Question

我是wpf的初学者，今天我遇到了一个奇怪的问题，如果我向网格列添加动画，gridsplitter就会停止工作，下面是代码片段，它是一个毫无意义但很简单的测试代码，它确实什么都没有，除非当鼠标进入右列时，它的宽度将从15扩展到100

    <Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Name="c1"/>
        <ColumnDefinition Name="c2" Width="15" MinWidth="15"/>
    </Grid.ColumnDefinitions>
    <Border Grid.Column="0" Background="Gray"></Border>
    <GridSplitter Width="8" Background="Yellow"></GridSplitter>
    <Border Grid.Column="1" Background="Silver" Name="bdRight" MouseEnter="bdRight_MouseEnter"></Border>
</Grid>

和此：

        bool flag = true;
    private void bdRight_MouseEnter(object sender, MouseEventArgs e)
    {
        if (flag)
        {
            flag = false;
            var da = new GridLengthAnimation();
            da.From = new GridLength(c2.MinWidth);
            da.To = new GridLength(100);
            var ef = new BounceEase();
            ef.EasingMode = EasingMode.EaseOut;
            da.EasingFunction = ef;
            this.c2.BeginAnimation(ColumnDefinition.WidthProperty, da);
        }
    }

这里是GridLengthAnimation，我发现DoubleAnimation不能用于网格列的宽度，我从互联网上得到它。

public class GridLengthAnimation : AnimationTimeline
{
    public static readonly DependencyProperty FromProperty;
    public static readonly DependencyProperty ToProperty;
    public static readonly DependencyProperty EasingFunctionProperty;

    static GridLengthAnimation()
    {
        FromProperty = DependencyProperty.Register("From", typeof(GridLength), typeof(GridLengthAnimation));
        ToProperty = DependencyProperty.Register("To", typeof(GridLength), typeof(GridLengthAnimation));
        EasingFunctionProperty = DependencyProperty.Register("EasingFunction", typeof(IEasingFunction), typeof(GridLengthAnimation));
    }

    protected override Freezable CreateInstanceCore()
    {
        return new GridLengthAnimation();
    }

    public override Type TargetPropertyType
    {
        get { return typeof(GridLength); }
    }

    public IEasingFunction EasingFunction
    {
        get
        {
            return (IEasingFunction)GetValue(GridLengthAnimation.EasingFunctionProperty);
        }
        set
        {
            SetValue(GridLengthAnimation.EasingFunctionProperty, value);
        }

    }

    public GridLength From
    {
        get
        {
            return (GridLength)GetValue(GridLengthAnimation.FromProperty);
        }
        set
        {
            SetValue(GridLengthAnimation.FromProperty, value);
        }
    }

    public GridLength To
    {
        get
        {
            return (GridLength)GetValue(GridLengthAnimation.ToProperty);
        }
        set
        {
            SetValue(GridLengthAnimation.ToProperty, value);
        }
    }

    public override object GetCurrentValue(object defaultOriginValue, object defaultDestinationValue, AnimationClock animationClock)
    {
        double fromValue = ((GridLength)GetValue(GridLengthAnimation.FromProperty)).Value;
        double toValue = ((GridLength)GetValue(GridLengthAnimation.ToProperty)).Value;

        IEasingFunction easingFunction = this.EasingFunction;

        double progress = (easingFunction != null) ? easingFunction.Ease(animationClock.CurrentProgress.Value) : animationClock.CurrentProgress.Value;

        if (fromValue > toValue)
        {
            return new GridLength((1 - progress) * (fromValue - toValue) + toValue, this.To.IsStar ? GridUnitType.Star : GridUnitType.Pixel);
        }
        else
        {
            return new GridLength((progress) * (toValue - fromValue) + fromValue, this.To.IsStar ? GridUnitType.Star : GridUnitType.Pixel);
        }
    }
}

如果我在MouseEnter事件处理程序中注释掉代码，则分割器工作正常，否则它将停止工作。有什么想法吗？

Answer 1

您必须设置动画的FillBehavior属性。默认值为HoldEnd，这意味着动画在结束后保留最终值。如果将FillBehavior设置为Stop，则动画值将恢复为动画之前的值。

如果将以下行添加到事件处理程序代码中，它应该按预期工作：

...
da.FillBehavior = FillBehavior.Stop;
c2.Width = da.To; // set final value before starting the animation
c2.BeginAnimation(ColumnDefinition.WidthProperty, da);

如果在开始动画之前设置最终值会产生闪烁效果，您可以改为在Completed处理程序中设置最终值：

...
da.FillBehavior = FillBehavior.Stop;
da.Completed += (s, e) => c2.Width = da.To;
c2.BeginAnimation(ColumnDefinition.WidthProperty, da);

Answer 2

只是为了扩展早期的答案（会发表评论但不允许stackoverflow overmaster）：

对我来说，在开始动画之前设置最终值会在动画开始前一瞬间为我的网格生成一个难看的闪烁效果。

我所做的是使用上面提到的FillBehavior.Stop但是订阅了Animation.Completed事件并在那里设置了网格列的最终高度。

像一个没有任何闪烁的魅力。

将动画应用于网格列后，GridSplitter无法正常工作

2 个答案: