XAML没有看到我的IValueConverter类

Question

I'm creating a simple WP8, but I'm having troubles hiding (changing the Visibility property) on a control.

In XAML I've added xmlns:local="clr-namespace:MyProjectName" (I've also tried with using ). The XAML is then structured as follows:

<phone:PhoneApplicationPage
x:Class="MyProjectName.Pages.Main"
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"
xmlns:local="clr-namespace:MyProjectName"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
mc:Ignorable="d"
shell:SystemTray.IsVisible="True" Margin="0,4,0,-4" Background="#FFBD3F3F">

<Grid x:Name="LayoutRoot" Background="{StaticResource PhoneBackgroundBrush}" >
    <Grid x:Name="ContentPanel" Grid.Row="1" >
        <Grid.Resources>
            <local:VisibilityFormatter x:Key="FormatConverter" />
        </Grid.Resources>

        <phone:LongListSelector Grid.Row="4">
            <phone:LongListSelector.ItemTemplate>
                <DataTemplate>
                     <TextBlock Text="{Binding Obj}" 
                                     Visibility="{Binding ObjVisibility, 
                                     Mode=OneWay, 
                                     Converter={StaticResource FormatConverter}}" />
                </DataTemplate>
            </phone:LongListSelector.ItemTemplate>
        </phone:LongListSelector>
    </Grid>
</Grid>

The problem is at the <local:...> line: The name "VisibilityFormatter" does not exist in the namespace "clr-namespace:MyProjectName".

The class is defined as follows:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Data;

namespace MyProjectName
{
    public class Formatter
    {
        public class VisibilityFormatter : IValueConverter
        {
            // Retrieve the format string and use it to format the value.
            public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
            {
                var visibility = parameter as bool?;
                return visibility.HasValue && visibility.Value ? Visibility.Visible : Visibility.Collapsed;
            }

            // No need to implement converting back on a one-way binding 
            public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
            {
                throw new NotImplementedException();
            }
        }
    }
}

The class ObjInfo is a simple public class with two properties:

namespace MyProjectName.Models
{
    public class ObjInfo
    {
        public bool ObjVisibility { get; set; }
        public string Obj { get; set; }
    }
}

It's similar to this question, but no migrating is involved. I'm developing on WP8 from the get-go.

What am I trying to achieve? Well. I'm storing whether the control should be visible or not in that bool property. Since the XAML control's property only grokks the Visibility enum , but not bool , I need to convert it to that enum .

Answer 1

The VisibilityFormatter is an inner class of the Formatter class. You don't really need the Formatter class, just make the VisibilityFormatter a top class, and the XAML parser will find it.

Also, the general naming convention for converters is XXXConverter and not XXXFormatter , but that's no rule.

Answer 2

You don't have MyProjectName.VisibilityFormatter in your project, you have

MyProjectName.Formatter.VisibilityFormatter

You should remove Formatter class and leave only:

namespace MyProjectName
{
        public class VisibilityFormatter : IValueConverter
        {
            // Retrieve the format string and use it to format the value.
            public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
            {
                var visibility = parameter as bool?;
                return visibility.HasValue && visibility.Value ? Visibility.Visible : Visibility.Collapsed;
            }

            // No need to implement converting back on a one-way binding 
            public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
            {
                throw new NotImplementedException();
            }
    }