wpf 如何在用户输入文本框时启用按钮
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How to enable a button when a user types into a textbox
提问by user253175
What is the simplest way in WPF to enable a Buttonwhen the user types something into a TextBox?
在 WPF 中启用 aButton当用户在 a 中键入内容时最简单的方法是TextBox什么？
采纳答案by Soni Ali
Use the Simple Command
使用简单命令
<TextBox Text={Binding Path=TitleText}/>
<Button Command="{Binding Path=ClearTextCommand}" Content="Clear Text"/>
Here is the sample code in the View Model
这是视图模型中的示例代码
public class MyViewModel : INotifyPropertyChanged
{
public ICommand ClearTextCommand { get; private set; }
private string _titleText;
public string TitleText
{
get { return _titleText; }
set
{
if (value == _titleText)
return;
_titleText = value;
this.OnPropertyChanged("TitleText");
}
}
public MyViewModel()
{
ClearTextCommand = new SimpleCommand
{
ExecuteDelegate = x => TitleText="",
CanExecuteDelegate = x => TitleText.Length > 0
};
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
For more information see Marlon Grechs SimpleCommand
有关更多信息，请参阅 Marlon Grechs SimpleCommand
Also check out the MVVM Project Template/Toolkit from http://blogs.msdn.com/llobo/archive/2009/05/01/download-m-v-vm-project-template-toolkit.aspx. It uses the DelegateCommand for commanding and it should be a great starting template for any project.
还可以从http://blogs.msdn.com/llobo/archive/2009/05/01/download-mv-vm-project-template-toolkit.aspx查看 MVVM 项目模板/工具包。它使用 DelegateCommand 进行命令，它应该是任何项目的一个很好的起始模板。
回答by user253175
Why is everyone making things so complicated!
为什么大家都把事情搞得这么复杂！
<TextBox x:Name="TB"/>
<Button IsEnabled="{Binding ElementName=TB,Path=Text.Length}">Test</Button>
Nothing else needed......
别的什么都不需要......
回答by Bert
Use a trigger!
使用触发器！
<TextBox x:Name="txt_Titel />
<Button Content="Transfer" d:IsLocked="True">
<Button.Style>
<Style>
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=txt_Titel, Path=Text}" Value="">
<Setter Property="Button.IsEnabled" Value="false"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
回答by Dennis
IF you were not using Commands, another alternative is using a Converter.
如果您没有使用命令，另一种选择是使用转换器。
For example, using a generic Int to Bool converter:
例如，使用通用的 Int 到 Bool 转换器：
[ValueConversion(typeof(int), typeof(bool))]
public class IntToBoolConverter : IValueConverter
{
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
try
{
return (System.Convert.ToInt32(value) > 0);
}
catch (InvalidCastException)
{
return DependencyProperty.UnsetValue;
}
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return System.Convert.ToBoolean(value) ? 1 : 0;
}
#endregion
}
Then on the buttons IsEnabled property:
然后在按钮 IsEnabled 属性上：
<Button IsEnabled={Binding ElementName=TextBoxName, Path=Text.Length, Converter={StaticResource IntToBoolConverter}}/>
HTH,
哈，
Dennis
丹尼斯
回答by George30
The key on this is on the binding itself..
关键在于绑定本身..
Add UpdateSourceTrigger = PropertyChanged
添加 UpdateSourceTrigger = PropertyChanged
this is the most simple solution
这是最简单的解决方案
回答by Anzurio
Add a callback to the TextBox that fires on every stroke. Test for emptiness in such callback and enable/disable the button.
将回调添加到在每个笔画上触发的 TextBox。在此类回调中测试是否为空并启用/禁用按钮。
