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C# WPF DataGrid：在触发器中设置ColumnWidth

c# wpf

C# WPF DataGrid：在触发器中设置ColumnWidth,c#,wpf,datagrid,datatrigger,column-width,C#,Wpf,Datagrid,Datatrigger,Column Width,我很难按照他的风格在触发器中设置DataGrid的ColumnWidth 我有这个： <DataGrid ItemsSource="{Binding Data}"> <DataGrid.Style> <Style TargetType="DataGrid"> <Style.Triggers> <DataTrigger Binding="{Binding Data.

我很难按照他的风格在触发器中设置DataGrid的ColumnWidth

我有这个：

<DataGrid ItemsSource="{Binding Data}">
    <DataGrid.Style>
        <Style TargetType="DataGrid">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Data.Count}" Value="2">
                    <Setter Property="Background" Value="LightGreen" />
                    <Setter Property="ColumnWidth" Value="400" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </DataGrid.Style>
</DataGrid>
这对我来说没问题，因为我的数据在执行时不会改变行数，所以ColumnWidth只需要在开始时计算一次

谢谢大家

请尝试下一个解决方案。如您所见，我使用代理对象将主数据上下文传递给每个数据网格单元。此外，还有一个DataTrigger，它在隐藏列的可见性发生更改时工作，并且有一个附加属性可帮助控制实际列宽。 代码如下：

Xaml代码

<Window x:Class="DataGridSoHelpAttempt.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dataGridSoHelpAttempt="clr-namespace:DataGridSoHelpAttempt"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    Title="MainWindow" Height="350" Width="525" x:Name="This">
<Window.DataContext>
    <dataGridSoHelpAttempt:MainViewModel/>
</Window.DataContext>
<Grid x:Name="MyGrid">
    <Grid.Resources>
        <dataGridSoHelpAttempt:FreezableProxyClass x:Key="ProxyElement" ProxiedDataContext="{Binding Source={x:Reference This}, Path=DataContext}"/>
    </Grid.Resources>
    <DataGrid x:Name="MyDataGrid" ItemsSource="{Binding DataSource}" AutoGenerateColumns="False">

        <DataGrid.Columns>
            <DataGridTextColumn Header="Name"  Binding="{Binding Name}"/>
            <DataGridTextColumn Header="Description" Binding="{Binding Description}"  Visibility="{Binding Source={StaticResource ProxyElement}, 
                Path=ProxiedDataContext.Visibility, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
            <DataGridTextColumn Header="Comments" Binding="{Binding Comments}"/>
            <DataGridTextColumn Header="Price (click to see total)" Binding="{Binding Price, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
        </DataGrid.Columns>
        <DataGrid.Resources>
            <Style TargetType="DataGridCell" BasedOn="{StaticResource {x:Type DataGridCell}}">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Source={StaticResource ProxyElement}, 
                Path=ProxiedDataContext.Visibility, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Value="Visible">
                        <Setter Property="Width" Value="200"></Setter>
                        <Setter Property="dataGridSoHelpAttempt:DataGridAttached.ColumnActualWidth" Value="200"/>
                    </DataTrigger>
                    <DataTrigger Binding="{Binding Source={StaticResource ProxyElement}, 
                Path=ProxiedDataContext.Visibility, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Value="Collapsed">
                        <Setter Property="Width" Value="400"></Setter>
                        <Setter Property="dataGridSoHelpAttempt:DataGridAttached.ColumnActualWidth" Value="400"/>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </DataGrid.Resources>
    </DataGrid>
    <StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Bottom">
        <Button Content="Show Description" Command="{Binding Command}"></Button>
    </StackPanel>
</Grid></Window>

public class DataGridAttached
{
    public static readonly DependencyProperty ColumnActualWidthProperty = DependencyProperty.RegisterAttached(
        "ColumnActualWidth", typeof (double), typeof (DataGridAttached), new PropertyMetadata(default(double), ColumnActualWidthPropertyChanged));

    private static void ColumnActualWidthPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var data = d.FindParent<DataGrid>();
        var control = (d as Control);
        if(data == null || control == null) return;
        data.Columns.ToList().ForEach(column =>
        {
            var cellWidth = control.Width;
            if(double.IsNaN(cellWidth) || double.IsInfinity(cellWidth)) return;
            column.Width = cellWidth;
        });
    }

    public static void SetColumnActualWidth(DependencyObject element, double value)
    {
        element.SetValue(ColumnActualWidthProperty, value);
    }

    public static double GetColumnActualWidth(DependencyObject element)
    {
        return (double) element.GetValue(ColumnActualWidthProperty);
    }
}
助手

    public static class VisualTreeHelperExtensions
{
    public static T FindParent<T>(this DependencyObject child) where T : DependencyObject
    {
        while (true)
        {
            //get parent item
            DependencyObject parentObject = VisualTreeHelper.GetParent(child);

            //we've reached the end of the tree
            if (parentObject == null) return null;

            //check if the parent matches the type we're looking for
            T parent = parentObject as T;
            if (parent != null)
                return parent;
            child = parentObject;
        }
    }
}

public class BaseObservableObject : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
    {
        var propName = ((MemberExpression)raiser.Body).Member.Name;
        OnPropertyChanged(propName);
    }

    protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
    {
        if (!EqualityComparer<T>.Default.Equals(field, value))
        {
            field = value;
            OnPropertyChanged(name);
            return true;
        }
        return false;
    }
}

public class RelayCommand : ICommand
{
    private readonly Func<bool> _canExecute;
    private readonly Action _execute;

    public RelayCommand(Action execute)
        : this(() => true, execute)
    {
    }

    public RelayCommand(Func<bool> canExecute, Action execute)
    {
        _canExecute = canExecute;
        _execute = execute;
    }

    public bool CanExecute(object parameter = null)
    {
        return _canExecute();
    }

    public void Execute(object parameter = null)
    {
        _execute();
    }

    public event EventHandler CanExecuteChanged;
}

public class RelayCommand<T> : ICommand
    where T:class 
{
    private readonly Predicate<T> _canExecute;
    private readonly Action<T> _execute;

    public RelayCommand(Action<T> execute):this(obj => true, execute)
    {
    }

    public RelayCommand(Predicate<T> canExecute, Action<T> execute)
    {
        _canExecute = canExecute;
        _execute = execute;
    }

    public bool CanExecute(object parameter)
    {
        return _canExecute(parameter as T);
    }

    public void Execute(object parameter)
    {
        _execute(parameter as T);
    }

    public event EventHandler CanExecuteChanged;
}

公共静态类VisualTreeHelperExtensions
{
公共静态T FindParent（此DependencyObject子级），其中T:DependencyObject
{
while（true）
{
//获取父项
DependencyObject parentObject=VisualTreeHelper.GetParent（子级）；
//我们已经到了树的尽头
if（parentObject==null）返回null；
//检查父项是否与我们要查找的类型匹配
T parent=parentObject作为T；
如果（父项！=null）
返回父母；
子对象=父对象；
}
}
}
公共类BaseObserveObject:INotifyPropertyChanged
{
公共事件属性更改事件处理程序属性更改；
受保护的虚拟void OnPropertyChanged（[CallerMemberName]字符串propertyName=null）
{
var handler=PropertyChanged；
if（handler！=null）handler（这是新的PropertyChangedEventArgs（propertyName））；
}
受保护的虚拟void OnPropertyChanged（表达式提升器）
{
var propName=（（MemberExpression）raiser.Body）.Member.Name；
OnPropertyChanged（propName）；
}
受保护的布尔集合（参考T字段，T值，[CallerMemberName]字符串名称=null）
{
如果（！EqualityComparer.Default.Equals（字段，值））
{
字段=值；
OnPropertyChanged（名称）；
返回true；
}
返回false；
}
}
公共类中继命令：ICommand
{
私有只读功能可执行；
私有只读操作\u执行；
公共中继命令（操作执行）
：此（（）=>true，执行）
{
}
公共RelayCommand（功能可执行，操作可执行）
{
_canExecute=canExecute；
_执行=执行；
}
公共布尔CanExecute（对象参数=null）
{
返回_canExecute（）；
}
public void Execute（对象参数=null）
{
_执行（）；
}
公共事件处理程序CanExecuteChanged；
}
公共类中继命令：ICommand
T:在哪里上课
{
私有只读谓词_canExecute；
私有只读操作\u执行；
public RelayCommand（Action execute）：这个（obj=>true，execute）
{
}
公共RelayCommand（谓词canExecute、操作execute）
{
_canExecute=canExecute；
_执行=执行；
}
公共布尔CanExecute（对象参数）
{
返回_canExecute（参数为T）；
}
public void Execute（对象参数）
{
_执行（参数为T）；
}
公共事件处理程序CanExecuteChanged；
}
这是一个完整的测试解决方案，您应该了解它是如何工作的。如果您在代码方面遇到问题，我将很乐意提供帮助

问候。

请尝试下一种解决方案。如您所见，我使用代理对象将主数据上下文传递给每个数据网格单元。此外，还有一个DataTrigger，它在隐藏列的可见性发生更改时工作，并且有一个附加属性可帮助控制实际列宽。 代码如下：

Xaml代码

<Window x:Class="DataGridSoHelpAttempt.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dataGridSoHelpAttempt="clr-namespace:DataGridSoHelpAttempt"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    Title="MainWindow" Height="350" Width="525" x:Name="This">
<Window.DataContext>
    <dataGridSoHelpAttempt:MainViewModel/>
</Window.DataContext>
<Grid x:Name="MyGrid">
    <Grid.Resources>
        <dataGridSoHelpAttempt:FreezableProxyClass x:Key="ProxyElement" ProxiedDataContext="{Binding Source={x:Reference This}, Path=DataContext}"/>
    </Grid.Resources>
    <DataGrid x:Name="MyDataGrid" ItemsSource="{Binding DataSource}" AutoGenerateColumns="False">

        <DataGrid.Columns>
            <DataGridTextColumn Header="Name"  Binding="{Binding Name}"/>
            <DataGridTextColumn Header="Description" Binding="{Binding Description}"  Visibility="{Binding Source={StaticResource ProxyElement}, 
                Path=ProxiedDataContext.Visibility, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
            <DataGridTextColumn Header="Comments" Binding="{Binding Comments}"/>
            <DataGridTextColumn Header="Price (click to see total)" Binding="{Binding Price, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
        </DataGrid.Columns>
        <DataGrid.Resources>
            <Style TargetType="DataGridCell" BasedOn="{StaticResource {x:Type DataGridCell}}">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Source={StaticResource ProxyElement}, 
                Path=ProxiedDataContext.Visibility, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Value="Visible">
                        <Setter Property="Width" Value="200"></Setter>
                        <Setter Property="dataGridSoHelpAttempt:DataGridAttached.ColumnActualWidth" Value="200"/>
                    </DataTrigger>
                    <DataTrigger Binding="{Binding Source={StaticResource ProxyElement}, 
                Path=ProxiedDataContext.Visibility, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Value="Collapsed">
                        <Setter Property="Width" Value="400"></Setter>
                        <Setter Property="dataGridSoHelpAttempt:DataGridAttached.ColumnActualWidth" Value="400"/>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </DataGrid.Resources>
    </DataGrid>
    <StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Bottom">
        <Button Content="Show Description" Command="{Binding Command}"></Button>
    </StackPanel>
</Grid></Window>

public class DataGridAttached
{
    public static readonly DependencyProperty ColumnActualWidthProperty = DependencyProperty.RegisterAttached(
        "ColumnActualWidth", typeof (double), typeof (DataGridAttached), new PropertyMetadata(default(double), ColumnActualWidthPropertyChanged));

    private static void ColumnActualWidthPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var data = d.FindParent<DataGrid>();
        var control = (d as Control);
        if(data == null || control == null) return;
        data.Columns.ToList().ForEach(column =>
        {
            var cellWidth = control.Width;
            if(double.IsNaN(cellWidth) || double.IsInfinity(cellWidth)) return;
            column.Width = cellWidth;
        });
    }

    public static void SetColumnActualWidth(DependencyObject element, double value)
    {
        element.SetValue(ColumnActualWidthProperty, value);
    }

    public static double GetColumnActualWidth(DependencyObject element)
    {
        return (double) element.GetValue(ColumnActualWidthProperty);
    }
}
助手

    public static class VisualTreeHelperExtensions
{
    public static T FindParent<T>(this DependencyObject child) where T : DependencyObject
    {
        while (true)
        {
            //get parent item
            DependencyObject parentObject = VisualTreeHelper.GetParent(child);

            //we've reached the end of the tree
            if (parentObject == null) return null;

            //check if the parent matches the type we're looking for
            T parent = parentObject as T;
            if (parent != null)
                return parent;
            child = parentObject;
        }
    }
}

public class BaseObservableObject : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
    {
        var propName = ((MemberExpression)raiser.Body).Member.Name;
        OnPropertyChanged(propName);
    }

    protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
    {
        if (!EqualityComparer<T>.Default.Equals(field, value))
        {
            field = value;
            OnPropertyChanged(name);
            return true;
        }
        return false;
    }
}

public class RelayCommand : ICommand
{
    private readonly Func<bool> _canExecute;
    private readonly Action _execute;

    public RelayCommand(Action execute)
        : this(() => true, execute)
    {
    }

    public RelayCommand(Func<bool> canExecute, Action execute)
    {
        _canExecute = canExecute;
        _execute = execute;
    }

    public bool CanExecute(object parameter = null)
    {
        return _canExecute();
    }

    public void Execute(object parameter = null)
    {
        _execute();
    }

    public event EventHandler CanExecuteChanged;
}

public class RelayCommand<T> : ICommand
    where T:class 
{
    private readonly Predicate<T> _canExecute;
    private readonly Action<T> _execute;

    public RelayCommand(Action<T> execute):this(obj => true, execute)
    {
    }

    public RelayCommand(Predicate<T> canExecute, Action<T> execute)
    {
        _canExecute = canExecute;
        _execute = execute;
    }

    public bool CanExecute(object parameter)
    {
        return _canExecute(parameter as T);
    }

    public void Execute(object parameter)
    {
        _execute(parameter as T);
    }

    public event EventHandler CanExecuteChanged;
}

公共静态类VisualTreeHelperExtensions
{
公共静态T FindParent（此DependencyObject子级），其中T:DependencyObject
{
while（true）
{
//获取父项
DependencyObject parentObject=VisualTreeHelper.GetParent（子级）；
//我们已经到了树的尽头
if（parentObject==null）返回null；
//检查父项是否与我们要查找的类型匹配
T parent=parentObject作为T；
如果（父项！=null）
返回父母；
子对象=父对象；
}
}
}
公共类BaseObserveObject:INotifyPropertyChanged
{
公共事件属性更改事件处理程序属性更改；
受保护的虚拟void OnPropertyChanged（[CallerMemberName]字符串propertyName=null）
{
var handler=PropertyChanged；
if（handler！=null）handler（这是新的PropertyChangedEventArgs（propertyName））；
}
受保护的虚拟void OnPropertyChanged（表达式提升器）
{
var propName=（（MemberExpression）raiser.Body）.Member.Name；
OnPropertyChanged（propName）；
}
受保护的布尔集合（参考T字段，T值，[CallerMemberName]字符串名称=null）
{
如果（！EqualityComparer.Default.Equals（字段，值））
{
字段=值；
OnPropertyChanged（名称）；
返回true；
}
返回false；
}
}
公共类中继命令：ICommand
{
私有只读功能可执行；
私有只读操作\u执行；
公共中继命令（操作执行）
：此（（）=>true，执行）
{
}
公共RelayCommand（功能可执行，操作可执行）
{
_canExecute=canExecute；
_执行=执行；
}
公共布尔CanExecute（对象参数=null）
{
返回_canExecute（）；
}
public void Execute（对象参数=null）
{
_执行（）；
}
公共事件处理程序CanExecuteChanged；
}
公共类中继命令：ICommand
T:在哪里上课
{
私有只读谓词_canExecute；
私人住宅

  public class FreezableProxyClass : Freezable
{
    protected override Freezable CreateInstanceCore()
    {
        return new FreezableProxyClass();
    }


    public static readonly DependencyProperty ProxiedDataContextProperty = DependencyProperty.Register(
        "ProxiedDataContext", typeof (object), typeof (FreezableProxyClass), new PropertyMetadata(default(object)));

    public object ProxiedDataContext
    {
        get { return (object) GetValue(ProxiedDataContextProperty); }
        set { SetValue(ProxiedDataContextProperty, value); }
    }
}



    public static class VisualTreeHelperExtensions
{
    public static T FindParent<T>(this DependencyObject child) where T : DependencyObject
    {
        while (true)
        {
            //get parent item
            DependencyObject parentObject = VisualTreeHelper.GetParent(child);

            //we've reached the end of the tree
            if (parentObject == null) return null;

            //check if the parent matches the type we're looking for
            T parent = parentObject as T;
            if (parent != null)
                return parent;
            child = parentObject;
        }
    }
}

public class BaseObservableObject : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
    {
        var propName = ((MemberExpression)raiser.Body).Member.Name;
        OnPropertyChanged(propName);
    }

    protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
    {
        if (!EqualityComparer<T>.Default.Equals(field, value))
        {
            field = value;
            OnPropertyChanged(name);
            return true;
        }
        return false;
    }
}

public class RelayCommand : ICommand
{
    private readonly Func<bool> _canExecute;
    private readonly Action _execute;

    public RelayCommand(Action execute)
        : this(() => true, execute)
    {
    }

    public RelayCommand(Func<bool> canExecute, Action execute)
    {
        _canExecute = canExecute;
        _execute = execute;
    }

    public bool CanExecute(object parameter = null)
    {
        return _canExecute();
    }

    public void Execute(object parameter = null)
    {
        _execute();
    }

    public event EventHandler CanExecuteChanged;
}

public class RelayCommand<T> : ICommand
    where T:class 
{
    private readonly Predicate<T> _canExecute;
    private readonly Action<T> _execute;

    public RelayCommand(Action<T> execute):this(obj => true, execute)
    {
    }

    public RelayCommand(Predicate<T> canExecute, Action<T> execute)
    {
        _canExecute = canExecute;
        _execute = execute;
    }

    public bool CanExecute(object parameter)
    {
        return _canExecute(parameter as T);
    }

    public void Execute(object parameter)
    {
        _execute(parameter as T);
    }

    public event EventHandler CanExecuteChanged;
}



    <DataGrid x:Name="Dgrid" Margin="0,58,0,0">
    <DataGrid.Style>
       <Style TargetType="DataGrid">
          <Style.Triggers>
             <DataTrigger Binding="{Binding Data.Count}" Value="4">
                 <Setter Property="ColumnWidth" Value="200" />
                 <Setter Property="ItemsSource" Value="{Binding Data}" />
                 <Setter Property="Background" Value="LightGreen" />                            
             </DataTrigger>
             <DataTrigger Binding="{Binding Data.Count, Converter={local:CountToBool}}" Value="true">
                 <Setter Property="ColumnWidth" Value="100" />
                 <Setter Property="ItemsSource" Value="{Binding Data}" />
                 <Setter Property="Background" Value="Red" />
              </DataTrigger>
           </Style.Triggers>
        </Style>
     </DataGrid.Style>
    </DataGrid>



    public class CountToBoolConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if ((int)value != 4)
                return true;

            return false;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

    public class CountToBoolExtension : MarkupExtension
    {
        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            return new CountToBoolConverter();
        }
    }



ViewModel vm = new ViewModel();

// removing 2 items and reassigning DataContext to viewmodel.
private void Button_Click(object sender, RoutedEventArgs e)
{
    Dgrid.DataContext = null;

    vm.Students.RemoveAt(1);
    vm.Students.RemoveAt(2);

    Dgrid.DataContext = vm;
}