wpf之转换器(Converter) 安静点

转换器 

作用：可以将源数据和目标数据之间进行特定的转化。

值转换器

将值从一种类型转换成另外一种类型。

比如说实现0与1转换成false和true

后台：

namespace MyWpf
{
    /// <summary>
    /// MyTestConverter.xaml 的交互逻辑
    /// </summary>
    public partial class MyTestConverter : UserControl
    {
        public MyTestConverter()
        {
            InitializeComponent();
        }
    }

    /// <summary>
    /// 自定义转换器
    /// </summary>
    public class IDisplayConverter : IValueConverter
    {
        /// <summary>
        /// 后台转换往前端传值
        /// </summary>
        /// <param name="value"></param>
        /// <param name="targetType"></param>
        /// <param name="parameter"></param>
        /// <param name="culture"></param>
        /// <returns></returns>
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value != null)
            {
                string str = value.ToString();
                if (str == "0")
                {
                    return false;
                }

                return true;
            }

            return true;
        }
        /// <summary>
        /// 前端往后端传值
        /// </summary>
        /// <param name="value"></param>
        /// <param name="targetType"></param>
        /// <param name="parameter"></param>
        /// <param name="culture"></param>
        /// <returns></returns>
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }


}

xaml：

<UserControl x:Class="MyWpf.MyTestConverter"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:MyWpf"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <!--在Usercontrol用户自定义控件中引用资源使用UserControl.Resources标签，如果在Windows中就是要使用<Window.Resources>标签-->
    <UserControl.Resources>
        <!--引入转换器资源-->
        <local:IDisplayConverter x:Key="converter"></local:IDisplayConverter>
    </UserControl.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition></ColumnDefinition>
            <ColumnDefinition></ColumnDefinition>
        </Grid.ColumnDefinitions>

        <StackPanel>
            <!--设置默认值，模拟已经从后台取到值了-->
            <TextBlock x:Name="t1"  FontSize="50" Text="0"></TextBlock>
            <TextBlock x:Name="t2"  FontSize="50" Text="1"></TextBlock>

            <TextBlock x:Name="t3" FontSize="50" 
                 Text="{Binding Path=Text,ElementName=t1,Converter={StaticResource ResourceKey=converter}}"></TextBlock>
            <TextBlock x:Name="t4"  FontSize="50" 
                 Text="{Binding Path=Text,ElementName=t2,Converter={StaticResource ResourceKey=converter}}"></TextBlock>

        </StackPanel>
    </Grid>
</UserControl>

结果：

多值转换器

后台：

    public class IMultiValueDisplayConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (values == null || values.Length < 3)
                return null;

            byte s1 = System.Convert.ToByte(values[0]);
            byte s2 = System.Convert.ToByte(values[1]);
            byte s3 = System.Convert.ToByte(values[2]);
            // 使用指定的 sRGB 颜色通道值创建一个新的 System.Windows.Media.Color 结构。
            Color color = Color.FromRgb(s1,s2,s3);
            return new SolidColorBrush(color); 
        }

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

xaml：

<UserControl x:Class="MyWpf.MyTestConverter"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:MyWpf"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <!--在Usercontrol用户自定义控件中引用资源使用UserControl.Resources标签，如果在Windows中就是要使用<Window.Resources>标签-->
    <UserControl.Resources>
        <!--引入转换器资源-->
        <local:IDisplayConverter x:Key="converter"></local:IDisplayConverter>
        <local:IMultiValueDisplayConverter x:Key="mul"></local:IMultiValueDisplayConverter>
    </UserControl.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition></ColumnDefinition>
            <ColumnDefinition></ColumnDefinition>
        </Grid.ColumnDefinitions>

        <StackPanel Grid.Column="0">
            <!--设置默认值，模拟已经从后台取到值了-->
            <TextBlock x:Name="t1"  FontSize="50" Text="0"></TextBlock>
            <TextBlock x:Name="t2"  FontSize="50" Text="1"></TextBlock>

            <TextBlock x:Name="t3" FontSize="50" Text="{Binding Path=Text,ElementName=t1,
Converter={StaticResource ResourceKey=converter}}"></TextBlock>
            <TextBlock x:Name="t4"  FontSize="50" Text="{Binding Path=Text,ElementName=t2,
Converter={StaticResource ResourceKey=converter}}"></TextBlock>
        </StackPanel>

        <!--多值转换器  -->
        <StackPanel Grid.Column="1">

            <Slider   Name="s1" Minimum="0" Maximum="255" Margin="10" Width="200"></Slider>
            <Slider  Name="s2" Minimum="0" Maximum="255" Margin="10" Width="200"></Slider>
            <Slider   Name="s3" Minimum="0" Maximum="255" Margin="10" Width="200"></Slider>

            <Path HorizontalAlignment="Center" >
                <Path.Data>
                    <EllipseGeometry Center="100,100" RadiusX="50" RadiusY="50">
                        
                    </EllipseGeometry>
                </Path.Data>
                <Path.Fill>
                    <MultiBinding Converter="{StaticResource ResourceKey=mul}">
                        <Binding ElementName="s1"  Path="Value"></Binding>
                        <Binding ElementName="s2"  Path="Value"></Binding>
                        <Binding ElementName="s3"  Path="Value"></Binding>
                    </MultiBinding>
                </Path.Fill>
                
            </Path>
        
        
        </StackPanel>
    </Grid>
</UserControl>

拖动3个Slider，圆形颜色也会对应改变