列表框IsSynchronizedWithCurrentItem导致第一项的选择，即使它没有告诉它做 [英] Listbox IsSynchronizedWithCurrentItem causes selection of the first item even though nothing its telling it to do it
本文介绍了列表框IsSynchronizedWithCurrentItem导致第一项的选择，即使它没有告诉它做的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我碰到的东西，也许是错误的WPF列表框来了。请查看代码，然后我解释发生了什么。
I came across something that maybe a bug in wpf listbox. Please see the code and then I explain what happens
窗口
<Window >
<Grid>
<local:MultiSelectionComboBox Width="200"
MinHeight="25"
HorizontalAlignment="Center"
VerticalAlignment="Center"
ASLDisplayMemberPath="FirstName"
ASLSelectedItems="{Binding SelectedModels}"
ItemsSource="{Binding Models}" />
<ListBox HorizontalAlignment="Right"
VerticalAlignment="Top"
DisplayMemberPath="FirstName"
ItemsSource="{Binding SelectedModels}" />
</Grid>
</Window>
用户控制
User control
<ComboBox>
<ComboBox.Style>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid x:Name="MainGrid"
Width="Auto"
Height="Auto"
SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="0" />
</Grid.ColumnDefinitions>
<Popup x:Name="PART_Popup"
Grid.ColumnSpan="2"
Margin="1"
AllowsTransparency="true"
IsOpen="{Binding Path=IsDropDownOpen,
RelativeSource={RelativeSource TemplatedParent}}"
Placement="Center"
PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}">
<Border x:Name="DropDownBorder"
MinWidth="{Binding Path=ActualWidth,
ElementName=MainGrid}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<ScrollViewer CanContentScroll="true">
<StackPanel>
<CheckBox x:Name="checkBox"
Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ComboBox}, Path=CheckAllCommand}">select all</CheckBox>
<ListBox x:Name="lstBox"
here lies the problem without the line below I dont get to see the result on start up,
with the it selects the first item even if nothing is triggering it
IsSynchronizedWithCurrentItem="True"
ItemsSource="{TemplateBinding ItemsSource}"
KeyboardNavigation.DirectionalNavigation="Contained"
SelectionChanged="ListBoxOnSelectionChanged"
SelectionMode="Multiple"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
</StackPanel>
</ScrollViewer>
</Border>
</Popup>
<ToggleButton Grid.ColumnSpan="2"
MinWidth="20"
HorizontalAlignment="Right"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
IsChecked="{Binding Path=IsDropDownOpen,
Mode=TwoWay,
RelativeSource={RelativeSource TemplatedParent}}"
Style="{DynamicResource ToggleButtonStyle1}" />
<ItemsControl x:Name="itemsControl"
Margin="4,2,0,2"
ItemsSource="{Binding Path=SelectedItems,
ElementName=lstBox}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel IsItemsHost="True" Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border Margin="1"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Background="#383838"
CornerRadius="2"
Padding="5,2,3,2">
<StackPanel Orientation="Horizontal">
<TextBlock x:Name="Test"
Foreground="White"
Loaded="Test_OnLoaded"
Text="{Binding RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType={x:Type ComboBox}},
Path=ASLDisplayMemberPathActualValue}" />
<Button Width="12"
Height="12"
Margin="5,0,0,0"
Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType=ComboBox},
Path=UnselectCommand}"
CommandParameter="{Binding}">
<Button.Template>
<ControlTemplate TargetType="{x:Type Button}">
<Grid>
<Ellipse x:Name="PART_ButtonBackground"
Fill="White"
Opacity="0" />
<TextBlock x:Name="PART_Text"
Margin="0,0,0,1"
HorizontalAlignment="Center"
VerticalAlignment="Center"
FontSize="10"
Foreground="White"
Text="X" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter TargetName="PART_ButtonBackground" Property="Opacity" Value="0.8" />
<Setter TargetName="PART_Text" Property="Foreground" Value="Black" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Button.Template>
</Button>
</StackPanel>
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ComboBox.Style>
</ComboBox>
背后的用户控件代码
code behind user control
public partial class MultiSelectionComboBox : ComboBox
{
#region fields, dependencies, command and constructor
private ListBox listBox;
private ItemsControl itemsControl;
private CheckBox checkBox;
public static readonly DependencyProperty ASLSelectedItemsProperty = DependencyProperty.Register("ASLSelectedItems", typeof(ObservableCollection<object>), typeof(MultiSelectionComboBox), new PropertyMetadata(null));
public static readonly DependencyProperty ASLDisplayMemberPathProperty = DependencyProperty.Register("ASLDisplayMemberPath", typeof(string), typeof(MultiSelectionComboBox), new PropertyMetadata("Description"));
public MultiSelectionComboBox()
{
InitializeComponent();
}
public DelegateCommand<object> UnselectCommand { get; private set; }
public DelegateCommand CheckAllCommand { get; private set; }
public ObservableCollection<object> ASLSelectedItems
{
get { return (ObservableCollection<object>)GetValue(ASLSelectedItemsProperty); }
set { SetValue(ASLSelectedItemsProperty, value); }
}
public string ASLDisplayMemberPath
{
get { return (string)GetValue(ASLDisplayMemberPathProperty); }
set { SetValue(ASLDisplayMemberPathProperty, value); }
}
#endregion
private void CheckAll()
{
if (checkBox.IsChecked == true)
{
listBox.SelectAll();
}
else
{
listBox.UnselectAll();
}
}
private void GetControls()
{
checkBox = Template.FindName("checkBox", this) as CheckBox;
listBox = Template.FindName("lstBox", this) as ListBox;
itemsControl = Template.FindName("itemsControl", this) as ItemsControl;
}
private bool bug = true;
private void ListBoxOnSelectionChanged(object sender, SelectionChangedEventArgs e)
{
e.AddedItems.Cast<object>().Where(item => !ASLSelectedItems.Contains(item)).ForEach(p => ASLSelectedItems.Add(p));
e.RemovedItems.Cast<object>().Where(item => ASLSelectedItems.Contains(item)).ForEach(p => ASLSelectedItems.Remove(p));
checkBox.IsChecked = (listBox.ItemsSource as IList).Count == listBox.SelectedItems.Count;
}
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
GetControls();
SetControls();
UnselectCommand = new DelegateCommand<object>(p => listBox?.SelectedItems.Remove(p));
CheckAllCommand = new DelegateCommand(CheckAll);
}
private void SetControls()
{
listBox.DisplayMemberPath = ASLDisplayMemberPath;
itemsControl.DisplayMemberPath = ASLDisplayMemberPath;
}
private void Test_OnLoaded(object sender, RoutedEventArgs e)
{
(sender as TextBlock)?.SetBinding(TextBlock.TextProperty, ASLDisplayMemberPath);
}
}
视图模型
view model
public class MainWindowViewModel
{
public ObservableCollection<Model> Models { get; set; }
public ObservableCollection<object> SelectedModels { get; set; }
public MainWindowViewModel()
{
Models = new ObservableCollection<Model>()
{
new Model() {FirstName = "Amelia", Age = 0},
new Model() {FirstName = "Bruno", Age = 5},
new Model() {FirstName = "Colin", Age = 47},
new Model() {FirstName = "Daniel", Age = 32},
new Model() {FirstName = "Iza", Age = 28},
new Model() {FirstName = "James", Age = 23},
new Model() {FirstName = "Simon", Age = 23}
};
SelectedModels = new ObservableCollection<object> {Models.FirstOrDefault() };
}
}
现在的问题是，如果用户控制内部（其中，列表框的），如果我不设置同步到真实的，那么它将不会看到在启动的第一个项目，如果我这样做设置，以后的东西迫使添加到集合。然后就算里面选择孩子我不设置一个值，但仍然设置了第一个孩子的价值。
Now the problem is that if inside the user control (where the listbox is) if I don’t set synchronize to true, then it won’t see the first item on start-up, if I do set it, then something forces an add to the collection. And then even if inside selected children I don’t set a value, it still sets the value of the first child.
这实际上是多选组合框，得到了这么远，这一个简单的事情把我拦住了一天的一半。而且我找不到是什么原因造成的。
This is actually multiselect combobox, got so far and this one simple thing stopped me for half of the day. And I can't find what is causing it.
任何帮助，将不胜感激。
Any help would be appreciated
推荐答案
这将帮助我们如何理解时IsSynchronizedWithCurrentItem设置为true，列表框的行为。的链接
This will help us on how to understand how listbox behaves when IsSynchronizedWithCurrentItem is set to true. Link
由于您的要求，这应该是假的。
Given your requirement, this should be false.
您LisBox.SelectionChanged事件处理程序将被调用每次你设置的值来ASLSelectedItems时间。
Your LisBox.SelectionChanged event handler will be invoked every time you set the Values to ASLSelectedItems.
我觉得它将被工作：
- 从你的列表框（lstBox）删除处理程序
-
然后修改DP
- Remove your handler from your ListBox (lstBox).
Then modify your DP
公共静态只读的DependencyProperty ASLSelectedItemsProperty = DependencyProperty.Register（ASLSelectedItems的typeof（的ObservableCollection<对象>）的typeof（ MultiSelectionComboBox），新PropertyMetadata（NULL，OnSelectedItemsChanged））;
私有静态无效OnSelectedItemsChanged（DependencyObject的D，DependencyPropertyChangedEventArgsê ）
{
//从您的处理程序
加入你的逻辑}
这篇关于列表框IsSynchronizedWithCurrentItem导致第一项的选择，即使它没有告诉它做的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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