我有一个 DataGrid，其中每一行都有一个删除按钮。如果我Command="Delete"在 XAML 中的 Delete button 元素上设置属性，则该按钮在运行时被禁用。为什么？？
XAML：
<Page x:Class="AxureExport.TargetPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:AxureExport"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400"
Title="Define Export Targets"
Loaded="Page_Loaded">
<Page.Resources>
<Style TargetType="{x:Type DataGridCell}">
<EventSetter Event="PreviewMouseLeftButtonDown"
Handler="DataGridCell_PreviewMouseLeftButtonDown" />
</Style>
</Page.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="7" />
<ColumnDefinition Width="65" />
<ColumnDefinition Width="458*" />
<ColumnDefinition Width="47" />
<ColumnDefinition Width="10" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="7" />
<RowDefinition Height="63*" />
</Grid.RowDefinitions>
<!-- target file -->
<TextBlock Name="textBlock3"
Text="2. Select the location where you want to save the string files:"
Height="23"
HorizontalAlignment="Left"
Margin="5,0,0,0"
VerticalAlignment="Top"
Grid.Row="2"
Grid.Column="1"
Grid.ColumnSpan="4"
Width="441" />
<TextBlock Name="textBlock4"
Text="(Warning: This tool overwrites files in the target folder.)"
Height="16"
HorizontalAlignment="Left"
Margin="54,15,0,0"
VerticalAlignment="Top"
Width="256"
FontStyle="Italic"
FontWeight="Light"
FontSize="10"
Grid.Row="2"
Grid.Column="1"
Grid.ColumnSpan="2" />
<TextBlock Name="textBlock5"
Text="Target:"
Height="23"
HorizontalAlignment="Left"
Margin="22,30,0,238"
VerticalAlignment="Center"
Grid.Row="1"
Grid.Column="1" />
<!-- ExportTargets Datagrid -->
<DataGrid Name="ExportTargets"
AutoGenerateColumns="False"
Grid.Column="2"
Grid.Row="1"
Margin="0,71,0,63"
ItemsSource="{Binding Path=., Mode=TwoWay}"
SelectionUnit="Cell"
GridLinesVisibility="None"
RowDetailsVisibilityMode="Collapsed"
CanUserReorderColumns="False"
CanUserResizeColumns="False"
CanUserResizeRows="False"
RowHeaderWidth="40"
IsSynchronizedWithCurrentItem="True"
HorizontalScrollBarVisibility="Disabled"
CanUserAddRows="True"
CanUserDeleteRows="True">
<DataGrid.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}"
Color="Transparent" />
<SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}"
Color="Transparent" />
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}"
Color="Black" />
<SolidColorBrush x:Key="{x:Static SystemColors.ControlTextBrushKey}"
Color="Black" />
</DataGrid.Resources>
<DataGrid.Columns>
<DataGridCheckBoxColumn Binding="{Binding IsXML, Mode=TwoWay}"
Header="XML"
CanUserSort="False"
CanUserReorder="False" />
<DataGridCheckBoxColumn Binding="{Binding IsProperty, Mode=TwoWay}"
Header="Property"
CanUserSort="False"
CanUserReorder="False" />
<DataGridTextColumn Binding="{Binding FolderName, Mode=TwoWay}"
Header="Folder"
Width="*"
CanUserReorder="False"
IsReadOnly="False" />
<DataGridTemplateColumn Header="Browse">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Name="Browse"
Command="{Binding BrowseCommand}"
HorizontalAlignment="Center"
Width="20">...</Button>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTemplateColumn Header="Delete" IsReadOnly="True">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Name="Delete"
Command="{x:Static DataGrid.DeleteCommand}"
HorizontalAlignment="Center"
Width="20"
IsEnabled="True">X</Button>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
<Button Name="NextButton"
Content="Next"
Grid.Column="2"
Grid.ColumnSpan="2"
Grid.Row="1"
Margin="0,0,2,12"
Width="100"
Height="40"
HorizontalAlignment="Right"
VerticalAlignment="Bottom"
Click="NextButton_Click" />
</Grid>
</Page>
代码隐藏：
// DataTable
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
namespace AxureExport {
/// <summary>
/// Interaction logic for TargetPage.xaml
/// </summary>
public partial class TargetPage : Page {
FrameWindow _frame;
//ExportTargetInfos _eti;
public TargetPage(FrameWindow frame) {
InitializeComponent();
_frame = frame;
_frame.ExportTargets = new ExportTargetInfos(Properties.Settings.Default.ExportTargetHistory);
this.DataContext = _frame.ExportTargets;
}
//
// enable editing on single-click
private void DataGridCell_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) {
DataGridCell cell = sender as DataGridCell;
if (!cell.IsEditing) {
if (!cell.IsFocused)
cell.Focus();
if (!cell.IsSelected)
cell.IsSelected = true;
}
}
private void Page_Loaded(object sender, RoutedEventArgs e) {
}
private void NextButton_Click(object sender, RoutedEventArgs e) {
Properties.Settings.Default.ExportTargetHistory = _frame.ExportTargets.GetExportTargets();
_frame.NavigateTo(typeof(ExportPage));
}
}
}
视图模型：
using System;
using System.Collections.ObjectModel; // ObservibleCollection<>
using System.Collections.Specialized; // StringCollection
using System.ComponentModel; // INotifyPropertyChanged
namespace AxureExport {
public class ExportTargetInfos : ObservableCollection<ExportTargetInfo> {
const char _SEP = '|'; // field seperator character
// default constructor
public ExportTargetInfos() : base() {
}
// copy constructors
public ExportTargetInfos(ExportTargetInfos etis) : base() {
if (etis == null) return;
foreach (ExportTargetInfo eti in etis) {
this.Add(new ExportTargetInfo(eti.FolderName, eti.IsXML, eti.IsProperty));
}
}
public ExportTargetInfos(StringCollection sc) : base() {
if (sc == null) return;
foreach (string s in sc)
Add(ParseExportTarget(s));
}
public StringCollection GetExportTargets() {
StringCollection sc = new StringCollection();
foreach (ExportTargetInfo et in this)
sc.Add(BuildExportTarget(et));
return sc;
}
// create a string from an ExportTarget (for persistance)
private static string BuildExportTarget(ExportTargetInfo et) {
return et.FolderName + _SEP + et.IsXML.ToString() + _SEP + et.IsProperty.ToString();
}
// create an ExportTarget from an unparsed string (for persistance)
private static ExportTargetInfo ParseExportTarget(string s) {
int count = s.Split(_SEP).Length - 1;
string[] items = s.Split(new[] { _SEP }, StringSplitOptions.None);
string name = (count < 1 ? String.Empty : items[0]);
bool isXML = (count > 0 ? Convert.ToBoolean(items[1]) : false);
bool isProp = (count > 1 ? Convert.ToBoolean(items[2]) : false);
return new ExportTargetInfo(name, isXML, isProp);
}
}
//
// represents an export target (folder plus options) in it's parsed form
public class ExportTargetInfo : INotifyPropertyChanged {
public event PropertyChangedEventHandler PropertyChanged;
public IDelegateCommand BrowseCommand { protected set; get; }
// default constructor is needed to enable datagrid to add rows
public ExportTargetInfo() {
_folderName = String.Empty;
_isXML = false;
_isProperty = false;
this.BrowseCommand = new DelegateCommand(ExecuteBrowse, CanExecuteBrowse);
}
public ExportTargetInfo(string targetFolderName, bool isXML, bool isProperties) {
_folderName = targetFolderName;
_isXML = isXML;
_isProperty = isProperties;
this.BrowseCommand = new DelegateCommand(ExecuteBrowse, CanExecuteBrowse);
}
private string _folderName;
public string FolderName {
get { return _folderName; }
set { SetProperty<string>(ref _folderName, value, @"FolderName"); }
}
private bool _isXML;
public bool IsXML {
get { return _isXML; }
set { SetProperty<bool>(ref _isXML, value, @"IsXML"); }
}
private bool _isProperty;
public bool IsProperty {
get { return _isProperty; }
set { SetProperty<bool>(ref _isProperty, value, @"IsProperty"); }
}
// browse button for selected row clicked
void ExecuteBrowse(object param) {
// use WPF-WinForms interop (:-p)
var folderDialog = new System.Windows.Forms.FolderBrowserDialog();
folderDialog.Description = "Please designate the target folder";
folderDialog.SelectedPath = FolderName;
folderDialog.ShowNewFolderButton = true;
if (folderDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
FolderName = folderDialog.SelectedPath;
}
bool CanExecuteBrowse(object param) {
return true;
}
protected bool SetProperty<T>(ref T storage, T value, string propertyName = null) {
if (object.Equals(storage, value))
return false;
storage = value;
OnPropertyChanged(propertyName);
return true;
}
protected void OnPropertyChanged(string propertyName) {
if (PropertyChanged != null)
PropertyChanged( this, new PropertyChangedEventArgs(propertyName));
}
}
}
有没有人知道原因是什么？