wpf - 如何在转换器中引用资源图像？

Question

我在 UI 的资源部分定义了一些图像：

<Window.Resources>
    <!-- Converters -->
    <loc:UserStatusToIconConverter x:Key="UserStatusToIconConverter" />

    <!-- Images -->
    <BitmapImage x:Key="ConnectIcon" UriSource="/WPFClient;component/Images/connect.png" />
    <BitmapImage x:Key="ActiveIcon" UriSource="/WPFClient;component/Images/active.png" />
    <BitmapImage x:Key="IdleIcon" UriSource="/WPFClient;component/Images/idle.png" />
    <BitmapImage x:Key="AwayIcon" UriSource="/WPFClient;component/Images/away.png" />
    <BitmapImage x:Key="UnknownIcon" UriSource="/WPFClient;component/Images/unknown.png" />
...

我想在我的转换器中选择其中一个进行绑定，我认为这比每次从转换器创建一个新图像（500 次）更有效。

public class UserStatusToIconConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string userStatus = value.ToString();
        string iconName = ...;

        switch (userStatus)
        {
            case "Active":
                // select ActiveIcon;
                break;
            case "Idle":
                // select IdleIcon;
                break;
            case "Away":
                ...
                break;
        }

        return iconName;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

这是我使用它的地方：

            <ListBox ItemsSource="{Binding Users}">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <DockPanel>
                            <Image Source="{Binding Status, Converter={StaticResource UserStatusToIconConverter}}" Height="16" Width="16" />
                            <TextBlock Text="{Binding Nick}" />
                        </DockPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>

Answer 1

我认为你最好DataTemplate.Triggers在这种情况下使用而不是转换器：

                 <DataTemplate>
                    <DockPanel>
                        <Image x:Name="Img" Height="16" Width="16" />
                        <TextBlock Text="{Binding Nick}" />
                    </DockPanel>

                    <DataTemplate.Triggers>
                       <DataTrigger Binding="{Binding Status}" Value="Active">
                          <Setter TargetName="Img" Property="Source" Value="{StaticResource ActiveIcon}"/>
                       </DataTrigger>

                       <DataTrigger Binding="{Binding Status}" Value="Idle">
                          <Setter TargetName="Img" Property="Source" Value="{StaticResource IdleIcon}"/>
                       </DataTrigger>

                       <!-- And So on... -->

                    </DataTemplate.Triggers>
                </DataTemplate>

Answer 2

您可以在 Convert 方法中执行以下操作：

return Application.Current.MainWindow.FindResource(iconName);