wpf 无法将“MS.Internal.NamedObject”类型的对象转换为 BitmapImage
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Unable to cast object of type 'MS.Internal.NamedObject' to BitmapImage
提问by SohamC
I am building a WPF application in which I am getting an error as
我正在构建一个 WPF 应用程序，其中出现错误
Unable to cast object of type 'MS.Internal.NamedObject' to type 'System.Windows.Media.Imaging.BitmapImage'
无法将“MS.Internal.NamedObject”类型的对象转换为“System.Windows.Media.Imaging.BitmapImage”
XAML Code:
XAML 代码：
<DataGridTemplateColumn Header="Active" Width="60">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button>
<Button.Content>
<MultiBinding Converter="{StaticResource myImageConverter}"
ConverterParameter="Active">
<Binding Path="IsClosed"/>
<Binding Path="IsChecked"/>
<Binding Path="IsActive"/>
<Binding Path="TickImage"/>
<Binding Path="CrossImage"/>
</MultiBinding>
</Button.Content>
</Button>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
C# Converter Code:
C# 转换器代码：
public class ImageConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
bool isClosed = (bool)values[0];
bool isChecked = (bool)values[1];
bool isActive = (bool)values[2];
Image img = new Image();
switch ((string)parameter)
{
case "Active":
if (isClosed == true && isChecked == true)
{
if (isActive == true)
{
img.Source = (BitmapImage)values[3];
img.Stretch = Stretch.Fill;
}
else
{
img.Source = (BitmapImage)values[4];
img.Stretch = Stretch.Fill;
}
}
break;
}
return img;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
TickImage and CrossImage are properties of the ViewModel Class. They are initialized in the ViewModel constructor as shown below.
TickImage 和 CrossImage 是 ViewModel 类的属性。它们在 ViewModel 构造函数中初始化，如下所示。
TickImage = new BitmapImage(new Uri("K:\projects\ContentSets\Ownership\SOMA\Staging\SOMA\Images\icon_tick.gif", UriKind.Absolute));
CrossImage = new BitmapImage(new Uri("K:\projects\ContentSets\Ownership\SOMA\Staging\SOMA\Images\icon_cross.gif", UriKind.Absolute));
TickImage.Freeze();
CrossImage.Freeze();
IsClosed, IsChecked and IsActive are properties of DataObject Class.
IsClosed、IsChecked 和 IsActive 是 DataObject 类的属性。
The error occurs at the 1st line of the condition if (isActive == true)
错误发生在条件的第一行 if (isActive == true)
I have also tried the following XAML code:
我还尝试了以下 XAML 代码：
<Button.Content>
<Image>
<Image.Source>
<MultiBinding Converter="{StaticResource myImageConverter}"
ConverterParameter="Active">
<Binding Path="IsClosed"/>
<Binding Path="IsChecked"/>
<Binding Path="IsActive"/>
<Binding Path="TickImage"/>
<Binding Path="CrossImage"/>
</MultiBinding>
</Image.Source>
</Image>
</Button.Content>
TickImage and CrossImage are simple strings in the ViewModel and with necessary changes in the Converter the same error is thrown as follows
TickImage 和 CrossImage 是 ViewModel 中的简单字符串，在 Converter 中进行必要的更改后，会抛出相同的错误，如下所示
Unable to cast object of type 'MS.Internal.NamedObject' to type 'System.String'
无法将“MS.Internal.NamedObject”类型的对象转换为“System.String”类型
采纳答案by Adi Lester
I'm pretty sure your bindings are incorrect. When you perform a binding inside a CellTemplateyou're actually binding to the cell's DataContext rather than your view's DataContext (i.e the viewmodel).
我很确定您的绑定不正确。当您在 a 中执行绑定时，CellTemplate您实际上是绑定到单元格的 DataContext 而不是视图的 DataContext（即视图模型）。
You should try modifying your bindings to take the values from your viewmodel, like this for example:
您应该尝试修改绑定以从视图模型中获取值，例如：
<Binding Path="DataContext.TickImage" RelativeSource="{RelativeSource AncestorType=DataGrid}" />
