在WPF中构建可逆的StackPanel

Question

我想构建一个StackPanel带有ReverseOrder属性的自定义,我可以声明性地将其设置为true,以使StackPanel中的元素以正常的相反顺序出现(例如从下到上或从右到左).它需要在运行中可逆.

我正在考虑从StackPanel派生一个新类,但我需要知道要覆盖哪些方法.

最终解决方案

protected override System.Windows.Size ArrangeOverride( System.Windows.Size arrangeSize ) {
    double x = 0;
    double y = 0;

    IEnumerable<UIElement> children = ReverseOrder ? InternalChildren.Cast<UIElement>().Reverse<UIElement>() : InternalChildren.Cast<UIElement>();
    foreach ( UIElement child in children ) {
        var size = child.DesiredSize;
        child.Arrange( new Rect( new Point( x, y ), size ) );

        if ( Orientation == Orientation.Horizontal )
            x += size.Width;
        else
            y += size.Height;
    }

    if ( Orientation == Orientation.Horizontal )
        return new Size( x, arrangeSize.Height );
    else
        return new Size( arrangeSize.Width, y );
}

如果更改,还要定义并注册ReverseOrder和调用UpdateLayout.

Answer 1

您可以重新实现FrameworkElement.ArrangeOverride并在必要时以相反的顺序调用所有child.Arrange.

http://msdn.microsoft.com/en-us/library/system.windows.uielement.arrange.aspx

像这样的东西(未经测试):

    double x = 0;
    double y = 0;

    var children = ReverseOrder ? InternalChildren.Reverse() : InternalChildren;
    foreach (UIElement child in children)
    {
        var size = child.DesiredSize;
        child.Arrange(new Rect(new Point(x, y), size));

        if (Orientation == Horizontal)
            x += size.Width;
        else
            y += size.Height;
    }

确保在更改ReverseOrder属性后调用UpdateLayout.