在WPF中为用户控件创建可绑定属性的正确方法是什么？

Question

这是对这个问题的跟进.我已经为控件开发了一个简单的界面,它允许用户能够以最简单的方式定义颜色 - 通过控制颜色本身的ARGB通道.

我希望此控件能够直接绑定到颜色属性,以便允许用户通过滑块调整它.

我碰壁了 - 我试图用它来实现MVVM,但这不起作用,因为这样做我完全无法从控件中提取控件本身定义的颜色属性.

我实际上甚至不觉得这是正确的方法.我需要有几个控件,允许用户更改我们的应用程序的行为和外观,但我无法弄清楚如何让UserControl绑定到应用程序的设置(我已经能够绑定单个,简单的控制,但是当涉及到像这样的复合控件时,我没有在哪里).

这是控件本身和MVVM的代码:

public partial class ColorDefiner : UserControl {

    public static readonly DependencyProperty
        _Color = DependencyProperty.Register( "Color", typeof( Color ), typeof( ColorDefiner ) );

    public Color Color {
        get { return ( Color )this.GetValue( ColorDefiner._Color ); }
        set { this.SetValue( ColorDefiner._Color, value ); }
    }

    public ColorDefiner( ) { InitializeComponent( ); }
}


public class ColorViewModel : INotifyPropertyChanged {

    public event PropertyChangedEventHandler PropertyChanged;

    private Color _Color = Colors.Black;

    public double A {
        get { return this.Color.ScA; }
        set {
            this._Color.ScA = ( float )value;
            if ( this.PropertyChanged != null ) {
                this.PropertyChanged( this, new PropertyChangedEventArgs( "A" ) );
                this.PropertyChanged( this, new PropertyChangedEventArgs( "Color" ) );
            }
        }
    }
    public double R {
        get { return this.Color.ScR; }
        set {
            this._Color.ScR = ( float )value;
            if ( this.PropertyChanged != null ) {
                this.PropertyChanged( this, new PropertyChangedEventArgs( "R" ) );
                this.PropertyChanged( this, new PropertyChangedEventArgs( "Red" ) );
                this.PropertyChanged( this, new PropertyChangedEventArgs( "Color" ) );
            }
        }
    }
    public double G {
        get { return this.Color.ScG; }
        set {
            this._Color.ScG = ( float )value;
            if ( this.PropertyChanged != null ) {
                this.PropertyChanged( this, new PropertyChangedEventArgs( "G" ) );
                this.PropertyChanged( this, new PropertyChangedEventArgs( "Green" ) );
                this.PropertyChanged( this, new PropertyChangedEventArgs( "Color" ) );
            }
        }
    }
    public double B {
        get { return this._Color.ScB; }
        set {
            this._Color.ScB = ( float )value;
            if ( this.PropertyChanged != null ) {
                this.PropertyChanged( this, new PropertyChangedEventArgs( "B" ) );
                this.PropertyChanged( this, new PropertyChangedEventArgs( "Blue" ) );
                this.PropertyChanged( this, new PropertyChangedEventArgs( "Color" ) );
            }
        }
    }

    public Color Color {
        get { return this._Color; }
        set {
            this._Color = value;
            if ( this.PropertyChanged != null )
                this.AllChanged( );
        }
    }
    public Color Red { get { return Color.FromScRgb( 1.0F, ( float )this.R, 0.0F, 0.0F ); } }
    public Color Green { get { return Color.FromScRgb( 1.0F, 0.0F, ( float )this.G, 0.0F ); } }
    public Color Blue { get { return Color.FromScRgb( 1.0F, 0.0F, 0.0F, ( float )this.B ); } }

    private void AllChanged( ) {
        this.PropertyChanged( this, new PropertyChangedEventArgs( "A" ) );
        this.PropertyChanged( this, new PropertyChangedEventArgs( "R" ) );
        this.PropertyChanged( this, new PropertyChangedEventArgs( "G" ) );
        this.PropertyChanged( this, new PropertyChangedEventArgs( "B" ) );
        this.PropertyChanged( this, new PropertyChangedEventArgs( "Red" ) );
        this.PropertyChanged( this, new PropertyChangedEventArgs( "Green" ) );
        this.PropertyChanged( this, new PropertyChangedEventArgs( "Blue" ) );
        this.PropertyChanged( this, new PropertyChangedEventArgs( "Color" ) );
    }
}

我已经尝试将Color依赖属性绑定到代码中的Color View Model; 我试过通过XAML中的Style Setter绑定它:

<UserControl.Resources>
    <Style TargetType="Controls:ColorDefiner">
        <Setter Property="Color" Value="{Binding Color, Mode=TwoWay}"/>
    </Style>
</UserControl.Resources>

什么都行不通 - 做这件事的合适方法是什么？(或者最好的方法,或者最正确的方法,或者最常用的方法？)如何从附加到控件的颜色视图模型中提取定义的Color属性？这甚至是正确的方法吗？

Answer 1

Color属性更改后,ColorDefiner控件不会响应.它应该使用依赖项属性元数据注册PropertyChangedCallback.属性元数据还可用于指定属性默认绑定为双向.您还应该遵循WPF中的命名约定,并命名DependencyProperty字段ColorProperty:

public partial class ColorDefiner : UserControl
{
    public static readonly DependencyProperty ColorProperty =
        DependencyProperty.Register(
            "Color", typeof(Color), typeof(ColorDefiner),
            new FrameworkPropertyMetadata(
                Colors.Black,
                FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
                (o, e) => ((ColorDefiner)o).ColorPropertyChanged((Color)e.NewValue)));

    public Color Color
    {
        get { return (Color)GetValue(ColorProperty); }
        set { SetValue(ColorProperty, value); }
    }

    public ColorDefiner()
    {
        InitializeComponent();
    }

    private void ColorPropertyChanged(Color color)
    {
        sliderA.Value = (double)color.A;
        sliderR.Value = (double)color.R;
        sliderG.Value = (double)color.G;
        sliderB.Value = (double)color.B;
    }

    private void SliderValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
    {
        Color = Color.FromArgb((byte)sliderA.Value,
            (byte)sliderR.Value, (byte)sliderG.Value, (byte)sliderB.Value);
    }
}

该SliderValueChanged事件处理程序用于在控件的XAML所有四个滑块:

<UserControl  ...>
    <StackPanel>
        <Slider x:Name="sliderA" Maximum="255" ValueChanged="SliderValueChanged"/>
        <Slider x:Name="sliderR" Maximum="255" ValueChanged="SliderValueChanged"/>
        <Slider x:Name="sliderG" Maximum="255" ValueChanged="SliderValueChanged"/>
        <Slider x:Name="sliderB" Maximum="255" ValueChanged="SliderValueChanged"/>
    </StackPanel>
</UserControl>

这个简单的例子展示了控件的工作原理:

<Grid>
    <Grid.Background>
        <SolidColorBrush x:Name="brush" Color="AliceBlue"/>
    </Grid.Background>
    <local:ColorDefiner Color="{Binding Color, ElementName=brush}"/>
</Grid>

它可以类似地绑定到具有Color属性的任何视图模型.