[UWP] [XAML]如何以编程方式访问Listbox的数据模板中存在的控件 [英] [UWP][XAML]How to access a control present inside Data template of Listbox programatically

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问题描述

在我的应用程序中，我想访问一个文本块列表框的DataTemplate中存在，我想根据
a条件隐藏textBlock的可见性。

这是我的代码：

< ListBox 名称= QUOT; ListUsageDetails" >
$
< ListBox.ItemTemplate>

&NBSP; < DataTemplate>

&NBSP; < con：CustomTemplateSelector Content =" {Binding}">

&NBSP; < con：CustomTemplateSelector.DataTemplateA>

&NBSP; < DataTemplate>

&NBSP; <网格宽度=" 435">

&NBSP; < Grid.RowDefinitions>

&NBSP; < RowDefinition Height =" Auto" />

&NBSP; < RowDefinition Height =" Auto" /> &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;

&NBSP; &NBSP; < /Grid.RowDefinitions>

&NBSP; &NBSP; < Grid.ColumnDefinitions>

&NBSP; &NBSP; < ColumnDefinition Width =" .6 *" />

&NBSP; &NBSP; < ColumnDefinition Width =" .3 *" />

&NBSP; &NBSP; < /Grid.ColumnDefinitions>

&NBSP; &NBSP; < TextBlock VerticalAlignment =" Bottom" FontFamily =" Segoe UI" 名称= QUOT; TxtBlock_CatagoryName" Grid.Row = QUOT; 0" Grid.Column = QUOT; 0" Text =" {Binding name}" fontWeight设置= QUOT; SemiBold"
Foreground =" Black" FontSize =" {Binding Converter = {StaticResource Scaler}，ConverterParameter = 24}" TextWrapping =" Wrap" />

&NBSP; < / Grid>

< / DataTemplate>

< / con：CustomTemplateSelector.DataTemplateA>

< con：CustomTemplateSelector.DataTemplateB>

&NBSP; < DataTemplate>

&NBSP; < Grid Width =" 435">

&NBSP; < Grid.RowDefinitions>

&NBSP; < RowDefinition Height =" Auto" /> &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;

&NBSP; &NBSP; < /Grid.RowDefinitions>

&NBSP; &NBSP; < Grid.ColumnDefinitions>

&NBSP; &NBSP; < ColumnDefinition Width =" .6 *" />

&NBSP; &NBSP; < ColumnDefinition Width =" .3 *" />

&NBSP; &NBSP; < /Grid.ColumnDefinitions>

&NBSP; &NBSP; < TextBlock VerticalAlignment =" Bottom" FontFamily =" Segoe UI" 名称= QUOT; TxtBlock_CatagoryName" TextWrapping = QUOT;包覆与QUOT;&NBSP; Grid.Row = QUOT; 0" Grid.Column = QUOT; 0"&NBSP; &NBSP;的HorizontalAlignment = QUOT;左"
Text =" {Binding name}"前景= QUOT;黑色" FontSize =" {Binding Converter = {StaticResource Scaler}，ConverterParameter = 24}" fontWeight设置= QUOT; SemiBold" />&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;

&NBSP; &NBSP; < / Grid>

&NBSP; &NBSP; < / DataTemplate>

&NBSP; &NBSP;< / CON：CustomTemplateSelector.DataTemplateB>&NBSP; &NBSP; &NBSP; &NBSP; &NBSP;

&NBSP; < con：CustomTemplateSelector.DataTemplateC>

&NBSP; &NBSP; < DataTemplate>

&NBSP; &NBSP; < Grid Width =" 435">

&NBSP; &NBSP; < Grid.RowDefinitions>

&NBSP; &NBSP; < RowDefinition Height =" Auto" /> &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;


&NBSP; &NBSP; < /Grid.RowDefinitions>

&NBSP; &NBSP; < Grid.ColumnDefinitions>

&NBSP; &NBSP; < ColumnDefinition Width =" .6 *" />

&NBSP; &NBSP; < ColumnDefinition Width =" .3 *" />

&NBSP; &NBSP; < /Grid.ColumnDefinitions>

&NBSP; &NBSP; < TextBlock VerticalAlignment =" Bottom" FontFamily =" Segoe UI" fontWeight设置= QUOT; SemiBold"&NBSP;名称= QUOT; TxtBlock_CatagoryName" Grid.Row = QUOT; 0" Grid.Column = QUOT; 0"&NBSP;的HorizontalAlignment = QUOT;左"&NBSP;
Text =" {Binding name}"前景= QUOT;黑色" FontSize =" {Binding Converter = {StaticResource Scaler}，ConverterParameter = 24}" TextWrapping = QUOT;包覆与QUOT;不透明度= QUOT 1 QUOT; />&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;

&NBSP; &NBSP; < / Grid>

&NBSP; < / DataTemplate>

< / con：CustomTemplateSelector.DataTemplateC>

< / con：CustomTemplateSelector>

&NBSP; < / DataTemplate>

< /ListBox.ItemTemplate>

< / ListBox>

CustomTemplateSelector的代码：

  公开   类    CustomTemplateSelector    ：    DataTemplateSelector   
   {  
  公开    DataTemplate     DataTemplateA     {   得到 ;    设置 ;    }   
  公开    DataTemplate     DataTemplateB     {   得到 ;    设置 ;    }   
  公开    DataTemplate     DataTemplateC     {   得到 ;    设置 ;    }   
 
  公开   覆盖    DataTemplate     SelectTemplate  （  object   item  < span class ="pun"style ="margin：0px; padding：0px; border：0px; font-style：inherit; font-variant：inherit; font-weight：inherit; line-height：inherit; font-family：inherit ; vertical-align：baseline; color：＃303336">，    DependencyObject  容器 ）  
   {  
 
  如果   （  item  ！=     null  ）  
   {  
 
  如果   （  // somecondition1）  
  返回    DataTemplateA  ;   
 
  其他   如果   （  // somecondition2）  
  返回    DataTemplateC  ;   
  其他  
  返回    DataTemplateB  ;   
 
  }   
  返回   基地 。  SelectTemplate  （  item  ， < span class ="pln"style ="margin：0px; padding：0px; border：0px; font-style：inherit; font-variant：inherit; font-weight：inherit; line-height：inherit; font-family：inherit ; vertical-align：baseline; color：＃303336"> container  ）;   
  }   
  }

解决方案

Hi Mars771，

如果要访问数据模板中的命名控件（如文本块），可以使用

VisualTreeHelper.GetChildrenCount（）方法。像这样：
 private List< FrameworkElement> GetChildren（DependencyObject parent，string ctrlName）
 {
 List< FrameworkElement> controls = new List< FrameworkElement>（）; 
 
 for（int i = 0; i< VisualTreeHelper.GetChildrenCount（parent）; ++ i）
 {
 var child = VisualTreeHelper.GetChild（parent，i）; 
 if（child is FrameworkElement&& child.Name == ctrlName）
 {
 controls。添加（child as FrameworkElement）; 
} 
 controls.AddRange（GetChildren（child））; 
} 
 
返回控件; 
} 
 
还有一个官方样本，你可以参考：

https://code.msdn.microsoft.com/windowsapps/How-to-access-a-control-6039571a

最好的问候，

罗伊

In my application I want to access a textblock which is present inside the DataTemplate of Listbox and I want to hide the visiblity of textBlock based on a condition.

Here is my code:

Code for CustomTemplateSelector:

public class CustomTemplateSelector : DataTemplateSelector
 {
    public DataTemplate DataTemplateA { get; set; }
    public DataTemplate DataTemplateB { get; set; }
    public DataTemplate DataTemplateC { get; set; }

  public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {

    if (item != null)
        {

            if (//somecondition1)
                return DataTemplateA;

            else if (//somecondition2)
                return DataTemplateC;              
            else
                return DataTemplateB;

        }
        return base.SelectTemplate(item, container);
    }
}

解决方案

Hi Mars771,

If you want to access to a named control in the data template like a textblock, you could use VisualTreeHelper.GetChildrenCount() method. Like this:
private List<FrameworkElement> GetChildren(DependencyObject parent , string ctrlName) 
        { 
            List<FrameworkElement> controls = new List<FrameworkElement>(); 
  
            for(int i = 0; i< VisualTreeHelper.GetChildrenCount(parent); ++i) 
            { 
                var child = VisualTreeHelper.GetChild(parent, i); 
                if (child is FrameworkElement && child.Name == ctrlName) 
                { 
                    controls.Add(child as FrameworkElement); 
                } 
                controls.AddRange(GetChildren(child)); 
            } 
  
            return controls; 
        }
There is also an official sample that you could refer: https://code.msdn.microsoft.com/windowsapps/How-to-access-a-control-6039571a

Best regards,

Roy

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[UWP] [XAML]如何以编程方式访问Listbox的数据模板中存在的控件 [英] [UWP][XAML]How to access a control present inside Data template of Listbox programatically

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[UWP] [XAML]如何以编程方式访问Listbox的数据模板中存在的控件 [英] [UWP][XAML]How to access a control present inside Data template of Listbox programatically

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