Question

我在MainPage.xaml中放置了一个Progress Bar控件。应用程序类型为Pivot。

出于某种原因，我放置在Progress Bar和TextBlock下的PivotItem 和 a Grid未显示。这两个控件正下方有一个LongListSelector。这两个控件是否因此没有显示？无论如何，我使用UI将LongListSelector拖到了下面，所以我不确定它为什么没有显示。

这是XAML：

<phone:Pivot Title="Title" Background="White" Foreground="Black">
    <!--Pivot item one-->
    <phone:PivotItem Header="Header" Foreground="Black">
        <Grid>
            <ProgressBar Name="progressBar" Value="0" IsIndeterminate="True" Margin="0,0,0,579"/>
            <TextBlock Name="txtLastUpdated" FontWeight="Black" FontStyle="Italic" Foreground="Black" Margin="0,24,0,541" />
            <phone:LongListSelector Name="llsLocations" ItemsSource="{Binding}" SelectionChanged="LongListSelector_OnSelectionChanged" Margin="0,62,0,0">
                <phone:LongListSelector.ItemTemplate>
                ...
                ...
                ...

如您所见，LongListSelector控件内部的Grid上方有一个ProgressBar和一个TextBlock。

为什么没有显示这两个控件的任何想法？

Answer 1

我认为保证金或物品定位有问题。我已经测试了以下代码并且可以运行：

<phone:Pivot Title="Title" Background="White" Foreground="Black">
  <!--Pivot item one-->
  <phone:PivotItem Header="Header" Foreground="Black">
     <Grid>
         <StackPanel Orientation="Vertical" VerticalAlignment="Center">
           <ProgressBar Name="progressBar" Value="0" IsIndeterminate="True" VerticalAlignment="Center" Margin="0"/>
           <TextBlock Name="txtLastUpdated" FontWeight="Black" FontStyle="Italic" Foreground="Black" 
                               HorizontalAlignment="Center" Text="Something"/>
         </StackPanel>
         <phone:LongListSelector Name="llsLocations" ItemsSource="{Binding}" SelectionChanged="LongListSelector_OnSelectionChanged" Margin="0,62,0,0"/>
     </Grid>
 </phone:PivotItem>
</phone:Pivot>

Answer 2

Remove margin of all child element of StackPanel. This will defiantly helps you. 

<phone:Pivot Title="Title" Background="White" Foreground="Black">
  <!--Pivot item one-->
 <phone:PivotItem Header="Header" Foreground="Black">
  <Grid>
   <StackPanel>
   <ProgressBar Name="progressBar" Value="0" IsIndeterminate="True"/>
   <TextBlock Name="txtLastUpdated" FontWeight="Black" FontStyle="Italic" Foreground="Black"  />
   <phone:LongListSelector Name="llsLocations" ItemsSource="{Binding}" SelectionChanged="LongListSelector_OnSelectionChanged" >
       <phone:LongListSelector.ItemTemplate>
   </StackPanel>
  </Grid>
  </phone:PivotItem>
</<phone:Pivot>

Answer 3

硬编码控件的位置（特别是通过拖动设计器中的控件）不是一个好习惯。尝试为Grid定义行，然后为Grid内的控件指定Grid.Row。有了它，您可以更整洁地安排网格内容。检查此link以获取有关Grid内部布局控件的更多示例和说明。以下是您的情况的示例：

<phone:PivotItem Header="Header" Foreground="Black">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <StackPanel Grid.Row="0">
            <ProgressBar Name="progressBar" Value="0" IsIndeterminate="True" />
            <TextBlock Name="txtLastUpdated" FontWeight="Black" FontStyle="Italic" Foreground="Black" />
        </StackPanel>
        <phone:LongListSelector Grid.Row="1" Name="llsLocations" ItemsSource="{Binding}" SelectionChanged="LongListSelector_OnSelectionChanged" >
            <phone:LongListSelector.ItemTemplate>
        ...
        ...

WP8进度条不渲染

3 个答案: