C# WPF System.Windows.Data Error: 4 の Binding Error メモ
2024-02-27
ざっくり
C# WPF で System.Windows.Controls.MenuItem のレイアウトデザインを xaml 連携で弄ってたら
Binding Error が出てきたのでちょっとだけ掘り下げたメモ
MenuItem 用に、独自 System.Windows.Style を組んで割り当てていた事(だけ)が原因かと思ったけど、
どうやらそれだけでも無い…らしい？ あまり掘り下げてないので適当な書き散らしです
コード類
App.xaml 側 リソース定義 抜粋 ( 長めの定義は 記事後半に載せました )
<Style x:Key="EditSubMenuitem" TargetType="{x:Type MenuItem}">
<Setter Property="VerticalContentAlignment" Value="Stretch"/>
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<!-- 以下クソ長いので省略 -->
</Style>今回ベースとなる コードビハインド側
Style _editSubMenuiItemStyle = (Style)(App.Current.Resources["EditSubMenuitem"]);
System.Windows.Controls.MenuItem _menuItem = new MenuItem();
// 以下、プロパティとか弄ったり、
// コントロールとかに突っ込んで HogeHogeしたい出てきたエラー文言
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')自環境でのとりあえず解決ムーブ
※ おま環 は否めない
順番を弄るとよさそう？
▼ 最速で MenuItem.Style に割り当てから他プロパティを弄る
エラーなし
MenuItem _menuItem = new MenuItem();
_menuItem.Style = _editSubMenuiItemStyle;
_menuItem.Header = "ほげほげ";エラーあり
MenuItem _menuItem = new MenuItem();
_menuItem.Header = "ほげほげ";
_menuItem.Style = _editSubMenuiItemStyle;▼ 手付でプロパティ割り当て
エラーなし
MenuItem _menuItem = new MenuItem();
_menuItem.Header = "ほげほげ";
_menuItem.VerticalContentAlignment = VerticalAlignment.Center;
_menuItem.HorizontalContentAlignment = System.Windows.HorizontalAlignment.Stretch;
_menuItem.Style = _editSubMenuiItemStyle;エラーあり
MenuItem _menuItem = new MenuItem();
_menuItem.Header = "ほげほげ";
_menuItem.Style = _editSubMenuiItemStyle;
_menuItem.VerticalContentAlignment = VerticalAlignment.Center;
_menuItem.HorizontalContentAlignment = System.Windows.HorizontalAlignment.Stretch;これは？
▼ コードビハインドは下記の順序固定で、xaml 側の2プロパティ記述を削った動作差分
MenuItem _menuItem = new MenuItem();
_menuItem.Style = _editSubMenuiItemStyle;
_menuItem.Header = "ほげほげ";エラーなし
<Style x:Key="EditSubMenuitem" TargetType="{x:Type MenuItem}">
<Setter Property="VerticalContentAlignment" Value="Stretch"/>
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<!-- 以下略 -->
</Style>削るとエラー出る
<Style x:Key="EditSubMenuitem" TargetType="{x:Type MenuItem}">
<!--Setter Property="VerticalContentAlignment" Value="Stretch"/-->
<!--Setter Property="HorizontalContentAlignment" Value="Center"/-->
<!-- 以下略 -->
</Style>App.xaml 側
本ケースで利用していた System.Windows.Controls.MenuItem 用の System.Windows.Style です。
雑ですんまそん
見てると頭痛くなってくる；；
<Application.Resources>
<Style x:Key="EditSubMenuitem" TargetType="MenuItem">
<Setter Property="FontSize" Value="20"/>
<Setter Property="VerticalContentAlignment" Value="Stretch"/>
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="MenuItem">
<Border x:Name="templateRoot" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
<Grid VerticalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<ContentPresenter x:Name="Icon" Content="{TemplateBinding Icon}" ContentSource="Icon" HorizontalAlignment="Center" Height="16" Margin="0,0,0,0" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="Center" Width="16"/>
<Path x:Name="GlyphPanel" Data="F1M10,1.2L4.7,9.1 4.5,9.1 0,5.2 1.3,3.5 4.3,6.1 8.3,0 10,1.2z" Fill="{TemplateBinding Foreground}" FlowDirection="LeftToRight" Margin="3" Visibility="Collapsed" VerticalAlignment="Center"/>
<ContentPresenter TextElement.FontSize="12" ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Grid.Column="1" ContentStringFormat="{TemplateBinding HeaderStringFormat}" ContentSource="Header" Margin="2,0,7,0" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
<Popup Grid.Column="1" x:Name="PART_Popup" AllowsTransparency="True" Focusable="False" IsOpen="{Binding IsSubmenuOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{DynamicResource {x:Static SystemParameters.MenuPopupAnimationKey}}" Placement="Right">
<Border x:Name="SubMenuBorder" BorderBrush="#FF999999" BorderThickness="1" Background="#FFF0F0F0" Padding="2">
<ScrollViewer x:Name="SubMenuScrollViewer" Style="{DynamicResource {ComponentResourceKey ResourceId=MenuScrollViewer, TypeInTargetAssembly={x:Type FrameworkElement}}}">
<Grid RenderOptions.ClearTypeHint="Enabled">
<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
<Rectangle x:Name="OpaqueRect" Fill="{Binding Background, ElementName=SubMenuBorder}" Height="{Binding ActualHeight, ElementName=SubMenuBorder}" Width="{Binding ActualWidth, ElementName=SubMenuBorder}"/>
</Canvas>
<Rectangle Fill="#FFD7D7D7" HorizontalAlignment="Left" Margin="29,2,0,2" Width="1"/>
<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Cycle" Grid.IsSharedSizeScope="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" KeyboardNavigation.TabNavigation="Cycle"/>
</Grid>
</ScrollViewer>
</Border>
</Popup>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSuspendingPopupAnimation" Value="True">
<Setter Property="PopupAnimation" TargetName="PART_Popup" Value="None"/>
</Trigger>
<Trigger Property="IsChecked" Value="True">
<Setter Property="Visibility" TargetName="GlyphPanel" Value="Visible"/>
<Setter Property="Visibility" TargetName="Icon" Value="Collapsed"/>
</Trigger>
<Trigger Property="IsHighlighted" Value="True">
<Setter Property="Background" TargetName="templateRoot" Value="#3D26A0DA"/>
<Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF26A0DA"/>
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="TextElement.Foreground" TargetName="templateRoot" Value="#FF707070"/>
<Setter Property="Fill" TargetName="GlyphPanel" Value="#FF707070"/>
</Trigger>
<Trigger Property="CanContentScroll" SourceName="SubMenuScrollViewer" Value="False">
<Setter Property="Canvas.Top" TargetName="OpaqueRect" Value="{Binding VerticalOffset, ElementName=SubMenuScrollViewer}"/>
<Setter Property="Canvas.Left" TargetName="OpaqueRect" Value="{Binding HorizontalOffset, ElementName=SubMenuScrollViewer}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Application.Resources>