Question

我的Windows应用商店应用中有一组ScrollViewer，需要在双击时始终执行操作（即，扩展为完整大小）。它们位于不同的文件中，或者我可能只是将它放在该文件的代码隐藏中：

private void ScrollViewer_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
{
    ScrollViewer sv = (ScrollViewer)sender;
    if (sv.HorizontalScrollBarVisibility == ScrollBarVisibility.Disabled)
    {
        sv.HorizontalScrollBarVisibility = ScrollBarVisibility.Hidden;
    }
    else
    {
        sv.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
    }
}

我被告知要调查行为，所以我研究了行为，并在几个在线教程的帮助下，我能够想出这个：

class ViewboxDoubleTap : DependencyObject, IBehavior
{
    public interface IBehavior
    {
        DependencyObject AssociatedObject { get; }
        void Attach(DependencyObject associatedObject);
        void Detach();
    }

    public void Attach(DependencyObject associatedObject)
    {
        if ((associatedObject != AssociatedObject) && !DesignMode.DesignModeEnabled)
        {
            if (AssociatedObject != null)
                throw new InvalidOperationException("Cannot attach behavior multiple times.");

            AssociatedObject = associatedObject;
            var fe = AssociatedObject as FrameworkElement;
            if (fe != null)
            {
                fe.AddHandler(UIElement.DoubleTappedEvent, new DoubleTappedEventHandler(ScrollViewer_DoubleTapped), true);
            }
        }
    }

    public void Detach()
    {
        var fe = AssociatedObject as FrameworkElement;
        if (fe != null)
        {
            fe.RemoveHandler(UIElement.DoubleTappedEvent, new DoubleTappedEventHandler(ScrollViewer_DoubleTapped));
        }

        AssociatedObject = null;
    }

    public DependencyObject AssociatedObject { get; private set; }

    private void ScrollViewer_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
    {
        ScrollViewer sv = (ScrollViewer)sender;
        if (sv.HorizontalScrollBarVisibility == ScrollBarVisibility.Disabled)
        {
            sv.HorizontalScrollBarVisibility = ScrollBarVisibility.Hidden;
        }
        else
        {
            sv.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
        }
    }
}

现在，所有内容都编译得很好，但我无法将其附加到XAML：

XML命名空间：

xmlns:i="using:Microsoft.Xaml.Interactivity"
xmlns:core="using:Microsoft.Xaml.Interactions.Core"
xmlns:local="using:MyApp.Folder"
xmlns:global="using:MyApp"

相关代码：

<ScrollViewer HorizontalAlignment="Left" VerticalScrollBarVisibility="Hidden" MaxZoomFactor="2" MinZoomFactor="1" MaxWidth="1067">

    <i:Interaction.Behaviors>
        <core:EventTriggerBehavior EventName="DoubleTapped">
            <global:ViewboxDoubleTap />
        </core:EventTriggerBehavior>
    </i:Interaction.Behaviors>

    <Border BorderBrush="Black" BorderThickness="1">
        <Image Source="MyImage.png"/>
    </Border>
</ScrollViewer>

当我尝试转到此页面时，没有任何反应，当我调试时，它会给我这个错误消息：

WinRT information: Cannot add instance of type 'LearnOneNote.ViewboxDoubleTap' to a collection of type 'Microsoft.Xaml.Interactivity.ActionCollection'. [Line: 25 Position: 30]

此外，它告诉我ViewboxDoubleTap不在namespace MyApp，但是当我输入<global:时，它会将其拉出来;我不知道这对这个问题是否重要。

任何帮助将不胜感激。

Answer 1

在被要求查看IAction（谢谢你，franssu）之后，我想出了这个：

[DefaultEvent(typeof(ScrollViewer),"DoubleTapped")]
public class ScrollViewerDoubleTap : DependencyObject, IAction
{
    public object Execute(object sender, object parameter)
    {
        ScrollViewer sv = (ScrollViewer)sender;
        if (sv.HorizontalScrollBarVisibility == ScrollBarVisibility.Disabled)
        {
            sv.HorizontalScrollBarVisibility = ScrollBarVisibility.Hidden;
        }
        else
        {
            sv.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
        }
        return sender;
    }
}

这很有效。

Windows-Runtime应用程序中的行为

1 个答案: