Question

我试图在单击时更改按钮的颜色。它采用分配的初始颜色，但单击后不会更新。我附上我的代码，让我知道我要去哪里了。我试图实现以下文章中提供的代码

MainWindow.xaml代码段

<Window.Resources>
    <viewModels:MainWindowViewModel x:Key="MainViewModel"/>
</Window.Resources>

<Border Padding="20">
    <StackPanel DataContext="{Binding Source={StaticResource MainViewModel}}">
        <Button Content="Button1" Margin="10 10 10 10" Command="{Binding ClickCommand, Mode=OneWay}" Background="{Binding BackgroundColorBtn1}"/>
        <Button Content="Button2 " Margin="10 10 10 10"></Button>
    </StackPanel>
</Border>

</Window>

MainWindow.xaml.cs

public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new MainWindowViewModel();
        }

        private void MainWindow_OnLoaded(object sender, RoutedEventArgs e)
        {
            var desktopWorkingArea = System.Windows.SystemParameters.WorkArea;
            this.Left = desktopWorkingArea.Right - this.Width;
            this.Top = desktopWorkingArea.Bottom - this.Height;
        }
    }

MainWindowViewModel.cs

namespace DockedPanel.ViewModels
{
    public class MainWindowViewModel:INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        public MainWindowViewModel()
        {
            _canExecute = true;
        }
        private ICommand _clickCommand;
        public ICommand ClickCommand
        {
            get
            {
                return _clickCommand ?? (_clickCommand = new CommandHandler(() => MyAction(), _canExecute));
            }
        }
        private bool _canExecute;
        public void MyAction()
        {
            _backgroundColorBtn1 = Colors.Blue;
        }

        private void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        private Color _backgroundColorBtn1 =  Colors.White;
        public Color BackgroundColorBtn1
        {
            get { return _backgroundColorBtn1; }
            set
            {
                if (value == _backgroundColorBtn1)
                    return;

                _backgroundColorBtn1 = value;

                OnPropertyChanged(nameof(BackgroundColorBtn1));
            }
        }
    }
}

最后 CommandHandler

namespace DockedPanel.ViewModels.Command
{
    public class CommandHandler : ICommand
    {
        private Action _action;
        private bool _canExecute;
        public CommandHandler(Action action, bool canExecute)
        {
            _action = action;
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute;
        }

        public event EventHandler CanExecuteChanged;

        public void Execute(object parameter)
        {
            _action();
        }
    }
}

Answer 1

由于您要更改私有支持变量，因此需要在BackgroundColorBtn1属性上调用OnPropertyChanged，并且需要通知View。

您可以按照以下步骤修改MyAction方法

 public void MyAction()
 {
      _backgroundColorBtn1 = Colors.Blue;
      OnPropertyChanged(nameof(BackgroundColorBtn1));
 }

或者，您可以直接设置Property而不是backing字段，这会调用OnPropertyChanged调用本身。

 public void MyAction()
 {
      BackgroundColorBtn1 = Colors.Blue;
 }

您还需要使用颜色画笔转换器。按钮的background属性接受画笔，而不接受颜色。转换器可让您将所选的颜色转换为画笔。

您可以按以下方式定义Converter

public class ColorToSolidColorBrushValueConverter : IValueConverter 
{

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (value == null)
            return null;

        if (value is Color)
            return new SolidColorBrush((Color)value);

        throw new InvalidOperationException("Unsupported type [" + value.GetType().Name + "], ColorToSolidColorBrushValueConverter.Convert()");
    }

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

然后，您可以将其用作

Background="{Binding BackgroundColorBtn1, Converter={StaticResource colorToSolidColorBrushConverter}}"

请确保您在使用“资源”部分之前添加了以下内容

<Window.Resources>
<ResourceDictionary>
        <myNameSpace:ColorToSolidColorBrushValueConverter  x:Key="colorToSolidColorBrushConverter"/>
</ResourceDictionary>
</Window.Resources>

使用WPF和绑定单击时更改按钮背景颜色

1 个答案: