详解WPF如何在Panel中实现设置所有子项间距

public static readonly DependencyProperty SpacingProperty =
    DependencyProperty.RegisterAttached("Spacing", typeof(double), typeof(PanelHelper), new UIPropertyMetadata(0d, OnSpacingChanged));

public static double GetSpacing(DependencyObject obj)
{
    return (double)obj.GetValue(SpacingProperty);
}
public static void SetSpacing(DependencyObject obj, double value)
{
    obj.SetValue(SpacingProperty, value);
}

private static void OnSpacingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    if (d is Panel panel)
    {
        double newValue = (double)e.NewValue;
        double oldValue = (double)e.OldValue;

        if (panel.IsLoaded)
        {
            UpdateChildrenSpacing(panel, newValue);
        }
        else
        {
            panel.Loaded -= OnPanelLoaded;
            panel.Loaded += OnPanelLoaded;
            panel.SetValue(SpacingProperty, newValue);
        }
    }
}

private static void OnPanelLoaded(object sender, RoutedEventArgs e)
{
    if (sender is Panel panel)
    {
        double spacing = (double)panel.GetValue(SpacingProperty);
        UpdateChildrenSpacing(panel, spacing);
        panel.Loaded -= OnPanelLoaded;
    }
}

private static void UpdateChildrenSpacing(Panel panel, double spacing)
{
    foreach (UIElement child in panel.Children)
    {
        if (child is FrameworkElement frameworkElement)
        {
            frameworkElement.Margin = new Thickness(spacing);
        }
    }
}

<!--<StackPanel wd:PanelHelper.Spacing="3"/>
<WrapPanel wd:PanelHelper.Spacing="3" />
<UniformGrid wd:PanelHelper.Spacing="3"/>
<DockPanel wd:PanelHelper.Spacing="3"/>
<Grid wd:PanelHelper.Spacing="3"/>-->
<TabControl>
    <TabItem Header="StackPanel">
        <StackPanel wd:PanelHelper.Spacing="3">
            <Button Content="Content 1" Style="{StaticResource WD.PrimaryButton}" />
            <Button Content="Content 2" Style="{StaticResource WD.PrimaryButton}" />
            <Button Content="Content 3" Style="{StaticResource WD.PrimaryButton}" />
        </StackPanel>
    </TabItem>
    <TabItem Header="WrapPanel">
        <WrapPanel wd:PanelHelper.Spacing="3">
            <Button Content="Content 1" Style="{StaticResource WD.DangerPrimaryButton}" />
            <Button Content="Content 2" Style="{StaticResource WD.DangerPrimaryButton}" />
            <Button Content="Content 3" Style="{StaticResource WD.DangerPrimaryButton}" />
        </WrapPanel>
    </TabItem>
    <TabItem Header="UniformGrid">
        <UniformGrid wd:PanelHelper.Spacing="3">
            <Button Content="Content 1" Style="{StaticResource WD.SuccessPrimaryButton}" />
            <Button Content="Content 2" Style="{StaticResource WD.SuccessPrimaryButton}" />
            <Button Content="Content 3" Style="{StaticResource WD.SuccessPrimaryButton}" />
        </UniformGrid>
    </TabItem>
    <TabItem Header="Grid">
        <Grid wd:PanelHelper.Spacing="3">
            <Button
                Width="200"
                Height="200"
                Content="Content 1"
                Style="{StaticResource WD.WarningPrimaryButton}" />
            <Button
                Width="180"
                Height="180"
                Content="Content 2"
                Style="{StaticResource WD.DangerPrimaryButton}" />
            <Button
                Width="160"
                Height="160"
                Content="Content 3"
                Style="{StaticResource WD.SuccessPrimaryButton}" />
        </Grid>
    </TabItem>
</TabControl>