Question

我创建了一个从Canvas继承的自定义Canvas，我声明了一个新的Dependency属性“ NewMouseOver”，希望通过触发器中的Setter对其进行影响。

public class CanvaNetwork : Canvas
{
public CanvaNetwork() { }



public bool NewMouseOver
{
get { return (bool)GetValue(NewMouseOverProperty); }
set { SetValue(NewMouseOverProperty, value); }
}

public static readonly DependencyProperty NewMouseOverProperty =
DependencyProperty.Register("NewMouseOver", typeof(bool), 
typeof(CanvaNetwork), new PropertyMetadata(false));


}

这是我的XAML：

<DataTemplate DataType="{x:Type local:Node}">
    <local:CanvaNetwork x:Name="ItemCanvas_Node" 
                        NewMouseOver="{Binding MyMouseOver}" 
                        Background="Transparent">

        <Path x:Name="Path_NodeProcess"

                Stroke="Green"
                Fill="Gray"
                Stretch="None"
                Data="{Binding  Path =Geometryform}"
                Visibility="{Binding Path=Visibility}">
        </Path>
        <local:CanvaNetwork.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter  Property="NewMouseOver"  Value="True" />
            </Trigger>
        </local:CanvaNetwork.Triggers>
    </local:CanvaNetwork>
</DataTemplate>

hera是我的Node类：

Public Node :DependencyObject
{

 public static readonly DependencyProperty MyMouseOverProperty =
            DependencyProperty.Register("MyMouseOver", typeof(bool), typeof(NodeProcess), new PropertyMetadata(true,new PropertyChangedCallback(On_MyMouseOver)));

        private static void On_MyMouseOver(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            //..some code

        }

        public bool MyMouseOver
        {
            get { return (bool)GetValue(MyMouseOverProperty); }
            set { SetValue(MyMouseOverProperty, value); }
        }



}

我想要的是： 1-i具有DependencyProperty：NewMouseOver（具有和设置不像原始Canvas类中的IsMouseOver）。通过触发器/设置器2-访问NewMouseOver并更改NewMouseOver的状态。 3-via XAML：将绑定绑定设置为：NewMouseOver（在CanvaNetwork中）和MyMouseOver（在Node类中） 4之后，我将使用On_MyMouseOver（位于Node类中）和MyMouseOver来制作一些东西。

Answer 1

我认为我可以回答有关如何更新画布对象中的DependencyProperty的问题。

要测试它，我将为依赖项属性定义一个“ on change”方法。您可以在此处放置一个断点以验证是否已设置依赖项属性。

class CanvaNetwork : Canvas
{
  public CanvaNetwork ( ) { }

  public static readonly DependencyProperty NewMouseOverProperty
                           = DependencyProperty.Register ( "NewMouseOver",
                                                           typeof (bool),
                                                           typeof (CanvaNetwork),
                                                           new PropertyMetadata (false, OnNewMouseOverChanged)) ;

  public bool NewMouseOver
  {
    get { return (bool)GetValue (NewMouseOverProperty); }
    set { SetValue (NewMouseOverProperty, value); }
  }

  public static void OnNewMouseOverChanged ( DependencyObject d, DependencyPropertyChangedEventArgs e )
  {
  }
}

在DataTemplate中，您必须在样式中定义触发器。

<DataTemplate DataType="{x:Type local:Node}">
  <local:CanvaNetwork x:Name="ItemCanvas_Node"
                Background="red" Height="100" Width="100">

    <Path x:Name="Path_NodeProcess"

        Stroke="Green"
        Fill="Gray"
        Stretch="None"
        Data="{Binding  Path =Geometryform}"
        Visibility="{Binding Path=Visibility}">
    </Path>

    <local:CanvaNetwork.Style>
      <Style>
        <Setter  Property="local:CanvaNetwork.NewMouseOver"  Value="False" />
        <Style.Triggers>
          <Trigger  Property="Canvas.IsMouseOver" Value="True">
            <Setter  Property="local:CanvaNetwork.NewMouseOver"  Value="True" />
          </Trigger>
        </Style.Triggers>
      </Style>
    </local:CanvaNetwork.Style>

  </local:CanvaNetwork>
</DataTemplate>

如果样式中设置了默认属性，则只能使用触发器更新属性。

为此，我删除了您的属性 NewMouseOver =“ {Binding MyMouseOver}” 。从您的列表中，第1点和第2点起作用，但是删除此属性意味着第3点不起作用。

但是，我认为您可能还是采取了错误的方法。将MouseOver事件连接到Node类中的command属性不是更好，如下所述：

How to make MouseOver event in MVVM?

Answer 2

我的xaml变成这样：

 <local:CanvaNetwork.Style>
     <Style TargetType="{x:Type local:CanvaNetwork}">
        <Setter Property="NewMouseOver" Value="False"/>
        <Style.Triggers>
          <Trigger Property="IsMouseOver" Value="True">
              <Setter Property="NewMouseOver" Value="True"/>
              <Setter Property="Cursor"  Value="Cross"/>
          </Trigger>
         </Style.Triggers>
       </Style>
     </local:CanvaNetwork.Style>             
   </local:CanvaNetwork>

我删除了`NewMouseOver =“ {Binding MyMouseOver}”

但是添加了这个：

<DataTemplate.Triggers>
   <DataTrigger Binding="{Binding ElementName=ItemCanvas_Node, Path=NewMouseOver}" Value="True">
       <Setter Property="{Binding MyMouseOver}" Value="True"/>
   </DataTrigger>
</DataTemplate.Triggers>

在添加DataTrigger代码之前，光标变成十字形，在该位置上我的“ MyMouseOver”设置程序上出现错误，它必须是依赖项属性...但这是一个依赖项属性！

如何访问自定义Canvas中的dependencyProperty

2 个答案: