使用EventTrigger设置属性 [英] Setting a property with an EventTrigger

问题描述

我希望能够使用EventTrigger设置属性，这有很多问题.

1)EventTriggers仅支持Actions，因此我必须使用StoryBoard设置我的属性.

2)使用情节提要板后，我有两个选择:

• 停止:动画停止播放后，该值将还原为动画开始播放之前的状态
• HoldEnd:这会锁定属性，因此代码和用户交互都无法更改动画持有的属性.

在下面的示例中，我希望在单击按钮时将IsChecked属性设置为False，并且希望用户能够更改IsChecked和/或希望在代码中更改该属性./p>

示例:

<EventTrigger
    SourceName="myButton"
    RoutedEvent="Button.Click">
    <EventTrigger.Actions>
        <BeginStoryboard>
            <Storyboard>
                <BooleanAnimationUsingKeyFrames
                    Storyboard.TargetName="myCheckBox"
                    Storyboard.TargetProperty="IsChecked"
                    FillBehavior="Stop">
                    <DiscreteBooleanKeyFrame
                        KeyTime="00:00:00"
                        Value="False" />
                </BooleanAnimationUsingKeyFrames>
            </Storyboard>
        </BeginStoryboard>
    </EventTrigger.Actions>
</EventTrigger>

我意识到在情节提要完成后，可以将"Completed"事件设置为False.但是，在这种情况下，我想将逻辑包含在XAML中，因为该逻辑将在自定义控件上使用，并且仅特定于UI.

解决方案

我非常喜欢XAML，因此对于此类任务，我切换到后面的代码. 附加行为是一个很好的模式.请记住，Expression Blend 3 提供了一种编程和使用行为的标准方法. Expression Community网站上有一些现有的./p>

I want to be able to set a property with an EventTrigger, there's a number of problems with this.

1) EventTriggers only support Actions, so I must use a storyBoard to set my properties.

2) Once I use a storyboard, I have two options:

• Stop: Once the animation has stopped the value reverts back to before the animation started
• HoldEnd: This locks the property, so that neither code, nor user interaction can change the property that the animation is holding.

In the below example, I want to set the IsChecked property to False when the button is clicked and I want the user to be able to change the IsChecked and/or I want to be able to change the property in code.

Example:

<EventTrigger
    SourceName="myButton"
    RoutedEvent="Button.Click">
    <EventTrigger.Actions>
        <BeginStoryboard>
            <Storyboard>
                <BooleanAnimationUsingKeyFrames
                    Storyboard.TargetName="myCheckBox"
                    Storyboard.TargetProperty="IsChecked"
                    FillBehavior="Stop">
                    <DiscreteBooleanKeyFrame
                        KeyTime="00:00:00"
                        Value="False" />
                </BooleanAnimationUsingKeyFrames>
            </Storyboard>
        </BeginStoryboard>
    </EventTrigger.Actions>
</EventTrigger>

I realize that I can use the "Completed" event after the storyboard completes to set the value to False. However, in this instance I want to contain the logic within the XAML, as this logic will be used on a custom control and is only specific to the UI.

解决方案

As much as I love XAML, for this kinds of tasks I switch to code behind. Attached behaviors are a good pattern for this. Keep in mind, Expression Blend 3 provides a standard way to program and use behaviors. There are a few existing ones on the Expression Community Site.

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