数据绑定WPF XAML

Question

Hello I am new to WPF and I am not sure how to do the data binding and the code behind to get my textbox and button to be enabled and disabled.

If you could show me how to get it to work in the example below it would help me out in my project.

XAML

<ComboBox Name="ComboBoxA"                  
          Margin="5"  
          SelectedIndex="0" SelectionChanged="ComboBoxA_SelectionChanged"  >
    <ComboBox.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapPanel Orientation="Vertical" Height="Auto" Margin="5" />
        </ItemsPanelTemplate>
    </ComboBox.ItemsPanel>
    <ComboBoxItem Content="Option1" Width="72"  />
    <ComboBoxItem Content="Option2" Width="72" />
    <ComboBoxItem Content="Option3" Width="72" />
</ComboBox>

<TextBox Name="TextBoxA"
         Margin="5" 
         Width="200"   
         IsEnabled="{Binding TextBoxEnabled}" />

<Button Name="ButtonA"
        Content="Next" 
        HorizontalAlignment="left"                
        Margin="5"                 
        IsEnabled="{Binding ButtonEnabled} />

C#

private void ComboBoxA_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    TextBoxA = new TextBox();
    ButtonA = new Button();

    if (ComboBoxAfterProcessing.SelectedIndex == 0)
    {                    
        TextBoxA.IsEnabled = false;                    
        ButtonA.IsEnabled = false;
    }
    else if (ComboBoxAfterProcessing.SelectedIndex == 1)
    {                   
        TextBoxA.IsEnabled = true;
        ButtonA.IsEnabled = true;
    }
    else if (ComboBoxAfterProcessing.SelectedIndex == 2)
    {
        TextBoxA.IsEnabled = true;
        ButtonA.IsEnabled = true;
    }
}

Answer 1

you can binding your textbox and button's IsEnabe Property to the Combox's SelectedIndex Property and you neednot response to ComboBoxA_SelectionChanged Event. in order to let the SelectedIndex change your button and textBox's IsEnabe you need a convetor in your binding for example:

Answer 2

1. Write a class as follows which shall look like below

    public class ViewMole:INotifyPropertyChanged { public ViewMole() { ListValues = new List<string>() { "Option1", "Option2", "Option3", "Option4", "Option5" }; } public ICommand Click { get { return new RelayCommand(); } } public List<string> ListValues { get; set; } string a; public string A { get { return a; } set { a = value; RaisePropertyChanged("A"); } } int index=0; public int SelectedIndex { get { return index; } set { index = value; RaisePropertyChanged("SelectedIndex"); A = ListValues[index]; if (index == 0) { IsEnabled = false; } else { IsEnabled = true; } } } bool isEnabled; public bool IsEnabled { get { return isEnabled; } set { isEnabled = value; RaisePropertyChanged("IsEnabled"); } } public event PropertyChangedEventHandler PropertyChanged; private void RaisePropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } 

   }

Write another class which implements ICommand as below. This is to handel button click events

     public class RelayCommand : ICommand
    {
    public bool CanExecute(object parameter)
    {
        return true;
    }

    public event EventHandler CanExecuteChanged;

    public void Execute(object parameter)
    {
        MessageBox.Show("Button cliked");
    }
}

Change your Xaml below

    <ComboBox Name="ComboBoxA"  SelectedIndex="{Binding SelectedIndex, UpdateSourceTrigger=PropertyChanged}" ItemsSource="{Binding ListValues}"/>

    <TextBox Name="TextBoxA"  Margin="5"    Width="200"   Text="{Binding A}" IsEnabled="{Binding IsEnabled}"/>

    <Button Name="ButtonA"   Content="Next"   HorizontalAlignment="left" Margin="5"    Command="{Binding Click}" IsEnabled="{Binding IsEnabled}"/>

In Xmal.cs set the data Context as beolw

    public MainWindow()
    {
        InitializeComponent();
        DataContext = new ViewMole();

    }

Refer the below links to understand why INotifyPropertyChanged and ICommand has to be used http://wpftutorial.net/INotifyPropertyChanged.html http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.aspx http://msdn.microsoft.com/en-us/library/system.windows.input.icommand.aspx