windows phone 8.1 ComboBox在项目数量更多时显示多个项目

Question

当组合框中有更多项目时,组合框将显示listpicker弹出窗口.如果我选择第一个并向下滚动,则多个项目将显示为已选中.但ComboBox的SelectedItem将是我选择的那个.我修改了ListPickerFlyout的样式并关闭了ListView的虚拟化.如果我这样做,ListView将不会保留SelectedItem.这是ComboBox的错误吗？有没有解决这个问题的方法

这是我修改过的风格

 <DataTemplate x:Key="ListPickerFlyoutPresenterContentTemplate" >
                <ListView VirtualizingStackPanel.VirtualizationMode="Recycling" SelectionMode="Single"   > 
                    <!--<ListView.ItemsPanel>
                        <ItemsPanelTemplate>
                            <VirtualizingStackPanel/>
                        </ItemsPanelTemplate>
                    </ListView.ItemsPanel>-->
                    <ListView.ItemContainerStyle>

                           <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate TargetType="ListViewItem">
                                        <Border x:Name="OuterContainer" RenderTransformOrigin="0.5,0.5">
                                            <VisualStateManager.VisualStateGroups>
                                                <VisualStateGroup x:Name="CommonStates">
                                                    <VisualState x:Name="Normal" />
                                                    <VisualState x:Name="Pressed"/>

                                                    <VisualState x:Name="Disabled"/>
                                                                                                                                                        <VisualStateGroup.Transitions>
                                                        <VisualTransition From="Pressed" To="Normal" />


                                                    </VisualStateGroup.Transitions>
                                                </VisualStateGroup>
                                                <VisualStateGroup x:Name="SelectionStates">
                                                    <VisualState x:Name="Unselected" />
                                                    <VisualState x:Name="Selected">
                                                        <Storyboard>
                                                            <DoubleAnimation Storyboard.TargetName="CheckGlyph" Storyboard.TargetProperty="Opacity" Duration="0" To="1" />
                                                            <DoubleAnimation Storyboard.TargetName="SelectedCheckMark" Storyboard.TargetProperty="Opacity" Duration="0" To="1" />
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="contentPresenter" Storyboard.TargetProperty="Foreground" Duration="0">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Green" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentBorder" Storyboard.TargetProperty="Background">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ListPickerFlyoutPresenterSelectedItemBackgroundThemeBrush}" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                    <VisualState x:Name="SelectedUnfocused">
                                                        <Storyboard>
                                                            <DoubleAnimation Storyboard.TargetName="CheckGlyph" Storyboard.TargetProperty="Opacity" Duration="0" To="1" />
                                                            <DoubleAnimation Storyboard.TargetName="SelectedCheckMark" Storyboard.TargetProperty="Opacity" Duration="0" To="1" />
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="contentPresenter" Storyboard.TargetProperty="Foreground" Duration="0">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Green" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentBorder" Storyboard.TargetProperty="Background">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ListPickerFlyoutPresenterSelectedItemBackgroundThemeBrush}" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                </VisualStateGroup>
                                                <VisualStateGroup x:Name="DataVirtualizationStates">
                                                    <VisualState x:Name="DataAvailable" />
                                                    <VisualState x:Name="DataPlaceholder">

                                                    </VisualState>
                                                </VisualStateGroup>
                                                <VisualStateGroup x:Name="MultiSelectStates">
                                                    <VisualState x:Name="NoMultiSelect" />
                                                    <VisualState x:Name="ListMultiSelect">

                                                    </VisualState>
                                                    <VisualState x:Name="GridMultiSelect" />
                                                    <VisualStateGroup.Transitions>
                                                        <VisualTransition From="ListMultiSelect" To="NoMultiSelect" GeneratedDuration="0:0:0.15" />
                                                        <VisualTransition From="NoMultiSelect" To="ListMultiSelect" GeneratedDuration="0:0:0.15" />
                                                    </VisualStateGroup.Transitions>
                                                </VisualStateGroup>
                                                <!--<VisualStateGroup x:Name="HighlightStates">
                                                    <VisualState x:Name="NoHighlight" />
                                                    <VisualState x:Name="Highlighted">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="contentPresenter" Storyboard.TargetProperty="Foreground" Duration="0">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Red" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentBorder" Storyboard.TargetProperty="Background">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ListPickerFlyoutPresenterSelectedItemBackgroundThemeBrush}" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                </VisualStateGroup>-->
                                            </VisualStateManager.VisualStateGroups>

                                                            <Grid>
                                                                <ContentPresenter x:Name="contentPresenter"
                                        ContentTransitions="{TemplateBinding ContentTransitions}"
                                        ContentTemplate="{TemplateBinding ContentTemplate}"
                                        Content="{TemplateBinding Content}"
                                        HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                        VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                        Margin="{TemplateBinding Padding}"
                                        Style="{ThemeResource FlyoutPickerListViewItemContentPresenterStyle}" />
                                                                 <!--The 'Xg' text simulates the amount of space one line of text will occupy.
                                            In the DataPlaceholder state, the Content is not loaded yet so we
                                            approximate the size of the item using placeholder text.--> 
                                                                <TextBlock x:Name="PlaceholderTextBlock"
                                 Opacity="0"
                                 Text="Xg"
                                 Foreground="{x:Null}"
                                 Margin="{TemplateBinding Padding}"
                                 IsHitTestVisible="False"
                                 AutomationProperties.AccessibilityView="Raw"/>
                                                                <Rectangle x:Name="PlaceholderRect"
                                 Visibility="Collapsed"
                                 Fill="{ThemeResource FlyoutBackgroundThemeBrush}"
                                 IsHitTestVisible="False" />
                                                            </Grid>
                                                        </Border>
                                                    </Border>
                                                </Border>
                                                <Border x:Name="SelectedBorder"
                      IsHitTestVisible="False"
                      Opacity="0"
                      BorderBrush="{ThemeResource ListViewItemSelectedBackgroundThemeBrush}"
                      BorderThickness="{ThemeResource GridViewItemMultiselectBorderThickness}">
                                                    <Grid x:Name="SelectedCheckMark"
                      Opacity="0"
                      Height="34"
                      Width="34"
                      HorizontalAlignment="Right"
                      VerticalAlignment="Top">
                                                        <Path x:Name="SelectedEarmark" Data="M0,0 L40,0 L40,40 z"
                        Fill="{ThemeResource ListViewItemSelectedBackgroundThemeBrush}"
                        Stretch="Fill" />
                                                        <Path x:Name="SelectedGlyph"
                        Data="M0,123 L39,93 L124,164 L256,18 L295,49 L124,240 z"
                        Fill="{ThemeResource ListViewItemCheckThemeBrush}"
                        Height="14.5"
                        Stretch="Fill"
                        Width="17"
                        HorizontalAlignment="Right"
                        Margin="0,1,1,0"
                        VerticalAlignment="Top"
                        FlowDirection="LeftToRight" />
                                                    </Grid>
                                                </Border>
                                            </Grid>
                                        </Border>
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>

                    </ListView.ItemContainerStyle>
                    <ListView.Footer>
                        <Border Height="{ThemeResource ListPickerFlyoutFooterThemeHeight}" Width="1" />
                    </ListView.Footer>                     
                </ListView>
            </DataTemplate>

当我选择一些项目时它不会进入选定的视觉状态,它实际上进入突出显示的视觉状态,当我关闭虚拟化之前突出显示状态不会被保留

Answer 1

问题在于 listviewitems 的虚拟化（它是控件中的一个错误）。

解决方案是设置列表视图的 itemsstackpanel 的CacheLength属性。

代码是：

<DataTemplate x:Key="ListPickerFlyoutPresenterContentTemplate">
    <ListView ItemContainerStyle="{StaticResource ListPickerFlyoutPresenterItemStyle}">
       <ListView.ItemsPanel>
           <ItemsPanelTemplate>
                <ItemsStackPanel  CacheLength="10" />
            </ItemsPanelTemplate>
        </ListView.ItemsPanel>

        <ListView.Footer>
            <Border Height="{ThemeResource ListPickerFlyoutFooterThemeHeight}"
                    Width="1" />
        </ListView.Footer>
    </ListView>
</DataTemplate>

该解决方案仅在实现该项目后一段时间（几秒钟）后才会删除选择突出显示。

希望解决方案没问题，否则您将不得不覆盖listview 的PrepareContainerForItemOverride