Question

在我的应用程序中，我有一个网格，其可见性绑定到视图模型中的属性。

我想要做的是当视图模型中的visibility属性发生变化时，网格根据可见性值淡入或淡出：Visible / Collapsed。

我怎样才能做到这一点？

Answer 1

受到“HDW Production”答案的启发，这里是Windows Store和Windows Phone Store应用程序的代码：

public class FadingVisibilityGrid : Grid
{
    public static readonly DependencyProperty DeferredVisibilityProperty = DependencyProperty.Register(
        "DeferredVisibility", typeof (Visibility), typeof (FadingVisibilityGrid), new PropertyMetadata(default(Visibility), DeferredVisibilityChanged));

    private static void DeferredVisibilityChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var newVisibility = (Visibility)e.NewValue;
        var grid = (FadingVisibilityGrid)sender;


        var animation = new DoubleAnimation
        {
            Duration = new Duration(TimeSpan.FromMilliseconds(200))
        };
        Storyboard.SetTarget(animation, grid);
        Storyboard.SetTargetProperty(animation, "Grid.Opacity");
        grid.FadeStoryBoard.Stop();
        grid.FadeStoryBoard = new Storyboard();
        grid.FadeStoryBoard.Children.Add(animation);

        if (newVisibility == Visibility.Visible)
        {
            animation.From = 0;
            animation.To = 1;
            grid.Visibility = Visibility.Visible;
            grid.FadeStoryBoard.Begin();
        }
        else
        {
            animation.From = 1;
            animation.To = 0;
            grid.FadeStoryBoard.Completed += (o, o1) =>
            {
                grid.Visibility = newVisibility;
            };
            grid.FadeStoryBoard.Begin();
        }

    }

    public Visibility DeferredVisibility
    {
        get { return (Visibility) GetValue(DeferredVisibilityProperty); }
        set { SetValue(DeferredVisibilityProperty, value); }
    }

    private Storyboard _fadeStoryBoard = new Storyboard();

    public Storyboard FadeStoryBoard
    {
        get { return _fadeStoryBoard; }
        set { _fadeStoryBoard = value; }
    }
}

Answer 2

您需要一个新的DependencyProperty，可以通过继承Grid并添加一个或创建附加属性。我们称之为DeferredVisibility，让它为Visibility类型。

当DeferredVisibility更改为Visible时，将Visibility设置为Visible，并将不透明度从0设置为1。

当DeferredVisibility更改为Collapsed时，将不透明度从1设置为0，然后将可见性设置为折叠。

Windows应用商店应用：可见性发生变化时的动画控制？

2 个答案: