c# - 动态菜单项中的 "System.Windows.Data Error: 4"

Question

我有一个 WPF MenuControl，我在运行时向其添加了几个菜单项。如果你有兴趣知道，原因是我们从数据库中读取数据并需要根据返回的数据创建 MenuItems。我们有我所说的复杂菜单样式(至少读起来很复杂 :))。现在，当我添加我的菜单项时，我不断在 Visual Studio 的调试窗口中收到此错误:

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')

我猜根据添加的 MenuItems 的数量，这两个重复了几次。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 自行下降(打开)，只需将鼠标移到它上面(而不是像往常一样单击它)。所以，我想一个与另一个有关。

知道发生了什么事吗？？ MenuControlCode 相当长，但如果需要，我也可以发布。

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>

Answer 1

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，在类的构造函数中将数据绑定(bind)源开关级别设置为关键。

public TestSample() //constructor of the class
{
   InitializeComponent();

   System.Diagnostics.PresentationTraceSources.DataBindingSource.Switch.Level =    System.Diagnostics.SourceLevels.Critical;

}