Question

我有一个自定义的WPF线，我想用鼠标选择时改变样式。

我尝试使用触发器（请参阅下面的代码），但这不起作用。

问题出在哪里？ IsSelected属性已更改，但StrokeThickness根本不会更改...（

XAML：

<UserControl.Resources>
 <Style TargetType="stops:MyLine" 
  x:Key="MyLineStyleKey" x:Name="MyLineStyleName">

  <Style.Triggers>
   <DataTrigger Binding="{Binding Path=IsSelected}" Value="true">
    <Setter Property="StrokeThickness" Value="10" />
   </DataTrigger>
  </Style.Triggers>
 </Style>
</UserControl.Resources>

<Canvas...
...
<my:MyLine Style="{StaticResource MyLineStyleKey}" x:Name="myLine1" 
 Stroke="Black" X11="10" X22="100" Y11="10" Y22="100"/>

代码：

class MyLine : Shape
{
    public static readonly DependencyProperty X11Property;
    public static readonly DependencyProperty X22Property;
    public static readonly DependencyProperty Y11Property;
    public static readonly DependencyProperty Y22Property;
    public static readonly DependencyProperty IsSelectedProperty;

    static MyLine()
    {
        X11Property = DependencyProperty.Register("X11", typeof(double), typeof(MyLine), new FrameworkPropertyMetadata(double.NaN, FrameworkPropertyMetadataOptions.AffectsRender));
        X22Property = DependencyProperty.Register("X22", typeof(double), typeof(MyLine), new FrameworkPropertyMetadata(double.NaN, FrameworkPropertyMetadataOptions.AffectsRender));
        Y11Property = DependencyProperty.Register("Y11", typeof(double), typeof(MyLine), new FrameworkPropertyMetadata(double.NaN, FrameworkPropertyMetadataOptions.AffectsRender));
        Y22Property = DependencyProperty.Register("Y22", typeof(double), typeof(MyLine), new FrameworkPropertyMetadata(double.NaN, FrameworkPropertyMetadataOptions.AffectsRender));
        IsSelectedProperty = DependencyProperty.Register("IsSelected", typeof(bool), typeof(MyLine), new FrameworkPropertyMetadata(false));
    }

    public MyLine()
        : base()
    {
        this.PreviewMouseLeftButtonDown += new System.Windows.Input.MouseButtonEventHandler(DirectionLine_PreviewMouseLeftButtonDown);
    }

    void DirectionLine_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        this.IsSelected = !this.IsSelected;
    }

    [TypeConverter(typeof(LengthConverter))]
    public double X11 { get { return (double)GetValue(X11Property); } set { SetValue(X11Property, value); } }
    [TypeConverter(typeof(LengthConverter))]
    public double X22 { get { return (double)GetValue(X22Property); } set { SetValue(X22Property, value); } }
    [TypeConverter(typeof(LengthConverter))]
    public double Y11 { get { return (double)GetValue(Y11Property); } set { SetValue(Y11Property, value); } }
    [TypeConverter(typeof(LengthConverter))]
    public double Y22 { get { return (double)GetValue(Y22Property); } set { SetValue(Y22Property, value); } }
    [TypeConverter(typeof(BooleanConverter))]
    public bool IsSelected { get { return (bool)GetValue(IsSelectedProperty); } set { SetValue(IsSelectedProperty, value); } }


    protected override System.Windows.Media.Geometry DefiningGeometry
    {
        get
        {
            var geometryGroup = new GeometryGroup();
            geometryGroup.Children.Add(new LineGeometry(new Point(X11, Y11), new Point(X22, Y22)));
            return geometryGroup;
        }
    }
}

Answer 1

尝试使用“<Trigger Property="IsSelected" ...>”而不是DataTrigger。 DataTrigger适用于FrameworkElement的DataContext。在您的情况下，这意味着它将查找控件的DataContext的IsSelected属性。另一方面，Trigger直接在FrameworkElement本身上工作，并查找FrameworkElement的依赖属性。

<UserControl x:Class="StackOverflow.MyUserControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:StackOverflow">
    <UserControl.Resources>
        <Style TargetType="local:MyLine" 
  x:Key="MyLineStyleKey" x:Name="MyLineStyleName">

            <Style.Triggers>
                <Trigger Property="IsSelected" Value="true">
                    <Setter Property="StrokeThickness" Value="10" />
                </Trigger>
            </Style.Triggers>
        </Style>
    </UserControl.Resources>
    <Canvas>
        <local:MyLine Style="{StaticResource MyLineStyleKey}" x:Name="myLine1" 
Stroke="Black" X11="10" X22="100" Y11="10" Y22="100"/>
    </Canvas>
</UserControl>

WPF触发器无法工作（示例）

1 个答案: