在 wpf 中绑定颜色的 R G B 属性 [英] Binding R G B properties of color in wpf

问题描述

我有一个自定义类FavoriteColor"，它具有三个属性，R、G 和 B.现在我想绘制一个矩形并用这些 R、G 和 B 值填充它(使用数据绑定).我在我的 xaml 中尝试了以下代码段，但给了我一个编译时错误.

I have a custom class, "FavoriteColor" that has three properties, R, G and B. Now I want to draw a rectangle and fill it with these R, G and B values (using databinding). I tried the following snippet in my xaml, but gives me a compile time error.

                <Rectangle Width="10" Height="10" Grid.Column="4">
                    <Rectangle.Fill>
                        <SolidColorBrush>
                            <SolidColorBrush.Color>
                                <Color R="{Binding Path=R}" />
                                <Color G="{Binding Path=G}" />
                                <Color B="{Binding Path=B}" />
                            </SolidColorBrush.Color>
                        </SolidColorBrush>
                    </Rectangle.Fill>
                </Rectangle>

它说 Color 类的属性 R、G 和 B 不是依赖属性.我知道您只能将数据绑定到依赖项属性，但在这种情况下，如何将我的 R、G 和 B 与矩形的填充颜色绑定.

It says that the properties R, G and B of Color class are not dependency properties. I know that you can bind data only to dependency properties, but in this case, how do I bind my R, G and B with the rectangle's fill color.

除了声明一个颜色类型的属性，然后在设置 R、G 和 B 时对其进行初始化之外，还有其他方法吗?还有为什么颜色类的R、G、B不是依赖属性?

推荐答案

让我们使用 MultiBinding 和 IMultiValueConverter 来做到这一点.这是一个完整的示例.

Let's do this using a MultiBinding and an IMultiValueConverter. Here's a full sample.

首先，Window1 的 xaml.我们将设置三个 Sliders 并通过 SolidColorBrush 将它们的值绑定到 Window 的 Background 属性.

First, the xaml for Window1. We'll set up three Sliders and bind their values to the Window's Background property via a SolidColorBrush.

<Window x:Class="WpfApplication16.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:my="clr-namespace:WpfApplication16"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <my:RgbConverter x:Key="RgbConverter" />
    </Window.Resources>
    <Window.Background>
        <SolidColorBrush>
            <SolidColorBrush.Color>
                <MultiBinding Converter="{StaticResource RgbConverter}">
                    <Binding Path="Value" ElementName="redSlider" />
                    <Binding Path="Value" ElementName="greenSlider" />
                    <Binding Path="Value" ElementName="blueSlider" />
                </MultiBinding>
            </SolidColorBrush.Color>
        </SolidColorBrush>
    </Window.Background>
    <StackPanel>
        <Slider Minimum="0" Maximum="255" x:Name="redSlider" />
        <Slider Minimum="0" Maximum="255" x:Name="greenSlider" />
        <Slider Minimum="0" Maximum="255" x:Name="blueSlider" />
    </StackPanel>
</Window>

接下来是转换器.请注意，我在这里没有进行任何错误检查 - 您确实应该检查 values 数组的长度是否为 3 以及各个值是否为有效字节等.

Next, the converter. Note that I'm not doing any error checking here - you really should check that the length of the values array is 3 and that the individual values are valid bytes etc.

public class RgbConverter : IMultiValueConverter
{
    #region IMultiValueConverter Members

    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var r = System.Convert.ToByte(values[0]);
        var g = System.Convert.ToByte(values[1]);
        var b = System.Convert.ToByte(values[2]);

        return Color.FromRgb(r, g, b);
    }

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

    #endregion
}

就是这样！不需要其他代码隐藏.

That's it! No other code-behind is necessary.

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