c# - 使用 MVVM 的可变网格行数

Question

我需要控制网格中的行数。
在不使用 MVVM 模式的情况下，我通过代码隐藏实现了这一点，这样:

<UserControl>
    <Grid x:Name="PART_Host" />
</UserControl>

private void UpdateHost(int rowCount) {
    PART_Host.RowDefinitions.Clear();
    PART_Host.Children.Clear();

    for (int i = 1; i <= rowCount; i++) {
        PART_Host.RowDefinitions.Add(new RowDefinition());
        Grid.SetRow(PART_Host.Children[index], i - 1);
    }
}

现在，我需要使用 MVVM 模式来执行此操作。我可以在我的 ViewModel 中访问所需的 rowCount 属性，但是如何在该属性更改时更新 View ？

谢谢 !

Answer 1

您是否尝试过附加属性？我不确定，但你可以这样做:

    public class GridExtensions
    {
        public static Int32 GetGridRowCount(DependencyObject obj)
        {
            return (Int32)obj.GetValue(GridRowCountProperty);
        }

        public static void SetGridRowCount(DependencyObject obj, UIElementCollection value)
        {
            obj.SetValue(GridRowCountProperty, value);
        }

        // Using a DependencyProperty as the backing store for GridRowCount.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty GridRowCountProperty =
            DependencyProperty.RegisterAttached("GridRowCount", typeof(Int32), typeof(Grid), new FrameworkPropertyMetadata(OnGridRowCountChanged));

        public static void OnGridRowCountChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
        {
            if (e.NewValue != null && obj is Grid)
            {
                Int32 rowCount = (Int32)e.NewValue;
                Grid grid = (Grid)obj;

                grid.RowDefinitions.Clear();
                grid.Children.Clear();

                for (int i = 1; i <= rowCount; i++)
                {
                    grid.RowDefinitions.Add(new RowDefinition());
                    Grid.SetRow(grid.Children[index], i - 1);
                }
            }
        }
    }

并像这样使用它:

<Grid local:GridExtensions.GridRowCount="10"></Grid>