我有一个使用DependencyProperties(或INotifyPropertyChanged)的ViewModel,它具有非常简单的复合类型的属性,如System.Windows.Point。 简单的复合类型不使用DependencyProperties或INotifyPropertyChanged,并且它打算保持这种状态(它不受我的控制)。
我现在要做的是创建与Point的X和Y属性绑定的双向数据,但是当其中一个被更改时,我希望替换整个Point类,而不是只更新构件。
代码示例仅用于说明:
<Window ...>
<StackPanel>
<TextBox Text="{Binding TestPoint.X, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, StringFormat=\{0:F\}}"/>
<TextBox Text="{Binding TestPoint.Y, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, StringFormat=\{0:F\}}"/>
<!-- make following label update based on textbox changes above -->
<Label Content="{Binding TestPoint, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}"/>
</StackPanel>
</Window>
代码隐藏:
public partial class MainWindow : Window
{
public Point TestPoint
{
get { return (Point)GetValue(TestPointProperty); }
set { SetValue(TestPointProperty, value); }
}
public static readonly DependencyProperty TestPointProperty = DependencyProperty.Register("TestPoint", typeof(Point), typeof(MainWindow), new PropertyMetadata(new Point(1.0, 1.0)));
}
我想的是将TextBoxes直接绑定到TestPoint属性并使用IValueConverter仅过滤掉特定成员,但是转换方法存在问题,因为修改X时Y值不再存在值。
我觉得必须有一个非常简单的解决方案,我没有得到。
修改
上面的代码只是一个简化的例子,实际应用程序比这更复杂。复合类型有大约7个成员,并且通常在应用程序中使用,因此将其拆分为单个成员并不感觉正确。另外,我想依赖依赖属性的OnChanged事件来调用其他更新,所以我真的需要替换整个类。
答案 0 :(得分:7)
为什么不使用访问者?
public partial class MainWindow : Window
{
public Point TestPoint
{
get { return (Point)GetValue(TestPointProperty); }
set { SetValue(TestPointProperty, value); }
}
public double TestPointX
{
get { return this.TestPoint.X; }
set
{
SetValue(TestPointProperty, new Point(value, this.TestPointY);
}
}
public double TestPointY
{
get { return this.TestPoint.Y; }
set
{
SetValue(TestPointProperty, new Point(this.TestPointX, value);
}
}
public static readonly DependencyProperty TestPointProperty = DependencyProperty.Register("TestPoint", typeof(Point), typeof(MainWindow), new PropertyMetadata(new Point(1.0, 1.0)));
}
在你的XAML中:
<Window ...>
<StackPanel>
<TextBox Text="{Binding TestPointX, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, StringFormat=\{0:F\}}"/>
<TextBox Text="{Binding TestPointY, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, StringFormat=\{0:F\}}"/>
<Label Content="{Binding TestPoint, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}"/>
</StackPanel>
</Window>
答案 1 :(得分:0)
我认为在这种情况下,引入两个DependencyProperties会更容易,一个用于X值,一个用于Y值并简单地绑定到它们。 在每个DependencyProperty的PropertyMetadata中注册一个方法,s。如果仍然需要,可以在每个值更改上替换Point对象。
您还可以使用适当的单向IMultiValueConverter将标签绑定到两个属性的MultiBinding。
答案 2 :(得分:0)
正如我在评论中所说,你可以这样试试。当我们将转换器添加到特定控件的资源时,相同的实例将用于子控件。
<Grid>
<Grid.Resources />
<StackPanel>
<StackPanel>
<StackPanel.Resources>
<local:PointConverter x:Key="PointConverter" />
</StackPanel.Resources>
<TextBox Text="{Binding TestPoint, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, Converter={StaticResource PointConverter}, ConverterParameter=x}" />
<TextBox Text="{Binding TestPoint, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, Converter={StaticResource PointConverter}, ConverterParameter=y}" />
<!-- make following label update based on textbox changes above -->
<Label Content="{Binding TestPoint, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}" />
</StackPanel>
<StackPanel>
<StackPanel.Resources>
<local:PointConverter x:Key="PointConverter" />
</StackPanel.Resources>
<TextBox Text="{Binding TestPoint2, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, Converter={StaticResource PointConverter}, ConverterParameter=x}" />
<TextBox Text="{Binding TestPoint2, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}, Converter={StaticResource PointConverter}, ConverterParameter=y}" />
<!-- make following label update based on textbox changes above -->
<Label Content="{Binding TestPoint2, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}" />
</StackPanel>
</StackPanel>
</Grid>
和代码背后,
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
public Point TestPoint
{
get
{
return (Point)GetValue(TestPointProperty);
}
set
{
SetValue(TestPointProperty, value);
}
}
// Using a DependencyProperty as the backing store for TestPoint. This enables animation, styling, binding, etc...
public static readonly DependencyProperty TestPointProperty =
DependencyProperty.Register("TestPoint", typeof(Point), typeof(MainWindow), new PropertyMetadata(new Point(1.0, 1.0)));
public Point TestPoint2
{
get
{
return (Point)GetValue(TestPoint2Property);
}
set
{
SetValue(TestPoint2Property, value);
}
}
// Using a DependencyProperty as the backing store for TestPoint. This enables animation, styling, binding, etc...
public static readonly DependencyProperty TestPoint2Property =
DependencyProperty.Register("TestPoint2", typeof(Point), typeof(MainWindow), new PropertyMetadata(new Point(1.0, 1.0)));
}
public class PointConverter : IValueConverter
{
double knownX = 0.0;
double knownY = 0.0;
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (parameter.ToString() == "x")
{
knownX = ((Point)value).X;
return ((Point)value).X;
}
else
{
knownY = ((Point)value).Y;
return ((Point)value).Y;
}
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
Point p = new Point();
if (parameter.ToString() == "x")
{
p.Y = knownY;
p.X = double.Parse(value.ToString());
}
else
{
p.X = knownX;
p.Y = double.Parse(value.ToString());
}
return p;
}
}
注意:我没有添加任何空检查。