嘿SO，在Silverlight中有一个关于TreeView控件的问题。
我有一个动态添加元素到树视图的应用程序。一些元素足够长，需要水平滚动。当它们被添加到树视图中时，我的树视图一直保持正确向左滚动，因此您必须滚动才能看到项目的结尾。但是，如果我单击其中一个项目（隐藏树视图），然后使用我实现的“返回结果”按钮（注意这只涉及可见性更改）树视图变为可见，它会自动滚动到中心。
当我回到结果时，有谁知道如何让树视图一直向左滚动？
我试过搞乱树视图模板：
<Style TargetType="controls:TreeView" x:Name="SCREW">
<Setter Property="Background" Value="#FFFFFFFF" />
<Setter Property="Foreground" Value="#FF000000" />
<Setter Property="HorizontalContentAlignment" Value="Left" />
<Setter Property="VerticalContentAlignment" Value="Top" />
<Setter Property="Cursor" Value="Arrow" />
<Setter Property="BorderThickness" Value="1" />
<Setter Property="Padding" Value="1" />
<Setter Property="BorderBrush" Value="#FF000000" />
<Setter Property="IsTabStop" Value="True" />
<Setter Property="TabNavigation" Value="Once" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="controls:TreeView" x:Name="SCREWTEMPLATE">
<Grid>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="MouseOver" />
<VisualState x:Name="Pressed" />
<VisualState x:Name="Disabled" />
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Unfocused" />
<VisualState x:Name="Focused" />
</VisualStateGroup>
<VisualStateGroup x:Name="ValidationStates">
<VisualState x:Name="Valid" />
<VisualState x:Name="InvalidUnfocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="Validation" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="InvalidFocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="Validation" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ValidationToolTip" Storyboard.TargetProperty="IsOpen">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>True</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="2">
<Border Padding="{TemplateBinding Padding}" Background="{TemplateBinding Background}" Margin="1">
<ScrollViewer x:Name="ScrollViewer" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" Background="{x:Null}" BorderBrush="Transparent" BorderThickness="0" IsTabStop="False" TabNavigation="Once" Loaded="ScrollViewer_Loaded">
<ItemsPresenter Margin="5" />
</ScrollViewer>
</Border>
</Border>
<Border x:Name="Validation" Grid.Column="1" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="#FFDB000C" CornerRadius="2" Visibility="Collapsed">
<ToolTipService.ToolTip>
<ToolTip x:Name="ValidationToolTip" Placement="Right" PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}" DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}" IsHitTestVisible="True" />
</ToolTipService.ToolTip>
<Grid Width="10" Height="10" HorizontalAlignment="Right" Margin="0,-4,-4,0" VerticalAlignment="Top" Background="Transparent">
<Path Margin="-1,3,0,0" Fill="#FFDC000C" Data="M 1,0 L6,0 A 2,2 90 0 1 8,2 L8,7 Z" />
<Path Margin="-1,3,0,0" Fill="#FFFFFFFF" Data="M 0,0 L2,0 L 8,6 L8,8" />
</Grid>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
但问题是我不知道如何从后面的代码访问ScrollViewer ...所以我不能调用ScrollView.setScrollOffset（0d，0d）或类似的东西。
有什么想法吗？万分感谢。
最后一件事，我想尽量避免实现扩展treeview的新控件。我真的希望有一种方法可以访问/修改和使用与c＃codebehind控件模板相关的函数。
答案 0 :(得分：0)
我只是为此设置了一个附加属性，并在那里创建你想要的逻辑。然后，您将使用附加属性装饰您的树视图。我们对包含滚动查看器的其他控件执行类似的操作：
public class ScrollResetService
{
public static DependencyProperty IsScrollResetProperty = DependencyProperty.RegisterAttached("IsScrollReset",
typeof(bool),
typeof(ScrollResetService),
new PropertyMetadata(false,
OnIsScrollResetChanged));
public static void SetIsScrollReset(DependencyObject d, bool value)
{
d.SetValue(IsScrollResetProperty, value);
}
public static bool GetIsScrollReset(DependencyObject d)
{
return d.GetValue(IsScrollResetProperty) == null ? false : (bool)d.GetValue(IsScrollResetProperty);
}
private static void OnIsScrollResetChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var treeView = d as TreeView;
bool isScrollReset;
if (e.NewValue!= null && bool.TryParse(e.NewValue.ToString(), out isScrollReset) && treeView != null)
{
treeView.SelectedItemChanged += (sender, args) =>
{
var scrolls =
treeView.GetAllLogicalChildrenOfType<IScrollInfo>();
scrolls.ForEach(i => i.SetVerticalOffset(0));
};
}
}
}
public static class Extensions
{
public static IEnumerable<T> GetAllLogicalChildrenOfType<T>(this FrameworkElement parent)
{
Debug.Assert(parent != null, "The parent cannot be null.");
return parent.GetVisualChildren().Flatten(item => item.GetVisualChildren()).OfType<T>();
}
public static IEnumerable<T> Flatten<T>(this IEnumerable<T> items, Func<T, IEnumerable<T>> childSelector)
{
if (items == null) return Enumerable.Empty<T>();
return items.Concat(items.SelectMany(i => childSelector(i).Flatten(childSelector)));
}
internal static IEnumerable<DependencyObject> GetVisualChildren(this DependencyObject parent)
{
int childCount = VisualTreeHelper.GetChildrenCount(parent);
for (int counter = 0; counter < childCount; counter++)
{
yield return VisualTreeHelper.GetChild(parent, counter);
}
}
}
答案 1 :(得分：0)
在处理SelectedItemChanged的{{1}}事件后，我将此代码置于行为中（在代码后面也会起作用）：
TreeView需要var offset = this.HorizontalScrollOffsetAfterSelect; // would be 0 if you don't want to make that adjustable
if (!Double.IsNaN(offset))
{
var scrollViewer = trv.GetVisualDescendants().OfType<ScrollViewer>().FirstOrDefault();
if (scrollViewer != null)
{
scrollViewer.ScrollToHorizontalOffset(offset);
// and because that wasn't enough because of timing issues:
var scrollBar = scrollViewer.GetVisualDescendants().OfType<ScrollBar>().Where(cur => cur.Orientation == Orientation.Horizontal).FirstOrDefault();
if (scrollBar != null)
{
RoutedPropertyChangedEventHandler<double> handler = null;
handler = (sender, e) =>
{
scrollBar.ValueChanged -= handler;
scrollViewer.ScrollToHorizontalOffset(offset);
};
scrollBar.ValueChanged += handler;
}
}
}
和using System.Linq;以及工具包ofc。
到目前为止，对我来说效果还不错。