Question

我在MVVM项目中遇到了设计师的问题。

我有TreeView个自定义DataTemplate：

                             <DataTemplate>
                                <StackPanel Orientation="Horizontal">
                                    <Image Name="img"  Width="20" Height="20" Stretch="Fill" 
                                       Source="{Binding 
                                       RelativeSource={RelativeSource 
                                       Mode=FindAncestor, 
                                       AncestorType={x:Type TreeViewItem}}, 
                                       Path=Header, 
                                       Converter={StaticResource HeaderToImageConverter}}"       
                                       />
                                    <TextBlock Text="{Binding}" Margin="5,0" />
                                </StackPanel>
                            </DataTemplate>

资源声明：

<Window x:Class="BlobWorld.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:Core="clr-namespace:BlobWorld;assembly=" 
        xmlns:helper="clr-namespace:BlobWorld.Helper"
        mc:Ignorable="d"
        Title="MainWindow" Height="350.459" Width="746.561"
        DataContext="{DynamicResource MainWindowViewModel}">
    <Window.Resources>
        <helper:HeaderToImageConverter x:Key="HeaderToImageConverter"/>
    </Window.Resources>

我的转换器是：

public class HeaderToImageConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if ((value as string).Contains(@"."))
            {
                Uri uri = new Uri("pack://application:,,,/images/File.png");
                BitmapImage source = new BitmapImage(uri);
                return source;
            }
            else
            {
                if (!(value as string).Contains(@":"))
                {
                    Uri uri = new Uri("pack://application:,,,/images/folder.png");
                    BitmapImage source = new BitmapImage(uri);
                    return source;
                }
                else
                {
                    Uri uri = new Uri("pack://application:,,,/images/diskdrive.png");
                    BitmapImage source = new BitmapImage(uri);
                    return source;
                }
            }
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotSupportedException("Cannot convert back");
        }
    }

它在运行时完美运行，但是当我使用xaml＆＃34; design＆＃34;在Visual Studio中的窗口而不是看到我的Windows的外观，我只有一个IOException : Cannot locate resource 'images/folder.png'

我的问题来自哪里？我该如何解决？

Answer 1

我注意到这个问题从未得到解决，我遇到了同样的问题，需要解决。解决此问题的方法如下：

更改：

pack://application:,,,/path/to/images/mypng.png

收件人：

/Project Namespace;component/path/to/images/mypng.png

就是这样！还要确保将图像上的 Build Action 设置为 Resource ，并且将 Copy to Output Directory 设置为请勿复制（由于这是资源，因此无需将映像复制到输出目录）。现在，您的控件将以设计模式显示。

Answer 2

您可以检查它是否在DesignMode上运行，如下所示;

    public class HeaderToImageConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            bool designMode = (LicenseManager.UsageMode == LicenseUsageMode.Designtime);
            if (!designMode)
            {
                if ((value as string).Contains(@"."))
                {
                    Uri uri = new Uri("pack://application:,,,/images/File.png");
                    BitmapImage source = new BitmapImage(uri);
                    return source;
                }
                else
                {
                    if (!(value as string).Contains(@":"))
                    {
                        Uri uri = new Uri("pack://application:,,,/images/folder.png");
                        BitmapImage source = new BitmapImage(uri);
                        return source;
                    }
                    else
                    {
                        Uri uri = new Uri("pack://application:,,,/images/diskdrive.png");
                        BitmapImage source = new BitmapImage(uri);
                        return source;
                    }
                }
            }
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotSupportedException("Cannot convert back");
        }
    }

IOException：无法仅在设计时找到资源

2 个答案: