我有一个 xaml 页面:
<Page x:Class="DailyStyleW8.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:DailyStyleW8"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:converters="using:DataTypes"
mc:Ignorable="d">
<Page.Resources>
<converters:PortableImageConverter x:Key="ImageConverter" />
</Page.Resources>
<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
<Grid>
<ProgressBar x:Name="loadingViewer"
IsIndeterminate="True"
Height="20" />
<FlipView x:Name="displayViewer"
ItemsSource="{Binding}"
Visibility="Collapsed">
<FlipView.ItemTemplate>
<DataTemplate>
<Grid>
<Image Source="{Binding Image,Converter={StaticResource ImageConverter}}" />
<TextBlock Text="{Binding Name}" />
</Grid>
</DataTemplate>
</FlipView.ItemTemplate>
</FlipView>
</Grid>
</Grid>
</Page>
并在文件后面的代码中:
using DailyStyleApp;
using PortableAPI;
using System;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
namespace DailyStyleW8
{
/// <summary>
/// Display a list of recent updates to the user
/// </summary>
public sealed partial class MainPage : Page
{
Controller controller = new Controller();
public MainPage()
{
this.InitializeComponent();
}
/// <summary>
/// Invoked when this page is about to be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached. The Parameter
/// property is typically used to configure the page.</param>
protected override void OnNavigatedTo(NavigationEventArgs e)
{
LoadContent();
}
private async void LoadContent()
{
var viewModel = await controller.GetMultiDayAsync(DateTime.Now, PortableAPIProvider.Storage.ReadFromSettings<int>("CacheDuration", 7));
displayViewer.ItemsSource = viewModel.Items;
displayViewer.Visibility = Windows.UI.Xaml.Visibility.Visible;
loadingViewer.Visibility = Windows.UI.Xaml.Visibility.Collapsed;
}
}
}
现在,当我运行代码时,LoadContent
函数被正确调用并且viewModel
对象被正确形成。如果我注释掉该行displayViewer.ItemsSource = viewModel.Items;
,则ProgressBar
可见性会按照您的预期进行更改。
当保留该行并逐步遍历LoadContent
方法内的所有 4 行时,运行该方法,但是FlipView
不会使用新项目进行更新,并且ProgressBar
可见性不会更改。viewModel.Items
是类型List<T>
。
我什至确定要在这里寻找什么。我猜 XAML 和我的绑定有问题?