WPF ItemsControl.ItemsPanelTemplate作為網格並在不同的列中添加新項目

Question

我正在動態創建的網格中工作，在每個新列中都包含一個添加到ItemsControl的新項目。

我正在使用Rachel Lim的GridHelper

現在，我有一個如下的主窗口，

XAML代碼：

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication1"
    Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <local:StarsConverter x:Key="conv"/>
    </Window.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="9*"/>
        </Grid.ColumnDefinitions>
        <Button Grid.Column="0" Command="{Binding Add}"/>
        <ItemsControl x:Name="list" Grid.Column="1" ItemsSource="{Binding Oc}">
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <Grid x:Name="grid" Background="Black"
                      local:GridHelpers.StarColumns="{Binding ColumnCount, Converter={StaticResource conv}, Mode=OneWay}" local:GridHelpers.ColumnCount="{Binding ColumnCount}"/>
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <Canvas Loaded="canvas_Loaded" x:Name="canvas" Background="White">
                        <Border  Canvas.Left="25" Canvas.Top="25" Height="25" Width="50" Background="Red">
                            <TextBlock Text="{Binding}"/>
                        </Border>
                    </Canvas>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </Grid>
</Window>

和Xaml.cs

public partial class MainWindow : Window
{
    private Canvas canvas;
    public MainWindow()
    {
        InitializeComponent();

        this.DataContext = new ViewModel();
    }

    private void canvas_Loaded(object sender, RoutedEventArgs e)
    {
        ViewModel vm = this.DataContext as ViewModel;
        canvas = sender as Canvas;
        Binding b = new Binding();
        b.Source = vm;
        b.Path = new PropertyPath(ViewModel.ColumnCountProperty);
        b.Mode = BindingMode.OneWay;
        canvas.SetBinding(Grid.ColumnProperty, b);
    }
}

此MainWindow具有一個ViewModel作為DataContext：

public class ViewModel : DependencyObject
{
    private RelayCommand add;

    public ViewModel()
    {
    }

    public ObservableCollection<String> Oc
    {
        get { return (ObservableCollection<String>)GetValue(OcProperty); }
        set { SetValue(OcProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Oc.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty OcProperty =
        DependencyProperty.Register("Oc", typeof(ObservableCollection<String>), typeof(ViewModel), new UIPropertyMetadata(new ObservableCollection<string>()));

    public int ColumnCount
    {
        get { return (int)GetValue(ColumnCountProperty); }
        set { SetValue(ColumnCountProperty, value); }
    }

    // Using a DependencyProperty as the backing store for ColumnCount.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty ColumnCountProperty =
        DependencyProperty.Register("ColumnCount", typeof(int), typeof(ViewModel), new UIPropertyMetadata(0));

    public RelayCommand Add
    {
        get
        {
            if (this.add == null)
                this.add = new RelayCommand(param => this.AddString(), param => this.CanAddString());
            return this.add;
        }
    }

    private bool CanAddString()
    {
        return true;
    }

    private void AddString()
    {
        this.Oc.Add("test" + ColumnCount);
        ColumnCount++;
    }
}

當我單擊按鈕時，命令運行良好，因此我有一個新的itemscontrol項，並且我的網格作為ItemsPanelTemplate使用新的ColumnDefinition更新，但該項不在右列中。

Answer 1

我知道它的答案很晚:)
一個更優雅的解決方案是在項目ViewModel中添加兩個Dependency Properties Row和Column。

然后在ItemsControl中定義一個ItemContainerStyle：

<ItemsControl>
     <ItemsControl.ItemContainerStyle>
       <Style>                            
          <Setter Property="Grid.Row" Value="{Binding Path=Row}" />
          <Setter Property="Grid.Column" Value="{Binding Path=Column}" />
       </Style>                  
    </ItemsControl.ItemContainerStyle>
</ItemsControl>

當您填充ItemsSource集合時，已設置“行”和“列”屬性：

for (uint i = 0; i < yourCollection.Count; ++i )
{
    var item = yourCollection[i];
    item.Row = (int)(i / ColumnCount);
    item.Column = (int)(i % ColumnCount);
}

Answer 2

實際上canvas_loaded沒用...

問題來自ColumnCountChanged中的GridHelpers類。

我將其添加到SetStarColumns（grid）之后ColumnCountChanged事件的末尾，以便在相應的單元格中添加項目：

for (int i = 0; i < childCount; i++)
{
    var child = grid.Children[i] as FrameworkElement;
    Grid.SetColumn(child, i);
}

而且有效！

編輯：我還對ColumnCount ViewModel屬性上GridHelper.StarColumns屬性的OneWay綁定使用了一個轉換器（在上面的Xaml示例中稱為“ conv”），以使所有新創建的列具有相同的大小：

public class StarsConverter : IValueConverter
{
    public object Convert(object value, Type TargetType, object parameter, CultureInfo culture)
    {
        int i = (int)value;
        string s = "0";
        for (int j = 1; j < i; j++)
        {
            s = s + ',' + j;

        }
        return s;
    }
    public object ConvertBack(object value, Type TargetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}