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

2024-08-15 12:02:40   218人阅读

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 < 2)            return DependencyProperty.UnsetValue;        double verValue = http://www.mamicode.com/(double)values[0];        double horValue = http://www.mamicode.com/(double)values[1];        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>

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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 < 3)            return null;        byte r = System.Convert.ToByte(values[0]);        byte g = System.Convert.ToByte(values[1]);        byte b = System.Convert.ToByte(values[2]);        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：

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 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


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