拖动时如何停止滑块的更新值? [英] How to stop update value of slider while dragging it?

问题描述

我有一个滑块，它的值绑定到某个属性，并且该属性一直在更新它.在拖动 [thumb on] 滑块时，我想阻止滑块的此更新值绑定，直到用户完成拖动.

I've slider that its value is bind to some property, and the property updates it all the time. While dragging the [thumb on] slider I want to stop this update value of slider from binding, until user finish it's dragging.

Slider 上是否有任何属性可以做到这一点，或者我需要为此编写代码?

Is there any property on Slider to do that, or I need to write code for that?

提前致谢！

推荐答案

Slider 的模板包含一个 Thumb，它会在鼠标移动时引发 ThumbDragDelta 事件.Slider 总是会在收到 ThumbDragDelta 事件时立即更新绑定值.

The template for Slider includes a Thumb, which raises the ThumbDragDelta event as the mouse is moved. Slider will always update the bound value immediately when it receives a ThumbDragDelta event.

诀窍是停止此事件.最简单的方法是继承 Slider:

The trick is to stop this event. The easiest way is to subclass Slider:

public class SliderIgnoreDelta : Slider
{
  protected override void OnThumbDragDelta(DragDeltaEventArgs e)
  {
    // Do nothing
  }
}

在拇指拖动完成之前，此滑块不会更新值.

This slider will not update the value until the thumb drag completes.

另一种解决方案是拦截 Thumb 上的 ThumbDragDelta 事件.如果您碰巧重新模板化 Slider，这可能是一个更好的解决方案.例如，如果您已经编写了一个 EventBlocker 类，在给定的 RoutedEvent 上将 Handled 设置为 true，您可以将其放入您的模板中:

Another solution is to intercept the ThumbDragDelta event on the Thumb. If you happen to be re-templating the Slider anyway, this might be a better solution. For example if you already have an EventBlocker class coded up that sets Handled true on the given RoutedEvent, you could put this in your template:

<Track.Thumb>
  <Thumb my:EventBlocker.EventToBlock="{x:Static Thumb.DragDeltaEvent}" />
</Track.Thumb>

但在大多数情况下，您可能希望使用我的第一个解决方案.

But for most cases you'll probably want to go with my first solution.

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