在WPF中折叠网格行

Question

我创建了一个自定义的WPF元素RowDefinition,当Collapsed元素的属性设置为时,该元素应该折叠网格中的行True.

它通过使用样式中的转换器和数据触发器将行的高度设置为0来实现.它基于此SO答案.

在下面的示例中,当网格分割器超过窗口的一半时,这非常有效.但是,当它不到一半时,行仍然会崩溃,但第一行不会展开.相反,过去的行只有一个白色的间隙.这可以在下图中看到.

同样,如果在任何折叠的行上设置MinHeight或者MaxHeight设置,则它根本不会折叠该行.我尝试通过在数据触发器中为这些属性添加setter来修复此问题,但它没有修复它.

我的问题是什么可以做不同的,这样也没关系有关行的大小或者MinHeight/ MaxHeight设置,它只是能够折叠行？

---

MCVE

MainWindow.xaml.cs

using System;
using System.ComponentModel;
using System.Globalization;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;

namespace RowCollapsibleMCVE
{
    public partial class MainWindow : INotifyPropertyChanged
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        private bool isCollapsed;

        public bool IsCollapsed
        {
            get => isCollapsed;
            set
            {
                isCollapsed = value;
                OnPropertyChanged();
            }
        }
    }

    public class CollapsibleRow : RowDefinition
    {
        #region Default Values
        private const bool COLLAPSED_DEFAULT = false;
        private const bool INVERT_COLLAPSED_DEFAULT = false;
        #endregion

        #region Dependency Properties
        public static readonly DependencyProperty CollapsedProperty =
            DependencyProperty.Register("Collapsed", typeof(bool), typeof(CollapsibleRow), new PropertyMetadata(COLLAPSED_DEFAULT));

        public static readonly DependencyProperty InvertCollapsedProperty =
            DependencyProperty.Register("InvertCollapsed", typeof(bool), typeof(CollapsibleRow), new PropertyMetadata(INVERT_COLLAPSED_DEFAULT));
        #endregion

        #region Properties
        public bool Collapsed {
            get => (bool)GetValue(CollapsedProperty);
            set => SetValue(CollapsedProperty, value);
        }

        public bool InvertCollapsed {
            get => (bool)GetValue(InvertCollapsedProperty);
            set => SetValue(InvertCollapsedProperty, value);
        }
        #endregion
    }

    public class BoolVisibilityConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (values.Length > 0 && values[0] is bool collapsed)
            {
                if (values.Length > 1 && values[1] is bool invert && invert)
                {
                    collapsed = !collapsed;
                }

                return collapsed ? Visibility.Collapsed : Visibility.Visible;
            }

            return Visibility.Collapsed;
        }

        public object[] ConvertBack(object value, Type[] targetType, object parameter, CultureInfo culture)
        {
            throw new NotSupportedException();
        }
    }
}

MainWindow.xaml

<Window x:Class="RowCollapsibleMCVE.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:RowCollapsibleMCVE"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.Resources>
        <Visibility x:Key="CollapsedVisibilityVal">Collapsed</Visibility>
        <local:BoolVisibilityConverter x:Key="BoolVisibilityConverter"/>

        <Style TargetType="{x:Type local:CollapsibleRow}">
            <Style.Triggers>
                <DataTrigger Value="{StaticResource CollapsedVisibilityVal}">
                    <DataTrigger.Binding>
                        <MultiBinding Converter="{StaticResource BoolVisibilityConverter}">
                            <Binding Path="Collapsed"
                                     RelativeSource="{RelativeSource Self}"/>
                            <Binding Path="InvertCollapsed"
                                     RelativeSource="{RelativeSource Self}"/>
                        </MultiBinding>
                    </DataTrigger.Binding>
                    <DataTrigger.Setters>
                        <Setter Property="MinHeight" Value="0"/>
                        <Setter Property="Height" Value="0"/>
                        <Setter Property="MaxHeight" Value="0"/>
                    </DataTrigger.Setters>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <CheckBox Content="Collapse Row"
                  IsChecked="{Binding IsCollapsed}"/>
        <Grid Row="1">
            <Grid.RowDefinitions>
                <local:CollapsibleRow Height="3*" />
                <local:CollapsibleRow Height="Auto" />
                <local:CollapsibleRow Collapsed="{Binding IsCollapsed}" Height="*" /> <!-- Using [MaxHeight="300"] breaks this completely -->
            </Grid.RowDefinitions>
            <StackPanel Background="Red"/>

            <GridSplitter Grid.Row="1"
                          Height="10"
                          HorizontalAlignment="Stretch">
                <GridSplitter.Visibility>
                    <MultiBinding Converter="{StaticResource BoolVisibilityConverter}" >
                        <Binding Path="IsCollapsed"/>
                    </MultiBinding>
                </GridSplitter.Visibility>
            </GridSplitter>

            <StackPanel Background="Blue"
                        Grid.Row="2">
                <StackPanel.Visibility>
                    <MultiBinding Converter="{StaticResource BoolVisibilityConverter}" >
                        <Binding Path="IsCollapsed"/>
                    </MultiBinding>
                </StackPanel.Visibility>
            </StackPanel>
        </Grid>
    </Grid>
</Window>

Answer 1

您只需要缓存可见行的高度即可.之后,您不再需要转换器或切换所包含控件的可见性.

CollapsibleRow

public class CollapsibleRow : RowDefinition
{
    #region Fields
    private GridLength cachedHeight;
    private double cachedMinHeight;
    #endregion

    #region Dependency Properties
    public static readonly DependencyProperty CollapsedProperty =
        DependencyProperty.Register("Collapsed", typeof(bool), typeof(CollapsibleRow), new PropertyMetadata(false, OnCollapsedChanged));

    private static void OnCollapsedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if(d is CollapsibleRow row && e.NewValue is bool collapsed)
        {
            if(collapsed)
            {
                if(row.MinHeight != 0)
                {
                    row.cachedMinHeight = row.MinHeight;
                    row.MinHeight = 0;
                }
                row.cachedHeight = row.Height;
            }
            else if(row.cachedMinHeight != 0)
            {
                row.MinHeight = row.cachedMinHeight;
            }
            row.Height = collapsed ? new GridLength(0) : row.cachedHeight;
        }
    }
    #endregion

    #region Properties
    public bool Collapsed
    {
        get => (bool)GetValue(CollapsedProperty);
        set => SetValue(CollapsedProperty, value);
    }
    #endregion
}

XAML

<Window x:Class="RowCollapsibleMCVE.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:RowCollapsibleMCVE"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <CheckBox Content="Collapse Row"
                  IsChecked="{Binding IsCollapsed}"/>
        <Grid Row="1">
            <Grid.RowDefinitions>
                <local:CollapsibleRow Height="3*" MinHeight="0.0001"/>
                <local:CollapsibleRow Collapsed="{Binding IsCollapsed}" Height="Auto" />
                <local:CollapsibleRow Collapsed="{Binding IsCollapsed}" Height="*" /> <!-- Using [MinHeight="50" MaxHeight="100"] behaves as expected -->
            </Grid.RowDefinitions>
            <StackPanel Background="Red"/>
            <GridSplitter Grid.Row="1" Height="10" HorizontalAlignment="Stretch" />
            <StackPanel Background="Blue" Grid.Row="2" />
        </Grid>
    </Grid>
</Window>

您应该MaxHeight在可折叠行(在我们的示例中为第三个)或MinHeight与分割器相邻的不可折叠行(第一个)上有一个.这样可以确保在将分离器一直向上并切换可见性时,星形大小的行具有一定的大小.只有这样它才能接管剩下的空间.

UPDATE

正如@Ivan在他的帖子中提到的,折叠行包含的控件仍然是可聚焦的,允许用户在不应该访问它们时访问它们.不可否认,手动设置所有控件的可见性可能会很痛苦,特别是对于大型XAML.因此,让我们添加一些自定义行为来将折叠的行与其控件同步.

1. 问题

首先,使用上面的代码运行示例,然后通过选中复选框来折叠底行.现在,按TAB键一次,然后使用箭头键移动GridSplitter.如您所见,即使拆分器不可见,用户仍然可以访问它.

2. 修复

添加新文件Extensions.cs以托管该行为.

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using RowCollapsibleMCVE;

namespace Extensions
{
    [ValueConversion(typeof(bool), typeof(bool))]
    public class BooleanConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return !(bool)value;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return Binding.DoNothing;
        }
    }

    public class GridHelper : DependencyObject
    {
        #region Attached Property

        public static readonly DependencyProperty SyncCollapsibleRowsProperty =
            DependencyProperty.RegisterAttached(
                "SyncCollapsibleRows",
                typeof(Boolean),
                typeof(GridHelper),
                new FrameworkPropertyMetadata(false,
                    FrameworkPropertyMetadataOptions.AffectsRender,
                    new PropertyChangedCallback(OnSyncWithCollapsibleRows)
                ));

        public static void SetSyncCollapsibleRows(UIElement element, Boolean value)
        {
            element.SetValue(SyncCollapsibleRowsProperty, value);
        }

        private static void OnSyncWithCollapsibleRows(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is Grid grid)
            {
                grid.Loaded += (o,ev) => SetBindingForControlsInCollapsibleRows((Grid)o);
            }
        }

        #endregion

        #region Logic

        private static IEnumerable<UIElement> GetChildrenFromPanels(IEnumerable<UIElement> elements)
        {
            Queue<UIElement> queue = new Queue<UIElement>(elements);
            while (queue.Any())
            {
                var uiElement = queue.Dequeue();
                if (uiElement is Panel panel)
                {
                    foreach (UIElement child in panel.Children) queue.Enqueue(child);
                }
                else
                {
                    yield return uiElement;
                }
            }
        }

        private static IEnumerable<UIElement> ElementsInRow(Grid grid, int iRow)
        {
            var rowRootElements = grid.Children.OfType<UIElement>().Where(c => Grid.GetRow(c) == iRow);

            if (rowRootElements.Any(e => e is Panel))
            {
                return GetChildrenFromPanels(rowRootElements);
            }
            else
            {
                return rowRootElements;
            }
        }

        private static BooleanConverter MyBooleanConverter = new BooleanConverter();

        private static void SyncUIElementWithRow(UIElement uiElement, CollapsibleRow row)
        {
            BindingOperations.SetBinding(uiElement, UIElement.FocusableProperty, new Binding
            {
                Path = new PropertyPath(CollapsibleRow.CollapsedProperty),
                Source = row,
                Converter = MyBooleanConverter
            });
        }

        private static void SetBindingForControlsInCollapsibleRows(Grid grid)
        {
            for (int i = 0; i < grid.RowDefinitions.Count; i++)
            {
                if (grid.RowDefinitions[i] is CollapsibleRow row)
                {
                    ElementsInRow(grid, i).ToList().ForEach(uiElement => SyncUIElementWithRow(uiElement, row));
                }
            }
        }

        #endregion
    }
}

3. 更多测试

更改XAML以添加行为和一些文本框(也是可聚焦的).

<Window x:Class="RowCollapsibleMCVE.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:RowCollapsibleMCVE"
        xmlns:ext="clr-namespace:Extensions"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <CheckBox Content="Collapse Row" IsChecked="{Binding IsCollapsed}"/>
        <!-- Set the desired behavior through an Attached Property -->
        <Grid ext:GridHelper.SyncCollapsibleRows="True" Row="1">
            <Grid.RowDefinitions>
                <RowDefinition Height="3*" MinHeight="0.0001" />
                <local:CollapsibleRow Collapsed="{Binding IsCollapsed}" Height="Auto" />
                <local:CollapsibleRow Collapsed="{Binding IsCollapsed}" Height="*" />
            </Grid.RowDefinitions>
            <StackPanel Background="Red">
                <TextBox Width="100" Margin="40" />
            </StackPanel>
            <GridSplitter Grid.Row="1" Height="10" HorizontalAlignment="Stretch" />
            <StackPanel Grid.Row="2" Background="Blue">
                <TextBox Width="100" Margin="40" />
            </StackPanel>
        </Grid>
    </Grid>
</Window>

到底:

• 逻辑完全隐藏在XAML(干净)之外.

• 我们仍在提供灵活性:

  • 对于每个,CollapsibleRow您可以绑定Collapsed到不同的变量.

  • 不需要该行为的行可以使用base RowDefinition(按需应用).

更新2

正如@Ash在评论中指出的那样,您可以使用WPF的本机缓存来存储高度值.导致具有自治属性的非常干净的代码,每个代码都处理自己的=>健壮的代码.例如,GridSplitter即使没有应用行为,使用下面的代码也无法移动何时折叠行.

当然,控件仍然可以访问,允许用户触发事件.所以我们仍然需要这种行为,但它CoerceValueCallback确实提供了Collapsed我们的各种高度依赖属性之间的一致联系CollapsibleRow.

public class CollapsibleRow : RowDefinition
{
    public static readonly DependencyProperty CollapsedProperty;

    public bool Collapsed
    {
        get => (bool)GetValue(CollapsedProperty);
        set => SetValue(CollapsedProperty, value);
    }

    static CollapsibleRow()
    {
        CollapsedProperty = DependencyProperty.Register("Collapsed",
            typeof(bool), typeof(CollapsibleRow), new PropertyMetadata(false, OnCollapsedChanged));

        RowDefinition.HeightProperty.OverrideMetadata(typeof(CollapsibleRow),
            new FrameworkPropertyMetadata(new GridLength(1, GridUnitType.Star), null, CoerceHeight));

        RowDefinition.MinHeightProperty.OverrideMetadata(typeof(CollapsibleRow),
            new FrameworkPropertyMetadata(0.0, null, CoerceHeight));

        RowDefinition.MaxHeightProperty.OverrideMetadata(typeof(CollapsibleRow),
            new FrameworkPropertyMetadata(double.PositiveInfinity, null, CoerceHeight));
    }

    private static object CoerceHeight(DependencyObject d, object baseValue)
    {
        return (((CollapsibleRow)d).Collapsed) ? (baseValue is GridLength ? new GridLength(0) : 0.0 as object) : baseValue;
    }

    private static void OnCollapsedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        d.CoerceValue(RowDefinition.HeightProperty);
        d.CoerceValue(RowDefinition.MinHeightProperty);
        d.CoerceValue(RowDefinition.MaxHeightProperty);
    }
}