使用Canvas选择绑定的ListBox项作为ItemsPanelTemplate

Question

我正在编写一个计划工具，我希望有一个类似于“日”的视图，这在许多日历应用程序中都可用。

它作为ListBox完成，因此用户可以选择一些事件。当我尝试绑定事件时出现问题 - 选择不能按预期工作。我的意思是它看起来像拉伸到容器的顶部，加上click事件不会在元素上处理，而是在元素和容器顶边之间的空间处理。

这是一个例子：在左侧 - 它应该如何工作和外观，这是通过手动放置两个ListBoxItems来完成的。在右侧，使用绑定。

我将这两种情况的可视树与WPF调试工具进行了比较，并且在例如 ContentPresenter 的东西，但我不明白到底发生了什么，为什么会出现差异以及如何删除它。

这是我的XAML：

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Class="PLA1.MainWindow"
    x:Name="Window"
    xmlns:local="clr-namespace:PLA1"
    Title="MainWindow"
    Width="640" Height="480">

    <Window.Resources>
        <local:MarginConverter x:Key="marginConverter"/>
    </Window.Resources>

    <Grid x:Name="LayoutRoot">
        <ListBox Margin="8,8,0,8" Background="#C9BBC0FF" HorizontalAlignment="Left" Width="160">
           <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <Canvas />
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <ListBoxItem Margin="{Binding Path=StartMinutes, Converter={StaticResource marginConverter}}" Height="{Binding Path=Duration}" Width="150" Background="#8000FF00" Foreground="White" BorderThickness="2" BorderBrush="#80000000">
                        <StackPanel>
                            <TextBlock Text="{Binding Path=Name}" Margin="5,0,0,0" Width="130" TextWrapping="Wrap" FontWeight="Bold" FontSize="18" />
                            <TextBlock Text="{Binding Path=Place}"  Margin="8,0,0,0" FontSize="14"/>
                        </StackPanel>
                    </ListBoxItem>
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.Effect>
                <DropShadowEffect Opacity="0.625"/>
            </ListBox.Effect>

            <!-- uncomment these two lines to test binding -->
            <!--local:Event Duration="200" StartMinutes="60" Name="Sprawdzian" Place="EA32" />
            <local:Event Duration="120" StartMinutes="300" Name="Oddanie projektu" Place="308" /-->

            <ListBoxItem Margin="0,60,0,0" Height="200" Width="150" Background="#8000FF00" Foreground="White" BorderThickness="2" BorderBrush="#80000000">
                <StackPanel>
                    <TextBlock Text="Sprawdzian" Margin="5,0,0,0" Width="130" TextWrapping="Wrap" FontWeight="Bold" FontSize="18" />
                    <TextBlock Text="EA32"  Margin="8,0,0,0" FontSize="14"/>
                </StackPanel>
            </ListBoxItem>      

            <ListBoxItem Margin="0,300,0,0" Height="120" Width="150" Background="#8000FF00" Foreground="White" BorderThickness="2" BorderBrush="#80000000">
                <StackPanel>
                    <TextBlock Text="Oddanie projektu" Margin="5,0,0,0" Width="130" TextWrapping="Wrap" FontWeight="Bold" FontSize="18" />
                    <TextBlock Text="308"  Margin="8,0,0,0" FontSize="14"/>
                </StackPanel>
            </ListBoxItem>  
        </ListBox>
    </Grid>
</Window>

活动类：

public class Event
{
    public int StartMinutes { get;set; }
    public int Duration { get; set; }
    public string Name { get; set; }
    public string Place { get; set; }

    public Event() { }
}

MarginConverter 类：

public class MarginConverter : IValueConverter
{
    public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return new Thickness(0, (int)(value), 0, 0);
    }

    public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return null;
    }
}

Answer 1

您应该在ListBoxItem资源中为ListBox添加样式，并在其中设置适当的属性并更改ItemTemplate：

<ListBox Margin="8,8,0,8" Background="#C9BBC0FF" HorizontalAlignment="Left" Width="160">
    <ListBox.Resources>                   
        <Style TargetType="ListBoxItem">
            <Setter Property="Margin" Value="{Binding Path=StartMinutes, Converter={StaticResource marginConverter}}" />
            <Setter Property="Height" Value="{Binding Path=Duration}" />
            <Setter Property="Foreground" Value="White" />
            <Setter Property="BorderThickness" Value="2" />
            <Setter Property="BorderBrush" Value="#80000000" />
            <Setter Property="Width" Value="150" />
            <Setter Property="Background" Value="#8000FF00" />
        </Style>
    </ListBox.Resources>
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ListBox.ItemTemplate>
        <DataTemplate>                    
                <StackPanel>
                    <TextBlock Text="{Binding Path=Name}" Margin="5,0,0,0" Width="130" TextWrapping="Wrap" FontWeight="Bold" FontSize="18" />
                    <TextBlock Text="{Binding Path=Place}"  Margin="8,0,0,0" FontSize="14"/>
                </StackPanel>                        
        </DataTemplate>
    </ListBox.ItemTemplate>
    <ListBox.Effect>
        <DropShadowEffect Opacity="0.625"/>
    </ListBox.Effect>

    <!-- uncomment these two lines to test binding -->
    <local:Event Duration="200" StartMinutes="60" Name="Sprawdzian" Place="EA32" />
    <local:Event Duration="120" StartMinutes="300" Name="Oddanie projektu" Place="308" />

    <!--<ListBoxItem Margin="0,60,0,0" Height="200" Width="150" Background="#8000FF00" Foreground="White" BorderThickness="2" BorderBrush="#80000000">
        <StackPanel>
            <TextBlock Text="Sprawdzian" Margin="5,0,0,0" Width="130" TextWrapping="Wrap" FontWeight="Bold" FontSize="18" />
            <TextBlock Text="EA32"  Margin="8,0,0,0" FontSize="14"/>
        </StackPanel>
    </ListBoxItem>

    <ListBoxItem Margin="0,300,0,0" Height="120" Width="150" Background="#8000FF00" Foreground="White" BorderThickness="2" BorderBrush="#80000000">
        <StackPanel>
            <TextBlock Text="Oddanie projektu" Margin="5,0,0,0" Width="130" TextWrapping="Wrap" FontWeight="Bold" FontSize="18" />
            <TextBlock Text="308"  Margin="8,0,0,0" FontSize="14"/>
        </StackPanel>
    </ListBoxItem>-->
</ListBox>

包含两个ListBoxItem项目的可视树：

在此示例中，一切正常，代码中设置了Height和Margin属性。

包含两个Event项目的可视树：

在此示例中，您将ItemTemplate定义为ListBoxItem，但默认情况下ListBox也会添加容器ListBoxItem，因此您有两个ListBoxItem，这里是问题是因为您只为内部ListBoxItem设置了高度和边距。外ListBoxItem具有默认属性。

如果你想自己检查一下，你可以用来做窥探（http://snoopwpf.codeplex.com/）。

Answer 2

尝试按以下方式更新ListBox：

  <ListBox Margin="8,8,0,8" Background="#C9BBC0FF" HorizontalAlignment="Left" Width="160">
       <ListBox.ItemsPanel>
            <ItemsPanelTemplate>
                <StackPanel/>
            </ItemsPanelTemplate>
        </ListBox.ItemsPanel>
        <ListBox.ItemContainerStyle>
           <Style TargetType="ListBoxItem">
                    <Setter Property="Height" Value="{Binding Duration}"/>
                     <Setter Property="Margin" Value="{Binding Path=StartMinutes, Converter={StaticResource marginConverter}}" />
            </Style>
        </ListBox.ItemContainerStyle>
        <ListBox.ItemTemplate>
            <DataTemplate>
                    <StackPanel Background="#8000FF00" BorderThickness="2" BorderBrush="#80000000">
                        <TextBlock Text="{Binding Path=Name}" Margin="5,0,0,0" Width="130" TextWrapping="Wrap" FontWeight="Bold" FontSize="18" />
                        <TextBlock Text="{Binding Path=Place}"  Margin="8,0,0,0" FontSize="14"/>
                    </StackPanel>
            </DataTemplate>
        </ListBox.ItemTemplate>