TypeConverterAttribute应用是如何实现的呢?那么这里向你介绍在C# WinForm控件开发中是如何操作的(C#实例详解),希望对你了解TypeConverterAttribute应用有所帮助。
C#实例详解TypeConverterAttribute应用在创建的控件代码中添加一个Scope属性:
- [Browsable(true)]
- public Scope Scope
- {
- get
- {
- return _scope;
- }
- set
- {
- _scope = value;
- }
- }
这个属性的类型是Scope类,代码如下:
- public class Scope
- {
- private Int32 _min;
- private Int32 _max;
- public Scope()
- {
- }
- public Scope(Int32 min, Int32 max)
- {
- _min = min;
- _max = max;
- }
- [Browsable(true)]
- public Int32 Min
- {
- get
- {
- return _min;
- }
- set
- {
- _min = value;
- }
- }
- [Browsable(true)]
- public Int32 Max
- {
- get
- {
- return _max;
- }
- set
- {
- _max = value;
- }
- }
- }
添加完属性后,build控件工程,然后在测试的工程里选中添加的控件,然后在属性浏览器里观察它的属性,发现Scope属性是灰的,不能编辑。前一篇文章提到了,在属性浏览器里可以编辑的属性都是有类型转换器的,而.NET框架为基本的类型和常用的类型都提供了默认的类型转换器。接下来我们为Scope类添加一个类型转换器,以便这个属性能够被编辑,而且也可以在源代码文件里自动生成相应的代码。下面是类型转换器的代码:
- public class ScopeConverter : TypeConverter
- {
- public override bool CanConvertFrom(
- ITypeDescriptorContext context, Type sourceType)
- {
- if (sourceType == typeof(String)) return true;
- return base.CanConvertFrom(context, sourceType);
- }
- public override bool CanConvertTo(
- ITypeDescriptorContext context, Type destinationType)
- {
- if (destinationType == typeof(String)) return true;
- if (destinationType == typeof(InstanceDescriptor)) return true;
- return base.CanConvertTo(context, destinationType);
- }
- public override object ConvertTo(
- ITypeDescriptorContext context,
- System.Globalization.CultureInfo culture,
- object value, Type destinationType)
- {
- String result = "";
- if (destinationType == typeof(String))
- {
- Scope scope = (Scope)value;
- result = scope.Min.ToString()+"," + scope.Max.ToString();
- return result;
- ///C#实例详解TypeConverterAttribute应用
- }
- if (destinationType == typeof(InstanceDescriptor))
- {
- ConstructorInfo ci = typeof(Scope).GetConstructor(
- new Type[] {typeof(Int32),typeof(Int32) });
- Scope scope = (Scope)value;
- return new InstanceDescriptor(ci, new object[] { scope.Min,scope.Max });
- }
- return base.ConvertTo(context, culture, value, destinationType);
- }
- public override object ConvertFrom(
- ITypeDescriptorContext context,
- System.Globalization.CultureInfo culture, object value)
- {
- if (value is string)
- {
- String[] v = ((String)value).Split(',');
- if (v.GetLength(0) != 2)
- {
- throw new ArgumentException("Invalid parameter format");
- }
- Scope csf = new Scope();
- csf.Min = Convert.ToInt32(v[0]);
- csf.Max = Convert.ToInt32(v[1]);
- return csf;
- }
- return base.ConvertFrom(context, culture, value);
- }
- }
现在我们为类型提供类型转换器,我们在类型前面添加一个TypeConverterAttribute,如下:
- [TypeConverter(typeof(ScopeConverter))]
- public class Scope
添加完以后build工程,然后切换到测试工程,选中控件,在属性浏览器里查看属性,现在的Scope属性可以编辑了,如下图所示:
我们修改默认的值,然后看看Form设计器为我们生成了什么代码:
- this.myListControl1.BackColor =
- System.Drawing.SystemColors.ActiveCaptionText;
- this.myListControl1.Item.Add(1);
- this.myListControl1.Item.Add(2);
- this.myListControl1.Item.Add(3);
- this.myListControl1.Item.Add(6);
- this.myListControl1.Item.Add(8);
- this.myListControl1.Item.Add(9);
- this.myListControl1.Location =
- new System.Drawing.Point(12, 34);
- this.myListControl1.Name = "myListControl1";
- this.myListControl1.Scope = new CustomControlSample.Scope(10, 200);
- this.myListControl1.Size = new System.Drawing.Size(220, 180);
- this.myListControl1.TabIndex = 1;
- this.myListControl1.Text = "myListControl1";
关键是这一行this.myListControl1.Scope = new CustomControlSample.Scope(10, 200),Scope类的类型转换器为属性提供了实例化的代码。
C#实例详解TypeConverterAttribute应用的相关内容就向你介绍到这里,希望那个对你了解和学习C#实例详解TypeConverterAttribute应用有所帮助。