WPF工具提示仅在Text是某些内容时显示

Question

我有以下代码:

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Window.Resources>
    <Style x:Key="{x:Type ToolTip}" TargetType="{x:Type ToolTip}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ToolTip}">
                    <Border Background="Black">
                        <TextBlock  FontFamily="Tahoma" FontSize="11" Text="{TemplateBinding Content}" Foreground="WhiteSmoke" Padding="2" />
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>
<StackPanel>
    <Label Content="Label 1" ToolTip="asd" />
    <Label Content="Label 2" ToolTip="" />
    <TextBlock Text="TextBlock 1" ToolTip="asd" />
    <TextBlock Text="TextBlock 2" ToolTip="" />
    <Button Content="Button 1" ToolTip="asd" />
    <Button Content="Button 2" ToolTip="" />
</StackPanel>

现在,您可以通过测试看到当您将鼠标悬停在标签2,文本块2,按钮2上时,工具提示仍会显示.我希望触发它,如果Tooltip为空或null,则它不应显示任何内容.我知道我可以简单地从XAML中移除它但是我在这里做的方式是不同的.

我已经尝试添加一个触发器来检查value =""和null和内部触发器,将模板设置为null但它们都没有工作

如果你们中的一些专家能够对它有所了解,我会很高兴的

Answer 1

当DataTrigger可以完成同样的事情时,转换器可能是过度的.以下样式是您的发布样式,有一些清理和必要的触发器.请注意以下事项:

1. 我通常设置最终将被触发器覆盖的默认样式.在这种情况下,默认样式是Visibility=Visible.
2. 有两个触发器.一个用于内容为空时,另一个用于内容为空时.

XAML

<Style TargetType="ToolTip">
    <Setter Property="Visibility" Value="Visible" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="ToolTip">
                <Border Background="Black">
                    <TextBlock FontFamily="Tahoma"
                               FontSize="11"
                               Foreground="WhiteSmoke"
                               Padding="2"
                               Text="{TemplateBinding Content}" />
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Style.Triggers>
        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Content}" Value="{x:Null}">
            <Setter Property="Visibility" Value="Collapsed" />
        </DataTrigger>
        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Content}" Value="">
            <Setter Property="Visibility" Value="Collapsed" />
        </DataTrigger>
    </Style.Triggers>
</Style>

Answer 2

您可以考虑使用IValueConverter来显示/隐藏工具提示边框.将此类添加到项目中:

class BorderVisibilitySetter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
       //check if the control's content property is null or empty        
        if(value == null || value.ToString() == string.Empty)
            return Visibility.Collapsed;
        else
            return Visibility.Visible;
    }

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

然后将您的xaml修改为:

<src:BorderVisibilitySetter x:Key="BorderVisible" />
    <Style x:Key="{x:Type ToolTip}" TargetType="{x:Type ToolTip}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ToolTip}">
                    <Border Background="Black" Visibility="{TemplateBinding Content, Converter={StaticResource BorderVisible}}" >
                        <TextBlock  FontFamily="Tahoma" FontSize="11" Text="{TemplateBinding Content}" Foreground="WhiteSmoke" Padding="2" />
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>