我无法在用户控件中设置默认的SelectedIndex值。
我为控件创建了这个 DependencyProperty (一个RadioButton组,它将ItemSource作为一个Dictionary(键:字符串值:Bitmap)并创建Radiobuttons和相应的Images)。
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>
如果我单击一个RadioButton,或者如果我从后面的代码中分配属性,那么它的工作原理(图标也正常切换), 问题是在XAML中我指定 SelectedIndex ,但显然绑定发生在之后,因此默认情况下没有选择RadioButton。
<cust:RadioGroup GroupTitle="Symmetry Axis" ItemsSource="{Binding SymmetryAxis}" Columns="3" ItemSelected="RadioGroup_OnSelected" SelectedIndex="2"/>
我该如何解决这个问题?
答案 0 :(得分:0)
好的,我设法解决了这个问题:
public RadioGroup()
{
InitializeComponent();
Loaded += RadioGroup_Loaded;
}
void RadioGroup_Loaded(object sender, RoutedEventArgs e)
{
((RadioButton)VisualTreeHelper.GetChild((container.ItemContainerGenerator.ContainerFromIndex(SelectedIndex)), 0)).IsChecked = true;
}