Question

我会学习在Wpf（xaml）上使用转换器。

<Window x:Class="TextExpanderGriglia.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:TextExpanderGriglia"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525" Loaded="Window_Loaded">
<Window.Resources>
    <local:BoolToVisibilityConverter x:Key="BoolToVisibilityConverter" />
</Window.Resources>
<Grid>
    <Button Content="CIAO" Width="50" Height="50" Visibility="{Binding vButton,Converter={StaticResource BoolToVisibilityConverter}}"> </Button>
    <Button Content="Cambia" Width="50" Height="50"  Margin="56,134,411,135" Click="Button_Click"/>
</Grid>

这是我的Xaml代码。愚蠢的例子开始，我有2个按钮和按钮＆＃34;坎比亚＆＃34;我设置了布尔值vButton =！vButton，但如果vButton为false，则第一个按钮不会隐藏。我的代码中缺少什么？

这是我的转换器

public class BoolToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        return (bool)value ? Visibility.Visible : Visibility.Hidden;
    }

    public object ConvertBack(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        return (Visibility)value == Visibility.Visible;
    }
}

MainWindows.xaml.cs

public partial class MainWindow : Window, INotifyPropertyChanged
{

    private bool vButton;

    public event PropertyChangedEventHandler PropertyChanged;

    public bool VButton
    {
        get
        {
            return vButton;
        }
        set
        {
            if (value != vButton)
            {
                this.vButton = value;
                NotifyPropertyChanged("VButton");
            }
        }
    }

    private void NotifyPropertyChanged(String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public MainWindow()
    {
        InitializeComponent();

    }


    private void Button_Click(object sender, RoutedEventArgs e)
    {

        vButton = !vButton;
    }

}

Answer 1

转换器看起来很好。

此处最有可能的情况是您绑定的属性不会引发更改通知。例如：

using System.ComponentModel;
using System.Runtime.CompilerServices;

public class MyModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private bool _isButtonVisible;

    public bool vButton
    {
        get { return _isButtonVisible; }
        set
        {
            if (value == _isButtonVisible)
                return;
            _isButtonVisible = value;
            OnPropertyChanged();
        }
    }

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

Answer 2

设置DataContext

在你的构造函数中：

height

在MVVM模式中，您应该与Windows分开定义ViewModel。对于前者在你的情况下：

@IBOutlet weak var content: UIView!
@IBAction func indexChanged(_ sender: UISegmentedControl)
{
if let vc = getViewController(sender.selectedSegmentIndex) {
        self.addChildViewController(vc)
        self.transition(from: self.currentViewController!,
                        to: vc,
                        duration: 0.5,
                        options: UIViewAnimationOptions.transitionCrossDissolve,
                        animations: {
                            self.currentViewController!.view.removeFromSuperview()
                            vc.view.frame = self.content.bounds
                            self.content.addSubview(vc.view)
                        },
                        completion: { finished in                   
         self.currentViewController!.removeFromParentViewController()
                            self.currentViewController = vc
                        })

    }
}

然后在你的MainWindow.xaml.cs

中

public MainWindow()
{
    InitializeComponent();
    DataContext = this;
}

转换器boolToVisibility

2 个答案: