F#中的自定义路由事件 [英] Custom Routed Event in F#

问题描述

我正在尝试翻译此C#代码.到目前为止，我的尝试:

I'm trying to translate this C# code. My attempt so far:

type MyButtonSimple() as self =
    inherit Button()

    static let TapEvent =
        EventManager.RegisterRoutedEvent
            ( "Tap", RoutingStrategy.Bubble, 
              typeof<RoutedEventHandler>, typeof<MyButtonSimple>)

    let tapEvent = new Event<RoutedEventHandler, RoutedEventArgs>()
    let raiseTapEvent() =
        let newEventArgs = new RoutedEventArgs(TapEvent)
        tapEvent.Trigger(self, newEventArgs)

    [<CLIEvent>]
    member x.Tap = tapEvent.Publish 

    // For demonstration purposes we raise the event when clicked
    override self.OnClick() =
        raiseTapEvent()

MainWindow.xaml

MainWindow.xaml

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:funk="clr-namespace:funk;assembly=appWPF"
    Title="Routed" Height="300" Width="400">
    <StackPanel Background="LightGray">
        <funk:MyButtonSimple Content="Spin" Background="#808080" Foreground="LightGray">
            <funk:MyButtonSimple.RenderTransform>
                <TransformGroup>
                    <RotateTransform x:Name="rotate"/>
                </TransformGroup>
            </funk:MyButtonSimple.RenderTransform>
            <funk:MyButtonSimple.Triggers>
                <EventTrigger RoutedEvent="funk:MyButtonSimple.Tap">
                    <BeginStoryboard>
                        <Storyboard RepeatBehavior="Forever">
                            <DoubleAnimation 
                                Storyboard.TargetName="rotate"
                                Storyboard.TargetProperty="Angle"
                                From="0" To="90" Duration="0:0:2"/>
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </funk:MyButtonSimple.Triggers>
        </funk:MyButtonSimple>
    </StackPanel>
</Window>

单击按钮不会启动动画.

Clicking the button doesn't start the animation.

将代码RoutedEvent="funk:MyButtonSimple.Tap"更改为RoutedEvent="GotFocus"给出了一个有效的示例(Button.Click被覆盖).

Changing the code RoutedEvent="funk:MyButtonSimple.Tap" to RoutedEvent="GotFocus" gives a working example (Button.Click is overridden).

有什么想法我在做什么错吗?

Any ideas what I'm doing wrong?

推荐答案

这很棘手，因为它做了很多F#中不标准的事情.

This is tricky because it's doing quite a bit of things that aren't standard in F#.

该C#代码的翻译如下:

A translation of that C# code would be:

type MyButtonSimple() as self =
    inherit Button()

    static let tapEvent = 
       EventManager.RegisterRoutedEvent
            ( "Tap", RoutingStrategy.Bubble, 
              typeof<RoutedEventHandler>, typeof<MyButtonSimple>)

    // Create a custom event so you can override AddHandler/RemoveHandler behavior
    let tapEvent = 
        { new IDelegateEvent<RoutedEventHandler> with
            member this.AddHandler del = self.AddHandler(MyButtonSimple.TapEvent, del)
            member this.RemoveHandler del = self.RemoveHandler(MyButtonSimple.TapEvent, del) }

    // Raise via routed eventing strategy
    let raiseTapEvent() =
        let newEventArgs = new RoutedEventArgs(MyButtonSimple.TapEvent)
        self.RaiseEvent newEventArgs

    // This isn't exactly the same, but public static fields aren't allowed in F#, and
    // this works for WPF
    static member TapEvent with get() = tapEvent  

    [<CLIEvent>]
    member x.Tap = tapEvent

    // For demonstration purposes we raise the event when clicked
    override self.OnClick() =
        raiseTapEvent()

这里的主要陷阱"是您需要覆盖标准事件行为，这需要您自己实现IDelegateEvent而不是使用常规的F#事件管理.另外，您无法在F#中执行公共静态只读字段，因此这会将事件包装到一个属性中.即使这不是实现路由事件的标准"方式，WPF似乎也可以.

The main "gotchas" here are that you need to override the standard event behavior, which requires implementing IDelegateEvent yourself instead of using the normal F# event management. Also, you can't do public static readonly fields in F#, so this wraps the event into a property. WPF seems to be fine with this, even though it's not the "standard" way to implement routed events.

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