CustomControl 在清理后可见，但在重建后不可见

Question

几周前我开始使用 WPF，所以我是新手。我试图创建一个用户控件。

但它在 Window 中不可见。如果我清理项目，UserControl 是可见的，并且有一个带有文本的警告标志：

"This document contains one or more controls which have been changed. Rebuild the project to show the changes in the design view."

当我重建或运行（包括重建）时，UserControl 消失。

那就是 XAML

    <Slider Name="sliderRed" Grid.Row="0" HorizontalAlignment="Stretch" VerticalAlignment="Top" Minimum="0" Maximum="255" Value="{Binding ElementName=colorPicker, Path=Red}"/>
    <Slider Name="sliderGreen" Grid.Row="1" HorizontalAlignment="Stretch" VerticalAlignment="Top" Minimum="0" Maximum="255" Value="{Binding ElementName=colorPicker, Path=Green}"/>
    <Slider Name="sliderBlue" Grid.Row="2" HorizontalAlignment="Stretch" VerticalAlignment="Top" Minimum="0" Maximum="255" Value="{Binding ElementName=colorPicker, Path=Blue}"/>

    <Rectangle Grid.Column="1" Grid.RowSpan="3">
        <Rectangle.Fill>
            <SolidColorBrush Color="{Binding ElementName=colorPicker,Path=Color}"/>
        </Rectangle.Fill>
    </Rectangle>

而这个是XAML后面的Class：

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace CustomControls
{
public partial class ColorPicker : UserControl
{
    public static DependencyProperty ColorProperty;

    public static DependencyProperty RedProperty;
    public static DependencyProperty GreenProperty;
    public static DependencyProperty BlueProperty;

    public static readonly RoutedEvent ColorChangedEvent;

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

    public byte Red
    {
        get { return (byte)GetValue(RedProperty); }
        set { SetValue(RedProperty, value); }
    }

    public byte Green
    {
        get { return (byte)GetValue(GreenProperty); }
        set { SetValue(GreenProperty, value); }
    }

    public byte Blue
    {
        get { return (byte)GetValue(BlueProperty); }
        set { SetValue(BlueProperty, value); }
    }

    public event RoutedPropertyChangedEventHandler<Color> ColorChanged
    {
        add { AddHandler(ColorChangedEvent, value); }
        remove { RemoveHandler(ColorChangedEvent, value); }
    }

    static ColorPicker()
    {
        ColorProperty = DependencyProperty.Register("Color", typeof(Color), typeof(ColorPicker), new FrameworkPropertyMetadata(Colors.Black, new PropertyChangedCallback(OnColorChanged)));

        RedProperty = DependencyProperty.Register("Red", typeof(byte), typeof(ColorPicker), new FrameworkPropertyMetadata(new PropertyChangedCallback(OnColorRGBChanged)));
        GreenProperty = DependencyProperty.Register("Green", typeof(byte), typeof(ColorPicker), new FrameworkPropertyMetadata(new PropertyChangedCallback(OnColorRGBChanged)));
        BlueProperty = DependencyProperty.Register("Blue", typeof(byte), typeof(ColorPicker), new FrameworkPropertyMetadata(new PropertyChangedCallback(OnColorRGBChanged)));

        ColorChangedEvent = EventManager.RegisterRoutedEvent("ColorChanged", RoutingStrategy.Bubble, typeof(RoutedPropertyChangedEventHandler<Color>), typeof(ColorPicker));
    }

    private static void OnColorRGBChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        ColorPicker colorPicker = (ColorPicker)sender;
        Color color = colorPicker.Color;

        if (e.Property == RedProperty)
        {
            color.R = (byte)e.NewValue;
        }
        else if (e.Property == GreenProperty)
        {
            color.G = (byte)e.NewValue;
        }
        else if (e.Property == BlueProperty)
        {
            color.B = (byte)e.NewValue;
        }

        colorPicker.Color = color;
    }

    private static void OnColorChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        Color newColor = (Color)e.NewValue;
        Color oldColor = (Color)e.OldValue;

        ColorPicker colorPicker = (ColorPicker)sender;
        colorPicker.Red = newColor.R;
        colorPicker.Green = newColor.G;
        colorPicker.Blue = newColor.B;

        RoutedPropertyChangedEventArgs<Color> args = new RoutedPropertyChangedEventArgs<Color>(oldColor, newColor);
        args.RoutedEvent = ColorPicker.ColorChangedEvent;

        colorPicker.RaiseEvent(args);

    }
}

}

这是我在 Main 中实现 UserControl 的方式Window:

<Window x:Class="CustomControls.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:CustomControls"
    x:Name="mainWindow"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525" Background="ForestGreen">
<Grid>
    <local:ColorPicker Grid.Column="0" Grid.Row="0" Height="300" Width="300"/>
</Grid>

我已经尝试将 XAML 放入 MainWindow 以查看是否失败但并没有失败，我尝试创建一个产生相同结果的空自定义用户控件喜欢拾色器。

Answer 1

好的，问题来了：您将 ctor 设置为静态，以注册所有 DependencyProperties，因此您不再拥有通常的 class ctor呼叫 InitializeComponents()。所以在你的 class 中添加这个 ctor:

public ColorPicker()
{
    this.InitializeComponent();
}

要了解为什么要进行此调用，请访问 this page

CustomControl 在清理后可见，但在重建后不可见

CustomControl is visible after clean but not after rebuild

c#

wpf

xaml

user-controls