调试易

我有一个自定义的控件,是扩展标准TextBox的,功能就是增加一个水印效果,本来在VS2008的写了一个,也没有什么大问题,但我把它弄到VS2010上的时候就会出现一些莫名其妙的报错:每次设置属性WaterMark后按F5,就会提示生成代码错误,未将对象引用到对象实例,或是类型为WaterMarkStyle的对象无法转换为WaterMarkStyle,.....还有就是如果我在窗体上创建这个定义的TextBox的一个实例,并在属性窗口的WaterMark属性上右击选"重置",再按F5,一定会出现下图的错误消息:同时,属性窗口中WaterMark前面的+号也消失,不会再出现里面的Text和Color属性下观是节选的部分代码:
        //
        //自定义的TextBox中WaterMark属性的定义
        //
        static object WaterMarkChangedEvent = new object();
        /// <summary>
        /// 当WaterMark属性更改时触发.
        /// </summary>
        public event EventHandler WaterMarkChanged
        {
            add { Events.AddHandler(WaterMarkChangedEvent, value); }
            remove { Events.RemoveHandler(WaterMarkChangedEvent, value); }
        }
        WaterMarkStyle waterMark = new WaterMarkStyle("",SystemColors.GrayText);
        /// <summary>
        /// 获取或设置控件的水印效果.
        /// </summary>
        [DefaultValue(typeof(WaterMarkStyle),"")]
        [Browsable(true)]
        public WaterMarkStyle WaterMark
        {
            get { return waterMark; }
            set 
            {
                if (waterMark==value) return ;
                waterMark = value;
                OnWaterMarkChanged(EventArgs.Empty);
            }
        }
       //... ...
    //
    //WaterMarkStyle类型定义
    //
    /// <summary>
    /// 可编辑控件的水印样式
    /// </summary>
    [TypeConverter(typeof(WaterMarkStyleTypeConverter))]
    [ComVisible(true)]
    [Serializable]
    public struct WaterMarkStyle
    {
        string text;
        Color color;
        /// <summary>
        /// 获取或设置水印文本.
        /// </summary>
        [DefaultValue("")]
        public string Text
        {
          
            get { return text; }
            set 
            {
                if (text == value) return;
                text = value;
            }
        }
        /// <summary>
        /// 获取或设置水印颜色.
        /// </summary>
        [DefaultValue(typeof(Color),"GrayText")]
        public Color Color
        {
            get { return color; }
            set 
            {
                if (color==value) return ;
                color = value;
            }
        }
        /// <summary>
        /// 重写父类的判等方法.
        /// </summary>
        /// <param name="obj">与当前实例比较的目标对象</param>
        /// <returns>如果两个对象相等则返回true,否则返回false.</returns>
        public override bool Equals(object obj)
        {
            if (obj == null || !(obj is WaterMarkStyle)) return false;
            WaterMarkStyle wms = (WaterMarkStyle)obj;
            return this.text == wms.text && this.color == wms.color;
        }
        /// <summary>
        /// 获取类型当前实例的哈希码.
        /// </summary>
        /// <returns></returns>
        public override int GetHashCode()
        {
            return this.text.GetHashCode() ^ this.color.GetHashCode();
        }
        /// <summary>
        /// 获取类型当前实例的文本值.
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            return this.text;
        }        /// <summary>
        /// 判断给定两个参数是否相等
        /// </summary>
        /// <param name="wm1"></param>
        /// <param name="wm2"></param>
        /// <returns></returns>
        public static bool operator  ==(WaterMarkStyle wm1,WaterMarkStyle wm2)
        {
            if (wm1==null ^wm2==null)
            {
                return false;
            }
            return wm1.text == wm2.text && wm1.color.ToArgb() == wm2.color.ToArgb();
        }
        /// <summary>
        /// 判断给定两个参数是否不等.
        /// </summary>
        /// <param name="wm1"></param>
        /// <param name="wm2"></param>
        /// <returns></returns>
        public static bool operator !=(WaterMarkStyle wm1, WaterMarkStyle wm2)
        {
            if (wm1 == null ^ wm2 == null)
            {
                return true;
            }
            return wm1.text != wm2.text || wm1.color.ToArgb() != wm2.color.ToArgb();
        }
        /// <summary>
        /// 根据给定的文本和文本颜色,构造当前类型实例.
        /// </summary>
        /// <param name="text"></param>
        /// <param name="color"></param>
        public WaterMarkStyle(string text,Color color):this()
        {
            this.text = text;
            this.color = color;
        }
        /// <summary>
        /// 根据给定的文本和默认颜色,构造当前类型实例.
        /// </summary>
        /// <param name="text"></param>
        public WaterMarkStyle(string text) : this() 
        {
            this.text = text;
            this.color =SystemColors.GrayText;
        }
    }
    //类型转换器
    class WaterMarkStyleTypeConverter:TypeConverter
    {
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
        {
            return sourceType==typeof(string) || base.CanConvertFrom(context, sourceType);
        }
        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
        {
            return destinationType ==typeof( InstanceDescriptor) || base.CanConvertTo(context, destinationType);
        }
        public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
        {
            if (value != null)// return new WaterMarkStyle("",SystemColors.GrayText);// throw new ArgumentNullException("value");
            {
                if (value is string)
                {
                    WaterMarkStyle obj = (WaterMarkStyle)TypeDescriptor.GetProperties(typeof(TextBox))["WaterMark"].GetValue(context.Instance);                    if (obj == null || obj.Color == Color.Empty)
                    {
                        return new WaterMarkStyle(value.ToString(), SystemColors.GrayText);
                    }
                    return new WaterMarkStyle(value.ToString(), obj.Color);
                }
            }
            return base.ConvertFrom(context, culture, value);
        }
        public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)
        {
            if (destinationType==null)
            {
                throw new ArgumentNullException("destinationType");
            }
            if (value != null)
            {
                WaterMarkStyle wms = (WaterMarkStyle)value;
                if (destinationType == typeof(string))
                {
                    return wms.Text;
                }
                if (destinationType == typeof(InstanceDescriptor))
                {
                    ConstructorInfo ctor = typeof(WaterMarkStyle).GetConstructor(new Type[] { typeof(string), typeof(Color) });
                    if (ctor != null)
                    {
                        return new InstanceDescriptor(ctor, new object[] { wms.Text, wms.Color });
                    }                }
            }
            return base.ConvertTo(context, culture, value, destinationType);
        }
        public override PropertyDescriptorCollection GetProperties(ITypeDescriptorContext context, object value, Attribute[] attributes)
        {
            return TypeDescriptor.GetProperties(typeof(WaterMarkStyle), attributes).Sort(new string[] { "Text", "Color" });
        }
        public override bool GetPropertiesSupported(ITypeDescriptorContext context)
        {
            return true;
        }        public override object CreateInstance(ITypeDescriptorContext context, IDictionary propertyValues)
        {
            if (propertyValues == null)
            {
                throw new ArgumentNullException("propertyValues");
            }
            object obj2 = propertyValues["Text"];
            object obj3 = propertyValues["Color"];
            if (((obj2 == null) || (obj3 == null)) || (!(obj2 is string) || !(obj3 is Color)))
            {
                throw new ArgumentException("无效属性值!");
            }
            return new WaterMarkStyle(obj2 as string, (Color)obj3);
            
        }        public override bool GetCreateInstanceSupported(ITypeDescriptorContext context)
        {
            return true;
        }
    }以上是水印样式的类型定义及类型转换器的定义.请高手们给看下,如果还需要其他的代码我再往上加!