我无法在我的用户控件中设置默认的 SelectedIndex 值。
我已经为控件创建了这个DependencyProperty(一个单选按钮组,它将字典(键:字符串值:位图)作为 ItemSource 并创建单选按钮和相应的图像)。
public int SelectedIndex
{
get { return (int)GetValue(SelectedIndexProperty); }
set { SetValue(SelectedIndexProperty, value); }
}
public static readonly DependencyProperty SelectedIndexProperty =
DependencyProperty.Register(
"SelectedIndex",
typeof(int),
typeof(RadioGroup),
new FrameworkPropertyMetadata(0, OnSelectedIndexChanged)
);
private static void OnSelectedIndexChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
{
var control = (RadioGroup)source;
if (control.ItemsSource == null) return; // When assigning SelectedIndex from the XAML the collection it`s not initialized yet
if (e.NewValue != null)
{
var radioButton =(RadioButton)VisualTreeHelper.GetChild((control.container.ItemContainerGenerator.ContainerFromIndex((int) e.NewValue)), 0);
radioButton.IsChecked = true;
}
var x = -1;
foreach (var item in control.ItemsSource)// Apparently I cannot convert the IEnumerable to List for this i do this odd loop with the external counter
{
x++;
var radioButton = (RadioButton)VisualTreeHelper.GetChild((control.container.ItemContainerGenerator.ContainerFromIndex(x)), 0);
if (radioButton.IsChecked != true) continue;
control.SelectedIndex = x;
var key = control.container.Items[x].ToString();
var currItem = (KeyValuePair<string, Bitmap>)item;
control.GroupIcon = currItem.Value;
return;
}
}
这是 XAML
<UserControl.Resources>
<local:DictToStringConverter x:Key="DictToStringConverter"/>
<DataTemplate DataType="{x:Type ItemsPanelTemplate}" x:Key="ItemPanelDatatemplate">
<RadioButton Margin="0,0,5,0" Content="{Binding}" GroupName="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=ItemsControl}, Path=Tag}" Checked="ToggleButton_OnChecked" />
</DataTemplate>
<ItemsPanelTemplate x:Key="ItemsPanelTemplate">
<UniformGrid x:Name="grdLayout" Columns="{Binding Path=Columns, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:RadioGroup}}}"/>
</ItemsPanelTemplate>
</UserControl.Resources>
<Border x:Name="brdMain">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<TextBlock x:Name="txtTitle" Grid.Column="0" Grid.ColumnSpan="2" Grid.Row="0" Text=""/>
<Image x:Name="imgImage" Grid.Column="0" Grid.Row="1" Source="{Binding Path=GroupIcon, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:RadioGroup}}}" VerticalAlignment="Top"/>
<ItemsControl Grid.Column="1" Grid.Row="1" Name="container" Width="{Binding ElementName=scroll, Path=ViewportWidth}"
ItemsSource="{Binding Path=ItemsSource, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:RadioGroup}},Converter={StaticResource DictToStringConverter}}"
ItemTemplate="{StaticResource ItemPanelDatatemplate}"
ItemsPanel="{StaticResource ItemsPanelTemplate}"
/>
</Grid>
</Border>
如果我单击 RadioButton 或者如果我从它背后的代码分配属性(图标也正确切换),问题是在 XAML 中我分配SelectedIndex但显然绑定发生在分配之后,因此没有选择 RadioButton默认。
<cust:RadioGroup GroupTitle="Symmetry Axis" ItemsSource="{Binding SymmetryAxis}" Columns="3" ItemSelected="RadioGroup_OnSelected" SelectedIndex="2"/>
我怎样才能解决这个问题 ?