我正在构建一个WPF应用程序,我在其中收到错误
无法将“MS.Internal.NamedObject”类型的对象强制转换为“System.Windows.Media.Imaging.BitmapImage”
XAML Code :
<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 :
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和IsActive是DataObject类的属性 .
错误发生在条件的第一行 if (isActive == true)
我也尝试了以下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和CrossImage是ViewModel中的简单字符串,并且在Converter中进行必要的更改时会抛出相同的错误,如下所示
无法将“MS.Internal.NamedObject”类型的对象强制转换为“System.String”类型
1 回答
我很确定你的绑定是不正确的 . 当您在
CellTemplate
中使用're actually binding to the cell'的DataContext而不是视图的DataContext(即视图模型)执行绑定时 .您应该尝试修改绑定以从视图模型中获取值,例如: