我有一个WPF MenuControl，我在运行时向其中添加了几个菜单项。如果您有兴趣知道，原因是我们从数据库中读取了数据，并且需要根据返回的数据创建MenuItems。我们要说的是一种复杂的菜单样式(至少是复杂的阅读:))。现在，当我添加菜单项时，我在Visual Studio的“调试”窗口中不断收到此错误:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
根据添加的MenuItem的数量，我猜这两次重复了几次。我注意到的另一个奇怪的行为是，在调试窗口中出现这些错误之后，MenuControl仅通过将鼠标移到它上面(而不是像通常那样单击它)就自行下拉(打开)。因此，我想其中一个与另一个有关。
任何想法怎么回事？ MenuControlCode相当长，但是如果需要，我也可以发布它。
这是MenuControl的XAML代码。之后，在代码中，我只使用“PrincipalMenu”并根据需要向其添加MenuItems:
<UserControl x:Class="EOGMapControl.MainPropertyGUI.MenuControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="41" d:DesignWidth="380">
<UserControl.Resources>
<SolidColorBrush x:Key="HighlightedBackgroundBrush" Color="#FFDEDEDE" />
<SolidColorBrush x:Key="MenuBackgroundBrush" Color="White" />
<SolidColorBrush x:Key="NormalBorderBrush" Color="#FFE5DFDF" />
<SolidColorBrush x:Key="SolidMenuFontBrush" Color="Black" />
<SolidColorBrush x:Key="HighlightedText" Color="White" />
<SolidColorBrush x:Key="menuItemBrush" Color="#FFB7B7B7" />
<SolidColorBrush x:Key="WindowBackgroundBrush" Color="#FFF" />
<SolidColorBrush x:Key="SolidBorderBrush" Color="#888" />
<Style x:Key="{x:Type Menu}" TargetType="{x:Type Menu}">
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="Height" Value="25"/>
<Setter Property="Foreground" Value="{StaticResource SolidMenuFontBrush}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Menu}">
<Border
Background="{StaticResource MenuBackgroundBrush}"
BorderBrush="{StaticResource MenuBackgroundBrush}"
BorderThickness="1">
<StackPanel ClipToBounds="True" Orientation="Horizontal" IsItemsHost="True"/>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="{x:Type MenuItem}" TargetType="{x:Type MenuItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type MenuItem}">
<Border x:Name="Border"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="0">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition x:Name="Col0" MinWidth="17" Width="Auto" SharedSizeGroup="MenuItemIconColumnGroup"/>
<ColumnDefinition Width="Auto" SharedSizeGroup="MenuTextColumnGroup"/>
<ColumnDefinition Width="Auto" SharedSizeGroup="MenuItemIGTColumnGroup"/>
<ColumnDefinition x:Name="Col3" Width="14"/>
</Grid.ColumnDefinitions>
<!-- ContentPresenter to show an Icon if needed -->
<ContentPresenter Grid.Column="0" Margin="4,0,6,0" x:Name="Icon" VerticalAlignment="Center" ContentSource="Icon"/>
<!-- Glyph is a checkmark if needed for a checkable menu -->
<Grid Grid.Column="0" Visibility="Hidden" Margin="4,0,6,0" x:Name="GlyphPanel" VerticalAlignment="Center">
<Path x:Name="GlyphPanelpath" VerticalAlignment="Center" Fill="{TemplateBinding Foreground}" Data="M0,2 L0,4.8 L2.5,7.4 L7.1,2.8 L7.1,0 L2.5,4.6 z" FlowDirection="LeftToRight"/>
</Grid>
<!-- Content for the menu text etc -->
<ContentPresenter Grid.Column="1"
Margin="{TemplateBinding Padding}"
x:Name="HeaderHost"
RecognizesAccessKey="True"
ContentSource="Header"/>
<!-- Content for the menu IGT -->
<ContentPresenter Grid.Column="2"
Margin="8,1,8,1"
x:Name="IGTHost"
ContentSource="InputGestureText"
VerticalAlignment="Center"/>
<!-- Arrow drawn path which points to the next level of the menu -->
<Grid Grid.Column="3" Margin="4,0,6,0" x:Name="ArrowPanel" VerticalAlignment="Center">
<Path x:Name="ArrowPanelPath" HorizontalAlignment="Right" VerticalAlignment="Center" Fill="{TemplateBinding Foreground}" Data="M0,0 L0,8 L4,4 z"/>
</Grid>
<!--IsOpen="{Binding Path=IsSubmenuOpen, RelativeSource={RelativeSource TemplatedParent}}"
PopupAnimation="{DynamicResource {x:Static SystemParameters.MenuPopupAnimationKey}}"
-->
<!-- The Popup is the body of the menu which expands down or across depending on the level of the item -->
<Popup Placement="Right" IsOpen="{TemplateBinding IsSubmenuOpen}" x:Name="SubMenuPopup" Focusable="false" PopupAnimation="Fade">
<Border x:Name="SubMenuBorder" SnapsToDevicePixels="True" Background="{StaticResource WindowBackgroundBrush}" BorderBrush="{StaticResource SolidBorderBrush}" BorderThickness="1" Padding="2,2,2,2">
<Grid x:Name="SubMenu" Grid.IsSharedSizeScope="True">
<!--StackPanel holds children of the menu. This is set by IsItemsHost=True-->
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Cycle"/>
<!--<ScrollViewer CanContentScroll="True">
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Cycle" />
</ScrollViewer>-->
</Grid>
</Border>
</Popup>
</Grid>
</Border>
<!-- These triggers re-configure the four arrangements of MenuItem to show different levels of menu via Role -->
<ControlTemplate.Triggers>
<!-- Role = TopLevelItem : this is a child menu item from the top level without any child items-->
<Trigger Property="Role" Value="TopLevelItem">
<Setter Property="Padding" Value="6,1,6,1"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="ArrowPanel"/>
</Trigger>
<!-- Role = SubMenuHeader : this is a child menu item which does not have children -->
<Trigger Property="Role" Value="SubmenuHeader">
<Setter Property="DockPanel.Dock" Value="Top"/>
<Setter Property="Padding" Value="0,2,0,2"/>
</Trigger>
<!-- Role = SubMenuItem : this is a child menu item which has children-->
<Trigger Property="Role" Value="SubmenuItem">
<Setter Property="DockPanel.Dock" Value="Top"/>
<Setter Property="Padding" Value="0,2,0,2"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="ArrowPanel"/>
</Trigger>
<Trigger Property="IsSuspendingPopupAnimation" Value="true">
<Setter Property="PopupAnimation" Value="None" TargetName="SubMenuPopup"/>
</Trigger>
<!-- If no Icon is present the we collapse the Icon Content -->
<Trigger Property="Icon" Value="{x:Null}">
<Setter Property="Visibility" Value="Collapsed" TargetName="Icon"/>
</Trigger>
<!-- The GlyphPanel contains the CheckMark -->
<Trigger Property="IsChecked" Value="true">
<Setter Property="Visibility" Value="Visible" TargetName="GlyphPanel"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="Icon"/>
</Trigger>
<!-- Using the system colors for the Menu Highlight and IsEnabled-->
<Trigger Property="IsHighlighted" Value="true">
<Setter Property="Background" Value="{StaticResource HighlightedBackgroundBrush}" TargetName="Border"/>
<Setter Property="Foreground" Value="{StaticResource HighlightedText}"/>
<Setter Property="BorderBrush" Value="{StaticResource NormalBorderBrush}" TargetName="Border"/>
</Trigger>
<Trigger Property="IsHighlighted" Value="false">
<Setter Property="Background" Value="{StaticResource MenuBackgroundBrush}" TargetName="Border"/>
<Setter Property="Foreground" Value="{StaticResource SolidMenuFontBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource MenuBackgroundBrush}" TargetName="Border"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="LightGray"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>
<UserControl.Foreground>
<SolidColorBrush />
</UserControl.Foreground>
<Grid Height="24" Width="250" HorizontalAlignment="Left">
<Grid.Background>
<SolidColorBrush />
</Grid.Background>
<Menu Name="PrincipalMenu" Margin="0,0,-100,0">
</Menu>
</Grid>
最佳答案
请引用以下链接:
http://www.codeproject.com/Tips/124556/How-to-suppress-the-System-Windows-Data-Error-warn
解决方案是，将数据绑定(bind)源开关级别设置为该类的构造函数中的关键级别。
public TestSample() //constructor of the class
{
InitializeComponent();
System.Diagnostics.PresentationTraceSources.DataBindingSource.Switch.Level = System.Diagnostics.SourceLevels.Critical;
}