CBr*_*eze 15 c# wpf xaml visibility button
我试图DataTriggers在我的上面设置多个Button.我做了一些研究,发现MultiDataTrigger允许你这样做.如果OR,我想将Visibilitymy 的属性Button设置为false .这就是我到目前为止所拥有的;CCTVPath == string.EmptyPermissionsFlag == false
<Button Grid.Column="3" x:Name="cctvFeedButton" Content="Live Feed"
Width="100" FontSize="16" HorizontalAlignment="Right" Margin="5" Click="OnCCTVButtonClick">
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding CCTVPath}" Value=""/>
<Condition Binding="{Binding PermissionsFlag}" Value="False"/>
</MultiDataTrigger.Conditions>
<Setter Property="Visibility" Value="Hidden"/>
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
在我的代码隐藏中,我这样设置PermissionsFlag;
public bool PermissionsFlag { get; set; }
private void OnPageLoaded(object sender, RoutedEventArgs e)
{
PermissionsFlag = false;
}
正如你所看到PermissionsFlag的那样绝对是假的,而且肯定是空的,CCTVPath但是Button永远不会被隐藏.我究竟做错了什么？
更新:
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private bool _permissionsFlag;
public bool Flag
{
get { return _permissionsFlag; }
set
{
_permissionsFlag = value;
OnPropertyChanged("PermissionsFlag");
}
}
private void OnPageLoaded(object sender, RoutedEventArgs e)
{
Flag = false;
CCTVImageCollection = GetImages();
imageListBox.ItemsSource = CCTVImageCollection;
DataContext = this;
}
在我的XAML中:
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<DataTrigger Binding="{Binding PermissionsFlag}" Value="False">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
ASh*_*ASh 22
将条件转换为两个独立的DataTriggers
<Style.Triggers>
<DataTrigger Binding="{Binding CCTVPath}" Value="">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
<DataTrigger Binding="{Binding PermissionsFlag}" Value="False">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
</Style.Triggers>
确保绑定路径正确(检查VS Output窗口是否有可能的异常消息)
OnCCTVButtonClick)中正确实现权限.在这里阅读原因:
auto-property PermissionsFlag(public bool PermissionsFlag { get; set; })不会通知视图有关更改.
可以实现INotifyPropertyChanged接口(在我的测试窗口中,它是这样完成的:) public partial class Window3 : Window, INotifyPropertyChanged,然后在属性更改时引发事件.
这是一个完整的工作示例,我用于测试
public partial class Window3 : Window, INotifyPropertyChanged
{
public Window3()
{
InitializeComponent();
this.DataContext = this;
//PermissionsFlag = true;
CCTVPath = "youtube.com";
}
private bool _permissionsFlag = false;
private string _cctvPath;
public bool PermissionsFlag
{
get { return _permissionsFlag; }
set
{
_permissionsFlag = value;
OnPropertyChanged("PermissionsFlag");
}
}
public string CCTVPath
{
get { return _cctvPath; }
set
{
_cctvPath = value;
OnPropertyChanged("CCTVPath");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
窗口xaml:
<Window x:Class="WpfDemos.Views.Window3"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window3" Height="300" Width="300">
<StackPanel>
<CheckBox Name="chkPermissionsFlag"
Content="PermissionsFlag"
IsChecked="{Binding Path=PermissionsFlag, UpdateSourceTrigger=PropertyChanged}"/>
<TextBox Text="{Binding Path=CCTVPath, UpdateSourceTrigger=PropertyChanged}"/>
<Button x:Name="cctvFeedButton" Content="Live Feed"
Width="100" FontSize="16" HorizontalAlignment="Right" Margin="5">
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=CCTVPath}" Value="">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
<DataTrigger Binding="{Binding Path=PermissionsFlag}" Value="False">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
</StackPanel>
</Window>
另一种解决方案是将单个 DataTrigger 与 MultiBinding 结合使用。您可以通过定义一个“特殊情况” IMultiValueConverter 来使其工作，该 IMultiValueConverter 假定对象数组中有 2 个项目，如果第一项是空字符串或第二项为假，则返回 true。但是，您可能永远不会在代码的其他任何地方使用该转换器。因此，如果您愿意预先做更多的工作，您可以定义 3 个简单/可重用的转换器。
1) 一个 [IMultiValueConverter] 'OrConverter'，它看起来像这样：
public class BooleanOrConverter : IMultiValueConverter {
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) {
return values.OfType<bool>().Any(b => b);
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) {
throw new NotImplementedException();
}
}
2) [IValueConverter] 'IsNullOrEmpty' 字符串转换器：
public class StringIsNullOrEmptyConverter : IValueConverter {
public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
return string.IsNullOrEmpty(value as string);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) {
throw new NotImplementedException();
}
}
3) 和 [IValueConverter] 'NotConverter:'
public class BooleanNotConverter : 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) {
throw new NotImplementedException();
}
}
然后，在您的 xaml 中，DataTrigger 将被定义为：
<Button x:Name="cctvFeedButton" Content="Live Feed"
Width="100" FontSize="16" HorizontalAlignment="Right" Margin="5">
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<DataTrigger Value="True">
<DataTrigger.Binding>
<MultiBinding Converter="{StaticResource OrConverter}">
<Binding Path="PermissionFlag" Converter="{StaticResource NotConverter}"/>
<Binding Path="CCTVPath" Converter="{StaticResource IsNullOrEmptyConverter}"/>
</MultiBinding>
</DataTrigger.Binding>
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
我更喜欢这个解决方案而不是使用 2 个单独的 DataTriggers 来提高可读性；它更好地表达了您正在定义的行为 - 它是“或”逻辑：应该隐藏按钮的 2 个条件的单一集合。