如何在共享资源中重用VisualState,VisualStateGroup和VsualStateManager？

Question

我创建了许多按钮,它在我的Windows Phone项目中使用相同的VisualStateManager,VisualStateGroup和VisualState.然后,我想重新使用它们作为共享资源作为其他类型的元素,如边距,颜色等.

但我发现只有重用故事板的方法才能更好地重用所有VisualState.

是否有可重用VisualState的解决方案？

Answer 1

我发现我在Windows 10 UWP应用程序上测试的解决方案,我已经测试了几个选项,如反序列化XAML,克隆等,但最后我发现以下是最佳解决方案:

1 - 将VisualStateGroup设置为资源

 <Application.Resources>
   <DataTemplate x:Key="VisualStateTemplate">
    <Grid>
    <VisualStateManager.VisualStateGroups>
        <VisualStateGroup >
            <VisualState x:Name="NarrowView" >
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="0" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="Text.(RelativePanel.Below)" Value="Image" />
                    <Setter Target="Content.(RelativePanel.Below)" Value="Text" />
                </VisualState.Setters>
            </VisualState>
            <VisualState x:Name="WideView">
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="860" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="Text.(RelativePanel.RightOf)" Value="Image" />
                    <Setter Target="Content.(RelativePanel.Below)" Value="Image" />
                </VisualState.Setters>
            </VisualState>
        </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>
  </Grid>
 </DataTemplate>
</Application.Resources>

这是第一个技巧,你可以VisualStateGroup多次'加载' .

2 - 实现附加属性以设置为VisualStateGroup的控件

public class VisualStateExtensions : DependencyObject
{
    public static void SetVisualStatefromTemplate(UIElement element, DataTemplate value)
    {
        element.SetValue(VisualStatefromTemplateProperty, value);
    }

    public static DataTemplate GetVisualStatefromTemplate(UIElement element)
    {
        return (DataTemplate) element.GetValue(VisualStatefromTemplateProperty);
    }

    public static readonly DependencyProperty VisualStatefromTemplateProperty = DependencyProperty.RegisterAttached("VisualStatefromTemplate", typeof(DataTemplate), typeof(VisualStateExtensions), new PropertyMetadata(null, VisualStatefromTemplateChanged));

    private static void VisualStatefromTemplateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is FrameworkElement frameworkElement)
        {               
            var visualStateGroups = VisualStateManager.GetVisualStateGroups(frameworkElement);
            if (visualStateGroups != null)
            {
                var template = (DataTemplate) e.NewValue;
                var content = (FrameworkElement) template.LoadContent();
                if (VisualStateManager.GetVisualStateGroups(content) is IList list)
                {
                    var source = list.Cast<VisualStateGroup>().ToList();
                    var original = source.First();

                    source.RemoveAt(0);

                    visualStateGroups.Add(original);
                }
            }
        }
    }
}

这一步只是复制和粘贴,现在在你的控件中只需添加:

3 - 添加附加属性

<UserControl x:Class="Example.MyUserControl1"...>
  <RelativePanel x:Name="Root" local:VisualStateExtensions.VisualStatefromTemplate="{StaticResource VisualStateTemplate}" >
</UserControl>

 <UserControl x:Class="Example.MyUserControl2"...>
   <RelativePanel x:Name="Root" local:VisualStateExtensions.VisualStatefromTemplate="{StaticResource VisualStateTemplate}" >
</UserControl>

通过这种方式,您可以在多个控件之间共享VisualStateGroup,而无需重复代码.