如何克服ItemsPanelTemplate中的Grid.Row / Column的错误？

Question

创建了一个简单的AP属性，以简化与元素模板的绑定。代替这个：

<ItemsControl ItemsSource="{Binding Mode=OneWay, Source={StaticResource Points.Grid}}" 
              ItemsPanel="{StaticResource Grid.Panel}">
    <ItemsControl.ItemTemplate>
        <DataTemplate DataType="Point">
            <Ellipse Fill="Coral"/>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
    <ItemsControl.ItemContainerStyle>
        <Style>
            <Setter Property="Grid.Row" Value="{Binding Y}"/>
            <Setter Property="Grid.Column" Value="{Binding X}"/>
        </Style>
    </ItemsControl.ItemContainerStyle>
</ItemsControl>

Можноприменятьтакую：

<ItemsControl Grid.Row="1"
        ItemsSource="{Binding Mode=OneWay, Source={StaticResource Points.Grid}}"
        ItemsPanel="{StaticResource Grid.Panel}">
    <ItemsControl.ItemTemplate>
        <DataTemplate DataType="Point">
            <Ellipse Fill="LightBlue"
                             pa:Grid.Row="{Binding Y}"
                             pa:Grid.Column="{Binding X}"/>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl> 

这里是完整的代码所附属性：

public static partial class Grid
{
    public static int GetRow(FrameworkElement element)
    {
        return (int)element.GetValue(RowProperty);
    }

    public static void SetRow(FrameworkElement element, int value)
    {
        element.SetValue(RowProperty, value);
    }

    // Using a DependencyProperty as the backing store for Row.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty RowProperty =
        DependencyProperty.RegisterAttached("Row", typeof(int), typeof(Grid),
        new FrameworkPropertyMetadata
        (
            0,
            FrameworkPropertyMetadataOptions.AffectsParentArrange | FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
            RowChanged
        ));

    private static void RowChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (!(d is FrameworkElement element))
            throw new ArgumentException("Должен быть  FrameworkElement", nameof(d));

        FrameworkElement parent;

        while ((parent = VisualTreeHelper.GetParent(element) as FrameworkElement) != null && !(parent is System.Windows.Controls.Grid))
            element = parent;

        if (parent is System.Windows.Controls.Grid grid)
            element.SetValue(System.Windows.Controls.Grid.RowProperty, (int)e.NewValue);
    }

    private static void GridLoaded(object sender, RoutedEventArgs e)
        => ((System.Windows.Controls.Grid)sender).InvalidateMeasure();

    public static int GetColumn(FrameworkElement element)
    {
        return (int)element.GetValue(ColumnProperty);
    }

    public static void SetColumn(FrameworkElement element, int value)
    {
        element.SetValue(ColumnProperty, value);
    }

    // Using a DependencyProperty as the backing store for Column.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty ColumnProperty =
        DependencyProperty.RegisterAttached("Column", typeof(int), typeof(Grid),
            new FrameworkPropertyMetadata
            (
                0,
                FrameworkPropertyMetadataOptions.AffectsParentArrange | FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
                ColumnChanged
            ));

    private static void ColumnChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (!(d is FrameworkElement element))
            throw new ArgumentException("Должен быть  FrameworkElement", nameof(d));

        FrameworkElement parent;

        while ((parent = VisualTreeHelper.GetParent(element) as FrameworkElement) != null && !(parent is System.Windows.Controls.Grid))
            element = parent;

        if (parent is System.Windows.Controls.Grid grid)
            element.SetValue(System.Windows.Controls.Grid.ColumnProperty, (int)e.NewValue);
    }
}

属性没什么复杂的。使用Canvas，同样可以正常工作。对于网格，在将元素附加到集合中或将第一个元素添加到集合时会出现问题-元素在网格中显示而与它们的位置无关。尽管在可视树和属性浏览器中查看时，Grid.Row / Column的附加属性设置正确。并且只要在窗口中有一点变化，元素就都就位。

我认为这是一个坦率的错误。但是如何处理呢？

完整的XAML演示代码：

<Window x:Class="AttachedPropertiesWPF.BindParentWind"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:AttachedPropertiesWPF"
        mc:Ignorable="d"
        Title="BindParentWind" Height="450" Width="800"
        xmlns:pa="clr-namespace:AttachedProperties;assembly=AttachedProperties">
    <Window.Resources>
        <x:Array x:Key="Points.Grid" Type="Point">
            <Point X="1" Y="0"/>
            <Point X="0" Y="2"/>
            <Point X="2" Y="1"/>
        </x:Array>
        <ItemsPanelTemplate x:Key="Grid.Panel">
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition/>
                    <ColumnDefinition/>
                    <ColumnDefinition/>
                </Grid.ColumnDefinitions>
            </Grid>
        </ItemsPanelTemplate>
    </Window.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <ItemsControl ItemsSource="{Binding Mode=OneWay, Source={StaticResource Points.Grid}}" 
                      ItemsPanel="{StaticResource Grid.Panel}">
            <ItemsControl.ItemTemplate>
                <DataTemplate DataType="Point">
                    <Ellipse Fill="Coral"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
            <ItemsControl.ItemContainerStyle>
                <Style>
                    <Setter Property="Grid.Row" Value="{Binding Y}"/>
                    <Setter Property="Grid.Column" Value="{Binding X}"/>
                </Style>
            </ItemsControl.ItemContainerStyle>
        </ItemsControl>
        <ItemsControl Grid.Row="1"
                      ItemsSource="{Binding Mode=OneWay, Source={StaticResource Points.Grid}}"
                      ItemsPanel="{StaticResource Grid.Panel}">
            <ItemsControl.ItemTemplate>
                <DataTemplate DataType="Point">
                    <Ellipse Fill="LightBlue"
                             pa:Grid.Row="{Binding Y}"
                             pa:Grid.Column="{Binding X}"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </Grid>
</Window>

输出如下：

它应该像这样：

Answer 1

欢迎您使用SO！

老实说，此代码有很多很多问题，但我会坚持您所发布的内容....

@@ Clemens是正确的，对于如何将元素放置在网格上似乎有些困惑。在第一个ItemsControl中，您将通过ItemContainerStyle进行操作，在第二个控件中，则将其直接应用到Ellipse中（尽管使用自定义的Grid helper DP会令人困惑）。您对第一个控件所做的操作不会影响第二个控件，因此，当然，您看到的布局行为在它们之间也将有所不同。

项目模板（例如椭圆）不会直接添加到父面板容器中，而是封装在ContentPresenter中。因此，您的第一个控件是正确执行此操作。还要在第二个ItemsControl中设置ItemContainerStyle，从第二个控件中的Ellipse标记中删除ap：Grid.Row和ap：Grid.Column设置器，并完全摆脱该Grid helper类，就不需要它了。