我为用户创建了一个 ListPicker 控件以更改其背景，但并非所有信息都正确填充到 ListPicker 控件中。当用户导航到我的 SettingsPage 时出现问题，所有 ListPicker 项目的文本都正确显示，但仅显示当前所选背景的图像。所有其他图像背景都是空白的。此外，奇怪的是，当我更改图像背景并在 MainPage 和 SettingsPage 之间来回导航时，选择的每个新图像背景都会显示在 ListPicker（以及所有其他先前选择的背景）中，而背景没有被选中的没有在 ListPicker 中显示的图像。到目前为止，我所拥有的如下：
设置页面.xaml
<toolkit:ListPicker x:Name="ThemeListPicker" Header="Theme" Grid.Row="2" Grid.ColumnSpan="2"
SelectedIndex="{Binding}"
SelectionChanged="ThemeListPicker_SelectionChanged">
<toolkit:ListPicker.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Image Source="{Binding Image}" Width="50" Height="37.59" Margin="0,0,12,0"/>
<TextBlock Text="{Binding Name}" TextWrapping="Wrap"/>
</StackPanel>
</DataTemplate>
</toolkit:ListPicker.ItemTemplate>
</toolkit:ListPicker>
SettingsPage.xaml.cs
List<ThemeItem> themeList;
public SettingsPage()
{
InitializeComponent();
themeList = new List<ThemeItem>()
{
new ThemeItem { Image = new BitmapImage(new Uri("Resources/Themes/PanoramaBackground.png", UriKind.Relative)), Name = "Default" },
new ThemeItem { Image = new BitmapImage(new Uri("Resources/Themes/Abstract Pattern.jpg", UriKind.Relative)), Name = "Abstract Pattern" },
new ThemeItem { Image = new BitmapImage(new Uri("Resources/Themes/Asian Beauty.jpg", UriKind.Relative)), Name = "Asian Beauty" },
new ThemeItem { Image = new BitmapImage(new Uri("Resources/Themes/Autumn Leaf.jpg", UriKind.Relative)), Name = "Autumn Leaf" },
new ThemeItem { Image = new BitmapImage(new Uri("Resources/Themes/Old Barn.png", UriKind.Relative)), Name = "Old Barn" }
};
ThemeListPicker.ItemsSource = themeList;
ThemeListPicker.DataContext = ThemeListPicker.SelectedIndex;
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
//Respect the saved Theme index setting
this.ThemeListPicker.SelectedIndex = Settings.ThemeIndex.Value;
}
private void ThemeListPicker_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (e.AddedItems.Count <= 0) //to eliminate IndexOutOfRangeException
{
return;
}
//string selectedItem = e.AddedItems[0] as string;
ThemeItem selectedItem = e.AddedItems[0] as ThemeItem;
if (selectedItem != null)
{
Settings.Theme.Value = selectedItem.Image.UriSource.ToString();
Settings.ThemeIndex.Value = ThemeListPicker.SelectedIndex;
}
}
其中 ThemeItem 是一个小的自定义类
public class ThemeItem
{
public BitmapImage Image { get; set; }
public string Name { get; set; }
}
当 SettingsPage 导航到时，我如何能够正确加载 ListPicker 控件中的所有图像背景和相应的文本名称？
编辑：添加设置类信息
public class Settings
{
//Theme settings
public static readonly Setting<int> ThemeIndex = new Setting<int>("ThemeIndex", 0);
//Theme Background
public static readonly Setting<string> Theme = new Setting<string>("Theme", "Resources/Themes/PanoramaBackground.png");
//public static readonly Setting<BitmapImage> Theme = new Setting<BitmapImage>("Theme", new Uri("/Resources/Themes/PanoramaBackground.png", UriKind.Relative));
}
//Encapsulates a key/value pair stored in Isolated Storage ApplicationSettings
public class Setting<T>
{
string name;
T value;
T defaultValue;
bool hasValue;
public Setting(string name, T defaultValue)
{
this.name = name;
this.defaultValue = defaultValue;
}
public T Value
{
get
{
//Check for the cached value
if (!this.hasValue)
{
//Try to get the value from Isolated Storage
if (!IsolatedStorageSettings.ApplicationSettings.TryGetValue(
this.name, out this.value))
{
//It has not been set yet
this.value = this.defaultValue;
IsolatedStorageSettings.ApplicationSettings[this.name] = this.value;
}
this.hasValue = true;
}
return this.value;
}
set
{
//Save the value to Isolated Storage
IsolatedStorageSettings.ApplicationSettings[this.name] = value;
this.value = value;
this.hasValue = true;
}
}
public T DefaultValue
{
get { return this.defaultValue; }
}
//"Clear" cached value
public void ForceRefresh()
{
this.hasValue = false;
}
}