来自 CustomPanel 的附加更改属性不会刷新面板

Question

我创建了虚拟自定义面板 ShelfPanel 并附加了属性 Exact 影响面板排列：

class ShelfPanel : Panel
{
    #region Start attached property
    public static DependencyProperty ExactProperty = DependencyProperty.RegisterAttached("Exact", typeof(int), typeof(ShelfPanel),
        new FrameworkPropertyMetadata(0, 
            FrameworkPropertyMetadataOptions.AffectsArrange | // Does this options have auto action?
            FrameworkPropertyMetadataOptions.AffectsRender)); // Does this options have auto action?

    public static void SetExact(UIElement element, int value)
    {
        element.SetValue(ExactProperty, value);
    }

    public static int GetExact(UIElement element)
    {
        return (int)element.GetValue(ExactProperty);
    }
    #endregion

    protected override Size MeasureOverride(Size availableSize)
    {
        Size final = new Size();
        foreach (UIElement child in InternalChildren)
        {
            child.Measure(availableSize);
            final.Height += child.DesiredSize.Height;
        }
        return final;
    }

    protected override Size ArrangeOverride(Size finalSize)
    {
        foreach (UIElement child in InternalChildren)
        {
            Point position = new Point();
            int exact = ShelfPanel.GetExact(child);
            // Calculate position based on attached Exact
            position.X = exact * 100;
            position.Y = exact * 100;
            child.Arrange(new Rect(position, child.DesiredSize));
        }
        return finalSize;
    }
}

<local:ShelfPanel>
     <local:Box local:ShelfPanel.Exact="0" MouseDown="Box_MouseDown"/>
     <local:Box local:ShelfPanel.Exact="1" />
     <local:Box local:ShelfPanel.Exact="2" />
</local:ShelfPanel>

public partial class MainWindow : Window // Codebehind for previous xaml
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Box_MouseDown(object sender, MouseButtonEventArgs e)
    {
        // I certainly sure this code get triggered after click.
        ShelfPanel.SetExact(sender as UIElement, 3); 
    }
}

本作品完美<local:Box>如期安排。正如您可以从代码中推断的那样，在点击第一个 <local:Box> 之后，它应该将其位置更改为 3，就在其他 2 之后。但令人惊讶的是没有任何反应。

FrameworkPropertyMetadataOptions.Affects Arrange 或 FrameworkPropertyMetadataOptions.AffectsRender 不会自动重绘面板吗？为了使这项工作有效，我需要添加 PropertyChangedCallback 并在那里调用 InvalidateVisual()?

Answer 1

您要在 Box 上设置附加的属性，但想要 Box 的父元素，即要排列的 ShelfPanel。

因此您应该设置 FrameworkPropertyMetadataOptions.AffectsParentArrange:

public static readonly DependencyProperty ExactProperty =
    DependencyProperty.RegisterAttached("Exact", typeof(int), typeof(ShelfPanel),
        new FrameworkPropertyMetadata(0,
            FrameworkPropertyMetadataOptions.AffectsParentArrange));

来自 CustomPanel 的附加更改属性不会刷新面板

Change attached property from CustomPanel doesn't refresh panel

c#

wpf

xaml

wpf-controls

propertychanged

来自 CustomPanel 的附加更改 属性 不会刷新面板

Change attached property from CustomPanel doesn't refresh panel

c#

wpf

xaml

wpf-controls

propertychanged

来自 CustomPanel 的附加更改属性不会刷新面板