将标题添加到列表框的滚动查看器，并保留virtualizingStackPanel(wp7) [英] adding a header to a listbox's scrollviewer and keeping the virtualizingStackPanel (wp7)
问题描述
我想将标题添加到我的ListBoxes，并通过使用模板来做到这一点. 问题在于，如果我扩展列表框的模板，列表框的virtualizingstackpanel似乎无法正常工作:它会在滚动之前加载所有内容.
I want to add a header to my ListBoxes and I do this by using a template. The problem is that if I extend the ListBox's template it seems that the listbox's virtualizingstackpanel doesn't work anymore as expected: it loads all content before I can scroll it.
我在stackoverflow中发现了一些相关问题，例如( VirtualizingStackPanel覆盖ScrollViewer的默认控制模板时停止工作)，但是给定的解决方案无法应用于WP7:我找不到滚动查看器的名为"CanContentScroll"的属性.
I found some relevant questions in stackoverflow like this (VirtualizingStackPanel stops working when overriding the default control template for ScrollViewer) but the solution given there cannot be applied to WP7: I can't find the property named "CanContentScroll" of the scrollviewer.
我的代码
<Style x:Key="ListBoxStyle1" TargetType="ListBox">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Foreground" Value="{StaticResource PhoneForegroundBrush}"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="BorderThickness" Value="0"/>
<Setter Property="BorderBrush" Value="Transparent"/>
<Setter Property="Padding" Value="0"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBox">
<ScrollViewer x:Name="ScrollViewer"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Foreground="{TemplateBinding Foreground}"
Padding="{TemplateBinding Padding}">
<StackPanel>
<TextBlock Text="..."/>
<ItemsPresenter/>
</StackPanel>
</ScrollViewer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
推荐答案
老实说，我真的不知道这里的实际问题是什么. VirtualizingStackPanel仍在可视树中，但似乎没有实际添加的项目.坏消息已足够，好消息是我找到了一种解决方法，方法是更改ScrollViewer的默认样式以将标头放置在此处，这将产生两种样式，如下所示:
To be honest, I'm really not sure what the actual problem is here; the VirtualizingStackPanel is still in the visual tree, but it seems that none of the items actually added. Enough of the bad news, the good news is I've found a way to work round it, by changing the default style of the ScrollViewer to place the header there instead, which results in two styles that look like this:
<Style x:Key="ScrollViewerStyle1" TargetType="ScrollViewer">
<Setter Property="VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="HorizontalScrollBarVisibility" Value="Disabled"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Padding" Value="0"/>
<Setter Property="BorderThickness" Value="0"/>
<Setter Property="BorderBrush" Value="Transparent"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ScrollViewer">
<Border BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="ScrollStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="00:00:00.5" />
</VisualStateGroup.Transitions>
<VisualState x:Name="Scrolling">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="VerticalScrollBar"
Storyboard.TargetProperty="Opacity"
To="1"
Duration="0" />
<DoubleAnimation Storyboard.TargetName="HorizontalScrollBar"
Storyboard.TargetProperty="Opacity"
To="1"
Duration="0" />
</Storyboard>
</VisualState>
<VisualState x:Name="NotScrolling">
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid Margin="{TemplateBinding Padding}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBlock Text="Header" Style="{StaticResource PhoneTextLargeStyle}"/>
<ScrollContentPresenter x:Name="ScrollContentPresenter"
Grid.Row="1"
Content="{TemplateBinding Content}"
ContentTemplate="{TemplateBinding ContentTemplate}" />
<ScrollBar x:Name="VerticalScrollBar"
Grid.RowSpan="2"
IsHitTestVisible="False"
Opacity="0"
Height="Auto"
Width="5"
HorizontalAlignment="Right"
VerticalAlignment="Stretch"
Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
IsTabStop="False"
Maximum="{TemplateBinding ScrollableHeight}"
Minimum="0"
Value="{TemplateBinding VerticalOffset}"
Orientation="Vertical"
ViewportSize="{TemplateBinding ViewportHeight}" />
<ScrollBar x:Name="HorizontalScrollBar"
Grid.RowSpan="2"
IsHitTestVisible="False"
Opacity="0"
Width="Auto"
Height="5"
HorizontalAlignment="Stretch"
VerticalAlignment="Bottom"
Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
IsTabStop="False"
Maximum="{TemplateBinding ScrollableWidth}"
Minimum="0"
Value="{TemplateBinding HorizontalOffset}"
Orientation="Horizontal"
ViewportSize="{TemplateBinding ViewportWidth}" />
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="ListBoxStyle2" TargetType="ListBox">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Foreground" Value="{StaticResource PhoneForegroundBrush}"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="BorderThickness" Value="0"/>
<Setter Property="BorderBrush" Value="Transparent"/>
<Setter Property="Padding" Value="0"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBox">
<ScrollViewer x:Name="ScrollViewer"
Grid.Row="1"
Style="{StaticResource ScrollViewerStyle1}"
Foreground="{TemplateBinding Foreground}"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Padding="{TemplateBinding Padding}">
<ItemsPresenter />
</ScrollViewer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>这篇关于将标题添加到列表框的滚动查看器，并保留virtualizingStackPanel(wp7)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！
