WPF Binding值转换器ValueConverter使用简介(二)-IMultiValueConverter

注：

需要继承IMultiValueConverter接口，接口使用和IValueConverter逻辑相同。

一、MultiBinding+Converter 多值绑定及多值转换实例

当纵向流量大于横向流量时指示灯应为绿色，当纵向流量小于横向流量时指示灯应为红色，否则指示灯为黄色。

1、定制ColorConverter类，此时Convert中参数是object[] values，values[0]对应MultiBinding中的第一个Binding值，这里是纵向流量值，依此类推，可以在MultiBinding对象中指定多个绑定。

public class ColorConverter : IMultiValueConverter

{

    //正向修改

    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)

    {

        if (values == null || values.Length < )

            return DependencyProperty.UnsetValue;

        double verValue = (double)values[];

        double horValue = (double)values[];

        if (verValue > horValue)

            return new SolidColorBrush(Colors.Green);

        else if (verValue < horValue)

            return new SolidColorBrush(Colors.Red);

        return new SolidColorBrush(Colors.Yellow);

    }

    //反向修改

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)

    {

        //返回空，标记不可双向转换

        return null;

    }

}

2.Xaml定义

添加命名空间

 xmlns:local="clr-namespace:AudioDemo.View"

<Window.Resources>

    <local:ColorConverter x:Key="cvtColor"/>

</Window.Resources>

<Grid>

    <Label x:Name="label" Content="纵向值：" HorizontalAlignment="Left" Margin="10,40,0,0" VerticalAlignment="Top"/>

    <Label x:Name="label1" Content="横向值：" HorizontalAlignment="Left" Margin="10,80,0,0" VerticalAlignment="Top"/>

    <Slider x:Name="sliderVer" HorizontalAlignment="Left" Margin="75,43,0,0" VerticalAlignment="Top" Width="192"/>

    <Slider x:Name="sliderHor" HorizontalAlignment="Left" Margin="75,81,0,0" VerticalAlignment="Top" Width="192"/>

    <Ellipse   HorizontalAlignment="Left" Height="100" Margin="75,120,0,0" Stroke="Black" VerticalAlignment="Top" Width="100">

        <Ellipse.Fill>

            <MultiBinding Converter="{StaticResource cvtColor}">

                <Binding Path="Value" ElementName="sliderVer"/>

                <Binding Path="Value" ElementName="sliderHor"/>

            </MultiBinding>

        </Ellipse.Fill>

    </Ellipse>

</Grid>

二、RGB颜色混合实例

1.转换器定义

public class RGBConverter : IMultiValueConverter

{

    //正向修改，整合颜色值

    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)

    {

        if (values == null || values.Length < )

            return null;

        byte r = System.Convert.ToByte(values[]);

        byte g = System.Convert.ToByte(values[]);

        byte b = System.Convert.ToByte(values[]);

        Color col = Color.FromRgb(r, g, b);

        SolidColorBrush brush = new SolidColorBrush(col);

        return brush;

    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)

    {

        return null;

    }

}

2.Xaml定义

别忘先添加命名空间

xmlns:local="clr-namespace:AudioDemo.View"

<Window.Resources>

    <local:RGBConverter  x:Key="rgbCvt"/>

</Window.Resources>

<Grid>

    <Label x:Name="label" Content="Red:" HorizontalAlignment="Left" Margin="10,48,0,0" VerticalAlignment="Top"/>

    <Label x:Name="label_Copy" Content="Green:" HorizontalAlignment="Left" Margin="7,85,0,0" VerticalAlignment="Top"/>

    <Label x:Name="label_Copy1" Content="Blue:" HorizontalAlignment="Left" Margin="7,123,0,0" VerticalAlignment="Top"/>

    <Slider x:Name="slider_r" Minimum="0" Maximum="255" Ticks="1"   HorizontalAlignment="Left" Margin="68,53,0,0" VerticalAlignment="Top" Width="207"/>

    <Slider x:Name="slider_g" Minimum="0" Maximum="255"  Ticks="1" HorizontalAlignment="Left" Margin="68,91,0,0" VerticalAlignment="Top" Width="207"/>

    <Slider x:Name="slider_b" Minimum="0" Maximum="255"  Ticks="1" HorizontalAlignment="Left" Margin="68,124,0,0" VerticalAlignment="Top" Width="207"/>

    <Rectangle  HorizontalAlignment="Left" Height="90" Margin="68,160,0,0" Stroke="Black" VerticalAlignment="Top" Width="142">

        <Rectangle.Fill>

            <MultiBinding Converter="{StaticResource rgbCvt}">

                <Binding ElementName="slider_r" Path="Value"></Binding>

                <Binding ElementName="slider_g" Path="Value"></Binding>

                <Binding ElementName="slider_b" Path="Value"></Binding>

            </MultiBinding>

        </Rectangle.Fill>

    </Rectangle>

</Grid>

运行结果：

更多参考：WPF Binding值转换器ValueConverter使用简介(一)

WPF Binding值转换器ValueConverter使用简介(二)-IMultiValueConverter的相关教程结束。