Question

我在xmal中有一个StackLayout属性，如下所示：

   <StackLayout x:Name="_infoView"
                 Margin="0,10,0,10"
                 BackgroundColor="Black"
                 IsVisible="{Binding State}"/>

和ViewModel中的绑定bool变量

    private Boolean _state = true;
    public Boolean State
    {
        get { return _state; }
        set { }
    }

我的xmal中有一个按钮，想控制StackLayout的可见性，所以我做了类似的事情：

        <Button x:Name="CloseButton"
                Grid.Row="0"
                Grid.Column="3"
                Command="{Binding CloseWindowCommand}"/>

并在ViewModel中

CloseWindowCommand = new Command(CloseWindowTapped, CanCloseWindowTapped);

public ICommand CloseWindowCommand { get; set; }
public void CloseWindowTapped()
{
     State = false;
}
public bool CanCloseWindowTapped()
{
    return true;
}

我假设，通过点击CloseButton，我的StackLayout将消失......但它无法正常工作

Answer 1

ViewModel应该实现INotifyPropertyChanged接口，以通知View有关更改。

public class ViewModel : INotifyPropertyChanged
{
    // Implementing INotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;

    protected void RaisePropertyChanged([CallerMemberName]string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName);
    }        

    // In the setter of property raise event to inform view about changes
    private Boolean _state = true;
    public Boolean State
    {
        get 
        { 
            return _state; 
        }
        set 
        { 
            _state = value;
            RaisePropertyChanged();
        }
    }
}

将xaml属性可见性绑定到ViewModel，使用按钮进行控制

1 个答案: