WPF 装饰器 、 转换器

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装饰器参考：https://www.cnblogs.com/xietianjiao/p/11239558.html

 wpf 转换器

详情参考：https://www.cnblogs.com/zh7791/p/9311332.html

单值转换器需继承自 IValueConverter

    public class MyNumberConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if(value!=null&& System.Convert.ToInt32(value) % 2 == 0)
            {
                return "偶数";
            }
            return "奇数";
        }

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

多值转换器需继承自IMultiValueConverter

    public class MyColorConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (values != null && values.Length > 2)
            {
                var R = System.Convert.ToByte(values[0]);
                var G = System.Convert.ToByte(values[1]);
                var B = System.Convert.ToByte(values[2]);
                System.Windows.Media.Color color = System.Windows.Media.Color.FromRgb(R,G,B);
                 return new SolidColorBrush(color);
            }
            return null;
        }

        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

使用转换器

xaml 如下：

<Window x:Class="WpfApp9.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:MyConverter="clr-namespace:WpfApp9.Converter"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="600">
    <Window.Resources>
        <MyConverter:MyNumberConverter x:Key="MyNumber"/>
        <MyConverter:MyColorConverter x:Key="MyColor"/>
         
    </Window.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <StackPanel Grid.Column="0">
            <TextBox x:Name="txt" Text="0" Width="100" Height="40" FontFamily="50"/>
            <TextBlock Text="{Binding ElementName=txt,Path=Text,Converter={StaticResource MyNumber}}" FontSize="50" />
        </StackPanel>

        <StackPanel Grid.Column="1">
            <Slider x:Name="Rcolor" Maximum="255" Minimum="0" Value="0" Width="200" Margin="10"/>
            <Slider x:Name="Gcolor" Maximum="255" Minimum="0" Value="0" Width="200" Margin="10"/>
            <Slider x:Name="Bcolor" Maximum="255" Minimum="0" Value="0" Width="200" Margin="10"/>
            <Path VerticalAlignment="Center"   Stroke="Black"  StrokeThickness="3">
                <Path.Data>
                    <EllipseGeometry Center="80,80" RadiusX="60" RadiusY="60"/>
                </Path.Data>
                <Path.Fill>
                    <MultiBinding Converter="{StaticResource MyColor}">
                        <Binding ElementName="Rcolor" Path="Value"></Binding>
                        <Binding ElementName="Gcolor" Path="Value"></Binding>
                        <Binding ElementName="Bcolor" Path="Value"></Binding>
                    </MultiBinding>
                </Path.Fill>
            </Path>
        </StackPanel>
    </Grid>
</Window>

效果：

 注：需要在资源中引入定义的转换器

    <Window.Resources>
        <MyConverter:MyNumberConverter x:Key="MyNumber"/>
        <MyConverter:MyColorConverter x:Key="MyColor"/>
         
    </Window.Resources>

使用如下：

<TextBlock Text="{Binding ElementName=txt,Path=Text,Converter={StaticResource MyNumber}}" FontSize="50" />