Question

我试图根据机器状态（关/开）设置的布尔变量的值在多个网格中显示红色或绿色图标。转换器是实现此目的的最佳方式吗？我遇到了将我的变量绑定到网格上的图像字段的麻烦。我似乎无法解雇我的booltoimageconverter类？感谢您的任何指导。

Answer 1

使用BoolToImageConverter。使用此代码时，请检查所有资源和路径。（图像，转换器，模型（用于模型和转换器检查命名空间））。

<强>演示：在本演示中，我使用名称 Flag 更改了属性，然后BoolToImageConverter读取此属性并创建了BitmapImage。

<强> App.xaml中：

<Application x:Class="WpfApplication1.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:conv="clr-namespace:converters"
         StartupUri="MainWindow.xaml">
<Application.Resources>
    <ResourceDictionary>
        <conv:BoolToImageConverter x:Key="BoolToImageConv" />
    </ResourceDictionary>
</Application.Resources>

<强> MainWindow.xaml：

<Grid x:Name="LayoutRoot">
    <!--Image for demonstration, with binding-->
    <Image x:Name="TargetImageBlock" Source="{Binding Flag, Converter={StaticResource BoolToImageConv}}" VerticalAlignment="Top" HorizontalAlignment="Left" Height="100" Width="100"/>
    <!--Button for changing property in view model-->
    <Button Content="Change" HorizontalAlignment="Right" VerticalAlignment="Top" Margin="15" Padding="15" Click="Button_Click"/>
</Grid>

<强> MainWindow.cs：

    public partial class MainWindow : Window
{
    // create some view model
    SomeModel model = new SomeModel();

    public MainWindow()
    {
        InitializeComponent();
        Loaded += MainWindow_Loaded;
    }

    void MainWindow_Loaded(object sender, RoutedEventArgs e)
    {
        Loaded -= MainWindow_Loaded;
        // set context
        this.DataContext = model;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        // change property in view model (not image)
        if (model.Flag)
            model.Flag = false;
        else
            model.Flag = true;
    }        
}

<强> SomeModel.cs：

        public class SomeModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private bool _flag = false;

    /// <summary>
    /// This flag is your bool value.
    /// </summary>
    public bool Flag
    {
        get { return _flag; }
        set
        {
            if (_flag != value)
            {
                _flag = value;
                Notify();
            }
        }
    }

    private void Notify([CallerMemberName] string name = "")
    {
        var h = PropertyChanged;
        if (h != null)
            h(this, new PropertyChangedEventArgs(name));
    }
}

<强> BoolToImageConverter：

    namespace converters
{
    public class BoolToImageConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            bool val = (bool)value;
            if (val)
            {
                return new BitmapImage(new Uri("/images/like.png", UriKind.RelativeOrAbsolute));
            }
            else
            {
                return new BitmapImage(new Uri("/images/favs.png", UriKind.RelativeOrAbsolute));
            }
        }

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

Answer 2

价值转换器可行。肯定。

尽管如此，我觉得所有与程序外观有关的内容都应该存在于xaml中。这就是它的设计方式。

想想如果用户想为你的网格选择颜色主题怎么办？使用转换器，您可能需要做一些黑客才能完成任务。但是对于样式它更自然 - 你只需要编写一个新的并动态设置它。

我即将展示基于触发器的解决方案。它设置颜色，但使用图像也是一样的。

的Xaml：

<Window x:Class="Wpf1.MainWindow"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       Title="MainWindow" Height="350" Width="525">
   <Window.Resources>
       <Style x:Key="ColorfulTextBlock" TargetType="{x:Type TextBlock}">
           <Style.Triggers>
               <DataTrigger Binding="{Binding IsGreen}" Value="True">
                   <Setter Property="Background" Value="Green" ></Setter>
               </DataTrigger>
               <DataTrigger Binding="{Binding IsGreen}" Value="False">
                   <Setter Property="Background" Value="Red" ></Setter>
               </DataTrigger>
           </Style.Triggers>
       </Style>
   </Window.Resources>
   <StackPanel>
       <TextBlock Style="{StaticResource ColorfulTextBlock}">
            Color is changed when checbox is clicked
        </TextBlock>
       <CheckBox IsChecked="{Binding IsGreen}"></CheckBox>
   </StackPanel>
</Window>

代码背后（只是原始分配vm，可以通过xaml完成）

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

ViewModel

   public sealed class MainVm : DependencyObject
    {
       public static readonly DependencyProperty IsGreenProperty =
           DependencyProperty.Register("IsGreen", typeof (bool), typeof (MainVm), new PropertyMetadata(default(bool)));

       public bool IsGreen
        {
           get { return (bool) GetValue(IsGreenProperty); }
           set { SetValue(IsGreenProperty,value); }
        }
    }

WPF将布尔值绑定到图像显示

2 个答案: