackPanel>
<TextBlock FontWeight="Bold">Music CD:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Artist: {0} Tracks: {1}">
<Binding Path="Artist"/>
<Binding Path="NumberOfTracks"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
<!--The DataTemplate for MovieDVD-->
<DataTemplate DataType="{x:Type src:MovieDVD}">
<StackPanel>
<TextBlock FontWeight="Bold">Movie DVD:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Director: {0} Genre: {1} Length: {2}">
<Binding Path="Director"/>
<Binding Path="Genre"/>
<Binding Path="Length"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
</StackPanel.Resources>
<!--Bind a ListBox to a collection of LibraryItem objects. The collection
can hold objects any type that inherits from LibraryItem.-->
<ListBox Name="catalogList" Height="350" AlternationCount="2"
ItemsSource="{StaticResource catalog}">
<!--Use alternating background styles to better distinguish each item.
See ItemsControl.AlternationIndex for more information.-->
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="Background"
Value="{Binding RelativeSource={RelativeSource Self},
Path=(ItemsControl.AlternationIndex),
Converter={StaticResource BackgroundConverter}}"/>
<Setter Property="Margin" Value="3"/>
</Style>
</ListBox.ItemContainerStyle>
</ListBox>
<!--Enable the user to choose a type of item to add to the collection.-->
<TextBlock>Select an item to add:</TextBlock>
<RadioButton Name="book" >Book</RadioButton>
<RadioButton Name="cd">Music CD</RadioButton>
<RadioButton Name="dvd">DVD</RadioButton>
<RadioButton>Other</RadioButton>
<Button Margin="0,3,0,0" Click="Button_Click">Add Item</Button>
</StackPanel>
O exemplo a seguir cria o AddItemWindow no qual o usuário adiciona dados para um novo item.
<StackPanel Margin="10" Width="250">
<StackPanel.Resources>
<!--Add an event handler to select all text when
a TextBox gets focus.-->
<Style TargetType="TextBox">
<EventSetter Event="GotFocus" Handler="TextBoxFocus"/>
</Style>
<!--Create a Template for HeaderedContentControl so the header is
to the left of the content.-->
<Style TargetType="HeaderedContentControl">
<Setter Property="Margin" Value="2"/>
<Setter Property="Focusable" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="HeaderedContentControl">
<DockPanel LastChildFill="False">
<ContentPresenter ContentSource="Header" DockPanel.Dock="Left"
Focusable="False" VerticalAlignment="Center"/>
<ContentPresenter ContentSource="Content" Margin="5,0,0,0"
DockPanel.Dock="Right" VerticalAlignment="Center"/>
</DockPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="Button">
<Setter Property="Width" Value="100"/>
<Setter Property="Margin" Value="10,15,15,15"/>
</Style>
<!--The DataTemplate that is used when the user
enters a new LibraryItem.-->
<DataTemplate DataType="{x:Type src:LibraryItem}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}">
</TextBox>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
<!--The DataTemplate that is used when the user
enters a new Book.-->
<DataTemplate DataType="{x:Type src:Book}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Author">
<TextBox Width="150" Text="{Binding Path=Author, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Genre">
<TextBox Width="150" Text="{Binding Path=Genre, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
<!--The DataTemplate that is used when the user
enters a new MusicCD.-->
<DataTemplate DataType="{x:Type src:MusicCD}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Artist">
<TextBox Width="150" Text="{Binding Path=Artist, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Tracks">
<TextBox Width="150" Text="{Binding Path=NumberOfTracks, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
<!--The DataTemplate that is used when the user
enters a new MovieDVD.-->
<DataTemplate DataType="{x:Type src:MovieDVD}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Director">
<TextBox Width="150" Text="{Binding Path=Director, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Length">
<TextBox Width="150" Text="{Binding Path=Length, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Genre">
<TextBox Width="150" Text="{Binding Path=Genre, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
</StackPanel.Resources>
<!--One of the DataTemplates that defined above
is used by this ContentControl when the window is created.-->
<ContentControl Content="{Binding}" />
<StackPanel Orientation="Horizontal">
<Button IsDefault="True" Click="Submit_Click">_Submit</Button>
<Button IsCancel="True">_Cancel</Button>
</StackPanel>
</StackPanel>
O exemplo a seguir mostra a lógica do AddItemWindow.
using System.Windows;
using System.Windows.Controls;
namespace IEditableCollectionViewAddItemExample
{
public partial class AddItemWindow : Window
{
public AddItemWindow()
{
InitializeComponent();
}
private void Submit_Click(object sender, RoutedEventArgs e)
{
DialogResult = true;
Close();
}
// Select all text when the TextBox gets focus.
private void TextBoxFocus(object sender, RoutedEventArgs e)
{
TextBox tbx = sender as TextBox;
tbx.SelectAll();
}
}
}
Imports System.Windows
Imports System.Windows.Controls
Partial Public Class AddItemWindow
Inherits Window
Public Sub New()
InitializeComponent()
End Sub
Private Sub Submit_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
DialogResult = True
Close()
End Sub
' Select all text when the TextBox gets focus.
Private Sub TextBoxFocus(ByVal sender As Object, ByVal e As RoutedEventArgs)
Dim tbx As TextBox = TryCast(sender, TextBox)
tbx.SelectAll()
End Sub
End Class
O exemplo a seguir mostra os tipos de dados e a coleção usados nos exemplos anteriores.
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
namespace IEditableCollectionViewAddItemExample
{
// LibraryItem implements INotifyPropertyChanged so that the
// application is notified when a property changes. It
// implements IEditableObject so that pending changes can be discarded.
public class LibraryItem : INotifyPropertyChanged, IEditableObject
{
struct ItemData
{
internal string Title;
internal string CallNumber;
internal DateTime DueDate;
}
ItemData copyData;
ItemData currentData;
public LibraryItem(string title, string callNum, DateTime dueDate)
{
Title = title;
CallNumber = callNum;
DueDate = dueDate;
}
public override string ToString()
{
return String.Format("{0}, {1:c}, {2:D}", Title, CallNumber, DueDate);
}
public string Title
{
get { return currentData.Title; }
set
{
if (currentData.Title != value)
{
currentData.Title = value;
NotifyPropertyChanged("Title");
}
}
}
public string CallNumber
{
get { return currentData.CallNumber; }
set
{
if (currentData.CallNumber != value)
{
currentData.CallNumber = value;
NotifyPropertyChanged("CallNumber");
}
}
}
public DateTime DueDate
{
get { return currentData.DueDate; }
set
{
if (value != currentData.DueDate)
{
currentData.DueDate = value;
NotifyPropertyChanged("DueDate");
}
}
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
#endregion
#region IEditableObject Members
public virtual void BeginEdit()
{
copyData = currentData;
}
public virtual void CancelEdit()
{
currentData = copyData;
NotifyPropertyChanged("");
}
public virtual void EndEdit()
{
copyData = new ItemData();
}
#endregion
}
public class MusicCD : LibraryItem
{
private struct MusicData
{
internal int SongNumber;
internal string Artist;
}
MusicData copyData;
MusicData currentData;
public MusicCD(string title, string artist, int songNum, string callNum, DateTime dueDate)
: base(title, callNum, dueDate)
{
currentData.SongNumber = songNum;
currentData.Artist = artist;
}
public string Artist
{
get { return currentData.Artist; }
set
{
if (value != currentData.Artist)
{
currentData.Artist = value;
NotifyPropertyChanged("Artist");
}
}
}
public int NumberOfTracks
{
get { return currentData.SongNumber; }
set
{
if (value != currentData.SongNumber)
{
currentData.SongNumber = value;
NotifyPropertyChanged("NumberOfTracks");
}
}
}
public override void BeginEdit()
{
base.BeginEdit();
copyData = currentData;
}
public override void CancelEdit()
{
base.CancelEdit();
currentData = copyData;
}
public override void EndEdit()
{
base.EndEdit();
copyData = new MusicData();
}
public override string ToString()
{
return string.Format(
"Album: {0}\nArtist: {1}\nTracks: {2}\nDue Date: {3:d}\nCall Number: {4}",
this.Title, this.Artist, this.NumberOfTracks, this.DueDate, this.CallNumber);
}
}
public class Book : LibraryItem
{
private struct BookData
{
internal string Author;
internal string Genre;
}
BookData currentData;
BookData copyData;
public Book(string title, string author, string genre, string callnum, DateTime dueDate)
: base (title, callnum, dueDate)
{
this.Author = author;
this.Genre = genre;
}
public string Author
{
get { return currentData.Author; }
set
{
if (value != currentData.Author)
{
currentData.Author = value;
NotifyPropertyChanged("Author");
}
}
}
public string Genre
{
get { return currentData.Genre; }
set
{
if (value != currentData.Genre)
{
currentData.Genre = value;
NotifyPropertyChanged("Genre");
}
}
}
public override void BeginEdit()
{
base.BeginEdit();
copyData = currentData;
}
public override void CancelEdit()
{
base.CancelEdit();
currentData = copyData;
}
public override void EndEdit()
{
base.EndEdit();
copyData = new BookData();
}
public override string ToString()
{
return String.Format(
"Title: {0}\nAuthor: {1}\nGenre: {2}\nDue Date: {3:d}\nCall Number: {4}",
this.Title, this.Author, this.Genre, this.DueDate, this.CallNumber);
}
}
public class MovieDVD : LibraryItem
{
private struct MovieData
{
internal TimeSpan Length;
internal string Director;
internal string Genre;
}
private MovieData currentData;
private MovieData copyData;
public MovieDVD(string title, string director, string genre, TimeSpan length, string callnum, DateTime dueDate)
: base(title, callnum, dueDate)
{
this.Director = director;
this.Length = length;
this.Genre = genre;
}
public TimeSpan Length
{
get { return currentData.Length; }
set
{
if (value != currentData.Length)
{
currentData.Length = value;
NotifyPropertyChanged("Length");
}
}
}
public string Director
{
get { return currentData.Director; }
set
{
if (value != currentData.Director)
{
currentData.Director = value;
NotifyPropertyChanged("Director");
}
}
}
public string Genre
{
get { return currentData.Genre; }
set
{
if (value != currentData.Genre)
{
currentData.Genre = value;
NotifyPropertyChanged("Genre");
}
}
}
public override void BeginEdit()
{
base.BeginEdit();
copyData = currentData;
}
public override void CancelEdit()
{
base.CancelEdit();
currentData = copyData;
}
public override void EndEdit()
{
base.EndEdit();
copyData = new MovieData();
}
public override string ToString()
{
return String.Format("Title: {0}\nDirector: {1}\nGenre: {2}\nLength: {3}\nDue Date: {4:d}\nCall Number: {5}",
this.Title, this.Director, this.Genre, this.Length, this.DueDate, this.CallNumber);
}
}
public class LibraryCatalog : ObservableCollection<LibraryItem>
{
public LibraryCatalog()
{
Add(new MusicCD("A Programmers Plight", "Jon Orton",
12, "CD.OrtPro", new DateTime(2010, 3, 24)));
Add(new Book("Cooking with Thyme", "Eliot J. Graff",
"Home Economics", "HE.GraThy", new DateTime(2010, 2, 26)));
Add(new MovieDVD("Terror of the Testers", "Molly Dempsey",
"Horror", new TimeSpan(1, 27, 19), "DVD.DemTer",
new DateTime(2010, 2, 1)));
Add(new MusicCD("The Best of Jim Hance", "Jim Hance",
15, "CD.HanBes", new DateTime(2010, 1, 31)));
Add(new Book("Victor and the VB Vehicle", "Tommy Hortono",
"YA Fiction", "YA.HorVic", new DateTime(2010, 3, 1)));
}
}
}
Imports System.Collections.ObjectModel
Imports System.ComponentModel
' LibraryItem implements INotifyPropertyChanged so that the
' application is notified when a property changes. It
' implements IEditableObject so that pending changes can be discarded.
Public Class LibraryItem
Implements INotifyPropertyChanged
Implements IEditableObject
Private Structure ItemData
Friend Title As String
Friend CallNumber As String
Friend DueDate As DateTime
End Structure
Private copyData As ItemData
Private currentData As ItemData
Public Sub New(ByVal title As String, ByVal callNum As String, ByVal dueDate As DateTime)
Me.Title = title
Me.CallNumber = callNum
Me.DueDate = dueDate
End Sub
Public Property Title() As String
Get
Return currentData.Title
End Get
Set(ByVal value As String)
If currentData.Title <> value Then
currentData.Title = value
NotifyPropertyChanged("Title")
End If
End Set
End Property
Public Property CallNumber() As String
Get
Return currentData.CallNumber
End Get
Set(ByVal value As String)
If currentData.CallNumber <> value Then
currentData.CallNumber = value
NotifyPropertyChanged("CallNumber")
End If
End Set
End Property
Public Property DueDate() As DateTime
Get
Return currentData.DueDate
End Get
Set(ByVal value As DateTime)
If value <> currentData.DueDate Then
currentData.DueDate = value
NotifyPropertyChanged("DueDate")
End If
End Set
End Property
#Region "INotifyPropertyChanged Members"
Public Event PropertyChanged As PropertyChangedEventHandler _
Implements INotifyPropertyChanged.PropertyChanged
Protected Sub NotifyPropertyChanged(ByVal info As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(info))
End Sub
#End Region
#Region "IEditableObject Members"
Public Overridable Sub BeginEdit() Implements IEditableObject.BeginEdit
copyData = currentData
End Sub
Public Overridable Sub CancelEdit() Implements IEditableObject.CancelEdit
currentData = copyData
NotifyPropertyChanged("")
End Sub
Public Overridable Sub EndEdit() Implements IEditableObject.EndEdit
copyData = New ItemData()
End Sub
#End Region
End Class
Public Class MusicCD
Inherits LibraryItem
Private Structure MusicData
Friend SongNumber As Integer
Friend Artist As String
End Structure
Private copyData As MusicData
Private currentData As MusicData
Public Sub New(ByVal title As String, ByVal artist As String,
ByVal songNum As Integer, ByVal callNum As String,
ByVal dueDate As DateTime)
MyBase.New(title, callNum, dueDate)
currentData.SongNumber = songNum
currentData.Artist = artist
End Sub
Public Property Artist() As String
Get
Return currentData.Artist
End Get
Set(ByVal value As String)
If value <> currentData.Artist Then
currentData.Artist = value
NotifyPropertyChanged("Artist")
End If
End Set
End Property
Public Property NumberOfTracks() As Integer
Get
Return currentData.SongNumber
End Get
Set(ByVal value As Integer)
If value <> currentData.SongNumber Then
currentData.SongNumber = value
NotifyPropertyChanged("NumberOfTracks")
End If
End Set
End Property
Public Overloads Overrides Sub BeginEdit()
MyBase.BeginEdit()
copyData = currentData
End Sub
Public Overloads Overrides Sub CancelEdit()
MyBase.CancelEdit()
currentData = copyData
End Sub
Public Overloads Overrides Sub EndEdit()
MyBase.EndEdit()
copyData = New MusicData()
End Sub
End Class
Public Class Book
Inherits LibraryItem
Private Structure BookData
Friend Author As String
Friend Genre As String
End Structure
Private currentData As BookData
Private copyData As BookData
Public Sub New(ByVal title As String, ByVal author As String,
ByVal genre As String, ByVal callnum As String,
ByVal dueDate As DateTime)
MyBase.New(title, callnum, dueDate)
Me.Author = author
Me.Genre = genre
End Sub
Public Property Author() As String
Get
Return currentData.Author
End Get
Set(ByVal value As String)
If value <> currentData.Author Then
currentData.Author = value
NotifyPropertyChanged("Author")
End If
End Set
End Property
Public Property Genre() As String
Get
Return currentData.Genre
End Get
Set(ByVal value As String)
If value <> currentData.Genre Then
currentData.Genre = value
NotifyPropertyChanged("Genre")
End If
End Set
End Property
Public Overloads Overrides Sub BeginEdit()
MyBase.BeginEdit()
copyData = currentData
End Sub
Public Overloads Overrides Sub CancelEdit()
MyBase.CancelEdit()
currentData = copyData
End Sub
Public Overloads Overrides Sub EndEdit()
MyBase.EndEdit()
copyData = New BookData()
End Sub
End Class
Public Class MovieDVD
Inherits LibraryItem
Private Structure MovieData
Friend Length As TimeSpan
Friend Director As String
Friend Genre As String
End Structure
Private currentData As MovieData
Private copyData As MovieData
Public Sub New(ByVal title As String, ByVal director As String,
ByVal genre As String, ByVal length As TimeSpan,
ByVal callnum As String, ByVal dueDate As DateTime)
MyBase.New(title, callnum, dueDate)
Me.Director = director
Me.Length = length
Me.Genre = genre
End Sub
Public Property Length() As TimeSpan
Get
Return currentData.Length
End Get
Set(ByVal value As TimeSpan)
If value <> currentData.Length Then
currentData.Length = value
NotifyPropertyChanged("Length")
End If
End Set
End Property
Public Property Director() As String
Get
Return currentData.Director
End Get
Set(ByVal value As String)
If value <> currentData.Director Then
currentData.Director = value
NotifyPropertyChanged("Director")
End If
End Set
End Property
Public Property Genre() As String
Get
Return currentData.Genre
End Get
Set(ByVal value As String)
If value <> currentData.Genre Then
currentData.Genre = value
NotifyPropertyChanged("Genre")
End If
End Set
End Property
Public Overloads Overrides Sub BeginEdit()
MyBase.BeginEdit()
copyData = currentData
End Sub
Public Overloads Overrides Sub CancelEdit()
MyBase.CancelEdit()
currentData = copyData
End Sub
Public Overloads Overrides Sub EndEdit()
MyBase.EndEdit()
copyData = New MovieData()
End Sub
End Class
Public Class LibraryCatalog
Inherits ObservableCollection(Of LibraryItem)
Public Sub New()
Add(New MusicCD("A Programmers Plight", "Jon Orton", 12,
"CD.OrtPro", New DateTime(2010, 3, 24)))
Add(New Book("Cooking with Thyme", "Eliot J. Graff",
"Home Economics", "HE.GraThy", New DateTime(2010, 2, 26)))
Add(New MovieDVD("Terror of the Testers", "Molly Dempsey", "Horror",
New TimeSpan(1, 27, 19), "DVD.DemTer", New DateTime(2010, 2, 1)))
Add(New MusicCD("The Best of Jim Hance", "Jim Hance", 15,
"CD.HanBes", New DateTime(2010, 1, 31)))
Add(New Book("Victor and the VB Vehicle", "Tommy Hortono",
"YA Fiction", "YA.HorVic", New DateTime(2010, 3, 1)))
End Sub
End Class
Comentários
A IEditableCollectionViewAddNewItem interface permite que os desenvolvedores de aplicativos especifiquem que tipo de objeto adicionar a uma coleção. Essa interface estende IEditableCollectionView, para que você possa adicionar, editar e remover itens em uma coleção. IEditableCollectionViewAddNewItem adiciona o AddNewItem método , que usa um objeto que é adicionado à coleção. Esse método é útil quando a coleção e os objetos que você deseja adicionar têm uma ou mais das seguintes características:
Os objetos no CollectionView são tipos diferentes.
Os objetos não têm um construtor sem parâmetros.
O objeto já existe.
Você deseja adicionar um
nullobjeto à coleção.
Propriedades
| CanAddNew |
Obtém um valor que indica se um novo item pode ser adicionado à coleção. (Herdado de IEditableCollectionView) |
| CanAddNewItem |
Obtém um valor que indica se um objeto especificado pode ser adicionado à coleção. |
| CanCancelEdit |
Obtém um valor que indica se a exibição de coleção pode descartar as alterações pendentes e restaurar os valores originais de um objeto editado. (Herdado de IEditableCollectionView) |
| CanRemove |
Obtém um valor que indica se um item pode ser removido da coleção. (Herdado de IEditableCollectionView) |
| CurrentAddItem |
Obtém o item que está sendo adicionado durante a transação de adição atual. (Herdado de IEditableCollectionView) |
| CurrentEditItem |
Obtém o item na coleção que está sendo editado. (Herdado de IEditableCollectionView) |
| IsAddingNew |
Obtém um valor que indica se uma transação de adição está em andamento. (Herdado de IEditableCollectionView) |
| IsEditingItem |
Obtém um valor que indica se uma transação de edição está em andamento. (Herdado de IEditableCollectionView) |
| NewItemPlaceholderPosition |
Obtém ou define a posição do novo espaço reservado de item na exibição da coleção. (Herdado de IEditableCollectionView) |
Métodos
| AddNew() |
Adiciona um novo item à coleção. (Herdado de IEditableCollectionView) |
| AddNewItem(Object) |
Adiciona o objeto especificado à coleção. |
| CancelEdit() |
Termina a transação de edição e, se possível, restaura o valor original para o item. (Herdado de IEditableCollectionView) |
| CancelNew() |
Termina a transação de adição e descarta o novo item pendente. (Herdado de IEditableCollectionView) |
| CommitEdit() |
Termina a transação de edição e salva as alterações pendentes. (Herdado de IEditableCollectionView) |
| CommitNew() |
Termina a transação de adição e salva o novo item pendente. (Herdado de IEditableCollectionView) |
| EditItem(Object) |
Inicia uma transação de edição do item especificado. (Herdado de IEditableCollectionView) |
| Remove(Object) |
Remove o item especificado da coleção. (Herdado de IEditableCollectionView) |
| RemoveAt(Int32) |
Remove o item na posição especificada da coleção. (Herdado de IEditableCollectionView) |
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