我想要实现的目标：折叠或展开在群组样式中共享相同群组名称的所有扩展器。
我们有一个ListBox和另一个嵌套在其中的ListBox来显示子项。子项ItemsSource绑定到附加了组描述的CollectionView。
组项模板非常简单：
<Expander IsExpanded="{Binding Path=WHAT_TO_DO, Mode=TwoWay}">
<Expander.Header>
<TextBlock Text="{Binding Name}" />
</Expander.Header>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" SharedSizeGroup="{Binding Name, Converter={StaticResource GroupNameToUniqueNameConverter}}" />
</Grid.RowDefinitions>
<ItemsPresenter/>
</Grid>
</Expander>
答案 0 :(得分：1)
我认为这不容易做到。这里可能有两种选择
1）手动 - 绑定您需要的每个扩展器，例如。小组中的第一个项目或其他任何合适的项目。
2）更自动的方式可能需要编写一个具有字典的类，该字典保存每个组的状态。这里的问题是控制器需要知道扩展器的哪个实例正在进行绑定或者它在哪个组中。我在这里看到的一个解决方案是编写一个自定义转换器，它具有带字典的类的静态实例并使用转换器传递组/引用的参数（你可以在这里使用绑定，所以在xaml中这是纯Ctrl + C，Ctrl + V操作）
答案 1 :(得分：0)
您可以在代码后面迭代所有列表框项目。对于每个列表框项，您应该看它是否包含扩展器。如果它，你只是展开或折叠它。请参阅此链接，了解如何迭代项目并查找特定控件。
答案 2 :(得分：0)
创建您自己的控件 - GroupExpander - 从Expander
继承它使用以下帮助程序方法查找可视层次结构中的任何父级：
public static IEnumerable<T> RecurseParents<T>(this DependencyObject child)
{
if (child is T)
{
yield return Get<T>(child);
}
if (child != null)
{
foreach (var parent in RecurseParents<T>(child.GetParentObject()))
{
yield return parent;
}
}
}
public static DependencyObject GetParentObject(this DependencyObject child)
{
if (child == null) return null;
// handle content elements separately
var contentElement = child as ContentElement;
if (contentElement != null)
{
var parent = ContentOperations.GetParent(contentElement);
if (parent != null) return parent;
var fce = contentElement as FrameworkContentElement;
return fce != null ? fce.Parent : null;
}
// also try searching for parent in framework elements (such as DockPanel, etc)
var frameworkElement = child as FrameworkElement;
if (frameworkElement != null)
{
var parent = frameworkElement.Parent;
if (parent != null) return parent;
}
// if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper
return VisualTreeHelper.GetParent(child);
}
现在通过查找父扩展器并计算这是哪个扩展器来编写找到LevelExpander的逻辑
您可以从以下代码中获得想法：
public class DataGridGroupExpander : GroupExpander
{
#region Class level variables
private bool mSettingIsExpanded = false;
#endregion
#region Constructors
public DataGridGroupExpander()
{
SetBinding(HeaderProperty, new Binding("Name"));
Loaded += DataGridGroupExpander_Loaded;
}
#endregion
#region Properties
#region Owner
private DataGrid mOwner = null;
public DataGrid Owner
{
get { return mOwner; }
private set
{
if (mOwner != value)
{
if (mOwner != null)
{
DetachOwner();
}
mOwner = value;
if (mOwner != null)
{
AttachOwner();
}
}
}
}
private void AttachOwner()
{
SetFieldName();
}
private void DetachOwner()
{
}
#endregion
#region ParentExpander
private DataGridGroupExpander mParentExpander = null;
public DataGridGroupExpander ParentExpander
{
get { return mParentExpander; }
private set
{
if (mParentExpander != value)
{
if (mParentExpander != null)
{
DetachParentExpander();
}
mParentExpander = value;
if (mParentExpander != null)
{
AttachParentExpander();
}
}
}
}
private void AttachParentExpander()
{
SetBinding(ParentExpanderLevelProperty, new Binding("Level") { Source = ParentExpander });
}
private void DetachParentExpander()
{
ClearValue(ParentExpanderLevelProperty);
}
#endregion
#endregion
#region Event handlers
private void DataGridGroupExpander_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
ParentExpander = this.RecurseParents<DataGridGroupExpander>().Skip(1).Take(20).FirstOrDefault();
Owner = this.RecurseParents<DataGrid>().FirstOrDefault();
LoadGroupIsExpandedState();
}
#endregion
#region Methods
private void LoadGroupIsExpandedState()
{
if (!mSettingIsExpanded && Owner != null)
{
mSettingIsExpanded = true;
try
{
IsExpanded = Owner.LoadGroupIsExpandedState(Header);
}
finally
{
mSettingIsExpanded = false;
}
}
}
private void PersistGroupIsExpandedState()
{
if (!mSettingIsExpanded && Owner != null)
{
Owner.PersistGroupIsExpandedState(Header, IsExpanded);
}
}
private void SetFieldName()
{
var fieldName = "";
if (Owner != null && Owner.Items != null && Owner.Items.GroupDescriptions.Count > Level)
{
var groupDescription = Owner.Items.GroupDescriptions[Level] as PropertyGroupDescription;
if(groupDescription!=null)
{
fieldName = groupDescription.PropertyName;
}
}
SetValue(FieldNameKey, fieldName);
}
#endregion
#region Overrides
tected override void HeaderUpdated()
{
LoadGroupIsExpandedState();
}
tected override void IsExpandedUpdated()
{
PersistGroupIsExpandedState();
}
#endregion
#region Dependency Properties
#region ParentExpanderLevel
public int ParentExpanderLevel
{
get { return (int)GetValue(ParentExpanderLevelProperty); }
set { SetValue(ParentExpanderLevelProperty, value); }
}
public static readonly System.Windows.DependencyProperty ParentExpanderLevelProperty =
System.Windows.DependencyProperty.Register(
"ParentExpanderLevel",
typeof(int),
typeof(DataGridGroupExpander),
new System.Windows.PropertyMetadata(-1, OnParentExpanderLevelPropertyChanged));
private static void OnParentExpanderLevelPropertyChanged(System.Windows.DependencyObject sender, System.Windows.DependencyPropertyChangedEventArgs e)
{
var control = sender as DataGridGroupExpander;
if (control != null)
{
control.ParentExpanderLevelUpdated();
}
}
private void ParentExpanderLevelUpdated()
{
SetValue(LevelKey, ParentExpanderLevel + 1);
}
#endregion
#region Level
public int Level
{
get { return (int)GetValue(LevelProperty); }
}
internal static readonly DependencyPropertyKey LevelKey = DependencyProperty.RegisterReadOnly(
"Level",
typeof(int),
typeof(DataGridGroupExpander),
new System.Windows.PropertyMetadata(0, OnLevelPropertyChanged));
public static readonly DependencyProperty LevelProperty = LevelKey.DependencyProperty;
private static void OnLevelPropertyChanged(System.Windows.DependencyObject sender, System.Windows.DependencyPropertyChangedEventArgs e)
{
var control = sender as DataGridGroupExpander;
if (control != null)
{
control.LevelUpdated();
}
}
private void LevelUpdated()
{
SetFieldName();
}
#endregion
#region FieldName
public string FieldName
{
get { return (string)GetValue(FieldNameProperty); }
}
internal static readonly DependencyPropertyKey FieldNameKey = DependencyProperty.RegisterReadOnly(
"FieldName",
typeof(string),
typeof(DataGridGroupExpander),
new PropertyMetadata(null, OnFieldNamePropertyChanged));
public static readonly DependencyProperty FieldNameProperty = FieldNameKey.DependencyProperty;
private static void OnFieldNamePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
var control = sender as DataGridGroupExpander;
if (control != null)
{
control.FieldNameUpdated();
}
}
private void FieldNameUpdated()
{
}
#endregion
#endregion
}