我的MainWindow中有3个UserControl，在我的UserControl1中，我有一个带有一些名称的ListBox。当我们启动应用程序时，UserControl2和3不可见。
当我在usercontrol1的列表框中选择一些名称时，usercontrol2应出现在我的主窗口上，当我选择其他名称时，usercontrol3应出现在我的主窗口上。请大家帮帮我，我是新来的
这是我的UserControlXaml代码
<UserControl x:Class="Wpf_MVVM.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
x:Name="uc1" Height="Auto" Width="Auto">
<Grid>
<ListBox Name="listbox" ItemsSource="{Binding mylist}" HorizontalAlignment="Left" Height="310" VerticalAlignment="Top" Width="150" Margin="0,40,0,0" FontSize="15">
</ListBox>
<Label Content="Conversations" HorizontalAlignment="Left" VerticalAlignment="Top" Height="40" Width="150" FontSize="20" Background="SkyBlue"/>
<Button Content="Create New Chat" Height="30" HorizontalAlignment="Left" Margin="0,350,0,0" VerticalAlignment="Top" Width="150"/>
</Grid>
</UserControl>
这是我的.cs代码
public partial class UserControl1 : UserControl
{
User1 User1 = new User1();
public UserControl1()
{
InitializeComponent();
this.DataContext = User1;
}
}
public class User1
{
private ObservableCollection<string> _mylist = new ObservableCollection<string>();
public ObservableCollection<string> mylist { get { return _mylist; } }
public User1()
{
mylist.Add("Name1");
mylist.Add("Name2");
mylist.Add("Name3");
mylist.Add("Name4");
}
这是我的mainwindow.xaml代码
<Window x:Class="Wpf_MVVM.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Wpf_MVVM"
Title="MainWindow" Background="SlateGray" Height="420" Width="550" >
<Window.Resources>
<BooleanToVisibilityConverter x:Key="VisibilityConverter" />
</Window.Resources>
<Grid>
<local:UserControl1 x:Name="uc1" HorizontalAlignment="Left" VerticalAlignment="Top"/>
<StackPanel>
<local:UserControl2 x:Name="uc2" Visibility="{Binding SelectedItem, Converter={StaticResource VisibilityConverter}}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="150,29,0,0" />
<local:UserControl3 x:Name="uc3" Visibility="{Binding SelectedItem1, Converter={StaticResource VisibilityConverter}}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="340,29,0,0"/>
</StackPanel>
</Grid>
</Window>
这是我的usercontrol2和3
的viewmodel代码 public class User : INotifyPropertyChanged
{
private bool _selectedItem;
public bool SelectedItem
{
get { return _selectedItem; }
set
{
_selectedItem = value;
PropertyChanged(this, new PropertyChangedEventArgs("SelectedItem"));
}
}
private bool _selectedItem1;
public bool SelectedItem1
{
get { return _selectedItem1; }
set
{
_selectedItem1 = value;
PropertyChanged(this, new PropertyChangedEventArgs("SelectedItem1"));
}
}
public class BooleanToVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value == null ? Visibility.Collapsed : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return null;
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void Notify(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
private readonly ObservableCollection<string> items = new ObservableCollection<string>();
private string text;
private readonly ObservableCollection<string> newitems = new ObservableCollection<string>();
private string newtext;
public class Command : ICommand
{
private readonly Action action;
public Command(Action action)
{
this.action = action;
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
action();
}
}
private readonly ICommand addCommand;
private readonly ICommand sendCommand;
public User()
{
addCommand = new Command(() => items.Add(Text));
sendCommand = new Command(() => newitems.Add(NewText));
}
public IEnumerable<string> Items
{
get { return items; }
}
public IEnumerable<string> NewItems
{
get { return newitems; }
}
public ICommand AddCommand
{
get { return addCommand; }
}
public ICommand SendCommand
{
get { return sendCommand; }
}
public string Text
{
get { return text; }
set
{
if (text == value)
return;
text = value;
Notify("Text");
}
}
public string NewText
{
get { return newtext; }
set
{
if (newtext == value)
return;
newtext = value;
Notify("NewText");
}
}
}
}
答案 0 :(得分：1)
如果您想使用BooleanToVisibilityConverter，则需要在视图模型中创建一些bool属性：
public bool IsControl1Visible
{
get { return isControl1Visible; }
set { isControl1Visible = value; NotifyPropertyChanged("IsControl1Visible"); }
}
public bool IsControl2Visible
{
get { return isControl2Visible; }
set { isControl2Visible = value; NotifyPropertyChanged("IsControl2Visible"); }
}
然后你需要一个SelectedItem属性：
public string SelectedItem
{
get { return selectedItem; }
set { selectedItem = value; NotifyPropertyChanged("SelectedItem"); }
}
您还需要在第一个SelectedItem DependencyProperty中创建UserControl并将其绑定到ListBox.SelectedItem属性（我假设您知道如何或可以找到如何创建DependencyProperty）：
在UserControl1：
<ListBox Name="listbox" ItemsSource="{Binding mylist}"
SelectedItem="{Binding SelectedItem, RelativeSource={AncestorType={x:Type
local:UserControl1}}}" HorizontalAlignment="Left" Height="310"
VerticalAlignment="Top" Width="150" Margin="0,40,0,0" FontSize="15" />
然后您可以Bind UserControl1.SelectedItem属性（内部绑定到ListBox.SelectedItem属性）到您的视图模型：
<local:UserControl1 x:Name="uc1" SelectedItem="{Binding SelectedItem}"
HorizontalAlignment="Left" VerticalAlignment="Top"/>
最后，我们可以更新我们的视图模型SelectedItem属性，以更改其他Usercontrol的可见性：
public string SelectedItem
{
get { return selectedItem; }
set
{
selectedItem = value;
NotifyPropertyChanged("SelectedItem");
if (selectedItem == "Some value")
{
IsControl1Visible = true;
IsControl2Visible = false;
}
else
{
IsControl2Visible = true;
IsControl1Visible = false;
}
}
}
作为此方法的替代方法，您可能会找到我对WPF MVVM navigate views帖子有用的答案。
答案 1 :(得分：0)
您可以使用Binding的强大功能而无需额外的C＃代码
<Grid>
<local:UserControl1 x:Name="uc1" HorizontalAlignment="Left" VerticalAlignment="Top"/>
<StackPanel>
<local:UserControl2 x:Name="uc2" Visibility="{Binding ElementName=uc1, Path=SelectedItem, Converter={StaticResource VisibilityConverter}}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="150,29,0,0" />
<local:UserControl3 x:Name="uc3" Visibility="{Binding ElementName=uc2, Path=SelectedItem, Converter={StaticResource VisibilityConverter}}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="340,29,0,0"/>
</StackPanel>
</Grid>
或使用数据触发器：
<Style TargetType="{x:Type Control}" x:Key="VisibilityStyle1">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding SelectedItem, ElementName=uc1}" Value="{x:Null}">
<Setter Property="Visibility" Value="Hidden" />
</DataTrigger>
</Style.Triggers>
</Style>
<Style TargetType="{x:Type Control}" x:Key="VisibilityStyle2">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding SelectedItem, ElementName=uc2}" Value="{x:Null}">
<Setter Property="Visibility" Value="Hidden" />
</DataTrigger>
</Style.Triggers>
</Style>
<Grid>
<local:UserControl1 x:Name="uc1" HorizontalAlignment="Left" VerticalAlignment="Top"/>
<StackPanel>
<local:UserControl2 x:Name="uc2" Style="{DynamicResource VisibilityStyle1}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="150,29,0,0" />
<local:UserControl3 x:Name="uc3" tyle="{DynamicResource VisibilityStyle2}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="340,29,0,0"/>
</StackPanel>
</Grid>