使用类型按钮作为基础的CustomControl不触发MouseLeftButtonUp事件

Question

我已经基于Button控件创建了一个简单的自定义ImageButton控件。我的想法是提供一个鼠标按下的图像和一个鼠标向上的图像，图像根据鼠标左键的操作进行交换。MouseLeftButtonDown事件触发正常，我的图像被更新，但MouseLeftButtonUp事件从不触发。

这是有原因的吗，是我没有正确地实现它吗？

自定义控件：

namespace Reader.Controls
{
    using System.IO;
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Input;
    using System.Windows.Media.Imaging;

    [TemplatePart(Name = "PART_Image", Type = typeof(Image))]
    public class ImageButton : Button
    {
        public Image PartImage;

        public ImageButton()
        {
            this.DefaultStyleKey = typeof(ImageButton);
        }

        public override void OnApplyTemplate()
        {
            this.PartImage = this.GetTemplateChild("PART_Image") as Image;

            if (this.PartImage != null)
            {
                this.PartImage.MouseLeftButtonDown += this.PartImageOnMouseLeftButtonDown;
                this.PartImage.MouseLeftButtonUp += this.PartImageOnMouseLeftButtonUp;

                this.SetImageSource(OffImageSource);
            }
        }

        #region Dependency properties

        public byte[] OffImageSource
        {
            get
            {
                return (byte[])this.GetValue(OffImageProperty);
            }
            set
            {
                this.SetValue(OffImageProperty, value);
            }
        }

        public static DependencyProperty OffImageProperty = DependencyProperty.Register(
            "OffImageSource", typeof(byte[]), typeof(ImageButton), new PropertyMetadata(null));

        public byte[] OnImageSource
        {
            get
            {
                return (byte[])this.GetValue(OnImageProperty);
            }
            set
            {
                this.SetValue(OnImageProperty, value);
            }
        }

        public static DependencyProperty OnImageProperty = DependencyProperty.Register(
            "OnImageSource", typeof(byte[]), typeof(ImageButton), new PropertyMetadata(null));

        #endregion

        #region Button events

        private void PartImageOnMouseLeftButtonDown(object sender, MouseButtonEventArgs mouseButtonEventArgs)
        {
            if (this.PartImage != null)
            {
                this.SetImageSource(OnImageSource);
            }
        }

        private void PartImageOnMouseLeftButtonUp(object sender, MouseButtonEventArgs mouseButtonEventArgs)
        {
            if (this.PartImage != null)
            {
                this.SetImageSource(OffImageSource);
            }
        }

        #endregion

        private void SetImageSource(byte[] imageSource)
        {
            using (var ms = new MemoryStream(imageSource, 0, imageSource.Length - 1))
            {
                var bi = new BitmapImage();
                bi.SetSource(ms);

                this.PartImage.Source = bi;
            }
        }
    }
}

默认样式模板：

<Style TargetType="Controls:ImageButton">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Controls:ImageButton">
                <Image x:Name="PART_Image" />
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

用法：

<Controls:ImageButton x:Name="btnLangEn" Click="btnLangEn_Click" />

使用代码(ImageLibrary是对资源文件的引用)：

public LanguageSelection()
{
    InitializeComponent();

    btnLangEn.OffImageSource = ImageLibrary.LangEn_off;
    btnLangEn.OnImageSource = ImageLibrary.LangEn_on;
}

private void btnLangEn_Click(object sender, RoutedEventArgs e)
{
    // handle click event here
}

Answer 1

我对此进行了排序，将点击处理程序替换为OnMouseLeftButtonDown和OnMouseLeftButtonUp的重写方法，如下所示：

    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
        base.OnMouseLeftButtonDown(e);

        if (this.PartImage != null)
        {
            this.SetImageSource(OnImageSource);
        }
    }

    protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
    {
        base.OnMouseLeftButtonUp(e);

        if (this.PartImage != null)
        {
            this.SetImageSource(OffImageSource);
        }
    }

在派生类中处理事件时，建议使用以下方式：http://msdn.microsoft.com/en-us/library/system.windows.controls.control.onmouseleftbuttonup(v=vs.95).aspx