在我的MainPage PanoramaItem2中，我有一个TextBlock。如何从另一个类设置TextBlock的文本？
我尝试创建MainPage的实例，然后找到TextBlock，但我找不到它。它不在那里。
这是我尝试的方式：
public async Task<Problem> DownloadFileFromWeb(Uri uriToDownload, string fileName, CancellationToken cToken)
{
var MainText = new MainPage();
//Set text here;
//MainText.Panorama2.DLText.Text = "New text";
}
这是我的MainPage的xaml：
<phone:PhoneApplicationPage
x:Class="PanoramaApp2.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DataContext="{d:DesignData SampleData/MainViewModelSampleData.xaml}"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
shell:SystemTray.IsVisible="False">
<!--LayoutRoot is the root grid where all page content is placed-->
<Grid x:Name="LayoutRoot" Background="Transparent">
<!-- LOCALIZATION NOTE:
To localize the displayed strings copy their values to appropriately named
keys in the app's neutral language resource file (AppResources.resx) then
replace the hard-coded text value between the attributes' quotation marks
with the binding clause whose path points to that string name.
For example:
Text="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}"
This binding points to the template's string resource named "ApplicationTitle".
Adding supported languages in the Project Properties tab will create a
new resx file per language that can carry the translated values of your
UI strings. The binding in these examples will cause the value of the
attributes to be drawn from the .resx file that matches the
CurrentUICulture of the app at run time.
-->
<!--Panorama control-->
<phone:Panorama Title="my application">
<phone:Panorama.Background>
<ImageBrush ImageSource="/PanoramaApp2;component/Assets/PanoramaBackground.png"/>
</phone:Panorama.Background>
<!--Panorama item one-->
<phone:PanoramaItem x:Name="Panorama1" Header="first item">
<!--Single line list with text wrapping-->
<phone:LongListSelector Margin="0,0,-22,0" ItemsSource="{Binding Items}">
<phone:LongListSelector.ItemTemplate>
<DataTemplate>
<StackPanel Margin="0,-6,0,12">
<TextBlock Text="{Binding LineOne}" TextWrapping="Wrap" Style="{StaticResource PhoneTextExtraLargeStyle}" FontSize="{StaticResource PhoneFontSizeExtraLarge}"/>
</StackPanel>
</DataTemplate>
</phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>
</phone:PanoramaItem>
<!--Panorama item two-->
<phone:PanoramaItem x:Name="Panorama2" Header="Songs">
<!--Double line list with image placeholder and text wrapping using a floating header that scrolls with the content-->
<phone:LongListSelector Margin="0,-38,-22,2" ItemsSource="{Binding Items}" Tap="LongListSelector_Tap">
<phone:LongListSelector.ListHeaderTemplate>
<DataTemplate>
<Grid Margin="12,0,0,38">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<TextBlock Name="DLText" Text="{Binding StatusText, Mode = TwoWay}"
Style="{StaticResource PanoramaItemHeaderTextStyle}"
Grid.Row="0"/>
</Grid>
</DataTemplate>
</phone:LongListSelector.ListHeaderTemplate>
<phone:LongListSelector.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Margin="12,2,0,4" Height="105" Width="432">
<StackPanel Width="311" Margin="8,-7,0,0">
<TextBlock Text="{Binding LineOne}" TextWrapping="Wrap" Margin="10,0" Style="{StaticResource PhoneTextExtraLargeStyle}" FontSize="{StaticResource PhoneFontSizeLarge}"/>
<TextBlock Text="{Binding LineTwo}" TextWrapping="Wrap" Margin="10,-2,10,0" Style="{StaticResource PhoneTextSubtleStyle}" />
</StackPanel>
<Image Source="{Binding PlayPhoto}" Width="50" Height="50" HorizontalAlignment="Left" Tap="Image_Tap_1"/>
<Image Source="{Binding DownloadPhoto}" Width="40" Height="40" HorizontalAlignment="Right" Tap="Image_Tap"/>
</StackPanel>
</DataTemplate>
</phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>
</phone:PanoramaItem>
<!--Panorama item three-->
<phone:PanoramaItem Header="third item" Orientation="Horizontal">
<!--Double wide Panorama with large image placeholders-->
<Grid>
<StackPanel Margin="0,4,16,0" Orientation="Vertical" VerticalAlignment="Top">
<StackPanel HorizontalAlignment="Left" Orientation="Horizontal">
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
</StackPanel>
<StackPanel HorizontalAlignment="Left" Orientation="Horizontal" Margin="0,12,0,0">
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
<Border Background="#FFFFC700" Height="173" Width="173" Margin="12,0,0,0"/>
</StackPanel>
</StackPanel>
</Grid>
</phone:PanoramaItem>
</phone:Panorama>
<!--Uncomment to see an alignment grid to help ensure your controls are
aligned on common boundaries. The image has a top margin of -32px to
account for the System Tray. Set this to 0 (or remove the margin altogether)
if the System Tray is hidden.
Before shipping remove this XAML and the image itself.-->
<!--<Image Source="/Assets/AlignmentGrid.png" VerticalAlignment="Top" Height="800" Width="480" Margin="0" Grid.Row="0" Grid.RowSpan="2" IsHitTestVisible="False" />-->
</Grid>
我在这里缺少什么？ 我在WP8.1上
答案 0 :(得分：1)
您无法以这种方式修改文本，因为它在模板中。您应该使用绑定来设置文本：
<TextBlock Name="DLText" Text="{Binding StatusText,Mode=TwoWay}"
Style="{StaticResource PanoramaItemHeaderTextStyle}"
Grid.Row="0"/>
添加＆＃34; StatusText＆＃34;属性为包含＆＃34;项目＆＃34;。
的相同视图模型然后，只需更新视图模型属性即可。如果＆＃34; MainPage＆＃34;在当前框架中，您可以使用以下内容：
// WinRT
// var frame = (Frame)Windows.UI.Xaml.Window.Current.Content;
// var page = (MainPage)frame.Content;
// Silverlight
var page = (MainPage)Application.Current.RootVisual;
var viewmodel = (MyViewModel)page.DataContext;
viewmodel.StatusText = "new text";