在VisualStateManager中绑定到控件的属性 [英] Bind to Control's Property inside VisualStateManager
问题描述
我在Stackoverflow上搜索了此问题，但我认为其他帖子均未涵盖此问题.
I searched for this Problem on Stackoverflow, but in my opinion the other Posts do not cover this question.
在我的自定义控件中，我正在使用Visual State Manager.在视觉状态管理器内部，有一个动画可以对元素的高度进行动画处理.当我尝试绑定到控件属性时，在启动时出现以下错误:
In my Custom Control i am using a Visual State Manager. Inside the Visual State Manager there is an Animation that Animates the Height of an Element. When i try to bind to the Controls Properties i get following Error on StartUp:
其他信息:找不到参考'RelativeSource FindAncestor，AncestorType = MyNameSpace.MyControl，AncestorLevel ='1''的绑定源.BindingExpression:Path = ActualHeight;DataItem = null;目标元素是"DoubleAnimation"(HashCode = 562002)；目标属性是"To"(类型为"Nullable'1")
Additional information: Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType=MyNameSpace.MyControl, AncestorLevel='1''. BindingExpression:Path=ActualHeight; DataItem=null; target element is 'DoubleAnimation' (HashCode=562002); target property is 'To' (type 'Nullable`1')
我的控件如下:
<Style TargetType="{x:Type local:MyControl}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:MyControl}">
<Grid x:Name="RootGrid" >
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="someElement"
Storyboard.TargetProperty="Height"
From="0"
To="{Binding RelativeSource={RelativeSource AncestorType=local:MyControl}, Path=CustomControlProperty}"
Duration="0:0:.7" />
...
我尝试了所有方式的绑定，但是似乎动画总是以自己为作用域.
I tried all ways of Bindings, but it seems that the Animations always takes itself as Scope.
再次感谢您的帮助.
推荐答案
我能够使用 BindingProxy /code> .我发现绑定代理是非直觉的.有时他们会在第一张照片上工作；这个经历了一点尝试和错误.而且，它们只是冰雹解决方案的一部分.
I was able to do this with a BindingProxy. I find binding proxies to be nonintuitive. Sometimes they work on the first shot; this one took a little trial and error. Also, they're a little bit of a hail-mary workaround.
XAML:
<Grid
x:Name="RootGrid"
>
<Grid.Resources>
<!--
When defined in ControlTemplate.Resources, this failed.
TemplateBinding failed too.
-->
<local:BindingProxy
x:Key="CustomControlPropertyProxy"
Data="{Binding CustomControlProperty, RelativeSource={RelativeSource TemplatedParent}}"
/>
</Grid.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimation
Storyboard.TargetName="someElement"
Storyboard.TargetProperty="Height"
From="0"
To="{Binding Data, Source={StaticResource CustomControlPropertyProxy}}"
Duration="0:0:5"
/>
</Storyboard>
C#(被盗，不是第一次，来自此答案):
C# (stolen, not for the first time, from this answer):
public class BindingProxy : Freezable
{
#region Overrides of Freezable
protected override Freezable CreateInstanceCore()
{
return new BindingProxy();
}
#endregion
public object Data
{
get { return (object)GetValue(DataProperty); }
set { SetValue(DataProperty, value); }
}
public static readonly DependencyProperty DataProperty =
DependencyProperty.Register("Data", typeof(object),
typeof(BindingProxy));
}
如果您最终将动画属性绑定到模板化父对象的多个属性，则这是XAML的另一种变体:
Here's another variant of the XAML, in case you end up binding animation properties to more than one property of the templated parent:
<Grid
x:Name="RootGrid"
>
<Grid.Resources>
<local:BindingProxy
x:Key="TemplatedParentProxy"
Data="{Binding ., RelativeSource={RelativeSource TemplatedParent}}"
/>
</Grid.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimation
Storyboard.TargetName="someElement"
Storyboard.TargetProperty="Height"
From="0"
To="{Binding Data.CustomControlProperty, Source={StaticResource TemplatedParentProxy}}"
Duration="0:0:5"
/>
</Storyboard>
盲人小巷
排除了 TemplateBinding 和 {RelativeSource TemplatedParent} 之后，我的下一个猜测是将 RootGrid.Tag 绑定到 CustomControlProperty ，并使用 To ="{Binding Tag，ElementName = RootGrid}" .那没有用.尽管intellisense在XAML设计器中了解 RootGrid ，但 Binding 在运行时找不到 RootGrid :
Blind Alleys
After ruling out TemplateBinding and {RelativeSource TemplatedParent}, my next guess was to bind RootGrid.Tag to CustomControlProperty and use To="{Binding Tag, ElementName=RootGrid}". That did not work. While intellisense knew about RootGrid in the XAML designer, the Binding couldn't find RootGrid at runtime:
<DoubleAnimation
Storyboard.TargetName="someElement"
Storyboard.TargetProperty="Height"
From="0"
To="{Binding Tag, ElementName=RootGrid, PresentationTraceSources.TraceLevel=High}"
Duration="0:0:1"
/>
调试跟踪:
System.Windows.Data Warning: 67 : BindingExpression (hash=15221148): Resolving source
System.Windows.Data Warning: 69 : BindingExpression (hash=15221148): Framework mentor not found
System.Windows.Data Warning: 67 : BindingExpression (hash=15221148): Resolving source (last chance)
System.Windows.Data Warning: 69 : BindingExpression (hash=15221148): Framework mentor not found
System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=Tag; DataItem=null; target element is 'DoubleAnimation' (HashCode=44950942); target property is 'To' (type 'Nullable`1')
治理FrameworkElement或FrameworkContentElement"爵士乐也是所有其他方法的基本问题.那就是绑定代理的用武之地:资源查找不受可视树父链的限制.
That "governing FrameworkElement or FrameworkContentElement" jazz is the essential problem with all of the other approaches as well. That's where binding proxies come in: Resource lookup isn't limited by that visual tree parent chain stuff.
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