Wpf treeview第一次没有正确扩展。如果在同一生命周期中再次加载，它正在工作 [英] Wpf treeview is not expanding correctly for the first time. It is working if loading again in same life cycle

问题描述

i我试图将xml树扩展到wpf的第一级，我使用附加属性。



i我面临当我第一次加载xml时出现问题，



这是第一次 uiElement.ItemContainerGenerator.ContainerFromItem（） 返回null，但是在同一生命周期中，如果我尝试加载xml，这个属性工作正常。





TreeViewItem treeItem = uiElement .ItemContainerGenerator.ContainerFromItem（item）as TreeViewItem;



任何人都可以帮助我。



我尝试了什么：



下面这行是null，这个函数首次为null ContainerFromItem



TreeViewItem treeItem = uiElement.ItemContainerGenerator.ContainerFromItem（item）as TreeViewItem





private static v oid OnTreeviewPropertyChanged（DependencyObject d，DependencyPropertyChangedEventArgs e）

{

try

{

TreeView uiElement =（TreeView） d;

uiElement.UpdateLayout（）;

TreeViewItem ti = GetItemFromObject（uiElement）;



foreach（ uiElement.Items中的对象项）

$



TreeViewItem treeItem = uiElement.ItemContainerGenerator.ContainerFromItem（item）as TreeViewItem;





if（treeItem！= null）

{

// ExpandAll（treeItem， true）;

treeItem.IsExpanded = true;

}





}





}

cat ch $>
{



}





}





查看：treeview在选项卡内



< ; window x：class =WpfApplication3.MainWindowxmlns：x =＃unknown>

xmlns =http://schemas.microsoft.com/winfx/2006/xaml/presentation

xmlns：x =http://schemas.microsoft.com/winfx/2006/xaml

Title =MainWindowHeight =350Width = 525>

< grid>

< tabcontrol>

< tabitem>

< treeview name =xmlTree> Horizo​​ntalAlignment =Stretch

VerticalAlignment =Stretch

ItemTemplate ={StaticResource NodeTemplate}

ItemsSource ={Binding xmldocumrnt，Mode = OneWay，NotifyOnSourceUpdated = True，UpdateSourceTrigger = PropertyChanged}

VirtualizingStackPanel.IsVirtualizing =False

VirtualizingStackPanel.VirtualizationMode =回收

Vm：ExpandXML.OpenXML ={Binding ISXmlExpand，UpdateSourceTrigger = PropertyChanged，NotifyOnSourceUpdated = True，Mode = TwoWay}>

< treeview.itemcontainerstyle> < Style TargetType ={x：Type TreeViewItem}>

< setter property =FontSizevalue =12>



< / Style>

解决方案

您好Avinesh，
 
 
您可以尝试添加Setter property =IsExpendedvalue =True。 
请在下面找到代码作为参考....... 
 
 
 <   TreeView    名称  =   TreeView    BorderThickness   =  0   前景  = 黑色   >  
 <   TreeView.ItemContainerStyle  >  
 <  麦粒肿le     TargetType   =  {x：Type TreeViewItem} >  
 <   Setter     Property   =  IsExpanded   值  =  True    /  >  
 <   /样式 >  
 <   / TreeView.ItemContainerStyle  >  
 
如果有帮助，请投票。 

Hi,
i am trying to expand xml tree to first level in wpf, iam using attached property for this.

i am facing problem when i am loading xml fo r the first time at that time ,

here for first time " uiElement.ItemContainerGenerator.ContainerFromItem() " is returning null ,but on same life cycle if i try to load xml this property is working properly.


TreeViewItem treeItem = uiElement.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem;

can any one help me.

What I have tried:

this below line is giving null , this funtion is null ContainerFromItem for the first time

TreeViewItem treeItem = uiElement.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem


private static void OnTreeviewPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
try
{
TreeView uiElement = (TreeView)d;
uiElement.UpdateLayout();
TreeViewItem ti = GetItemFromObject(uiElement);

foreach (object item in uiElement.Items)
{

TreeViewItem treeItem = uiElement.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem;


if (treeItem != null)
{
// ExpandAll(treeItem, true);
treeItem.IsExpanded = true;
}


}


}
catch
{

}


}


view: treeview is inside a tab

<window x:class="WpfApplication3.MainWindow" xmlns:x="#unknown">
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<grid>
<tabcontrol>
<tabitem>
<treeview name="xmlTree"> HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
ItemTemplate= "{StaticResource NodeTemplate}"
ItemsSource="{Binding xmldocumrnt, Mode=OneWay, NotifyOnSourceUpdated=True, UpdateSourceTrigger=PropertyChanged}"
VirtualizingStackPanel.IsVirtualizing="False"
VirtualizingStackPanel.VirtualizationMode="Recycling"
Vm:ExpandXML.OpenXML="{Binding ISXmlExpand,UpdateSourceTrigger=PropertyChanged,NotifyOnSourceUpdated=True,Mode=TwoWay}" >
<treeview.itemcontainerstyle> <Style TargetType="{x:Type TreeViewItem}">
<setter property="FontSize" value="12">

</Style>

解决方案

Hi Avinesh,

 
you can try to add Setter property="IsExpended" value="True".
please find below code as Reference.......  


<TreeView Name="TreeView" BorderThickness="0" Foreground="Black" >
                                <TreeView.ItemContainerStyle>
                                    <Style TargetType="{x:Type TreeViewItem}">
                                        <Setter Property="IsExpanded" Value="True" />
                                    </Style>
                                </TreeView.ItemContainerStyle>

Please vote if it helpful . 

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