为什么没有 XAML 控件的 UserControl 不继承属性？答案

【问题标题】：Why UserControl without XAML controls do not inherit properties?为什么没有 XAML 控件的 UserControl 不继承属性？
【发布时间】：2011-12-11 10:46:16
【问题描述】：

我在 XAML 中的 WPF 中完成了一个工作用户控件。现在我删除了 XAML 并使用代码创建了用户控件，因为我需要从该控件继承。以前我在使用控件的代码上有这样的代码：

<mc:MyControl Foreground="White">

并且 MyControl 控件中的所有控件都使用了这个 Foreground 设置。现在我已经使用 C# 创建了控件，这不再发生了。

有人知道为什么以及如何解决这个问题吗？

提前致谢。

编辑：

这是 XAML：

<UserControl x:Class="Utils.Wpf.Chart.Chart"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         SizeChanged="UserControl_SizeChanged">
<Grid>
    <Border Margin="5" HorizontalAlignment="Stretch"  VerticalAlignment="Stretch">
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="*"/>
                <RowDefinition Height="*"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>

            <Canvas Grid.Column="1" Grid.ColumnSpan="2" Grid.Row="0" Grid.RowSpan="2"  x:Name="DrawArea" Canvas.Background="Transparent" MouseEnter="DrawArea_MouseEnter" MouseLeave="DrawArea_MouseLeave" MouseMove="DrawArea_MouseMove" Cursor="None">
                <Line x:Name="Border1" X1="0" X2="{Binding Path=ActualWidth, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Canvas}}}" Y1="{Binding Path=ActualHeight, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Canvas}}}" Y2="{Binding Path=ActualHeight, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Canvas}}}" StrokeThickness="1" Stroke="{Binding BorderBrush, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}"/>
                <Line x:Name="Border2" Y1="0" Y2="{Binding Path=ActualHeight, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Canvas}}}" X1="0" X2="0" StrokeThickness="1" Stroke="{Binding BorderBrush, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}"/>
                <TextBlock x:Name="CrossValue" Text="[-,-]" Foreground="#EBDE11" Visibility="Hidden"/>
            </Canvas>

            <TextBlock Grid.Column="0" Grid.Row="0" VerticalAlignment="Top" HorizontalAlignment="Right" Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=MaxYCaption, TargetNullValue=MaxY}" Margin="3,0,6,0"/>
            <TextBlock Grid.Column="0" Grid.Row="1" VerticalAlignment="Bottom" HorizontalAlignment="Right" Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=MinYCaption, TargetNullValue=MinY}" Margin="3,0,6,0"/>

            <TextBlock Grid.Column="1" Grid.Row="2" HorizontalAlignment="Left" VerticalAlignment="Top" Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=MinX, TargetNullValue=MinX}" Margin="3,3,0,0"/>
            <TextBlock Grid.Column="2" Grid.Row="2" HorizontalAlignment="Right" VerticalAlignment="Top" Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=MaxX, TargetNullValue=MaxX}" Margin="0,3,3,0"/>
        </Grid>
    </Border>
</Grid>
</UserControl>

这是 C#：

        _outerGrid = new Grid();
        _border = new Border();
        _innerGrid = new Grid();
        _canvas = new Canvas();
        _line1 = new Line();
        _line2 = new Line();
        _cursorText = new TextBlock();
        _maxXText = new TextBlock();
        _maxYText = new TextBlock();
        _minXText = new TextBlock();
        _minYText = new TextBlock();

        this.Content = _outerGrid;

        _border.Margin = new Thickness(5);
        _border.HorizontalAlignment = HorizontalAlignment.Stretch;
        _border.VerticalAlignment = VerticalAlignment.Stretch;

        _outerGrid.Children.Add(_border);

        _column1 = new ColumnDefinition();
        _column1.Width = new GridLength(0, GridUnitType.Auto);
        _column2 = new ColumnDefinition();
        _column2.Width = new GridLength(1, GridUnitType.Star);
        _column3 = new ColumnDefinition();
        _column3.Width = new GridLength(1, GridUnitType.Star);

        _row1 = new RowDefinition();
        _row1.Height = new GridLength(1, GridUnitType.Star);
        _row2 = new RowDefinition();
        _row2.Height = new GridLength(1, GridUnitType.Star);
        _row3 = new RowDefinition();
        _row3.Height = new GridLength(0, GridUnitType.Auto);

        _innerGrid.ColumnDefinitions.Add(_column1);
        _innerGrid.ColumnDefinitions.Add(_column2);
        _innerGrid.ColumnDefinitions.Add(_column3);

        _innerGrid.RowDefinitions.Add(_row1);
        _innerGrid.RowDefinitions.Add(_row2);
        _innerGrid.RowDefinitions.Add(_row3);

        _border.Child = _innerGrid;

        _canvas.Background = Brushes.Transparent;
        _canvas.Cursor = Cursors.None;
        _canvas.MouseEnter += new MouseEventHandler(_canvas_MouseEnter);
        _canvas.MouseMove += new MouseEventHandler(_canvas_MouseMove);
        _canvas.MouseLeave += new MouseEventHandler(_canvas_MouseLeave);

        Grid.SetColumn(_canvas,1);
        Grid.SetColumnSpan(_canvas,2);
        Grid.SetRowSpan(_canvas,2);

        _innerGrid.Children.Add(_canvas);

        _line1.X1 = 0;
        _line1.StrokeThickness = 1;

        Binding x2Binding = new Binding("ActualWidth");
        x2Binding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) {AncestorType = _canvas.GetType()};
        _line1.SetBinding(Line.X2Property, x2Binding);

        Binding yBinding = new Binding("ActualHeight");
        yBinding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) { AncestorType = _canvas.GetType() };
        _line1.SetBinding(Line.Y1Property, yBinding);
        _line1.SetBinding(Line.Y2Property, yBinding);

        _line2.Y1 = 0;
        _line2.X1 = 0;
        _line2.X2 = 0;
        _line2.StrokeThickness = 1;

        Binding y2Binding = new Binding("ActualHeight");
        y2Binding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) { AncestorType = _canvas.GetType() };
        _line2.SetBinding(Line.Y2Property, x2Binding);

        Binding strokeBinding = new Binding("BorderBrush");
        strokeBinding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) { AncestorType = typeof(UserControl) };
        _line2.SetBinding(Shape.StrokeProperty, strokeBinding);

        _cursorText.Text = "[-,-]";
        _cursorText.Foreground = new SolidColorBrush(Color.FromRgb(0xeb, 0xde, 11));
        _cursorText.Visibility = Visibility.Hidden;

        _canvas.Children.Add(_line1);
        _canvas.Children.Add(_line2);
        _canvas.Children.Add(_cursorText);

        _maxYText.VerticalAlignment = VerticalAlignment.Top;
        _maxYText.HorizontalAlignment = HorizontalAlignment.Right;
        _maxYText.Margin = new Thickness(3, 0, 6, 0);

        Binding maxYBinding = new Binding("MaxYCaption");
        maxYBinding.TargetNullValue = "MaxY";
        maxYBinding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) { AncestorType = typeof(UserControl) };
        _maxYText.SetBinding(TextBlock.TextProperty, maxYBinding);

        _minYText.VerticalAlignment = VerticalAlignment.Bottom;
        _minYText.HorizontalAlignment = HorizontalAlignment.Right;
        _minYText.Margin = new Thickness(3, 0, 6, 0);

        Binding minYBinding = new Binding("MinYCaption");
        minYBinding.TargetNullValue = "MinY";
        minYBinding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) { AncestorType = typeof(UserControl) };
        _minYText.SetBinding(TextBlock.TextProperty, minYBinding);

        _maxXText.VerticalAlignment = VerticalAlignment.Top;
        _maxXText.HorizontalAlignment = HorizontalAlignment.Right;
        _maxXText.Margin = new Thickness(0, 3, 3, 0);

        Binding maxXBinding = new Binding("MaxX");
        maxXBinding.TargetNullValue = "MaxX";
        maxXBinding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) { AncestorType = typeof(UserControl) };
        _maxXText.SetBinding(TextBlock.TextProperty, maxXBinding);

        _minXText.VerticalAlignment = VerticalAlignment.Top;
        _minXText.HorizontalAlignment = HorizontalAlignment.Left;
        _minXText.Margin = new Thickness(3, 3, 0, 0);

        Binding minXBinding = new Binding("MinX");
        minXBinding.TargetNullValue = "MinX";
        minXBinding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor) { AncestorType = typeof(UserControl) };
        _minXText.SetBinding(TextBlock.TextProperty, minXBinding);

        _innerGrid.Children.Add(_maxYText);
        _innerGrid.Children.Add(_maxXText);
        _innerGrid.Children.Add(_minYText);
        _innerGrid.Children.Add(_minXText);

        Grid.SetColumn(_maxXText, 2);
        Grid.SetColumn(_minXText, 1);
        Grid.SetRow(_minYText, 1);
        Grid.SetRow(_minXText, 2);
        Grid.SetRow(_maxXText, 2);

        this.SizeChanged += new System.Windows.SizeChangedEventHandler(Chart2_SizeChanged);

【问题讨论】：

如果您在 XAML 或 C# 中定义控件，究竟有何不同？如果有 is 不同，那么你做错了什么。此外，用户控件永远不会被继承。
当 XAML 转换为 C# 代码时，可能会发生一些事情，从而产生影响。不继承不是一种选择。
如果您在需要自定义控件时坚持使用 UserControl，这肯定是一种选择。
为什么我要朝自己的脚开枪？
UserControls 并不是为了提供这种功能，而不得不像上面那样处理 C# 就是自取其辱的定义。

标签： c# wpf xaml user-controls dependency-properties

【解决方案1】：

@SoMoS - 我认为您所说的是 CustomControl，而不是 UserControl。如果是这样，您是否将控件模板应用于继承的控件？

您可以在此处阅读自定义控件与用户控件之间的差异-

http://wangmo.wordpress.com/2007/09/28/user-controls-vs-custom-controls/

http://www.wpftutorial.net/CustomVsUserControl.html

如果要将控件模板应用于自定义控件，则可以像使用 XAML 的用户控件一样管理其外观。

【讨论】：

我需要继承控件来重写一些属性类型和方法，而不是改变控件的外观。我不在乎控件的外观，它只是功能上的变化。
如果你不想改变它的外观，那你为什么要在代码中设计你的控件呢？你的确切问题是什么？那个控件的子UI元素不继承背景色？我不确定你的问题是什么。
如果 UserControl 是用 XAML 设计的，则不能从 UserControl 继承，因为您会收到错误：不能成为 XAML 文件的根，因为它是使用 XAML 定义的。
您要从哪个控件继承？如果您使用 CustomControl 而不是 UserControl，则可以从控件继承。
我自己做的。也许我会研究 CustomControl 后者。谢谢。