WPF: impostazione dell'allineamento del testo di una GridViewColumn

Question

Per impostazione predefinita, il testo è centrato nelle intestazioni di uno ListView (non nelle celle di contenuto!), Ho faticato a farlo allineato a sinistra, ecco cosa sono io ve venire con:

<ListView.Resources> 
    <DataTemplate x:Key="Templ"> 
     <TextBlock HorizontalAlignment="Left" Text="{Binding}"/> 
    </DataTemplate> 
</ListView.Resources> 
... 
<GridViewColumn HeaderTemplate="{StaticResource Templ}">File</GridViewColumn> 

Questo sembra essere il posto giusto per modificare l'aspetto della testata, dato che posso modificare altre proprietà come Margin, ecc, ma non risponde alla proprietà HorizontalAlignment! Immagino che la casella di testo sia ridimensionata al contenuto e centrata su se stessa, rendendo così ridondante la proprietà dell'allineamento.

Come posso allineare il testo a sinistra?

Answer 1

Impostare la HeaderContainerStyle ad uno stile che imposta HorizontalContentAlignment a sinistra:

<ListView.Resources> 
    <DataTemplate x:Key="Templ"> 
     <TextBlock HorizontalAlignment="Left" Text="{Binding}"/> 
    </DataTemplate> 
    <Style x:Key="HeaderStyle" TargetType="GridViewColumnHeader"> 
     <Setter Property="HorizontalContentAlignment" Value="Left"/> 
    </Style> 
</ListView.Resources> 
<ListView.View> 
    <GridView> 
     <GridView.Columns> 
      <GridViewColumn HeaderTemplate="{StaticResource Templ}" HeaderContainerStyle="{StaticResource HeaderStyle}">File</GridViewColumn> 
     </GridView.Columns> 
    </GridView> 
</ListView.View> 

Answer 2

Ecco un proprietà associata per impostare l'allineamento contenuto della intestazione:

#region HeaderContentAlignment 

    /// <summary>Gets a <see cref="GridViewColumn"/>'s header content alignment.</summary> 
    [Category("Common")] 
    [AttachedPropertyBrowsableForType(typeof(GridViewColumn))] 
    public static HorizontalAlignment GetHeaderContentAlignment(GridViewColumn gridViewColumn) 
    { 
     return (HorizontalAlignment)gridViewColumn.GetValue(HeaderContentAlignmentProperty); 
    } 
    /// <summary>Sets a <see cref="GridViewColumn"/>'s header content alignment.</summary> 
    public static void SetHeaderContentAlignment(GridViewColumn gridViewColumn, HorizontalAlignment value) 
    { 
     gridViewColumn.SetValue(HeaderContentAlignmentProperty, value); 
    } 

    /// <summary>Indicates a <see cref="GridViewColumn"/>'s <see cref="GridViewColumn.HeaderContainerStyle"/>.</summary> 
    public static readonly DependencyProperty HeaderContentAlignmentProperty = 
     DependencyProperty.RegisterAttached(
      "HeaderContentAlignment", 
      typeof(HorizontalAlignment), // type 
      typeof(GridViewExtensions), // containing static class 
      new PropertyMetadata(HorizontalAlignment.Center, OnHeaderContentAlignmentChanged) 
      ); 

    private static void OnHeaderContentAlignmentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
    { 
     OnHeaderContentAlignmentChanged((GridViewColumn)d, (HorizontalAlignment)e.NewValue); 
    } 

    private static void OnHeaderContentAlignmentChanged(GridViewColumn gridViewColumn, HorizontalAlignment alignment) 
    { 
     Style style; 
     if (ColumnHeaderAlignments.TryGetValue(alignment, out style) == false) 
     {// style NOT created -> create, cache 
      style = new Style(typeof(GridViewColumnHeader)); 
      style.Setters.Add(new Setter(Control.HorizontalContentAlignmentProperty, alignment)); 
      ColumnHeaderAlignments.Add(alignment, style); 
     } 
     gridViewColumn.HeaderContainerStyle = style; 
    } 

    /// <summary>cache [HorizontalAlignment]: [Style]</summary> 
    static readonly Dictionary<HorizontalAlignment, Style> ColumnHeaderAlignments = new Dictionary<HorizontalAlignment, Style>(4); 

    #endregion HeaderContentAlignment