列表框交替着色 PowerShell

Question

我似乎一直在尝试为我的表单添加一些样式。我有一个 ListBox，我想为每隔一行添加备用底纹。这甚至可能吗？我尝试查看 $ListBox.Items 属性，在该属性下方我看不到任何背景选项。有什么想法吗？

$ListBox = New-Object System.Windows.Forms.ListBox
$ListBox.Size = '325,95'
$ListBox.Location = '345,25'
$ListBox.Items.Add("Checking...") > $null

Answer 1

在 Windows 窗体中使用 ListBox 控件执行此操作的唯一方法是劫持每一行的实际绘图。

首先，更改ListBox的DrawMode属性：

$ListBox.DrawMode = [System.Windows.Forms.DrawMode]::OwnerDrawFixed

这将允许我们通过the DrawItem event 覆盖项目的图形渲染。

现在我们只需要定义将绘制项目的函数。我发现this great example in C# 在不影响所选项目的情况下进行交替行颜色。

幸运的是，C# 是 easily ported to PowerShell:

$ListBox.add_DrawItem({

    param([object]$s, [System.Windows.Forms.DrawItemEventArgs]$e)

    if ($e.Index -gt -1)
    {
        Write-Host "Drawing item at index $($e.Index)"

        <# If the item is selected set the background color to SystemColors.Highlight 
         or else set the color to either WhiteSmoke or White depending if the item index is even or odd #>
        $color = if(($e.State -band [System.Windows.Forms.DrawItemState]::Selected) -eq [System.Windows.Forms.DrawItemState]::Selected){ 
            [System.Drawing.SystemColors]::Highlight
        }else{
            if($e.Index % 2 -eq 0){
                [System.Drawing.Color]::WhiteSmoke
            }else{
                [System.Drawing.Color]::White
            }
        }

        # Background item brush
        $backgroundBrush = New-Object System.Drawing.SolidBrush $color
        # Text color brush
        $textBrush = New-Object System.Drawing.SolidBrush $e.ForeColor

        # Draw the background
        $e.Graphics.FillRectangle($backgroundBrush, $e.Bounds)
        # Draw the text
        $e.Graphics.DrawString($s.Items[$e.Index], $e.Font, $textBrush, $e.Bounds.Left, $e.Bounds.Top, [System.Drawing.StringFormat]::GenericDefault)

        # Clean up
        $backgroundBrush.Dispose()
        $textBrush.Dispose()
    }
    $e.DrawFocusRectangle()
})

瞧：

Answer 2

从您的代码看起来，您没有使用 XAML，但我还是想添加它作为替代方法。

您可以通过将 XAML 编写为 UI 的前端代码并在触发器中指定设置器属性来设置样式触发器。然后在您的 ListBox 控件中，您可以指定您在 ItemContanerStyle 属性上创建的样式的名称，并将 AlertnationCount 指定为 2，以便它使用您指定的颜色突出显示每一行。

下面的示例显示了当您将文本添加到列表框时它是如何工作的。

#Build the GUI
[xml]$xaml = @"
<Window 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Name="Window" Title="Initial Window" WindowStartupLocation = "CenterScreen" 
    Width = "313" Height = "800" ShowInTaskbar = "True" Background = "lightgray"> 
    <ScrollViewer VerticalScrollBarVisibility="Auto">
        <StackPanel >
            <StackPanel.Resources>
                <Style x:Key="AlternatingRowStyle" TargetType="{x:Type Control}" >
                    <Setter Property="Background" Value="LightBlue"/>
                    <Setter Property="Foreground" Value="Black"/>
                    <Style.Triggers>
                        <Trigger Property="ItemsControl.AlternationIndex" Value="1">                            
                            <Setter Property="Background" Value="White"/>
                            <Setter Property="Foreground" Value="Black"/>                                
                        </Trigger>                            
                    </Style.Triggers>
                </Style>     
            </StackPanel.Resources>
            <TextBox  IsReadOnly="True" TextWrapping="Wrap">
                Type something and click Add
            </TextBox>
            <TextBox x:Name = "inputbox"/>
            <Button x:Name="button1" Content="Add"/>
            <Button x:Name="button2" Content="Remove"/>
            <Expander IsExpanded="True">
                <ListBox x:Name="listbox" SelectionMode="Extended" AlternationCount="2"                 
                ItemContainerStyle="{StaticResource AlternatingRowStyle}"/>
            </Expander >
        </StackPanel>
    </ScrollViewer >
</Window>
"@

$reader=(New-Object System.Xml.XmlNodeReader $xaml)
$Window=[Windows.Markup.XamlReader]::Load( $reader )
 
#region Connect to Controls    
Write-Verbose "Connecting to controls"
$xaml.SelectNodes("//*[@*[contains(translate(name(.),'n','N'),'Name')]]") | ForEach {
    New-Variable -Name $_.Name -Value $Window.FindName($_.Name) -Force
}
#endregion Connect to Controls

$Window.Add_SourceInitialized({
    #Have to have something initially in the collection
    $Script:observableCollection = New-Object System.Collections.ObjectModel.ObservableCollection[string]
    $listbox.ItemsSource = $observableCollection
    $inputbox.Focus()
})
 
#Events
$button1.Add_Click({
     $observableCollection.Add($inputbox.text)
     $inputbox.Clear()
})
$button2.Add_Click({
    ForEach ($item in @($listbox.SelectedItems)) {
        $observableCollection.Remove($item)
    }
}) 
$Window.ShowDialog() | Out-Null